Medicine – Causes of Pleuritic Chest Pain

Pleuritic chest pain is a sharp, stabbing chest pain that is typically worse on inspiration, coughing, sneezing, or movement. It usually occurs when the parietal pleura or another pain-sensitive thoracic structure becomes inflamed or irritated.

The most important initial task is to distinguish benign musculoskeletal causes from potentially serious conditions such as pulmonary embolism, pneumothorax, pneumonia, or pericarditis.

1. Pleurisy

Pleurisy means inflammation of the pleura.

When the inflamed pleural surfaces rub against each other during breathing, the patient develops sharp inspiratory chest pain.

A pleural friction rub may sometimes be heard on auscultation.

Pleurisy is not a single diagnosis in itself; it may occur secondary to infection, pulmonary embolism, autoimmune disease, or other pleural disorders.

2. Pneumonia

Pneumonia can cause pleuritic pain when inflammation extends from the lung parenchyma to the adjacent pleural surface.

The pain is often associated with fever, cough, sputum production, dyspnoea, and focal chest signs.

The pleuritic pain is therefore caused by accompanying pleuritis rather than by the lung tissue itself.

3. Pulmonary Embolism

Pulmonary embolism (PE) is an important and potentially life-threatening cause of pleuritic chest pain.

The pain is often sudden and results from irritation of the pleura by a peripheral pulmonary infarct or inflammatory reaction.

Associated features may include sudden breathlessness, tachycardia, haemoptysis, hypoxaemia, syncope, or signs of deep-vein thrombosis.

A normal chest examination does not exclude PE.

4. Pneumothorax

A pneumothorax occurs when air enters the pleural cavity and causes partial or complete lung collapse.

It classically produces sudden unilateral pleuritic chest pain and acute breathlessness.

Examination may show reduced chest expansion, hyperresonance, and diminished breath sounds on the affected side.

A tension pneumothorax is a medical emergency because increasing intrathoracic pressure can impair venous return and cause cardiovascular collapse.

5. Rib Fracture

A rib fracture causes localized chest-wall pain that is typically worsened by deep inspiration, coughing, or movement.

There is often a history of trauma, although fractures can also occur after severe coughing, particularly in older adults or patients with osteoporosis.

The pain is usually reproducible with direct palpation over the affected rib.

6. Costochondritis

Costochondritis is inflammation of the costochondral or costosternal junctions.

It causes localized anterior chest pain that can mimic pleuritic or cardiac pain.

A useful feature is that the pain is often reproducible by pressing over the affected costochondral junctions.

Unlike true pleural disease, there is no underlying abnormality of the lung or pleura.

7. Pleural Effusion

A pleural effusion can cause pleuritic chest pain, particularly during the early inflammatory phase when the pleural surfaces are irritated.

As the effusion enlarges and physically separates the two pleural surfaces, the pleuritic pain may actually become less prominent.

Large effusions may instead cause progressive breathlessness, reduced breath sounds, and stony dullness to percussion.

8. Pericarditis

Acute pericarditis commonly causes sharp, pleuritic-type central chest pain.

The pain is often worse on inspiration and when lying flat, and may improve when the patient sits forward.

A pericardial friction rub may be present.

Because pericarditis can resemble pleuritic pulmonary pain, associated ECG changes and the clinical context are important.

9. Muscular Chest Pain

Muscular chest-wall pain may occur after exercise, coughing, lifting, trauma, or repetitive movement.

The pain is usually worsened by movement of the chest wall and can often be reproduced by palpation or resisted muscle contraction.

This helps distinguish it from many intrathoracic causes.

Causes of Pleuritic Chest Pain – Note Form

Pleurisy: inflammation of the pleura causing sharp pain on inspiration.

Pneumonia: pleural irritation adjacent to infected lung produces pleuritic pain.

Pulmonary embolism: sudden pleuritic pain, often with breathlessness, tachycardia, or haemoptysis.

Pneumothorax: sudden unilateral pleuritic pain with acute dyspnoea.

Rib fracture: localized pain after trauma or coughing, worsened by breathing and reproducible on palpation.

Costochondritis: localized costosternal pain reproducible by pressure over the chest wall.

Pleural effusion: may cause pleuritic pain early, with breathlessness if the effusion is large.

Pericarditis: sharp pain worse on inspiration or lying flat and often relieved by sitting forward.

Muscular chest pain: movement-related and usually reproducible on examination.

Key Clinical Pattern

Think of pleuritic chest pain as:

Sharp pain + worse with inspiration or cough.

The main serious causes to exclude early are:

Pulmonary embolism, pneumothorax, pneumonia, and pericarditis.

Pain that is reproducible with palpation or movement is more suggestive of a musculoskeletal cause such as rib injury, costochondritis, or muscular strain, although this finding alone does not completely exclude more serious disease.

Medicine – Causes of Breathlessness

Breathlessness, or dyspnoea, is the subjective sensation of uncomfortable or difficult breathing. It is a very common clinical symptom and may result from disorders of the respiratory system, cardiovascular system, or other systemic and functional conditions.

When assessing breathlessness, it is important to determine whether the onset is acute or chronic, whether symptoms occur at rest or on exertion, and whether associated features such as chest pain, cough, wheeze, fever, orthopnoea, haemoptysis, or palpitations are present.

1. Respiratory Causes

Respiratory disease is one of the major causes of breathlessness. Dyspnoea can result from airway obstruction, impaired gas exchange, reduced lung expansion, pulmonary vascular disease, pleural disease, or respiratory muscle dysfunction.

Asthma

Asthma causes episodic breathlessness because reversible bronchoconstriction and airway inflammation narrow the conducting airways.

Patients typically experience wheeze, cough, chest tightness, and variable breathlessness. Symptoms may be triggered by allergens, exercise, respiratory infections, smoke, or certain medications.

Chronic Obstructive Pulmonary Disease

COPD produces gradually progressive breathlessness because of persistent airflow obstruction.

Patients commonly have a history of significant smoking or other inhalational exposure and may experience chronic productive cough, wheeze, exertional dyspnoea, and recurrent exacerbations.

Emphysema additionally causes loss of alveolar surface area, hyperinflation, and impaired gas exchange.

Pneumonia

Pneumonia can cause acute breathlessness because infection produces inflammation and filling of the alveoli with inflammatory exudate.

This interferes with ventilation and gas exchange, producing V/Q mismatch and hypoxaemia.

Associated features commonly include fever, cough, sputum production, pleuritic chest pain, and systemic illness.

Pneumothorax

A pneumothorax occurs when air enters the pleural space and causes partial or complete collapse of the affected lung.

It classically presents with sudden-onset breathlessness and unilateral pleuritic chest pain.

A tension pneumothorax can cause severe respiratory and haemodynamic compromise and requires immediate treatment.

Pulmonary Embolism

Pulmonary embolism (PE) occurs when a thrombus, usually originating from the deep veins of the lower limbs or pelvis, travels to the pulmonary circulation.

It can produce sudden unexplained breathlessness, pleuritic chest pain, tachycardia, hypoxaemia, haemoptysis, or syncope.

Massive PE may cause acute right-heart strain and cardiovascular collapse.

Bronchiectasis

Bronchiectasis is characterised by permanent abnormal dilatation of the bronchi associated with impaired mucus clearance and recurrent infection.

Patients typically experience chronic productive cough, large amounts of purulent sputum, recurrent chest infections, haemoptysis, and varying degrees of breathlessness.

Pulmonary Fibrosis

Pulmonary fibrosis causes progressive scarring and stiffening of the lungs.

Reduced lung compliance increases the work required to breathe, while abnormalities of the alveolar–capillary interface impair oxygen transfer.

The typical presentation is progressive exertional breathlessness, persistent dry cough, and fine bibasal inspiratory crackles.

Lung Cancer

Lung cancer can cause breathlessness through several different mechanisms.

The tumour may obstruct a major bronchus, cause collapse of part of the lung, produce a pleural or pericardial effusion, cause lymphangitic spread, or coexist with underlying COPD.

Other concerning features include persistent cough, haemoptysis, chest pain, unexplained weight loss, and recurrent pneumonia.

Pleural Effusion

A pleural effusion is an abnormal accumulation of fluid within the pleural space.

A sufficiently large effusion compresses the underlying lung and restricts its expansion, producing breathlessness.

Examination may demonstrate reduced breath sounds, reduced chest expansion, and stony dullness to percussion over the affected area.

Pulmonary Hypertension

Pulmonary hypertension causes progressive exertional breathlessness because increased pulmonary vascular resistance impairs the ability of the right ventricle to increase pulmonary blood flow during exercise.

Patients may eventually develop fatigue, exertional chest discomfort, syncope, raised JVP, peripheral oedema, and right-sided heart failure.

Phrenic Nerve Palsy

The phrenic nerve supplies the diaphragm.

Phrenic nerve injury can therefore cause diaphragmatic weakness or paralysis. Unilateral paralysis may cause relatively mild symptoms, whereas bilateral involvement can cause substantial breathlessness and ventilatory impairment.

An elevated hemidiaphragm may be visible on chest imaging in unilateral disease.

2. Cardiac Causes

Cardiovascular disease is another major cause of breathlessness.

Dyspnoea can result from reduced cardiac output, elevated left-sided filling pressures, pulmonary venous congestion, pulmonary oedema, arrhythmias, or impaired ventricular filling.

Angina and Myocardial Ischaemia

Myocardial ischaemia usually causes chest discomfort, but some patients—particularly older adults and people with diabetes—may present predominantly with exertional breathlessness.

Dyspnoea can therefore occasionally represent an anginal equivalent.

Left Ventricular Failure

Left ventricular failure is an important cardiac cause of breathlessness.

Failure of the left ventricle increases left atrial and pulmonary venous pressures, causing pulmonary congestion and potentially pulmonary oedema.

Patients may develop exertional dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea, bibasal crackles, and reduced exercise tolerance.

Valvular Heart Disease

Significant valvular heart disease can cause breathlessness by reducing effective cardiac output or increasing pressures within the pulmonary circulation.

Important examples include aortic stenosis, aortic regurgitation, mitral stenosis, and mitral regurgitation.

The image appears to state “atrial stenosis” and “atrial regurgitation”; this should be corrected to aortic stenosis and aortic regurgitation.

Aortic Stenosis

Aortic stenosis obstructs blood flow from the left ventricle into the aorta.

Advanced disease may produce the classic combination of exertional breathlessness, angina, and syncope.

Aortic Regurgitation

Aortic regurgitation causes blood to flow backwards from the aorta into the left ventricle during diastole.

Chronic severe regurgitation eventually causes left ventricular dilatation and failure, producing exertional breathlessness and symptoms of heart failure.

Mitral Stenosis

Mitral stenosis obstructs blood flow from the left atrium into the left ventricle.

The resulting elevation of left atrial and pulmonary venous pressures produces exertional breathlessness, orthopnoea, and sometimes pulmonary oedema or haemoptysis.

Mitral Regurgitation

Mitral regurgitation allows blood to flow backwards from the left ventricle into the left atrium during systole.

Severe disease increases left atrial and pulmonary venous pressures and can eventually cause pulmonary congestion and breathlessness.

Arrhythmias

Both rapid and slow cardiac arrhythmias can cause breathlessness by reducing effective cardiac output.

Patients may also report palpitations, dizziness, chest discomfort, presyncope, or syncope.

