Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest Cardiac Arrest Cardiac arrest is the cessation of cardiac mechanical activity resulting in the absence of circulating blood flow. Cardiac arrest stops blood from flowing to vital organs, depriving them of... read more , including
Recognition of absent breathing and circulation
Basic life support with chest compressions and rescue breathing
Advanced cardiac life support (ACLS) with definitive airway and rhythm control
(See also Neonatal Resuscitation Neonatal Resuscitation Extensive physiologic changes accompany the birth process, sometimes unmasking conditions that posed no problem during intrauterine life. For that reason, a person with neonatal resuscitation... read more and Cardiopulmonary Resuscitation in Infants and Children Cardiopulmonary Resuscitation (CPR) in Infants and Children Despite the use of cardiopulmonary resuscitation (CPR), mortality rates for out-of-hospital cardiac arrest are about 90% for infants and children. Mortality rates for in-hospital cardiac arrest... read more .)
Prompt initiation of chest compressions and early defibrillation (when indicated) are the keys to success. Speed, efficiency, and proper application of CPR with the fewest possible interruptions determine successful outcome; the rare exception is profound hypothermia caused by cold water immersion, when successful resuscitation may be accomplished even after prolonged arrest (up to 60 minutes).
Overview of CPR
(See also the American Heart Association [AHA] 2020 guidelines for CPR and emergency cardiovascular care.)
Guidelines for health care professionals from the AHA are followed (see figure Adult comprehensive emergency cardiac care Adult comprehensive emergency cardiac care ). If a person has collapsed with possible cardiac arrest, a rescuer first establishes unresponsiveness and confirms absence of breathing or the presence of only gasping respirations. Then, the rescuer calls for help. Anyone answering is directed to activate the emergency response system (or appropriate in-hospital resuscitation personnel) and, if possible, obtain a defibrillator.
If no one responds, the rescuer first activates the emergency response system and then begins basic life support by giving 30 chest compressions at a rate of 100 to 120/minute and a depth of 5 to 6 cm, allowing the chest wall to return to full height between compressions, and then opening the airway (lifting the chin and tilting back the forehead) and giving 2 rescue breaths. The cycle of compressions and breaths is continued (see table CPR Techniques for Health Care Practitioners CPR Techniques for Health Care Practitioners ) without interruption; preferably each rescuer is relieved every 2 minutes. It is crucial that even untrained bystanders begin and maintain continuous chest compressions until skilled help arrives. Therefore, many emergency response providers now give pre-arrival instructions to callers, including phone instruction in compressions-only CPR.
When a defibrillator (manual or automated) becomes available, a person in ventricular fibrillation Ventricular Fibrillation (VF) Ventricular fibrillation causes uncoordinated quivering of the ventricle with no useful contractions. It causes immediate syncope and death within minutes. Treatment is with cardiopulmonary... read more (VF) or pulseless ventricular tachycardia Ventricular Tachycardia (VT) Ventricular tachycardia is ≥ 3 consecutive ventricular beats at a rate ≥ 120 beats/minute. Symptoms depend on duration and vary from none to palpitations to hemodynamic collapse and death. Diagnosis... read more (VT) is given an unsynchronized shock (see also Defibrillation Defibrillation Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest, including Recognition of absent breathing and circulation Basic life support with chest compressions... read more ). If the cardiac arrest is witnessed and a defibrillator is on the scene, a person in VF or VT should be immediately defibrillated, with compressions immediately resumed after shock is delivered; early defibrillation may promptly convert VF or pulseless VT to a perfusing rhythm. If the initial rhythm is pulseless electrical activity or asystole, an initial dose of epinephrine 1 mg IV/IO (intravenous/intraosseous) should be administered as soon as possible after recognition of cardiac arrest.
Adult comprehensive emergency cardiac care
* If an adequate number of trained personnel are available, patient assessment, CPR, and activation of the emergency response system should occur simultaneously.
