Cardiac arrest - Basic Resuscitation Techniques

Management of Cardiac Arrest Introduction: The Critical Role of Early Intervention Cardiac arrest represents a medical emergency where the heart stops pumping blood effectively. Survival depends critically on early, uninterrupted cardiopulmonary resuscitation (CPR) begun as soon as possible. The first few minutes are crucial—every minute of delay significantly reduces the chance of survival with good brain function. This section covers the essential interventions that save lives during cardiac arrest. Chest Compressions: The Foundation of CPR Effective chest compressions are the cornerstone of CPR. When you perform chest compressions, you manually pump blood through the body, maintaining critical perfusion to the brain and heart while advanced interventions are arranged. The specific technique matters: Rate: Perform compressions at 100–120 compressions per minute. This pace ensures adequate blood circulation without going so fast that compression quality suffers. Depth: Press down 5–6 centimeters into the chest. This depth allows the heart to compress and refill with blood between compressions. Recoil: Allow full chest recoil after each compression. This relaxation phase is just as important as the compression itself, as it allows the heart to fill with blood before the next compression. These parameters create the optimal mechanical conditions for moving blood forward during arrest. Inexperienced rescuers often compress too slowly or incompletely, reducing effectiveness. Rhythm Checks and the Two-Minute Cycle CPR is not performed continuously without assessment. Instead, the approach follows a two-minute cycle: Perform continuous chest compressions for two minutes Check the patient's cardiac rhythm If a shockable rhythm is detected, deliver a defibrillation shock Resume compressions immediately This rhythm-checking approach prevents unnecessary interruptions to compressions (which would stop blood flow) while ensuring that shockable rhythms—which respond dramatically to defibrillation—are treated promptly. Airway Management and Oxygen High-flow oxygen is administered during CPR to maximize the oxygen content of blood being circulated by chest compressions. The goal is to deliver oxygen-rich blood to vital organs. Breathing is assisted using one of two methods: Bag-valve-mask ventilation: A manual device that delivers oxygen-enriched air to the lungs. This is often the initial approach. Advanced airway placement: Devices like endotracheal tubes that secure the airway and provide direct access to the lungs. Important clinical point: While advanced airway management might seem ideal, endotracheal intubation has not been shown to improve survival or neurological outcomes and may actually worsen outcomes in the prehospital setting. This is because intubation requires stopping chest compressions and carries risk of tube placement errors. Current evidence supports maintaining continuous compressions over pursuing advanced airway management early in resuscitation. Bag-valve-mask ventilation is preferred initially because it can be performed without interrupting compressions. Defibrillation: Recognizing and Treating Shockable Rhythms What Are Shockable Rhythms? When the heart stops working, it may enter one of two categories of rhythm: Shockable rhythms (respond to electrical therapy): Ventricular fibrillation (VF): The heart quivers chaotically rather than beating in an organized way. The muscle fibers contract randomly and independently. Pulseless ventricular tachycardia (PVT): The heart beats very fast but produces no pulse—blood isn't being effectively pumped. Non-shockable rhythms (don't respond to electrical therapy): Asystole (complete cardiac standstill—"flatline") Pulseless electrical activity (the heart shows electrical activity on the monitor but produces no pulse) The Crucial Difference in Outcomes The distinction between shockable and non-shockable rhythms is critical for prognosis: Shockable rhythms: 25–40% survival rate with appropriate treatment Non-shockable rhythms: Less than 5% survival rate This dramatic difference explains why identifying and treating shockable rhythms immediately is so important. Defibrillation and Device Types Defibrillation delivers an electrical shock to the heart to terminate chaotic electrical activity (VF or PVT) and allow the heart's natural pacemaker to resume organized beating. Modern defibrillators are biphasic devices, meaning the electrical current flows in two directions. Biphasic defibrillators are more likely to convert abnormal rhythms to normal rhythm with a single shock compared to older monophasic devices (which used current flowing in one direction only). Automated External Defibrillators (AEDs) Automated external defibrillators (AEDs) are portable devices