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Emergency and Acute Medicine – Cardiac Arrest
Critical Update Notice
This summary reflects principles derived from the 2010 ACLS guidelines. Key updates emphasized early chest compressions with a C–A–B sequence, greater focus on post–cardiac arrest care including targeted temperature management, and removal of atropine from PEA/asystole algorithms.
Clinical Overview
Sudden cardiac arrest is defined by unresponsiveness, absence of a palpable pulse, and minimal or absent respirations. Survival is influenced by the presenting rhythm, total downtime, speed of defibrillation when indicated, and early initiation of high-quality basic life support.
Underlying Causes
Reversible contributors are commonly recalled as the “Hs and Ts”: hypovolemia, hypoxia, hydrogen ion excess (acidosis), hypo- or hyperkalemia, hypothermia, toxins, cardiac tamponade, tension pneumothorax, thrombosis (coronary or pulmonary), and trauma.
Special Populations
In children, arrest is more often secondary to respiratory failure rather than primary cardiac causes. Pediatric resuscitation requires shallower compressions (approximately one-third to one-half of chest depth), a 15:2 compression-to-ventilation ratio for two rescuers, and weight-based medication dosing.
In pregnancy, airway management may be difficult, compressions should be performed slightly higher on the sternum, and manual left uterine displacement should be used. Maternal survival remains the priority; emergent cesarean delivery may be considered if maternal resuscitation fails.
Clinical Recognition
Patients present with sudden loss of responsiveness, pulselessness, and agonal or absent respirations. Arrest may be preceded by chest pain, dyspnea, palpitations, seizure-like activity, hypotension, or altered mental status.
Immediate Assessment
Rapidly assess airway, breathing, and circulation, determine whether the rhythm is shockable or nonshockable, and initiate treatment according to ACLS algorithms without delay.
Diagnostic Evaluation After ROSC
Laboratory testing is indicated only after return of spontaneous circulation and may include electrolytes, renal function, cardiac biomarkers, arterial blood gas, CBC, lactate, therapeutic drug levels, and toxicology screening. ECG should assess for STEMI or acute coronary syndrome. Chest radiography confirms airway placement and evaluates for pulmonary causes. Echocardiography may identify tamponade or wall-motion abnormalities. Head CT may be required postresuscitation to evaluate neurologic causes.
Conditions To Exclude
Alternative causes of sudden collapse with a pulse include syncope, seizure, stroke, hypoglycemia, airway obstruction, head trauma, and toxic exposures.
Prehospital Management
Begin immediate high-quality CPR, confirm rhythm, and defibrillate pulseless VT or VF as early as possible. Secure the airway only if it does not interrupt compressions. After ROSC, stabilize blood pressure, obtain a 12-lead ECG, and transport to a facility capable of advanced postarrest and interventional cardiac care.
Early In-Hospital Resuscitation
Initiate ACLS with uninterrupted CPR, brief rhythm and pulse checks, early defibrillation when indicated, IV or IO access, continuous cardiac monitoring, and rhythm-directed therapy.
Definitive Emergency Treatment
For pulseless VT/VF, perform immediate defibrillation followed by CPR, epinephrine, and antiarrhythmics such as amiodarone or lidocaine; magnesium is used for torsades de pointes.
For asystole and pulseless electrical activity, confirm rhythm, administer epinephrine, and aggressively search for and correct reversible causes.
After ROSC, address the underlying etiology, provide ventilatory and hemodynamic support, correct metabolic abnormalities, evaluate for coronary ischemia with early catheterization when appropriate, initiate targeted temperature management in eligible patients, and monitor for seizures with continuous EEG when indicated.
Pharmacologic Support
Medications commonly used include epinephrine, amiodarone, lidocaine, magnesium sulfate, vasopressin (as an epinephrine substitute in adults), and sodium bicarbonate in select circumstances. Drug delivery should never interrupt CPR.
Disposition Planning
All patients with ROSC require ICU admission for comprehensive postarrest care and management of the precipitating cause. There are no discharge criteria directly from the arrest setting.
Follow-Up And Systems Care
Postarrest patients benefit from admission to intensive care units experienced in targeted temperature management and advanced cardiac support. Referral to regional cardiac arrest centers may improve outcomes.
Clinical Pearls And Pitfalls
Targeted temperature management improves neurologic outcomes in comatose postarrest patients. Recurrent arrest is common, requiring vigilant monitoring and rapid intervention. Early cardiology consultation is essential to determine candidacy for urgent cardiac catheterization.