Based on the 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
The techniques used in basic 1- and 2-rescuer CPR are listed in Table CPR Techniques for Health Care Practitioners CPR Techniques for Health Care Practitioners . Mastery is best acquired by hands-on training such as that provided in the US under the auspices of the American Heart Association (1-800-AHA-USA1) or corresponding organizations in other countries.
Airway and Breathing
Opening the airway is 2nd priority (see Clearing and Opening the Upper Airway Clearing and Opening the Upper Airway Airway management consists of Clearing the upper airway Maintaining an open air passage with a mechanical device Sometimes assisting respirations (See also Overview of Respiratory Arrest.) read more ) after beginning chest compressions. For witnessed out-of-hospital cardiac arrest with an initial shockable rhythm, it is acceptable to provide passive oxygenation for the first 6 minutes, as part of an emergency medical services bundle of care aimed at minimizing pauses in the initial provision of CPR and defibrillation. For mechanical measures regarding resuscitation in children, see table Guide to Pediatric Resuscitation—Mechanical Measures Guide to Pediatric Resuscitation—Mechanical Measures .
For health care professionals, bag-valve-mask ventilation should be started as early as possible, but this should not delay initiation of compressions or defibrillation. Lay rescuers trained in CPR may give rescue breaths delivered mouth-to-mouth (adults, adolescents, and children) or combined mouth-to-mouth-and-nose (infants). If available, an oropharyngeal airway may be inserted to maintain airway patency during bag-mask ventilation. Cricoid pressure is not recommended.
If abdominal distention develops, the airway is rechecked for patency, and the amount of air delivered during rescue breathing is reduced. Nasogastric intubation to relieve gastric distention is delayed until suction equipment is available because regurgitation with aspiration of gastric contents may occur during insertion. If marked gastric distention interferes with ventilation prior to availability of suction and cannot be corrected by the above methods, patients are positioned on their side, the epigastrium is compressed, and the airway is cleared.
When qualified rescuers are present, an advanced airway (endotracheal tube or supraglottic airway) is placed without interruption of chest compressions after initial CPR and defibrillation attempts, as described under Airway Establishment and Control Airway Establishment and Control Airway management consists of Clearing the upper airway Maintaining an open air passage with a mechanical device Sometimes assisting respirations (See also Overview of Respiratory Arrest.) read more . A breath is given every 6 seconds (10 breaths/minute) without interrupting chest compression in adults; infants and children are given breaths every 2 to 3 seconds (20 to 30 breaths/minute). However, chest compression and defibrillation take precedence over endotracheal intubation. Unless highly experienced rescuers are available, endotracheal intubation may be delayed in favor of ventilation with a bag-valve-mask Bag-Valve-Mask Devices If no spontaneous respiration occurs after airway opening and no respiratory devices are available, rescue breathing (mouth-to-mask or mouth-to-barrier device) is started; mouth-to-mouth ventilation... read more , laryngeal mask airway Laryngeal Mask Airways (LMA) If no spontaneous respiration occurs after airway opening and no respiratory devices are available, rescue breathing (mouth-to-mask or mouth-to-barrier device) is started; mouth-to-mouth ventilation... read more , or similar device.
For patients suspected of having COVID-19, the American Heart Association released a revised CPR algorithm (1 Airway and breathing reference Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest, including Recognition of absent breathing and circulation Basic life support with chest compressions... read more ), which advises the following:
Initial passive oxygenation
Preference for endotracheal intubation over bag-valve-mask ventilation or supraglottic airway placement
Use of a viral filter on bag-valve devices or ventilators
This guidance aims to decrease the risk to the health care workers providing care during cardiac arrest.