designed to be used by lay rescuers—people without medical training. They revolutionized cardiac arrest management by enabling early defibrillation outside of hospitals. Key features of AEDs: Automatic rhythm analysis: The device automatically interprets the patient's cardiac rhythm Voice prompts: Clear instructions guide the rescuer through each step Shock advisory: The device determines whether a shock is needed Compression feedback: Many modern AEDs provide real-time feedback on compression quality, helping rescuers maintain proper depth and rate <extrainfo> Public Access Defibrillation Programs Public access defibrillation programs strategically place AEDs in high-traffic public locations (shopping centers, airports, office buildings) and train staff to use them. The goal is to minimize the time from collapse to defibrillation. These programs have been shown to improve early defibrillation rates and survival. </extrainfo> Why Bystander CPR and Dispatcher-Assisted CPR Matter <extrainfo> Bystander CPR Statistics Bystander CPR—CPR performed by someone at the scene rather than waiting for emergency services—significantly increases survival. However, it is performed in fewer than 30% of out-of-hospital arrests, highlighting a gap between its life-saving potential and actual implementation. Dispatcher-Assisted CPR When the emergency dispatcher provides instructions to a bystander, outcomes improve compared to unassisted bystander attempts. Dispatcher guidance increases both the likelihood that CPR will be performed and the quality of compressions delivered. </extrainfo> Medications During Cardiac Arrest Medications are used during advanced cardiac life support (ACLS) and follow specific timing protocols based on rhythm checks and the duration of resuscitation. Epinephrine Epinephrine (also called adrenaline) is the primary medication used in cardiac arrest. It works by: Increasing coronary perfusion pressure (the pressure that pushes blood through the coronary arteries supplying the heart muscle itself) Increasing cerebral perfusion pressure (pressure perfusing the brain) These effects help vital organs receive blood during CPR. Amiodarone and Lidocaine For patients with refractory ventricular fibrillation or pulseless ventricular tachycardia—meaning the rhythm persists despite defibrillation attempts—either amiodarone or lidocaine may be administered. These are antiarrhythmic medications that stabilize the heart's electrical system. Medication Timing Medications are not given randomly. Instead, they follow algorithmic protocols (step-by-step treatment plans) that specify when medications should be given based on: Current cardiac rhythm Duration of CPR Number of defibrillation attempts This systematic approach ensures medications are used at optimal times during resuscitation. Post-Resuscitation Care: Stabilization After Return of Spontaneous Circulation After a patient achieves return of spontaneous circulation (ROSC)—meaning the heart has resumed effective pumping—the focus shifts to preventing further deterioration and minimizing organ damage. Immediate Stabilization Airway protection and mechanical ventilation: Secure the airway and provide breathing support, often with continued high-flow oxygen Blood pressure maintenance: Monitor and support blood pressure to ensure adequate organ perfusion Fluid resuscitation: Careful intravenous fluid administration restores circulating volume Vasopressor support: Medications that increase blood pressure may be needed if fluids alone are insufficient Electrolyte and Temperature Management Electrolyte correction: Abnormalities in potassium, calcium, magnesium, and other electrolytes must be corrected promptly, as they can trigger fatal arrhythmias Targeted temperature management (therapeutic hypothermia): Cooling the patient's core body temperature to 32–36°C has been shown to potentially improve neurological outcomes after cardiac arrest. The hypothermia reduces the brain's metabolic rate, limiting damage from the period of inadequate blood flow during arrest. Preventing Recurrence Implantable cardioverter-defibrillator (ICD): Survivors of cardiac arrest from shockable rhythms may be candidates for an ICD—a device implanted under the skin that automatically detects and treats dangerous rhythms. ICDs significantly reduce the risk of sudden cardiac death recurrence. Summary: Management of cardiac arrest requires rapid initiation of high-quality chest compressions, early defibrillation for shockable rhythms, appropriate airway management and oxygenation, timely medication administration per protocol, and comprehensive post-resuscitation care focused on organ protection and stabilization. Every intervention—from the first compression to post-arrest cooling—works together to maximize survival and neurological recovery.