Examples include atrial fibrillation, supraventricular tachycardia, ventricular arrhythmias, and severe bradyarrhythmias.

Pericardial Effusion

A pericardial effusion is an accumulation of fluid within the pericardial sac.

Large or rapidly developing effusions may interfere with cardiac filling and cause breathlessness.

If intrapericardial pressure becomes sufficiently high, cardiac tamponade can develop, producing hypotension, raised JVP, tachycardia, and circulatory compromise.

Cardiomyopathy

Cardiomyopathy can impair ventricular contraction, relaxation, or filling.

Reduced cardiac output and increased intracardiac pressures can cause exercise intolerance, fatigue, pulmonary congestion, and progressive breathlessness.

Depending on the underlying condition, cardiomyopathy may be dilated, hypertrophic, restrictive, or another recognised subtype.

3. Other Causes of Breathlessness

Not all breathlessness originates directly from the lungs or heart. Several systemic, mechanical, and functional disorders can produce a sensation of dyspnoea.

Psychogenic and Functional Breathlessness

Anxiety, panic attacks, and dysfunctional breathing patterns can produce significant breathlessness even when cardiopulmonary investigations are normal.

Hyperventilation may be accompanied by light-headedness, tingling around the mouth or fingers, chest tightness, and a sensation of being unable to obtain a satisfying breath.

However, breathlessness should not be attributed to anxiety until important organic causes have been appropriately considered.

Massive Ascites

Massive ascites increases intra-abdominal pressure and pushes the diaphragm upward.

This restricts diaphragmatic movement, reduces lung volumes, and can cause significant breathlessness, particularly when lying flat.

Treating the underlying cause and reducing severe ascites can improve respiratory symptoms.

4. Additional Important Causes

A broader differential diagnosis should also include several common systemic causes that were not shown in the original image.

Anaemia

Anaemia reduces the oxygen-carrying capacity of blood.

Patients may therefore develop exertional breathlessness, fatigue, palpitations, dizziness, and tachycardia, despite having structurally normal lungs.

Obesity and Deconditioning

Severe obesity increases the mechanical work of breathing and may restrict diaphragmatic movement.

Physical deconditioning can also produce disproportionate breathlessness during relatively minor exertion.

Metabolic Acidosis

Conditions causing severe metabolic acidosis, such as diabetic ketoacidosis, stimulate respiratory compensation.

Patients may develop rapid, deep breathing known as Kussmaul respiration, which may be perceived as breathlessness.

5. Causes of Breathlessness – Note Form

Respiratory Causes

Asthma: variable airflow obstruction with wheeze, cough, chest tightness, and episodic breathlessness.

COPD: persistent airflow obstruction causing progressive exertional dyspnoea, cough, sputum, and wheeze.

Pneumonia: alveolar infection and inflammation causing impaired gas exchange and acute breathlessness.

Pneumothorax: sudden breathlessness with pleuritic chest pain due to air within the pleural space.

Pulmonary embolism: often sudden unexplained dyspnoea ± pleuritic pain, tachycardia, haemoptysis, or syncope.

Bronchiectasis: chronic productive cough, recurrent infections, haemoptysis, and breathlessness.

Pulmonary fibrosis: progressive exertional dyspnoea with dry cough and fine inspiratory crackles.

Lung cancer: may cause dyspnoea through airway obstruction, lung collapse, effusion, or extensive pulmonary involvement.

Pleural effusion: pleural fluid compresses the lung and restricts expansion.

Pulmonary hypertension: progressive exertional dyspnoea due to increased pulmonary vascular resistance.

Phrenic nerve palsy: diaphragmatic weakness or paralysis causes impaired ventilation.

Cardiac Causes

Myocardial ischaemia/angina: exertional breathlessness may occasionally be an anginal equivalent.

Left ventricular failure: pulmonary venous congestion produces exertional dyspnoea, orthopnoea, and paroxysmal nocturnal dyspnoea.

Aortic stenosis: exertional dyspnoea, angina, and syncope in advanced disease.

Aortic regurgitation: chronic volume overload eventually causes left ventricular failure and dyspnoea.

Mitral stenosis: raised left atrial pressure produces pulmonary venous congestion and breathlessness.

Mitral regurgitation: severe regurgitation can cause pulmonary congestion and heart failure.

Arrhythmias: impaired cardiac output can cause breathlessness, palpitations, and dizziness.

Pericardial effusion: impaired ventricular filling can cause breathlessness and, when severe, cardiac tamponade.

Cardiomyopathy: impaired cardiac function produces reduced exercise tolerance and dyspnoea.

Other Causes

Psychogenic/functional: anxiety, panic attacks, and dysfunctional breathing may cause breathlessness and hyperventilation.

Massive ascites: upward displacement of the diaphragm restricts lung expansion.

Anaemia: reduced oxygen-carrying capacity causes exertional dyspnoea.

Obesity: increased respiratory workload and reduced lung volumes can cause breathlessness.

Deconditioning: reduced cardiovascular and muscular fitness causes early exertional dyspnoea.

Metabolic acidosis: compensatory hyperventilation can present as rapid, deep breathing.

Key Clinical Pattern

A useful way to approach breathlessness is to divide the differential into three major groups:

Respiratory → asthma, COPD, pneumonia, pneumothorax, PE, bronchiectasis, pulmonary fibrosis, lung cancer, pleural effusion, pulmonary hypertension, and diaphragmatic dysfunction.

Cardiac → myocardial ischaemia, left ventricular failure, valvular heart disease, arrhythmias, pericardial effusion, and cardiomyopathy.

Other → anxiety or dysfunctional breathing, massive ascites, anaemia, obesity, deconditioning, and metabolic disorders.

The time course is particularly useful diagnostically. Sudden breathlessness should raise concern for conditions such as PE, pneumothorax, acute pulmonary oedema, acute severe asthma, or an acute cardiac event, whereas gradually progressive breathlessness is more typical of conditions such as COPD, pulmonary fibrosis, chronic heart failure, pulmonary hypertension, anaemia, or malignancy.

Medicine – Respiratory Failure

Respiratory failure occurs when the respiratory system is unable to maintain adequate gas exchange. This results in inadequate arterial oxygenation, abnormal carbon dioxide elimination, or both.

Respiratory failure is traditionally divided into Type I (hypoxaemic) respiratory failure and Type II (hypercapnic or ventilatory) respiratory failure.

1. Type I Respiratory Failure

Type I respiratory failure is primarily a failure of oxygenation.

It is characterised by significant hypoxaemia with a normal or low arterial carbon dioxide level.

Definition

The traditional arterial blood gas definition is:

PaO₂ <8 kPa (60 mmHg)

with

PaCO₂ normal or low.

Therefore, the main abnormality is a fall in arterial oxygen rather than carbon dioxide retention.

Pathophysiology

Type I respiratory failure commonly results from ventilation–perfusion (V/Q) mismatch.

This means that some areas of the lung receive adequate blood flow but insufficient ventilation, so blood leaving these regions remains poorly oxygenated.

However, V/Q mismatch is not the only mechanism. Type I respiratory failure can also result from intrapulmonary shunting, diffusion impairment, and severe abnormalities of the alveolar–capillary membrane.

Why PaCO₂ Is Usually Normal or Low

Patients with hypoxaemia frequently respond by increasing their respiratory rate and ventilation.

Carbon dioxide diffuses across the alveolar membrane more readily than oxygen and can therefore often still be eliminated effectively.

As a result, PaCO₂ commonly remains normal or becomes reduced because of hyperventilation.

Causes of Type I Respiratory Failure

2. Severe Acute Asthma – Early Stage

During the earlier stages of a severe acute asthma attack, marked airway obstruction causes V/Q mismatch and hypoxaemia.

The patient responds by hyperventilating, so the PaCO₂ is usually low.

A very important clinical point is that a normal or rising PaCO₂ in severe acute asthma is dangerous, because it may indicate respiratory muscle fatigue and progression toward ventilatory failure.

3. Emphysema

Patients with predominantly emphysematous COPD may initially develop hypoxaemia while maintaining sufficient ventilation to prevent significant carbon dioxide retention.

This corresponds to the historical “pink puffer” pattern.

As COPD becomes advanced, however, some patients can develop hypercapnia and therefore progress to Type II respiratory failure.

4. Pneumonia

Pneumonia can produce Type I respiratory failure because infected alveoli become filled with inflammatory exudate.

These alveoli may continue to receive blood but are poorly ventilated, producing severe V/Q mismatch and intrapulmonary shunting.

The result is hypoxaemia, which can become profound in extensive pneumonia.

5. Pulmonary Embolism

A pulmonary embolism (PE) disrupts pulmonary blood flow and produces major abnormalities in ventilation–perfusion matching.

Patients often hyperventilate in response to hypoxaemia and physiological stress.

Consequently, a typical blood gas pattern is low PaO₂ with low PaCO₂, although blood gases vary and cannot by themselves diagnose or exclude PE.

6. Pulmonary Oedema

Pulmonary oedema causes accumulation of fluid within the pulmonary interstitium and alveoli.

This interferes with oxygen transfer and produces V/Q mismatch and shunting.

Acute pulmonary oedema can therefore cause significant Type I hypoxaemic respiratory failure.

7. Interstitial Lung Disease

Interstitial lung disease (ILD) causes thickening and fibrosis of the alveolar–capillary interface.

This impairs oxygen diffusion and may also produce V/Q abnormalities.

Hypoxaemia is often particularly noticeable during exercise, when blood passes through the pulmonary capillaries more rapidly and there is less time available for oxygen equilibration.

Advanced ILD can eventually cause severe resting hypoxaemia.

8. Type II Respiratory Failure

Type II respiratory failure is primarily a failure of alveolar ventilation.

The lungs cannot eliminate carbon dioxide adequately, resulting in hypercapnia together with hypoxaemia.

It is therefore also called hypercapnic respiratory failure or ventilatory failure.

Definition

Traditionally, Type II respiratory failure is characterised by:

PaO₂ <8 kPa (60 mmHg)

and

PaCO₂ >6.0–6.7 kPa (45–50 mmHg), depending on the definition being used.

The older notes use PaCO₂ >6.7 kPa, which represents definite hypercapnia.

Pathophysiology

The fundamental problem in Type II respiratory failure is inadequate alveolar ventilation.

When ventilation is insufficient, the body cannot eliminate the carbon dioxide generated by metabolism.

Therefore:

↓ Alveolar ventilation → ↑ PaCO₂ + ↓ PaO₂

This can result from severe lung disease, abnormalities of the chest wall, neuromuscular weakness, or suppression of the brain’s respiratory drive.

Respiratory Causes of Type II Respiratory Failure

9. COPD

COPD is one of the most important causes of Type II respiratory failure.

Severe airflow obstruction, V/Q mismatch, respiratory muscle loading, and inadequate alveolar ventilation can eventually cause CO₂ retention.

Some patients with advanced COPD develop chronic hypercapnia, while others develop Type II respiratory failure mainly during acute exacerbations.

10. Severe Asthma

Very severe asthma can progress from an initial Type I pattern to Type II respiratory failure.

Initially:

Hyperventilation → low PaCO₂

As respiratory muscles fatigue:

Ventilation falls → PaCO₂ becomes normal

With further deterioration:

PaCO₂ rises → Type II respiratory failure

Therefore, a rising carbon dioxide level in severe asthma is a major warning sign of impending respiratory failure.

