Kembara Xtra - Medicine - Acute Respiratory Distress Syndrome Acute respiratory distress syndrome (ARDS) is characterized by bilateral opacities (patchy, diffuse, or homogeneous) on imaging that are consistent with pulmonary edema and the start of acute hypoxemia within 7 days of a known clinical insult. The ratio of arterial partial pressure of oxygen (PaO2) to fraction of inspired oxygen (FiO2) at positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) of at least 5 cm H2O is used to determine the severity of ARDS. PaO2/FiO2 levels of 200 mm Hg for mild conditions and 100 mm Hg for moderate conditions. PaO2/FiO2 100 mm Hg for severe. Synonym(s): noncardiac pulmonary edema, high permeability pulmonary edema, acute lung injury Cardiovascular and pulmonary systems are affected. Epidemiology Incidence ARDS incidence ranges from 10 to 86 cases per 100,000 people, making it a highly variable and underrecognized disease. Pathophysiology and Etiology ARDS is a reaction to diffuse alveolar damage brought on by direct or indirect alveolar injury. Etiologies Opportunistic, viral, fungal, or bacterial pneumonia Aspirating stomach contents Near drowning; Pulmonary contusion; Indirect Inhalation Injury; Sepsis (nonpulmonary); Shock; Blood Product Transfusion; Major Burn Injury; Nonthoracic Trauma. Drug overdose, cardiopulmonary bypass, reperfusion edema following embolectomy, and more. Three phases make up the progression of diffuse alveolar injury in ARDS. Exudative phase: The initial, intensely inflammatory stage that occurs after lung damage when alveolar macrophages become engaged, causing complement activation, the production of proinflammatory mediators, and neutrophil activation. Due to the rupture of the epithelial-endothelial barrier, the alveoli and extra-alveoli are flooded with fluid. Hyaline membrane development follows, which causes alveolar collapse. Proliferative phase: The second phase, which is characterized by the repair-mediated activity of fibroblasts, myofibroblasts, and alveolar epithelial cells (ACE) II. Aquaporin and ion channels are expressed, which aids in the reabsorption of fluid, as new matrix is formed, differentiation into ACE I begins, and cellular junctions are formed. Fibrotic phase: This last stage, which not all patients encounter, is marked by protracted mechanical breathing and is linked to higher mortality. Genetics No specific gene has been discovered for clinical application. Risk Elements Unfavorable results have been linked to higher levels of systemic inflammatory markers. Prevention Early detection of sepsis with effective antibiotic usage and resuscitation Accompanying Conditions 85% of instances of ARDS are brought on by pneumonia, sepsis, and aspiration of stomach contents. Other potential causes include: Burns, cardiothoracic surgery, and trauma - Near-drowning incidents and inhalational injuries - Shock - Transfusion-related acute lung damage - Toxicity of medications Clinical Evaluation increased oxygen needs; tachypnea and tachycardia within the first 12 to 24 hours; decreased breath sounds with or without rales Differential Diagnosis: Congestive heart failure, COVID-19, and bilateral pneumonia. Hypersensitivity pneumonitis, endobronchial tuberculosis, diffuse alveolar hemorrhage, interstitial and airway disorders, and venous occlusive disease,Drug-induced lung illness, particularly vascular leak syndrome with immunotherapy; Mitral stenosis: intravascular volume overload; Laboratory Results Initial examinations (lab, imaging) Initial laboratory tests should show hypoxemia in the form of a CBC, CMP, and ABG. ECG: sinus tachycardia and non-specific ST-T wave alterations may be seen. Bilateral opacities on a chest x-ray (CXR); air bronchograms are occasionally seen. diffuse interstitial opacities on chest CT scan Tests in the Future & Special Considerations COVID-19 PCR, sputum cultures, and blood cultures .When the diagnosis of heart failure cannot be ruled out, patients should take into account transthoracic echocardiography (TTE). When the cause of ARDS cannot be definitively determined, think about bronchoscopy. Other/Diagnostic Procedures The invasive monitoring of pulmonary artery wedge pressure (PAWP), which was once popular, has lost favor as a result of clinical trials showing no additional benefits and an increase in catheter-related problems. New strategy: Esophageal pressure can be measured with a manometer to estimate pleural pressure, which enables PEEP to be adjusted to generate a positive end-expiratory transpulmonary pressure gradient. This strategy is becoming more popular in clinical treatment and is especially helpful for morbidly obese patients. Test Interpretation With the addition of the Berlin criteria, ARDS can now be diagnosed when the computed PaO2/FiO2 is less than 300 mm Hg and there is radiologic proof of brand-new bilateral infiltrates. The oxygen saturation can be used as a substitute for the PaO2 in the absence of an ABG. According to the Berlin criteria, severity: - Mild: PaO2/FiO2 = 200 mm Hg, 300 mm Hg - Moderate: PaO2/FiO2 200 mm Hg, 100 mm Hg - Extremely serious—PaO2/FiO2 100 mm Hg Management Define and address the ARDS's underlying cause. Conservative fluid treatment and pulmonary protective ventilation. The mortality rate was shown to be lower when tidal volumes of 6 mL/kg of estimated body weight were used, with a plateau pressure aim of 30 cm H2O. If plateau pressures are higher than 30 cm H2O, tidal volumes can be decreased to 4 mL/kg. You can adjust your breathing rate to keep getting enough minute ventilation. If the pH is more than 7.30, permissive hypercapnia is acceptable. Lower respiratory rates are supported by recent data. ● PEEP doesn't have any established rules. High PEEP has not consistently proven