CPR Quality and Post-Cardiac Arrest Care

• Cardiopulmonary resuscitation (CPR) quality is critical to successful resuscitation from cardiac arrest.
• Key benchmarks of quality CPR:
• Compression rate of 100–120 compressions/min.
• Compression depth of 5–6 cm.
• Compression fraction of at least 80%.
• Full chest recoil between compressions.
• A ventilation rate of 10 breaths/min.
• Restoration of adequate cardiac function is the defining factor of return of spontaneous circulation (ROSC).
• Restoration of good neurologic function is the defining factor of a successful resuscitation.
• Resuscitation of a cardiac arrest victim does not end with ROSC.
• Rapid diagnosis and proper management of the pathologic condition(s) that precipitated and resulted from the arrest, as well as goal- directed post–cardiac arrest care, can improve outcomes.
• Immediate percutaneous coronary intervention is indicated in patients with ST segment elevation myocardial infarction following ROSC, independent of neurological status.
• Hypothermic targeted temperature management (32°C–36°C [89.6°F–96.8°F] for 24 h) has been shown to improve survival and functional outcome of comatose cardiac arrest survivors.

Background and Importance:

• Cardiopulmonary arrest is defined by the triad of unconsciousness, apnea, and pulselessness.
• An estimated 340,000 out-of-hospital cardiac arrests (OHCAs) occur annually in the United States, an estimated annual incidence of 140/100,000.
• Approximately 180,000 OHCAs are treated by emergency medical services (EMS).
• Most EMS-treated OHCAs occur at home (70%) and are unwitnessed (50%).
• The proportion of EMS-treated cardiac arrest patients with an initial shockable rhythm of ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) has declined to approximately 18%.
• The number of patients receiving bystander cardiopulmonary resuscitation (CPR) remains low, averaging 40%.
• Automated external defibrillators (AEDs) are applied prior to EMS arrival in a minority of cases.
• Recent data indicates the survival rate to hospital discharge for EMS-treated OHCA is about 10%.
• Survival to hospital discharge following in-hospital cardiac arrest (IHCA) is about 26%.
• Of patients surviving to hospital discharge, 79% have good neurologic function (cerebral performance category of 1 or 2), independent of neurologic status on presentation.
• For comatose post-cardiac arrest patients who underwent hypothermic targeted temperature management (HTTM), the reported survival rate with good neurologic function has ranged from 20% to 50%.
• Regional and inter-institutional variability in survival exists after EMS-treated cardiac arrest.
• The entire system of care affects patient outcomes, and differences in outcomes across the country may reflect local practice variability and differences in delivery of the chain of survival.

Anatomy, Physiology, and Pathophysiology:

• Awareness of underlying causes of cardiac arrest helps direct therapy and diagnostic testing both during resuscitation and in the immediate post-cardiac arrest period.
• Cardiac arrest with presenting rhythm of VF or pVT often has a primary cardiac origin.
• Coronary artery disease is a common pathologic condition found in patients who experience OHCA
• Other primary cardiac etiologies of cardiac arrest include syndromes associated with sudden cardiac death due to ventricular dysrhythmias, including hypertrophic cardiomyopathy, Brugada syndrome, long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia, and arrhythmogenic right ventricular cardiomyopathy.
• Cardiac arrest can result from non-cardiac origins, and common etiologies include circulatory causes, metabolic disturbances, and drug toxicities.
• Circulatory etiologies of cardiac arrest include tension pneumothorax, pericardial tamponade, pulmonary embolus, and hypovolemia/hemorrhage.
• The most common electrolyte disturbance leading to cardiac arrest is hyperkalemia, which results in progressive widening of the QRS complex that can deteriorate to pVT, VF, asystole, or pulseless electrical activity (PEA).
• Cardiac arrest from drug toxicity has specific characteristics, depending on the offending agent and presenting toxidrome.
• Specific therapy directed at drug toxicity (e.g., naloxone for opiate overdose) is essential, but may not be immediately effective depending on the agent involved.
• Environmental etiologies including electrocution, hypothermia, and drowning can also result in cardiac arrest.
• Electrocution causes cardiac arrest through primary dysrhythmias or apnea.
• Alternating current in the range of 100 mA to 1 A (household and light industry) generally causes VF, whereas currents greater than 10 A (heavy industry or electrical transmission infrastructure) can cause ventricular asystole.
• Lightning produces a massive direct current electrocution that can result in asystole and prolonged apnea
• Hypothermia-induced cardiac arrest can manifest with any electrocardiographic rhythm, and successful resuscitation depends on rapid rewarming
• Once circulation is restored, patients should be warmed to a target of 32°C to 36°C (89.6° to 96.8°F) for 24 hours.
• Drowning is a form of asphyxia usually resulting in bradyasystolic arrest.
• Patients experiencing cardiac arrest secondary to hypothermia or drowning may benefit from prolonged resuscitation efforts.