11. Bronchiectasis

Advanced bronchiectasis can cause chronic airflow obstruction, extensive V/Q mismatch, and impaired alveolar ventilation.

Patients with severe disease may eventually develop hypoxaemia and hypercapnia, particularly during infective exacerbations.

Thoracic Cage Causes

12. Kyphoscoliosis

Severe kyphoscoliosis restricts expansion of the chest wall.

This produces a restrictive ventilatory defect and can substantially reduce alveolar ventilation.

Advanced disease may therefore cause chronic Type II respiratory failure.

13. Ankylosing Spondylitis

Severe ankylosing spondylitis may restrict movement of the thoracic cage because of involvement and fusion of spinal and costovertebral structures.

When sufficiently advanced, this restriction can contribute to alveolar hypoventilation and hypercapnic respiratory failure.

14. Chest Trauma and Surgery

Severe chest trauma can interfere with effective ventilation because of pain, rib fractures, flail chest, or mechanical disruption of chest-wall movement.

Following major thoracic or abdominal surgery, pain, sedation, and impaired respiratory mechanics can similarly produce hypoventilation.

If ventilation becomes inadequate, PaCO₂ rises and Type II respiratory failure can develop.

Neuromuscular Causes

15. Muscular Dystrophy

Muscular dystrophies can progressively weaken the diaphragm and other respiratory muscles.

As respiratory muscle strength declines, patients become unable to generate sufficient ventilation, particularly during sleep and eventually while awake.

This can produce chronic hypercapnic respiratory failure.

16. Guillain–Barré Syndrome

Guillain–Barré syndrome can cause rapidly progressive respiratory muscle weakness.

Severe weakness of the diaphragm and accessory respiratory muscles may result in inadequate ventilation and acute Type II respiratory failure.

Respiratory function therefore requires close monitoring in patients with significant Guillain–Barré syndrome.

17. Myasthenia Gravis

Severe myasthenia gravis, particularly during a myasthenic crisis, can weaken the respiratory muscles.

Progressive respiratory muscle fatigue may eventually cause alveolar hypoventilation, CO₂ retention, and respiratory failure.

Drug Causes

18. Opioids

Opioids can suppress the respiratory centres within the brainstem.

Respiratory rate and tidal volume decrease, causing reduced alveolar ventilation.

The characteristic sequence is:

Respiratory depression → hypoventilation → CO₂ retention → hypoxaemia

Severe opioid toxicity can therefore cause acute Type II respiratory failure.

19. Benzodiazepines

Benzodiazepines can also depress central nervous system activity and contribute to respiratory depression.

The risk is particularly important when benzodiazepines are combined with opioids, alcohol, or other sedative drugs, or when used in patients who already have significant respiratory disease.

20. Type I Respiratory Failure – Note Form

Main problem: failure of oxygenation.

PaO₂: <8 kPa.

PaCO₂: normal or low.

Main mechanism: usually V/Q mismatch, although shunting and diffusion impairment may also contribute.

Ventilation: generally preserved or increased.

Typical causes: pneumonia, pulmonary embolism, pulmonary oedema, interstitial lung disease, early severe asthma, and some patients with emphysema.

Asthma: early severe attacks usually produce hypoxaemia with a low PaCO₂ because the patient hyperventilates.

21. Type II Respiratory Failure – Note Form

Main problem: failure of alveolar ventilation.

PaO₂: reduced.

PaCO₂: raised, traditionally >6.0–6.7 kPa.

Main mechanism: inadequate alveolar ventilation causes CO₂ retention.

Respiratory causes: COPD, very severe asthma, and advanced bronchiectasis.

Thoracic cage causes: kyphoscoliosis, severe ankylosing spondylitis, and major chest trauma or surgery.

Neuromuscular causes: muscular dystrophy, Guillain–Barré syndrome, and myasthenia gravis.

Drug causes: opioids and sedative drugs such as benzodiazepines.

22. Acute vs Chronic Type II Respiratory Failure

The pH and bicarbonate concentration help determine whether hypercapnic respiratory failure is acute or chronic.

In acute Type II respiratory failure, PaCO₂ rises rapidly and there has been little time for renal compensation. The patient therefore develops respiratory acidosis with a reduced pH.

In chronic Type II respiratory failure, the kidneys retain bicarbonate to compensate for persistent CO₂ retention. Therefore, the bicarbonate is elevated and the pH may be relatively close to normal despite a high PaCO₂.

This distinction is particularly important in patients with advanced COPD.

Key Clinical Pattern

Type I respiratory failure = oxygenation failure.

↓ PaO₂ + normal/↓ PaCO₂

Think particularly of pneumonia, PE, pulmonary oedema, ILD, and early severe asthma.

Type II respiratory failure = ventilation failure.

↓ PaO₂ + ↑ PaCO₂

Think of COPD, very severe asthma, severe bronchiectasis, chest-wall restriction, neuromuscular weakness, and respiratory-depressant drugs.

A particularly important examination point is the change in PaCO₂ during severe asthma:

Early severe asthma → hyperventilation → ↓ PaCO₂

Deterioration/fatigue → PaCO₂ becomes normal

Respiratory muscle failure → ↑ PaCO₂ → Type II respiratory failure

Therefore, a normal or rising PaCO₂ in a patient with severe acute asthma is an ominous sign rather than evidence of improvement.

Medicine – Chronic Asthma

Asthma is a chronic inflammatory disorder of the airways characterised by variable respiratory symptoms and variable expiratory airflow limitation. The airways become hyperresponsive to different stimuli, resulting in episodes of bronchoconstriction that are usually reversible either spontaneously or with treatment.

The characteristic symptoms are wheeze, breathlessness, chest tightness, and cough, which typically vary in intensity over time. Unlike the persistent airflow obstruction of COPD, airflow limitation in asthma is often substantially reversible.

1. Prevalence

Asthma is extremely common and can occur at any age, although it frequently begins during childhood.

Older teaching quotes figures of approximately 20% in children and 15% in adults, but prevalence varies substantially according to country, age group, diagnostic criteria, and population studied. It is therefore better to regard these as approximate historical figures rather than universal incidence rates.

2. Chronic Airway Inflammation

Asthma is fundamentally a chronic inflammatory airway disease.

The bronchial mucosa contains increased numbers of inflammatory cells, including eosinophils, mast cells, and T lymphocytes in many asthma phenotypes.

Inflammation causes airway hyperresponsiveness, mucosal oedema, increased mucus production, and increased sensitivity of bronchial smooth muscle to various stimuli.

3. Variable Airflow Obstruction

A defining characteristic of asthma is that airflow obstruction is variable.

Bronchial smooth-muscle contraction, airway inflammation, mucosal oedema, and mucus production narrow the airways during symptomatic periods.

When the trigger disappears or bronchodilator treatment is administered, airway calibre may improve considerably.

Genetic and Environmental Factors

4. Genetic Predisposition

Asthma has an important genetic component, although it is not inherited through a simple single-gene pattern.

A family history of asthma or other allergic disorders increases the likelihood of developing the condition.

5. Atopy

Atopy describes a genetic tendency to develop exaggerated IgE-mediated responses to common environmental allergens.

Atopic individuals are more likely to develop conditions such as asthma, allergic rhinitis, and atopic eczema.

However, not every patient with asthma is atopic, and several distinct inflammatory asthma phenotypes are now recognised.

6. Environmental Factors

Environmental exposures interact with genetic susceptibility to influence the development and expression of asthma.

Important factors include allergens, respiratory infections, tobacco smoke, occupational exposures, and air pollution.

Pulmonary Function Tests

Objective evidence of variable expiratory airflow limitation is important when establishing the diagnosis of asthma.

7. Peak Expiratory Flow Variability

Serial peak expiratory flow (PEF) measurements may demonstrate significant variation over time.

Older teaching often uses >20–25% variability as evidence supporting asthma. Modern diagnostic thresholds and calculation methods vary between guidelines, so the exact percentage should be interpreted within the appropriate diagnostic protocol.

The important principle is that substantial variability in expiratory airflow supports asthma.

8. FEV₁

During periods of airflow obstruction, the forced expiratory volume in one second (FEV₁) may be reduced.

Between attacks, however, spirometry may return completely to normal, particularly in patients with mild asthma.

9. FEV₁/FVC Ratio

Airflow obstruction causes the FEV₁/FVC ratio to decrease because FEV₁ falls disproportionately compared with forced vital capacity.

Again, the ratio may normalise when asthma is well controlled.

10. Bronchodilator Reversibility

A characteristic feature is an improvement in airflow following administration of a bronchodilator.

Both FEV₁ and peak expiratory flow may increase significantly after inhaled salbutamol or another rapidly acting bronchodilator.

Demonstrating significant bronchodilator reversibility provides objective evidence supporting the diagnosis of asthma.

11. Lung Volumes

During significant airway obstruction, air trapping and hyperinflation may increase residual volume and sometimes total lung capacity.

However, increased lung volumes are not required for the diagnosis, and patients with well-controlled or mild asthma may have completely normal lung volumes.

Triggers of Asthma

Asthma symptoms and acute exacerbations can be triggered by numerous environmental, physiological, and pharmacological factors.

12. Allergens

Exposure to allergens is an important trigger in patients with allergic asthma.

Common allergens include grass and tree pollens, house-dust mites, moulds, and animal dander, particularly from cats and dogs.

Exposure triggers airway inflammation and bronchoconstriction in susceptible individuals.

13. Exercise

Exercise can provoke transient bronchoconstriction, particularly when breathing large volumes of cold or dry air.

Patients may develop cough, wheeze, chest tightness, or breathlessness during or shortly after exercise.

Well-controlled asthma should generally allow patients to remain physically active.

14. Aspirin and NSAIDs

Aspirin and other NSAIDs can provoke severe bronchospasm in susceptible patients.

This is particularly important in aspirin/NSAID-exacerbated respiratory disease, which is associated with asthma and chronic rhinosinusitis with nasal polyps.

Not every patient with asthma needs to avoid NSAIDs; the problem occurs in susceptible individuals.

15. β-Blockers

β-blockers can cause bronchoconstriction by blocking β₂ receptors in bronchial smooth muscle.

Non-selective β-blockers present the greatest concern, although even β₁-selective drugs require appropriate consideration in patients with asthma.

β-blocking ophthalmic preparations can also occasionally cause systemic bronchospasm.

16. Respiratory Infection

Respiratory viral infections are among the most common triggers of asthma exacerbations.

Inflammation produced by infection increases airway hyperresponsiveness and can substantially worsen pre-existing asthma.

17. Gastro-Oesophageal Reflux

Gastro-oesophageal reflux disease (GORD/GERD) frequently coexists with asthma and may worsen respiratory symptoms in some patients.

However, reflux is not necessarily the cause of poor asthma control in every patient who has both conditions.

18. Smoke and Air Pollution

Cigarette smoke, vaping aerosols, environmental pollution, fumes, and other respiratory irritants can aggravate airway inflammation and trigger asthma symptoms.

Smoking can also reduce responsiveness to inhaled corticosteroids and contributes to poorer asthma control.

19. Poor Adherence

Poor adherence to regular controller medication, particularly inhaled corticosteroid-containing treatment, is an important cause of poorly controlled asthma and exacerbations.