Critical Update Notice
This summary reflects principles derived from the 2010 ACLS guidelines. Key updates emphasized early chest compressions with a C–A–B sequence, greater focus on post–cardiac arrest care including targeted temperature management, and removal of atropine from PEA/asystole algorithms.
Clinical Overview
Sudden cardiac arrest is defined by unresponsiveness, absence of a palpable pulse, and minimal or absent respirations. Survival is influenced by the presenting rhythm, total downtime, speed of defibrillation when indicated, and early initiation of high-quality basic life support.
Underlying Causes
Reversible contributors are commonly recalled as the “Hs and Ts”: hypovolemia, hypoxia, hydrogen ion excess (acidosis), hypo- or hyperkalemia, hypothermia, toxins, cardiac tamponade, tension pneumothorax, thrombosis (coronary or pulmonary), and trauma.
Special Populations
In children, arrest is more often secondary to respiratory failure rather than primary cardiac causes. Pediatric resuscitation requires shallower compressions (approximately one-third to one-half of chest depth), a 15:2 compression-to-ventilation ratio for two rescuers, and weight-based medication dosing.
In pregnancy, airway management may be difficult, compressions should be performed slightly higher on the sternum, and manual left uterine displacement should be used. Maternal survival remains the priority; emergent cesarean delivery may be considered if maternal resuscitation fails.
Clinical Recognition
Patients present with sudden loss of responsiveness, pulselessness, and agonal or absent respirations. Arrest may be preceded by chest pain, dyspnea, palpitations, seizure-like activity, hypotension, or altered mental status.
Immediate Assessment
Rapidly assess airway, breathing, and circulation, determine whether the rhythm is shockable or nonshockable, and initiate treatment according to ACLS algorithms without delay.
Diagnostic Evaluation After ROSC
Laboratory testing is indicated only after return of spontaneous circulation and may include electrolytes, renal function, cardiac biomarkers, arterial blood gas, CBC, lactate, therapeutic drug levels, and toxicology screening. ECG should assess for STEMI or acute coronary syndrome. Chest radiography confirms airway placement and evaluates for pulmonary causes. Echocardiography may identify tamponade or wall-motion abnormalities. Head CT may be required postresuscitation to evaluate neurologic causes.
Conditions To Exclude
Alternative causes of sudden collapse with a pulse include syncope, seizure, stroke, hypoglycemia, airway obstruction, head trauma, and toxic exposures.
Prehospital Management
Begin immediate high-quality CPR, confirm rhythm, and defibrillate pulseless VT or VF as early as possible. Secure the airway only if it does not interrupt compressions. After ROSC, stabilize blood pressure, obtain a 12-lead ECG, and transport to a facility capable of advanced postarrest and interventional cardiac care.
Early In-Hospital Resuscitation
Initiate ACLS with uninterrupted CPR, brief rhythm and pulse checks, early defibrillation when indicated, IV or IO access, continuous cardiac monitoring, and rhythm-directed therapy.
Definitive Emergency Treatment
For pulseless VT/VF, perform immediate defibrillation followed by CPR, epinephrine, and antiarrhythmics such as amiodarone or lidocaine; magnesium is used for torsades de pointes.
For asystole and pulseless electrical activity, confirm rhythm, administer epinephrine, and aggressively search for and correct reversible causes.
After ROSC, address the underlying etiology, provide ventilatory and hemodynamic support, correct metabolic abnormalities, evaluate for coronary ischemia with early catheterization when appropriate, initiate targeted temperature management in eligible patients, and monitor for seizures with continuous EEG when indicated.
Pharmacologic Support
Medications commonly used include epinephrine, amiodarone, lidocaine, magnesium sulfate, vasopressin (as an epinephrine substitute in adults), and sodium bicarbonate in select circumstances. Drug delivery should never interrupt CPR.
Disposition Planning
All patients with ROSC require ICU admission for comprehensive postarrest care and management of the precipitating cause. There are no discharge criteria directly from the arrest setting.
Follow-Up And Systems Care
Postarrest patients benefit from admission to intensive care units experienced in targeted temperature management and advanced cardiac support. Referral to regional cardiac arrest centers may improve outcomes.
Clinical Pearls And Pitfalls
Targeted temperature management improves neurologic outcomes in comatose postarrest patients. Recurrent arrest is common, requiring vigilant monitoring and rapid intervention. Early cardiology consultation is essential to determine candidacy for urgent cardiac catheterization.
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