Prehospital

• Most cardiac arrest cases managed in the emergency department (ED) initially occur outside the hospital.
• An increasing number of first responders, nontraditional providers (e.g., teachers, flight attendants), and public venues (e.g., airports, casinos, sports arenas, schools) are being equipped with AEDs.
• When coupled with regional and statewide campaigns to improve bystander CPR rates, including hands-only and dispatcher-assisted CPR, dramatic resuscitation rates have been achieved in communities where lay public providers feel empowered to respond within the first few minutes of arrest.
• Programs that fail to improve rates of bystander CPR or AED use within this critical time window are less likely to achieve increased survival rates.
• Advanced life support units staffed by paramedics often have standing orders to follow advanced cardiac resuscitation protocols.
• In cases of cardiac arrest refractory to properly performed advanced prehospital measures, the patient may be pronounced dead at the scene per protocols.
• If advanced hospital-based resuscitation strategies such as extracorporeal cardiopulmonary resuscitation (ECPR) or percutaneous coronary intervention (PCI) are available, then transport to a comprehensive resuscitation center may still be warranted.
• In systems where patients are transported in cardiac arrest, mechanical CPR results in better quality chest compressions during transport and is likely to be safer for EMS providers.
• Mechanical CPR can minimize interruptions in chest compressions, eliminate the need to switch rescuers due to provider fatigue, and can deliver consistent depth and rate of compressions.

History and Physical Examination

• It is often difficult to determine the cause of cardiac arrest at presentation.
• A differential diagnosis can be formulated based on history, physical examination, and electrocardiographic rhythm on arrival, key information is often unreliable or not available.
• The differential diagnosis can potentially be narrowed by the patient’s age, underlying diseases, and medications, when known.
• Historical information from family, bystanders, and EMS personnel provides key information regarding cause and prognosis.
• Information surrounding the event includes whether the arrest was witnessed, time of arrest, what the patient was doing (e.g., eating, exercising, trauma), possibility of drug ingestion, whether bystander CPR was performed, time of initial CPR, initial electrocardiographic rhythm, and interventions by EMS providers.
• Important past medical history includes baseline health, previous heart, lung, or renal disease, malignancy, hemorrhage, infection, and risk factors for coronary artery disease and pulmonary embolism.
• The patient’s current medications and allergies should be obtained if possible.
• Physical examination of a cardiac arrest patient is necessarily focused on a few key goals:
• ensuring the adequacy of airway patency and ventilation
• confirming the diagnosis of cardiac arrest
• finding evidence of the cause
• monitoring for complications of therapeutic interventions.
• This examination occurs in descending order of importance, simultaneously with therapeutic interventions, and is repeated frequently to assess for response to therapy and occurrence of complications.
• After the initial minutes of cardiac arrest, the physical examination may provide little evidence of the duration of arrest.
• Pupils dilate within 1 minute but may constrict if CPR is initiated immediately and performed effectively.
• Dependent lividity and rigor mortis develop after hours of cardiac arrest.
• Temperature is an unreliable predictor of duration of cardiac arrest because it does not crease significantly during the first hours of arrest, and hypothermia may cause cardiac arrest or be caused by prolonged arrest.

CPR Rate should maintain 100-120 compressions/min and depth of 5-6 cm. Restoration of cardiac and neurologic function are key. Post-cardiac arrest care and rapid diagnosis of the cause improves outcomes. Immediate PCI is needed for patients with STEMI after ROSC.