Before escalating treatment, clinicians should therefore assess adherence, inhaler technique, ongoing triggers, and whether the diagnosis is correct.

Treatment of Chronic Asthma

Modern asthma treatment differs considerably from the older stepwise regimen in the supplied notes.

The major change is that treatment now emphasises inhaled corticosteroid (ICS)-containing therapy from an early stage, because airway inflammation is present even in patients with apparently mild asthma.

Reliance on a short-acting β₂-agonist such as salbutamol alone is generally no longer preferred in modern adult and adolescent asthma management.

20. Reliever Treatment

Historically, patients with mild asthma were treated with a short-acting β₂-agonist (SABA) such as salbutamol whenever symptoms occurred.

Modern approaches increasingly favour an ICS-containing reliever strategy, commonly using a low-dose inhaled corticosteroid combined with the rapid-onset LABA formoterol, where appropriate and available.

This provides both rapid bronchodilation and anti-inflammatory treatment when symptoms occur.

21. Inhaled Corticosteroids

Inhaled corticosteroids are the foundation of long-term asthma control.

They suppress airway inflammation, reduce symptoms, improve lung function, decrease airway hyperresponsiveness, and importantly reduce the risk of severe exacerbations and asthma-related death.

Examples include budesonide, beclometasone, and fluticasone.

22. Leukotriene Receptor Antagonists

A leukotriene receptor antagonist, such as montelukast, may be useful as additional controller therapy in selected patients.

It may be particularly helpful when asthma coexists with allergic rhinitis or in some patients with exercise- or aspirin/NSAID-associated symptoms.

It is generally less effective than inhaled corticosteroids as the main anti-inflammatory controller treatment.

23. Long-Acting β₂-Agonists

A long-acting β₂-agonist (LABA) may be added when asthma remains inadequately controlled with inhaled corticosteroid therapy.

Examples include formoterol and salmeterol.

Importantly, a LABA should not normally be used without an inhaled corticosteroid in asthma, because LABA monotherapy does not treat the underlying airway inflammation and is associated with safety concerns.

24. ICS–Formoterol Maintenance and Reliever Therapy

An important modern strategy is maintenance-and-reliever therapy (MART) using an ICS–formoterol inhaler.

The same inhaler provides regular maintenance anti-inflammatory treatment and additional doses when symptoms occur.

Because formoterol has a rapid onset of bronchodilation, it can function as both a long-acting controller and a reliever when combined appropriately with an ICS.

Escalation of Treatment

25. Persistent Symptoms

If asthma remains uncontrolled, treatment should be increased gradually while repeatedly checking adherence, inhaler technique, environmental exposures, comorbidities, and diagnostic accuracy.

Increasing the dose of inhaled corticosteroid or adding another controller may be appropriate depending on the treatment pathway being followed.

26. Long-Acting Muscarinic Antagonists

A long-acting muscarinic antagonist (LAMA), such as tiotropium, may be added in selected patients whose asthma remains inadequately controlled despite appropriate ICS/LABA treatment.

This has largely replaced the older concept of routinely adding short-acting ipratropium for long-term asthma control.

27. Theophylline

Theophylline was historically used more frequently as additional therapy for chronic asthma.

Its role is now limited because it has a narrow therapeutic index, important drug interactions, and significant adverse effects, while more effective and safer treatment options are available.

28. Nebulised Bronchodilators

Regular nebulised bronchodilators are not standard routine maintenance therapy for most patients with chronic asthma.

Nebulised therapy is much more commonly used during significant acute exacerbations.

Severe Asthma

29. Specialist Assessment

Patients whose asthma remains uncontrolled despite appropriately prescribed high-level inhaled therapy should undergo specialist assessment.

Before diagnosing severe treatment-resistant asthma, clinicians should confirm the diagnosis and carefully evaluate adherence, inhaler technique, smoking, allergen exposure, occupational factors, obesity, rhinosinusitis, reflux, and other comorbidities.

30. Biological Therapies

Modern treatment of severe asthma includes biological therapies directed at specific inflammatory pathways.

Depending on the asthma phenotype and biomarkers, treatment may target IgE, interleukin-5 or its receptor, interleukin-4/13 signalling, or other inflammatory pathways.

These therapies can substantially reduce exacerbations and the need for systemic corticosteroids in appropriately selected patients.

31. Oral Corticosteroids

Maintenance oral corticosteroids should generally be avoided whenever possible because prolonged systemic steroid exposure can cause major adverse effects.

These include osteoporosis, diabetes, hypertension, weight gain, cataracts, adrenal suppression, infection, and muscle weakness.

They may still be necessary in selected patients with severe refractory asthma, but modern biologic therapies can often reduce the requirement for long-term oral steroids.

32. Treatment Escalation – Note Form

Initial/Mild Asthma

Preferred principle: use an ICS-containing treatment strategy, rather than relying solely on salbutamol.

Reliever: low-dose ICS–formoterol is commonly preferred in appropriate adult/adolescent treatment pathways.

Alternative approaches: regular or symptom-linked low-dose ICS with an appropriate reliever may be used according to the treatment guideline and patient circumstances.

Persistent Asthma

Controller treatment: regular low-dose inhaled corticosteroid-containing therapy.

If symptoms persist: increase anti-inflammatory treatment and/or add a LABA.

Important: LABA therapy in asthma should be combined with an ICS, rather than used alone.

Moderate Asthma

Treatment: combination ICS + LABA therapy.

Option: ICS–formoterol may be used as maintenance-and-reliever therapy (MART) when appropriate.

Before escalation: always reassess inhaler technique, adherence, triggers, and comorbidities.

More Difficult-to-Control Asthma

Treatment: increase ICS-containing therapy according to the appropriate treatment pathway.

Additional options: consider a LAMA or other add-on controller treatment.

Theophylline: now has a limited role because of adverse effects and drug interactions.

Regular nebulisers: not routinely required for chronic stable asthma.

Severe Asthma

Management: specialist respiratory assessment.

Treatment options: phenotype-directed biological therapies may be appropriate.

Oral corticosteroids: intermittent courses may be required for exacerbations, while long-term maintenance therapy should be minimised whenever possible because of significant systemic toxicity.

Key Clinical Pattern

Think of asthma as:

Chronic airway inflammation + bronchial hyperresponsiveness + variable symptoms + variable expiratory airflow obstruction.

Typical symptoms are wheeze, breathlessness, chest tightness, and cough, with objective evidence such as variable peak flow, reduced FEV₁/FVC during obstruction, and improvement following bronchodilator treatment.

Important triggers include allergens, exercise, respiratory infections, smoke, NSAIDs/aspirin in susceptible patients, β-blockers, and poor adherence to controller treatment.

For modern treatment, the key principle is early ICS-containing therapy, followed when necessary by ICS/LABA treatment, MART where appropriate, additional controller therapy, and phenotype-directed biologics for severe asthma, while avoiding unnecessary dependence on SABA-only therapy or long-term oral corticosteroids.

Medicine – Acute Asthma

Acute asthma is a sudden or progressive worsening of asthma symptoms caused by increased bronchial smooth-muscle constriction, airway inflammation, mucosal oedema, and mucus production. Patients develop worsening breathlessness, wheeze, cough, and chest tightness, together with a measurable reduction in expiratory airflow.

A severe asthma attack can progress rapidly to life-threatening respiratory failure, so recognising markers of severity and starting treatment promptly are essential.

1. Mortality

Asthma continues to cause preventable deaths in the UK, although the older figure of approximately 1,500 deaths per year varies between years and should not be regarded as a fixed contemporary number.

Many fatal attacks are associated with delayed recognition of severity, inadequate use of anti-inflammatory treatment, or delayed escalation of emergency care.

Assessment of Acute Asthma

The severity of an acute attack should be assessed using the patient’s clinical appearance, ability to speak, respiratory rate, heart rate, oxygen saturation, peak expiratory flow (PEF), and—when indicated—arterial blood gases.

An important correction to the older notes is that some listed findings, particularly PEF <33%, silent chest, hypoxaemia, and normal or raised PaCO₂, are markers of life-threatening asthma, rather than merely severe asthma.

2. Severe Acute Asthma

In adults, acute severe asthma is suggested by the presence of any of the following major features.

Difficulty Speaking

The patient may be unable to complete sentences in one breath because of severe breathlessness.

Speech becoming increasingly fragmented is an important bedside indication of worsening respiratory distress.

Tachycardia

A heart rate ≥110 beats/minute is a marker of acute severe asthma.

Tachycardia can result from respiratory distress, hypoxaemia, sympathetic activation, and β₂-agonist treatment.

Tachypnoea

A respiratory rate ≥25 breaths/minute is commonly used in modern UK adult criteria for acute severe asthma.

The older threshold of >30/min still indicates substantial respiratory distress but is not the usual current threshold for defining acute severe asthma.

Peak Expiratory Flow

A PEF of 33–50% of the patient’s best or predicted value indicates acute severe asthma.

Peak flow provides an objective measurement of the degree of airflow obstruction and should be recorded whenever the patient is capable of performing the manoeuvre safely.

3. Life-Threatening Asthma

Life-threatening asthma is suggested by particularly severe clinical or physiological abnormalities.

These patients require immediate treatment, senior medical involvement, and consideration of intensive care.

Peak Flow Below 33%

A PEF <33% of the patient’s best or predicted value is a major marker of life-threatening asthma.

This represents very severe expiratory airflow limitation.

Silent Chest

A silent chest is an ominous finding.

Although wheezing is characteristic of asthma, extremely severe airflow obstruction can reduce airflow so dramatically that little or no wheeze is audible.

Therefore, disappearance of wheeze in a deteriorating patient does not necessarily indicate improvement.

Hypoxaemia

Significant hypoxaemia indicates severe impairment of ventilation and gas exchange.

Oxygen saturation should therefore be monitored continuously in a severe attack.

Normal or Raised PaCO₂

A normal or elevated arterial PaCO₂ is a particularly concerning finding in acute asthma.

Early in an asthma attack, patients usually hyperventilate and therefore have a low PaCO₂.

As obstruction becomes extreme and respiratory muscles fatigue, the patient can no longer maintain adequate ventilation. PaCO₂ then returns toward normal and subsequently rises.

Therefore:

Low PaCO₂ → expected during significant acute asthma.

Normal PaCO₂ → concerning for deterioration.

Raised PaCO₂ → severe ventilatory failure and potentially impending respiratory arrest.

Other Life-Threatening Features

Additional warning signs include cyanosis, poor respiratory effort, exhaustion, hypotension, arrhythmia, altered consciousness, and confusion.

These features indicate that the patient may be approaching respiratory failure.

4. Pulsus Paradoxus

Pulsus paradoxus refers to an exaggerated fall in systolic blood pressure during inspiration.

It may occur in severe asthma because large changes in intrathoracic pressure influence ventricular filling.

Although historically included in severity assessment, it is not routinely relied upon in modern acute asthma assessment, because simpler clinical and physiological measurements are more useful.

Management of Acute Severe Asthma

Treatment should begin immediately while severity is being assessed.

The major aims are to correct hypoxaemia, reverse bronchoconstriction, suppress airway inflammation, and recognise patients requiring intensive respiratory support.

5. Oxygen

Patients who are hypoxaemic should receive supplemental oxygen, titrated to an appropriate oxygen saturation.