beneficial in any clinical investigation. Reduced mortality may be an advantage for individuals with moderate to severe ARDS and high PEEP. Using neuromuscular blockade with sedation compared to placebo decreased mortality in individuals with early moderate to severe ARDS (PaO2/FiO2 150 mm Hg). The suggested processes include reducing patient-ventilator dyssynchrony, preventing breath stacking, and enhancing lung-protective ventilation effectiveness. In patients with moderate to severe ARDS (PaO2/FiO2 150 mm Hg and PEEP >5 cm H2O) who have been intubated for less than 36 hours, prone placement has been associated with a reduction in mortality and early extubation. Patients are left prone for 16 hours straight per day for up to 28 days or until their PaO2/FiO2 ratio is below 150 mm Hg. Patients who are supine require a PEEP of 10 cm H2O and a FiO2 of 0.6 for more than 4 hours. Posing on one's back reduces the negative effects of positive pressure ventilation on independent and less damaged airspaces. Extracorporeal membrane oxygenation (ECMO) is only used in cases of severe ARDS when other forms of support have failed. In patients with very severe ARDS (PaO2/FiO2 80 mm Hg), the use of early ECMO versus conventional mechanical ventilation that included ECMO as a rescue therapy had no difference in 60-day mortality. One randomized controlled trial suggested improved mortality in select ARDS patients referred to an ECMO center. Medication There is no single drug or drug cocktail that can prevent or enhance clinical outcomes in ARDS. The majority of treatment is supportive and focuses on resolving the underlying reason. Further Treatments Central venous pressure (CVP) can be used to evaluate fluid status for fluid management. Comparing a liberal fluid management strategy with a CVP aim of 10 to 14 cm H2O to a conservative fluid management strategy with a CVP target of 4 cm H2O. With no change in mortality, the cautious approach resulted in an increase in ventilator-free days and a decrease in ICU stays. Although a meta-analysis indicated some benefit for patients with PaO2/FiO2 60 mm Hg, a clinical trial on high-frequency oscillation breathing revealed higher mortality. Ventilation with airway pressure release may increase oxygenation, however studies have not found a mortality advantage. Noninvasive ventilation may enhance the risk of ventilation-induced lung injury in ARDS in individuals with severe hypoxemia. Although there is disagreement on the mortality benefit of corticosteroids in ARDS, they may increase oxygenation and airway pressures. Starting the treatment after the disease has been present for 14 days could be harmful. Clinical trials have not demonstrated any benefit for inhaled nitric oxide, surfactant, statins, nonsteroidal anti-inflammatory drugs, antioxidants, albuterol, or neutrophil elastase inhibitor. Clinical trials are currently being conducted for other treatments such dexamethasone, vitamin D, aspirin, mesenchymal stem cells, and others. pregnant women's issues The management of pregnant women with ARDS continues to revolve around supportive care while determining the underlying etiology. The health of the fetus, the potential need for delivery, and the physiologic changes brought on by pregnancy must all be taken into account. An obstetrician should monitor every pregnant patient. Admission Every patient with ARDS needs to be treated in an intensive care unit. Utilize lung protection ventilation while supplying sufficient PEEP. If PaO2/FiO2 is between 120 and 150 mm Hg, think about lying on your back and becoming paralyzed. If the first round of supportive measures fails, think about initiating an ECMO center referral. Vasopressor therapy is necessary if perfusion is insufficient even after intravascular volume has been restored (for example, in septic shock). Early physical treatment The following, in any combination, may be part of nursing care: - Mouth, skin, and eye care Prophylaxis for stress ulcers, deep vein thrombosis (DVT), and endotracheal tube suction - Adequate care while moving a patient from a supine to a prone position and vice versa - Maintain a sufficient amount of paralysis or sedation while using mechanical ventilation. - Care for tracheostomy Discharge standards - Resolving or correcting the underlying issue, enhancing respiratory condition, and restoring baseline oxygenation Patient Follow-Up Monitoring Important measurements of lung mechanics include driving pressure and static lung compliance. Until the patient is no longer in critical condition, daily labs are required. Daily CXRs are not required, but they should be requested in cases where endotracheal tube installation, the presence of developing infiltrates, catheter placement, deteriorating hypoxia, or problems with mechanical ventilation (such air leaks) might be present. While early parenteral nutrition may be hazardous, diet Trophic and full-calorie enteral feeds have demonstrated no difference in mortality. The mortality rate is expected to climb significantly across all severity groups, reaching up to 45%. Mortality rates for mild, moderate, and severe ARDS are 34.9%, 40.3%, and 46.1%, respectively. Complications Barotrauma - Nosocomial infection are some of the short-term effects. Delirium and an infection linked to a catheter - DVT - Internal bleeding brought on by a stress ulcer. Poor dietary habits - Syndrome of multiple organ dysfunction - Death The patient's age and concomitant conditions are associated to long-term problems. Reduced health-related quality of life, pulmonary dysfunction, and persistent reticular pattern/ground glass opacities on radiographic imaging - Neuropsychological impairment, including PTSD and depression
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