The older instruction to automatically administer unrestricted high-flow oxygen to every patient has been replaced by controlled oxygen therapy guided by oxygen saturation.

In adults with acute asthma, a target oxygen saturation of approximately 94–98% is commonly used.

6. Nebulised β₂-Agonists

A rapidly acting inhaled β₂-agonist, most commonly salbutamol, is a cornerstone of treatment.

In severe attacks, repeated or continuous nebulised therapy may be required.

Nebulisers can be driven by oxygen when appropriate in significantly hypoxaemic patients.

7. Ipratropium Bromide

Nebulised ipratropium bromide should be added to β₂-agonist treatment in severe or life-threatening asthma.

The combination produces greater bronchodilation than either treatment alone in severe attacks.

8. Systemic Corticosteroids

Systemic corticosteroids should be administered early because acute asthma involves significant airway inflammation as well as bronchoconstriction.

Oral prednisolone is often appropriate when the patient can swallow and absorb medication.

Intravenous hydrocortisone can be used when oral treatment is unsuitable.

Steroids do not produce immediate bronchodilation, but they reduce airway inflammation and decrease the likelihood of ongoing deterioration and relapse.

Additional Treatment

9. Intravenous Magnesium Sulfate

Intravenous magnesium sulfate may be considered in severe or life-threatening asthma that responds inadequately to initial inhaled bronchodilator treatment.

Magnesium has a bronchodilator effect and can be useful in selected severe attacks.

It is not routinely required for every asthma exacerbation.

10. Intravenous Aminophylline

Intravenous aminophylline was historically used more frequently in severe asthma.

It is no longer routinely recommended because the additional bronchodilator benefit is limited and adverse effects, including nausea, vomiting, arrhythmias, and seizures, can occur.

It may occasionally be considered in specialist-managed refractory cases.

11. Intravenous Salbutamol

Intravenous β₂-agonists such as salbutamol are also not routinely used when effective inhaled or nebulised therapy can be delivered.

They may occasionally be considered in highly selected refractory cases under specialist supervision.

12. Antibiotics

Antibiotics are not routinely indicated in acute asthma.

Most asthma exacerbations are not caused by bacterial infection, and purulent-looking sputum alone does not necessarily indicate bacterial disease.

Antibiotics should be given when there is convincing evidence of a bacterial infection, such as bacterial pneumonia.

Respiratory Failure

13. When to Consider Intensive Care

Urgent intensive care assessment should be considered when the patient is deteriorating despite appropriate treatment or develops features such as exhaustion, altered consciousness, worsening hypoxaemia, rising PaCO₂, poor respiratory effort, or haemodynamic instability.

A patient with severe asthma can deteriorate very rapidly.

14. Mechanical Ventilation

Mechanical ventilation may become necessary when respiratory failure develops despite maximal medical treatment.

Important indications include worsening hypercapnia, severe hypoxaemia, exhaustion, reduced consciousness, respiratory arrest, or inability to maintain adequate ventilation.

Intubation and ventilation of a patient with severe asthma are challenging because severe airflow obstruction and air trapping can produce dynamic hyperinflation and dangerously high intrathoracic pressures, so experienced critical-care management is essential.

15. Severe vs Life-Threatening Asthma – Note Form

Acute Severe Asthma

Speech: unable to complete sentences in one breath.

Respiratory rate: ≥25/min.

Heart rate: ≥110/min.

PEF: 33–50% of best or predicted.

Life-Threatening Asthma

PEF: <33% of best or predicted.

Chest examination: silent chest.

Oxygenation: significant hypoxaemia.

PaCO₂: normal or raised.

Cyanosis: may be present.

Respiratory effort: poor or decreasing.

Neurological state: exhaustion, confusion, or reduced consciousness.

Cardiovascular features: hypotension or arrhythmia may develop.

16. Immediate Management – Note Form

Oxygen: controlled supplemental oxygen, generally targeting SpO₂ around 94–98%.

Bronchodilator: repeated or nebulised salbutamol.

Antimuscarinic: add nebulised ipratropium in severe or life-threatening attacks.

Steroids: give systemic corticosteroids early.

Magnesium: consider IV magnesium sulfate if the response to initial treatment is inadequate.

Antibiotics: only when bacterial infection is suspected or confirmed.

Aminophylline/IV salbutamol: not routine; reserve for selected refractory cases with specialist input.

Ventilation: consider urgently if respiratory failure, exhaustion, deteriorating consciousness, worsening hypoxaemia, or rising PaCO₂ develops.

Key Clinical Pattern

In acute asthma, a patient initially tends to hyperventilate and lower their PaCO₂. Therefore, a normal PaCO₂ is not reassuring in a severely breathless asthmatic—it may indicate that respiratory muscles are beginning to fail.

Remember the distinction:

Acute severe asthma → PEF 33–50%, RR ≥25/min, HR ≥110/min, inability to complete sentences.

Life-threatening asthma → PEF <33%, silent chest, hypoxaemia, normal/raised PaCO₂, cyanosis, exhaustion, hypotension, arrhythmia, or altered consciousness.

Initial treatment centres on oxygen when hypoxaemic + repeated inhaled/nebulised β₂-agonist + ipratropium + early systemic corticosteroids, with IV magnesium and critical-care support when the response is inadequate.

Medicine – Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a common, progressive respiratory disorder characterised by persistent airflow limitation that is not fully reversible. The airflow obstruction usually develops gradually over years and reflects a combination of small-airway disease, chronic bronchitis, and emphysema.

COPD is associated with substantial morbidity, recurrent exacerbations, reduced exercise tolerance, impaired quality of life, and increased mortality.

1. Definition

COPD is characterised by chronic respiratory symptoms together with persistent airflow obstruction.

The obstruction does not fluctuate markedly over short periods in the way that asthma often does, although some reversibility can still be present.

Modern diagnosis relies on post-bronchodilator spirometry, rather than simply describing airflow obstruction as “fixed.”

2. Main Cause

The most important risk factor is cigarette smoking.

Long-term exposure to tobacco smoke causes chronic airway inflammation, mucus hypersecretion, small-airway narrowing, and destruction of alveolar tissue.

However, COPD can also occur in never-smokers because of factors such as biomass fuel exposure, occupational dusts and fumes, air pollution, impaired lung development, and α1-antitrypsin deficiency.

3. Chronic Bronchitis and Emphysema

Patients with COPD may have varying proportions of chronic bronchitis, small-airway disease, and emphysema.

These abnormalities frequently overlap, so patients do not usually fall neatly into one category.

4. Chronic Bronchitis

Chronic bronchitis is a clinical definition.

Traditionally, it is defined as a productive cough for at least 3 months in each of 2 consecutive years, after excluding other causes of chronic cough.

The condition reflects chronic mucus hypersecretion and airway inflammation.

5. Emphysema

Emphysema is a pathological condition characterised by permanent enlargement of airspaces distal to the terminal bronchioles with destruction of alveolar walls.

This destruction reduces elastic recoil and causes premature airway collapse during expiration.

Although originally defined pathologically, emphysema can now often be identified and quantified on CT imaging.

Clinical Features

6. Chronic Cough

A chronic cough is common and is often productive of sputum.

Some patients may have cough and sputum production for years before significant breathlessness develops.

7. Breathlessness

Progressive exertional breathlessness is one of the most important symptoms of COPD.

It usually worsens gradually over time and eventually may limit ordinary daily activities.

8. Wheeze

Wheeze may occur because of airflow narrowing and dynamic airway collapse.

Its presence does not automatically indicate asthma, since wheeze is common in COPD as well.

9. Recurrent Exacerbations

Patients may experience recurrent acute exacerbations, characterised by a sustained worsening of respiratory symptoms beyond normal day-to-day variation.

Typical features include increased breathlessness, increased cough, greater sputum volume, and sometimes increased sputum purulence.

Exacerbations may be triggered by viral infections, bacterial infections, air pollution, or other environmental factors.

Spirometry

10. FEV₁/FVC Ratio

The diagnosis of persistent airflow obstruction is based on spirometry.

The modern standard is a post-bronchodilator FEV₁/FVC ratio <0.70.

Older teaching sometimes used thresholds such as <75%, but the fixed 0.70 ratio is more commonly used in modern guidelines, with interpretation adjusted for age when appropriate.

11. FEV₁

FEV₁ is useful for assessing the degree of airflow limitation.

An FEV₁ below 80% predicted may support obstructive lung disease, but COPD diagnosis is not based on FEV₁ alone.

Severity assessment now also considers symptoms, exacerbation frequency, hospitalisations, oxygenation, comorbidities, and functional limitation, not just spirometric percentage bands.

Acute Management

12. Bronchodilators

Acute exacerbations are treated with short-acting bronchodilators, typically a short-acting β₂-agonist such as salbutamol, often with an antimuscarinic such as ipratropium.

Nebulised therapy may be used in more severe attacks.

13. Controlled Oxygen Therapy

Oxygen must be given carefully in patients at risk of hypercapnic respiratory failure.

In many acute COPD exacerbations, the usual target oxygen saturation is 88–92% until arterial blood gas results are available.

The aim is to correct dangerous hypoxaemia without causing excessive worsening of CO₂ retention.

14. Corticosteroids

Short courses of systemic corticosteroids are commonly used in moderate or severe exacerbations because they can shorten recovery time and improve lung function.

They are not used simply as an old-style “steroid reversibility trial” to decide long-term treatment.

15. Antibiotics

Antibiotics may be indicated when there is evidence of bacterial infection, especially with increased sputum purulence, increased sputum volume, or more severe exacerbation requiring ventilation.

Chronic Management

16. Smoking Cessation

Smoking cessation is the single most important intervention for patients who smoke.

It slows the accelerated decline in lung function and reduces exacerbations, cardiovascular risk, and overall mortality.

It is more accurate to say that smoking cessation is the most important modifiable measure rather than the only treatment that can influence disease progression.

17. Vaccination

Patients with COPD should receive appropriate influenza vaccination and pneumococcal vaccination.

Other vaccines may also be indicated depending on age and local recommendations.

18. Short-Acting Bronchodilators

Patients with intermittent symptoms may use a short-acting β₂-agonist (SABA) or a short-acting muscarinic antagonist (SAMA) as required.

These drugs provide rapid symptom relief.

19. Long-Acting Bronchodilators

For persistent symptoms, modern treatment generally relies on long-acting bronchodilators.

These include:

LABA – long-acting β₂-agonists

and

LAMA – long-acting muscarinic antagonists.

Many symptomatic patients benefit from LABA + LAMA combination therapy.

This has largely replaced older stepwise regimens based mainly on repeated short-acting bronchodilator use.

20. Inhaled Corticosteroids

Inhaled corticosteroids (ICS) are not routinely given to every patient with COPD.

They are most useful in selected patients with frequent exacerbations, higher blood eosinophil counts, or coexisting asthma features.

ICS is often used in combination with long-acting bronchodilators rather than as monotherapy.

The older practice of giving a steroid trial and continuing ICS only if FEV₁ improves by >15% is no longer the standard approach.

21. Triple Therapy

Patients with persistent exacerbations despite dual bronchodilation may benefit from triple inhaler therapy:

LABA + LAMA + ICS.

The decision depends on symptoms, exacerbation history, blood eosinophils, pneumonia risk, and other clinical factors.

22. Pulmonary Rehabilitation

Pulmonary rehabilitation is an important non-drug treatment for symptomatic patients.

It combines exercise training, education, breathing strategies, and multidisciplinary support and can improve exercise capacity, breathlessness, and quality of life.

23. Long-Term Oxygen Therapy

Long-term oxygen therapy (LTOT) is indicated in selected patients with persistent severe chronic hypoxaemia.

It is not prescribed simply because the COPD is spirometrically “severe.”

Typical eligibility depends on arterial oxygen tension and complications such as pulmonary hypertension, cor pulmonale, or secondary polycythaemia.

Complications

24. Respiratory Failure

Advanced COPD can cause respiratory failure.

Patients may initially develop hypoxaemia and later progress to type 2 respiratory failure with hypercapnia, especially during exacerbations.

25. Recurrent Exacerbations

Frequent exacerbations accelerate functional decline and are associated with worse quality of life and increased mortality.

Patients with repeated exacerbations may require escalation of inhaled therapy and further investigation for contributing factors.

26. Cor Pulmonale

Chronic hypoxaemia can cause hypoxic pulmonary vasoconstriction, leading to pulmonary hypertension.

Over time, this may produce right-sided heart strain and cor pulmonale.

27. Secondary Polycythaemia

Persistent hypoxaemia stimulates erythropoietin production and may cause secondary polycythaemia.

The resulting increase in red cell mass can increase blood viscosity.

28. Pneumothorax

Patients with emphysema may develop bullae, which can rupture and produce a spontaneous pneumothorax.

This may cause sudden pleuritic chest pain and acute worsening of breathlessness.

29. Lung Cancer

COPD is strongly associated with lung cancer, largely because tobacco exposure is a major shared risk factor.

COPD itself may also be associated with additional cancer risk beyond smoking alone.

30. Osteoporosis

Patients with COPD have an increased risk of osteoporosis.

Contributing factors include smoking, low body weight, reduced physical activity, chronic inflammation, vitamin D deficiency, and repeated or prolonged exposure to systemic corticosteroids.

31. Pink Puffer and Blue Bloater

Older teaching divided COPD patients into “pink puffers” and “blue bloaters.”

The pink-puffer pattern was associated mainly with emphysema, marked breathlessness, relatively preserved ventilation, and normal or low PaCO₂ until later disease.

The blue-bloater pattern was associated more with chronic bronchitis, hypoxaemia, hypercapnia, cyanosis, pulmonary hypertension, and cor pulmonale.

These terms are now regarded as historical rather than formal clinical classifications, because most patients have overlapping features.

Key Clinical Pattern

Think of COPD in a patient, usually with a significant smoking or inhalational exposure history, who has progressive exertional breathlessness, chronic cough with or without sputum, wheeze, and recurrent exacerbations.

The key spirometric finding is persistent post-bronchodilator airflow obstruction with FEV₁/FVC <0.70.

Modern long-term treatment centres on smoking cessation, vaccination, long-acting bronchodilators, pulmonary rehabilitation, selective use of inhaled corticosteroids, prevention of exacerbations, and LTOT when severe chronic hypoxaemia is present.

Important complications include respiratory failure, recurrent exacerbations, pulmonary hypertension and cor pulmonale, secondary polycythaemia, pneumothorax, osteoporosis, and lung cancer.

Medicine – Pink Puffer vs Blue Bloater in COPD

The terms “pink puffer” and “blue bloater” are traditional descriptions of two clinical phenotypes of chronic obstructive pulmonary disease (COPD). The pink-puffer pattern was associated mainly with emphysema, whereas the blue-bloater pattern was associated mainly with chronic bronchitis.

These terms are now considered outdated because many patients have overlapping emphysema and airway disease rather than fitting neatly into one category. However, the comparison remains useful for understanding the underlying physiology.

1. Pink Puffer – Emphysema-Predominant Pattern

The traditional pink puffer describes a patient whose COPD is predominantly emphysematous.

Destruction of alveolar walls causes loss of elastic recoil, air trapping, hyperinflation, and reduced surface area for gas exchange. These patients often compensate by increasing their respiratory effort and ventilation.

Hyperventilation

Patients with emphysema may maintain relatively effective alveolar ventilation by increasing their respiratory rate and work of breathing.

This increased ventilation helps remove carbon dioxide and can maintain arterial oxygenation relatively well during the earlier stages of disease.

Carbon Dioxide

Because ventilation is relatively well maintained, PaCO₂ may remain normal or low until advanced disease.

The image associates this with type 1 respiratory failure, but this requires clarification. Type 1 respiratory failure is defined primarily by hypoxaemia with a normal or low PaCO₂, rather than simply by a low carbon dioxide concentration.

Therefore:

Type 1 respiratory failure = low PaO₂ with normal or low PaCO₂.

Breathlessness

Breathlessness is often prominent in emphysema-predominant COPD because patients must work hard to maintain ventilation despite severe airflow obstruction and hyperinflation.

Patients may use accessory respiratory muscles and sometimes adopt pursed-lip breathing, which helps prevent premature small-airway collapse during expiration.

Why “Pink”?

The historical term “pink” refers to the observation that these patients may remain relatively well oxygenated and therefore show less obvious cyanosis, particularly earlier in the disease.

This does not mean that patients with emphysema cannot become hypoxaemic or cyanosed. Both can occur as disease progresses.

Typical Body Habitus

Classically, emphysema-predominant patients were described as thin or underweight.

The increased energy expenditure associated with persistent respiratory effort, together with systemic effects of advanced COPD, can contribute to weight loss and muscle wasting.

2. Blue Bloater – Chronic Bronchitis-Predominant Pattern

The traditional blue bloater describes a patient whose COPD is predominantly associated with chronic bronchitis and severe airway obstruction.

Excess mucus production, airway inflammation, airway narrowing, and mucus plugging impair ventilation and produce substantial ventilation–perfusion mismatch.

Hypoventilation

Compared with the traditional emphysema phenotype, these patients may have relatively inadequate alveolar ventilation.

As ventilation becomes insufficient, carbon dioxide is retained and arterial oxygen falls.

Carbon Dioxide Retention

The resulting hypercapnia may contribute to type 2 respiratory failure.

The complete definition is:

Type 2 respiratory failure = low PaO₂ with raised PaCO₂.

Therefore, the raised carbon dioxide shown in the image is an important distinguishing physiological feature.

Cyanosis

Significant hypoxaemia can cause central cyanosis, producing the historical description “blue.”

Cyanosis is therefore more prominent in the traditional chronic bronchitis phenotype than in the compensated emphysema phenotype.

Breathlessness

The image describes these patients as “cyanosed but not breathless.” This should not be interpreted literally.

Patients with chronic bronchitis-predominant COPD can certainly experience significant breathlessness. The traditional comparison simply suggests that dyspnoea may be less disproportionately prominent than in severe emphysema, despite greater abnormalities in blood gases.

3. Cor Pulmonale

Cor pulmonale is classically associated with the chronic bronchitis-predominant phenotype.

Persistent alveolar hypoxia causes hypoxic pulmonary vasoconstriction. Over time, this increases pulmonary vascular resistance and can produce pulmonary hypertension.

The right ventricle must pump against the increased pulmonary arterial pressure and may eventually develop right-sided heart dysfunction.

Peripheral Oedema

Patients with advanced cor pulmonale may develop peripheral oedema, contributing to the historical term “bloater.”

Other findings can include a raised jugular venous pressure and additional evidence of right-sided cardiac dysfunction.

4. Comparison in Note Form

Pink Puffer

Traditional association: emphysema.

Ventilation: increased or relatively well maintained.

PaO₂: may be relatively preserved in earlier disease, although hypoxaemia can develop later.

PaCO₂: usually normal or reduced initially because of increased ventilation.

Respiratory failure: may develop a type 1 respiratory failure pattern, with low PaO₂ and normal or low PaCO₂.

Breathlessness: usually prominent and often severe.

Cyanosis: less prominent in earlier disease.

Body habitus: classically thin or underweight.

Cor pulmonale: generally develops later and is less characteristic than in chronic bronchitis-predominant disease.

Peripheral oedema: less characteristic unless significant right-sided heart failure develops.

Blue Bloater

Traditional association: chronic bronchitis.

Ventilation: relatively reduced, with a greater tendency toward alveolar hypoventilation.

PaO₂: more markedly reduced because of significant ventilation–perfusion mismatch.

PaCO₂: typically raised because of carbon dioxide retention.

Respiratory failure: more likely to develop type 2 respiratory failure, with low PaO₂ and raised PaCO₂.

Breathlessness: can occur and may be significant, although traditionally described as less prominent relative to the degree of hypoxaemia.

Cyanosis: more prominent because of chronic hypoxaemia.

Body habitus: traditionally described as more oedematous or “bloated,” particularly when cor pulmonale develops.

Cor pulmonale: more characteristic because chronic hypoxia causes pulmonary hypertension and right-heart strain.

Peripheral oedema: may occur as part of right-sided heart dysfunction.

5. Main Physiological Difference

The central difference between the traditional two patterns is how well the patient maintains alveolar ventilation.

In the emphysema-predominant pink-puffer pattern, the patient compensates by breathing harder and maintaining ventilation, so CO₂ tends to remain normal or low for longer.

In the chronic bronchitis-predominant blue-bloater pattern, ventilation is less effective, so oxygen falls and CO₂ rises, creating a greater tendency toward chronic type 2 respiratory failure.

Key Clinical Pattern

The traditional pink puffer represents emphysema-predominant COPD: severe breathlessness, increased respiratory effort, relatively maintained ventilation, and normal or low PaCO₂ until later disease.

The traditional blue bloater represents chronic bronchitis-predominant COPD: greater hypoxaemia, CO₂ retention, type 2 respiratory failure, cyanosis, pulmonary hypertension, cor pulmonale, and peripheral oedema.

For modern clinical practice, it is better to describe the patient’s actual COPD phenotype, symptoms, exacerbation history, spirometry, emphysema burden, oxygenation, and hypercapnia rather than label patients strictly as pink puffers or blue bloaters.

Medicine – Long-Term Oxygen Therapy

Long-term oxygen therapy (LTOT) is the regular administration of supplemental oxygen at home for patients with chronic severe resting hypoxaemia. It is used mainly in chronic respiratory diseases such as advanced COPD when persistent hypoxaemia remains despite optimal treatment of the underlying condition.

The major purpose of LTOT is not simply to relieve breathlessness. In appropriately selected patients with severe chronic hypoxaemia, prolonged oxygen therapy can improve survival and reduce some of the consequences of chronic tissue hypoxia.

⸻

1. Survival Benefit

Classic clinical trials demonstrated a significant survival benefit from long-term oxygen in patients with severe chronic hypoxaemia, particularly when oxygen was used for prolonged periods each day.

Older teaching sometimes describes approximately a 50% improvement in three-year survival in appropriately selected patients. The important clinical principle is that LTOT has a proven mortality benefit in patients with severe chronic resting hypoxaemia.

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2. Duration of Oxygen Therapy

For LTOT to provide its established benefit, oxygen should generally be administered for at least 15 hours per day.

Greater daily use may provide additional benefit, and many patients are therefore encouraged to use oxygen for as much of the day and night as clinically appropriate.

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3. Target Oxygenation

The oxygen flow rate is individually adjusted to correct significant hypoxaemia.

Traditional teaching aims to increase the arterial oxygen tension (PaO₂) above approximately 8 kPa (60 mmHg) while maintaining safe carbon dioxide levels.

The patient’s oxygen requirement should therefore be determined by formal assessment rather than simply prescribing an arbitrary oxygen flow rate.

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Assessment for LTOT

4. Patient Must Be Clinically Stable

LTOT should not normally be permanently prescribed solely on measurements obtained during an acute respiratory exacerbation, because hypoxaemia may improve after recovery.

Assessment is therefore performed when the patient’s underlying disease has been optimally treated and clinically stable.

Older protocols commonly required arterial blood gases on two occasions several weeks apart. Current protocols vary by healthcare system, but the principle remains that chronic hypoxaemia should be confirmed in a stable patient.

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5. Severe Resting Hypoxaemia

A classic indication for LTOT is a resting:

PaO₂ ≤7.3 kPa (55 mmHg)

when measured in a clinically stable patient.

This degree of persistent hypoxaemia is associated with adverse physiological consequences and is the group in which the survival benefit of LTOT is best established.

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6. PaO₂ Between 7.3 and 8.0 kPa

LTOT may also be indicated when the resting PaO₂ is approximately 7.3–8.0 kPa (55–60 mmHg) if there is evidence of complications resulting from chronic hypoxaemia.

Important examples include pulmonary hypertension, peripheral oedema suggesting cor pulmonale, or secondary polycythaemia.

Therefore, a patient does not necessarily need a PaO₂ below 7.3 kPa if there is evidence that chronic hypoxaemia is already producing significant physiological consequences.

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Cor Pulmonale

7. Chronic Hypoxaemia and the Right Heart

Persistent alveolar hypoxia causes pulmonary vasoconstriction.

When this occurs chronically, pulmonary vascular resistance increases and may eventually produce pulmonary hypertension.

The right ventricle must then pump against increased resistance, potentially resulting in right-sided cardiac dysfunction or cor pulmonale.

Correcting chronic hypoxaemia with LTOT can reduce hypoxic pulmonary vasoconstriction and help limit these consequences.

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Carbon Dioxide

8. PaCO₂ May Be Normal or Raised

A raised arterial carbon dioxide tension (PaCO₂) does not automatically exclude a patient from receiving LTOT.

Some patients with advanced COPD have chronic hypercapnic respiratory failure and may still obtain substantial benefit from oxygen when they meet the appropriate hypoxaemia criteria.

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9. Checking the Response to Oxygen

The patient’s response to supplemental oxygen should be assessed to ensure that oxygenation improves appropriately and that treatment does not cause clinically important worsening of hypercapnia or respiratory acidosis.

The older criterion that PaO₂ must rise above 8 kPa without a significant increase in PaCO₂ reflects this concern.

However, chronic hypercapnia itself is not an absolute contraindication to LTOT.

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FEV₁ and LTOT

10. FEV₁ Below 1.5 L

Older criteria sometimes included an FEV₁ below 1.5 L as a requirement for LTOT.

This is now considered outdated as a strict eligibility criterion.

The decision to prescribe LTOT is primarily based on persistent chronic hypoxaemia and its complications, rather than a specific absolute FEV₁ value.

A patient can therefore meet criteria for LTOT without having an FEV₁ below 1.5 L.

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Smoking and Oxygen Therapy

11. Smoking

Older protocols often stated that patients had to be non-smokers before LTOT could be prescribed.

Smoking cessation remains extremely important because continued smoking accelerates COPD progression and substantially reduces the overall benefit of respiratory treatment.

There is also a major fire and burn risk when smoking or using an open flame near supplemental oxygen.

However, whether active smoking represents an absolute contraindication to providing home oxygen varies according to local policies and individual risk assessment. It should therefore not be regarded as a universal physiological eligibility criterion in the same way as PaO₂.

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Practical Use

12. Home Oxygen

LTOT is usually delivered at home using an oxygen concentrator, with the prescribed flow rate determined during specialist assessment.

Patients and household members require education about safe oxygen use, particularly avoidance of smoking, flames, and other ignition sources.

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13. LTOT Is Different from Oxygen for Breathlessness

LTOT should not be prescribed simply because a patient feels breathless.

A patient can have severe breathlessness while maintaining adequate oxygenation, and supplemental oxygen has not demonstrated the same survival benefit in patients who do not have qualifying chronic hypoxaemia.

The key indication is therefore documented persistent hypoxaemia, not breathlessness alone.

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Key Clinical Pattern

Think of LTOT in a clinically stable patient with persistent severe chronic hypoxaemia despite optimal treatment.

The classic threshold is PaO₂ ≤7.3 kPa (55 mmHg), or approximately 7.3–8.0 kPa (55–60 mmHg) when complications of chronic hypoxaemia such as cor pulmonale/pulmonary hypertension or secondary polycythaemia are present.

Oxygen is generally required for at least 15 hours per day, and the prescription should be titrated to improve oxygenation safely.

Remember that the older requirements of FEV₁ <1.5 L and universal exclusion of smokers are not modern physiological criteria for LTOT, while chronic hypercapnia does not automatically exclude treatment.

Medicine – α1-Antitrypsin Deficiency

α1-Antitrypsin deficiency (AATD) is an inherited disorder caused by pathogenic variants in the SERPINA1 gene on chromosome 14. It primarily affects the lungs and liver and is an important genetic cause of early-onset emphysema, particularly in patients who smoke.

1. Inheritance

α1-Antitrypsin deficiency is inherited in an autosomal codominant manner.

This means that both inherited alleles contribute to the amount and type of α1-antitrypsin produced. Different combinations of alleles therefore produce different serum concentrations and different risks of developing disease.

2. Function of α1-Antitrypsin

α1-Antitrypsin (AAT) is a circulating protease inhibitor produced mainly by hepatocytes.

Its major pulmonary role is to protect lung tissue from proteolytic enzymes released by inflammatory cells, particularly neutrophil elastase.

Normally, AAT neutralises elastase and prevents excessive degradation of elastin and other structural proteins within the alveolar walls.

3. Mechanism of Emphysema

When AAT concentrations are severely reduced, the lungs become inadequately protected against neutrophil elastase and other proteases.

Unopposed proteolytic activity gradually destroys alveolar walls, reducing the surface area available for gas exchange and producing emphysema.

Smoking accelerates this process by increasing pulmonary inflammation and neutrophil recruitment while also impairing the protective activity of AAT.

4. Pattern of Emphysema

The characteristic pulmonary abnormality is panacinar or panlobular emphysema.

Unlike the centriacinar emphysema typically associated with cigarette smoking, which often has an upper-lobe predominance, AAT deficiency classically produces emphysema that is most pronounced in the lower lobes and lung bases.

5. Protective Threshold

Severe deficiency increases the likelihood of progressive lung injury.

Older teaching sometimes describes tissue destruction occurring when AAT levels fall below approximately 40% of normal, but contemporary assessment more commonly considers the absolute serum concentration and the patient’s genotype rather than relying on a single percentage threshold.

The greatest pulmonary risk occurs in individuals with severe AAT deficiency, particularly those with the ZZ genotype.

Genotypes

The traditional genotype nomenclature uses letters such as M, S, and Z to describe different forms of the AAT protein.

6. MM Genotype

The MM genotype is considered the normal genotype.

People with PiMM generally have normal circulating α1-antitrypsin concentrations and are not considered to have clinically significant AAT deficiency.

7. MZ Genotype

People with the MZ genotype have one normal M allele and one deficient Z allele.

Serum AAT levels are moderately reduced, traditionally quoted at around 60% of normal, although the exact concentration varies.

Most nonsmokers with MZ do not develop severe early emphysema, but smoking and other respiratory exposures can increase their risk.

8. SZ Genotype

The SZ genotype produces a greater reduction in circulating AAT than MZ.

Older teaching commonly quotes levels of approximately 40% of normal.

The risk of emphysema is intermediate and becomes substantially greater with cigarette smoking.

9. ZZ Genotype

The ZZ genotype is the classic form associated with severe α1-antitrypsin deficiency.

Circulating levels may be only around 10–20% of normal, often quoted historically as approximately 15%.

These patients have a particularly high risk of early-onset panacinar emphysema and liver disease.

Clinical Presentation

10. Early-Onset Emphysema

Severely affected individuals may develop respiratory symptoms in the third or fourth decade of life.

Typical features include progressive exertional breathlessness, wheezing, chronic cough, and reduced exercise tolerance.

Smoking can cause symptoms to appear much earlier and can dramatically accelerate the decline in lung function.

11. Pulmonary Function

Pulmonary function testing typically demonstrates an obstructive ventilatory defect, with reduced FEV₁ and FEV₁/FVC ratio.

Gas transfer may also be reduced because destruction of alveolar walls decreases the surface area available for diffusion.

Liver Disease

12. Mechanism of Liver Injury

AAT deficiency can also cause liver disease, particularly with the Z allele.

The mechanism is different from that causing lung disease. In the liver, abnormal Z-type AAT proteins are misfolded and become retained within hepatocytes rather than being efficiently secreted into the circulation.

This intracellular accumulation causes progressive hepatocellular injury.

13. Clinical Liver Manifestations

Severe AAT deficiency can cause neonatal hepatitis, chronic hepatitis, fibrosis, cirrhosis, and an increased risk of hepatocellular carcinoma.

Thus, the disorder simultaneously produces low circulating AAT—predisposing to lung destruction—and abnormal AAT accumulation in the liver—predisposing to hepatic damage.

Diagnosis

Diagnosis involves measurement of the serum α1-antitrypsin concentration, often followed by phenotyping or SERPINA1 genotyping when deficiency is suspected.

Testing should be considered particularly in patients with emphysema at a young age, basilar-predominant emphysema, unexplained airflow obstruction, unexplained liver disease, or a family history of AAT deficiency.

Management

The most important intervention is complete avoidance of cigarette smoking, including avoiding significant occupational exposure to respiratory irritants.

Treatment of associated COPD includes appropriate inhaled therapies, vaccination, pulmonary rehabilitation, and management of exacerbations.

Selected patients with severe deficiency and established emphysema may be considered for intravenous AAT augmentation therapy, depending on clinical criteria and local availability.

Advanced pulmonary disease may eventually require lung transplantation, while severe liver disease may require liver transplantation.

Key Clinical Pattern

Think of α1-antitrypsin deficiency in a relatively young patient with early-onset emphysema, particularly when CT shows lower-lobe predominant panacinar emphysema.

The key mechanism is failure to inhibit neutrophil elastase → destruction of alveolar walls → emphysema.

Remember the genotype pattern: MM = normal, MZ = mild reduction, SZ = intermediate deficiency, ZZ = severe deficiency.

Also remember the important contrast: lung disease results from too little circulating AAT, whereas liver disease results from accumulation of abnormal AAT within hepatocytes.

Medicine – Pneumonia

Pneumonia is an acute infection of the lung parenchyma involving the alveoli and surrounding tissues. Infection produces inflammation and accumulation of inflammatory exudate within the alveoli, leading to consolidation and impaired gas exchange. Pneumonia may be classified according to where it was acquired, the causative organism, or the patient’s immune status.

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1. Clinical Features

The classic presentation is an acute cough, which may be productive of purulent sputum. However, sputum production is not universal, particularly with viral or so-called atypical infections.

Patients commonly develop fever, breathlessness, malaise, and tachypnoea. Older adults and immunocompromised patients may have less typical presentations, including confusion or functional deterioration without prominent fever.

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Haemoptysis

Haemoptysis may occur because inflammation damages the respiratory mucosa and small pulmonary vessels.

Blood may appear as streaking within sputum, although significant haemoptysis should prompt consideration of complications or alternative diagnoses such as pulmonary embolism, tuberculosis, or malignancy.

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Chest Pain

Chest discomfort may be a nonspecific dull ache or sharp pleuritic chest pain.

Pleuritic pain is caused by inflammation extending to the pleural surface and typically becomes worse during deep inspiration or coughing.

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Sepsis

Severe pneumonia can produce sepsis, with systemic manifestations such as hypotension, altered mental status, tachycardia, tachypnoea, and organ dysfunction.

Sepsis associated with pneumonia requires urgent assessment and treatment.

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Community-Acquired Pneumonia

2. Definition

Community-acquired pneumonia (CAP) refers to pneumonia acquired outside a hospital or similar healthcare environment.

The exact frequency of individual organisms varies considerably with age, geography, vaccination, comorbidities, season, and diagnostic methods, so older fixed percentages should not be regarded as universally applicable.

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3. Streptococcus pneumoniae

Streptococcus pneumoniae (pneumococcus) remains a major bacterial cause of community-acquired pneumonia.

Classically, pneumococcal pneumonia produces acute fever, productive cough, pleuritic chest pain, and lobar consolidation.

Although older texts quote S. pneumoniae as causing 60–75% of CAP, contemporary studies generally find a lower and highly variable proportion.

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Atypical Pneumonias

The traditional term “atypical pneumonia” describes pneumonia caused by organisms such as Mycoplasma pneumoniae, Legionella species, Chlamydia pneumoniae, and Chlamydia psittaci.

These organisms may produce prominent systemic features and relatively little sputum production, although the clinical distinction between typical and atypical pneumonia is not always reliable.

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4. Mycoplasma pneumoniae

Mycoplasma pneumoniae commonly causes respiratory infection in children and younger adults, particularly in households, schools, universities, and other close-contact environments.

It may occur in cyclical epidemics every few years.

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Clinical Pattern of Mycoplasma

The illness may begin with a relatively long prodrome, including headache, malaise, low-grade fever, sore throat, and a persistent dry cough.

Respiratory symptoms can subsequently progress to pneumonia.

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Cold Agglutinins

Mycoplasma pneumoniae infection can stimulate production of cold agglutinins, usually IgM antibodies that react with red blood cells at lower temperatures.

In some patients this can produce haemolytic anaemia, although cold agglutinins are neither sufficiently sensitive nor specific to serve as the main diagnostic test for Mycoplasma infection.

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5. Legionella Pneumonia

Legionella pneumophila causes Legionnaires’ disease, an important cause of potentially severe community-acquired pneumonia.

The organism proliferates in water systems and infection occurs through inhalation of contaminated aerosols rather than usual person-to-person respiratory transmission.

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Environmental Sources

Potential sources include showers, cooling towers, complex plumbing systems, hot-water systems, and other aerosol-producing water sources.

The older association with “air-conditioning” is more accurately understood as an association with contaminated water-containing cooling systems, rather than ordinary air-conditioning units themselves.

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Risk Factors

Legionella infection is more likely to become severe in older adults, smokers, people with chronic lung disease, and immunocompromised patients.

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Extrapulmonary Features

Legionella may produce prominent systemic manifestations in addition to pneumonia.

Patients can develop gastrointestinal symptoms, confusion, headache, neurological abnormalities, and abnormal liver function tests. Jaundice may occasionally occur but is not a defining feature.

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Laboratory Findings

Important laboratory clues include hyponatraemia, sometimes associated with inappropriate antidiuretic hormone activity, and abnormal liver enzymes.

The total white cell count is variable, and lymphopenia may occur.

These findings can support suspicion of Legionella but are not sufficiently specific to establish the diagnosis.

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6. Chlamydial Pneumonia

Chlamydia pneumoniae can cause respiratory infections ranging from mild upper respiratory disease to pneumonia.

Chlamydia psittaci causes psittacosis, which is particularly associated with exposure to infected birds such as parrots, pigeons, and poultry.

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7. Haemophilus influenzae

Haemophilus influenzae is another cause of community-acquired pneumonia.

It is particularly important in patients with chronic respiratory disease, including COPD and bronchiectasis.

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8. Moraxella catarrhalis

Moraxella catarrhalis can cause lower respiratory tract infection and pneumonia, particularly in older adults and patients with chronic lung disease such as COPD.

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9. Viral Pneumonia

Respiratory viruses are important causes of pneumonia and may also predispose to secondary bacterial infection.

Important viruses include influenza, respiratory syncytial virus (RSV), parainfluenza viruses, SARS-CoV-2, and varicella-zoster virus in appropriate clinical circumstances.

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Staphylococcal Pneumonia

10. Staphylococcus aureus

Staphylococcus aureus can cause severe pneumonia and is particularly important following influenza infection.

Damage to the respiratory epithelium caused by influenza facilitates secondary bacterial invasion, which can result in rapidly progressive pneumonia.

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Intravenous Drug Use

People who inject drugs are at increased risk of S. aureus bacteraemia and right-sided infective endocarditis.

Septic emboli from right-sided endocarditis can travel to the lungs and produce multiple peripheral pulmonary infections, nodules, or abscesses.

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Complications

Staphylococcal pneumonia can produce extensive tissue destruction and is associated with lung abscess formation, cavitation, parapneumonic effusion, and empyema.

MRSA should be considered when appropriate epidemiological or healthcare-associated risk factors are present.

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Assessing Severity

11. CURB-65 Score

A commonly used severity assessment for community-acquired pneumonia is the CURB-65 score.

One point is assigned for each of the following:

C – Confusion

U – Urea >7 mmol/L

R – Respiratory rate ≥30/min

B – Blood pressure: systolic <90 mmHg or diastolic ≤60 mmHg

65 – Age ≥65 years

The score ranges from 0 to 5.

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Interpreting CURB-65

In general, 0–1 suggests lower mortality risk, while a score of 2 indicates increased risk and usually warrants consideration of hospital-based assessment or treatment.

A score of 3 or more indicates severe pneumonia and a substantially increased risk of mortality, requiring urgent hospital management and consideration of higher-level care depending on the overall clinical picture.

The score supports rather than replaces clinical judgement.

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Hospital-Acquired Pneumonia

12. Definition

Hospital-acquired pneumonia (HAP) generally refers to pneumonia developing 48 hours or more after hospital admission that was not already incubating when the patient entered hospital.

The spectrum of causative organisms differs from CAP because hospitalised patients may become colonised with more resistant bacteria.

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13. Causative Organisms

Important organisms include Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA) in patients with appropriate risk factors.

Gram-negative organisms are also particularly important and include Klebsiella species, Escherichia coli, Enterobacterales, and Pseudomonas aeruginosa.

The likely pathogen depends strongly on the hospital environment, previous antibiotic exposure, duration of hospitalisation, local resistance patterns, and whether mechanical ventilation is present.

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Anaerobic Infection

Anaerobic bacteria are particularly relevant when there is significant aspiration, especially in patients with impaired consciousness, swallowing dysfunction, or poor dentition.

They are therefore not necessarily routine causes of every case of hospital-acquired pneumonia.

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Pneumocystis Pneumonia

14. Pneumocystis jirovecii

The organism historically called Pneumocystis carinii in humans is now called Pneumocystis jirovecii.

The disease continues to be abbreviated PCP, meaning Pneumocystis pneumonia.

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15. Risk Factors for PCP

PCP occurs predominantly in patients with impaired cell-mediated immunity.

It is classically associated with advanced HIV infection, particularly when the CD4 count is below approximately 200 cells/µL, but it can also occur with transplantation, malignancy, prolonged corticosteroid therapy, and other immunosuppressive treatments.

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16. Clinical Features of PCP

The characteristic presentation consists of progressive breathlessness, fever, and a dry or minimally productive cough.

Symptoms often develop gradually over days to weeks, particularly in patients with HIV.

Hypoxaemia can become severe and may be disproportionately marked compared with the initial chest examination.

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17. Imaging in PCP

A chest radiograph may initially be normal, particularly early in the disease.

The classic abnormality is bilateral diffuse or perihilar interstitial/ground-glass opacity.

High-resolution CT is more sensitive and commonly demonstrates widespread ground-glass opacities.

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18. Diagnosis of PCP

Because P. jirovecii cannot be diagnosed by routine bacterial culture, respiratory material is examined using specific methods.

Samples may be obtained from induced sputum or bronchoalveolar lavage, with the organism demonstrated by staining, immunofluorescence, or PCR.

PCR is highly sensitive but must be interpreted in the clinical context because detection does not always prove active disease.

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Treatment of Pneumonia

19. Community-Acquired Pneumonia

Amoxicillin remains a common first-line antibiotic for uncomplicated, lower-severity community-acquired bacterial pneumonia when pneumococcal infection is likely.

A macrolide, such as clarithromycin, may be used when atypical infection is suspected or as part of broader treatment for more severe disease.

The exact antibiotic regimen should follow local antimicrobial guidelines, disease severity, allergies, comorbidities, and local resistance patterns.

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20. Staphylococcal Pneumonia

When methicillin-sensitive S. aureus is established or strongly suspected, an appropriate antistaphylococcal beta-lactam such as flucloxacillin may be used.

Suspected or confirmed MRSA requires appropriate MRSA-active treatment, such as vancomycin or another agent selected according to local guidelines and susceptibility results.

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21. Hospital-Acquired Pneumonia

Treatment of hospital-acquired pneumonia requires broader consideration of Gram-negative organisms, Pseudomonas, resistant Enterobacterales, and MRSA.

The older universal recommendation of a third-generation cephalosporin plus metronidazole is no longer an appropriate standard regimen for all HAP.

Empirical therapy should instead be determined by local hospital antimicrobial guidelines, previous microbiology, recent antibiotic exposure, illness severity, and individual resistance risk, followed by narrowing of treatment when culture results become available.

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22. Treatment of PCP

The first-line treatment for Pneumocystis jirovecii pneumonia is generally co-trimoxazole (trimethoprim-sulfamethoxazole).

Patients with moderate-to-severe PCP and significant hypoxaemia may additionally require adjunctive corticosteroids, particularly in HIV-associated disease.

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Key Clinical Pattern

Think of pneumonia in a patient with an acute illness characterised by cough, fever, breathlessness, purulent sputum and pleuritic chest pain, with pulmonary infiltrates or consolidation supporting the diagnosis.

For CAP, S. pneumoniae remains a major bacterial pathogen. Remember the characteristic associations: Mycoplasma → younger patients and cold agglutinins; Legionella → water aerosols, hyponatraemia, abnormal LFTs and neurological/GI features; S. aureus → post-influenza pneumonia, cavitation, abscess and empyema.

For severity assessment, remember CURB-65: Confusion, Urea >7, Respiratory rate ≥30, low Blood pressure, and age ≥65. For immunocompromised patients with dry cough + fever + progressive dyspnoea + bilateral ground-glass changes, consider Pneumocystis jirovecii pneumonia.