Airway and breathing reference
1. Edelson DP, Sasson C, Chan PS, et al; American Heart Association ECC Interim COVID Guidance Authors: Interim Guidance for Basic and Advanced Life Support in Adults, Children, and Neonates With Suspected or Confirmed COVID-19: From the Emergency Cardiovascular Care Committee and Get With The Guidelines-Resuscitation Adult and Pediatric Task Forces of the American Heart Association. Circulation. 141(25):e933–e943, 2020. doi: 10.1161/CIRCULATIONAHA.120.047463
Chest compression should be started immediately on recognition of cardiac arrest and done with minimal interruption until defibrillation is available. In an unresponsive patient whose collapse was unwitnessed, the trained rescuer should immediately begin external (closed chest) cardiac compressions, followed by rescue breathing. Chest compressions must not be interrupted for>10 seconds at any time (eg, for intubation, defibrillation, rhythm analysis, central IV catheter placement, or transport). A compression cycle should consist of 50% compression and 50% release; during the release phase, it is important to allow the chest to recoil fully. Rhythm interpretation and defibrillation (if appropriate) are done as soon as a defibrillator is available.
The recommended chest compression depth for adults is about 5 to 6 cm. Ideally, external cardiac compression produces a palpable pulse with each compression, although cardiac output is only 20 to 30% of normal. However, palpation of pulses during chest compression is difficult, even for experienced clinicians, and often unreliable. Quantitative end-tidal carbon dioxide monitoring may provide a better estimate of cardiac output during chest compressions; patients with inadequate perfusion have little venous return to the lungs and hence a low end-tidal carbon dioxide (as do those with hyperventilation). While there is limited evidence supporting specific numbers in physiologic monitoring, it is generally accepted that an end-tidal carbon dioxide level of 10 to 20 mm Hg is associated with adequate CPR. A sudden significant rise in end-tidal carbon dioxide level, usually to a value greater than 30 mm Hg, or a palpable pulse during pause in compressions, indicates restoration of spontaneous circulation.
Mechanical chest compression devices are available; these devices are as effective as properly executed manual compressions and can minimize effects of performance error and fatigue. They may be particularly helpful in some circumstances, such as during patient transport or in the cardiac catheterization laboratory.
Open-chest cardiac compression may be effective but is used only in patients with penetrating chest injuries, shortly after cardiac surgery (ie, within 48 hours), in cases of cardiac tamponade, and most especially after cardiac arrest in the operating room when the patient’s chest is already open. However, thoracotomy Thoracotomy Thoracotomy is surgical opening of the chest. It is done to evaluate and treat pulmonary problems when noninvasive procedures are nondiagnostic or unlikely to be definitive. The principal indications... read more requires training and experience and is best done only within these limited indications.
Complications of chest compression
A frequent complication is regurgitation followed by aspiration of gastric contents, causing life-threatening aspiration pneumonia Aspiration Pneumonitis and Pneumonia Aspiration pneumonitis and pneumonia are caused by inhaling toxic and/or irritant substances, most commonly large volumes of upper airway secretions or gastric contents, into the lungs. Chemical... read more in resuscitated patients.
Costochondral separation and fractured ribs often cannot be avoided because it is important to compress the chest enough to produce sufficient blood flow. Fractures are quite rare in children because of the flexibility of the chest wall. Bone marrow emboli to the lungs have rarely been reported after external cardiac compression, but there is no clear evidence that they contribute to mortality. Lung injury is rare, but pneumothorax Pneumothorax (Traumatic) Traumatic pneumothorax is air in the pleural space resulting from trauma and causing partial or complete lung collapse. Symptoms include chest pain from the causative injury and sometimes dyspnea... read more after a penetrating rib fracture may occur. Tension pneumothorax should be considered in a patient who has achieved return of spontaneous circulation after prolonged CPR, and subsequently becomes difficult to ventilate, or who is hypoxic and suddenly rearrests. Serious myocardial injury caused by compression is highly unlikely, with the possible exception of injury to a preexisting ventricular aneurysm. Concern for these injuries should not deter the rescuer from doing CPR.
Laceration of the liver is a rare but potentially serious (sometimes fatal) complication and is usually caused by compressing the abdomen below the sternum. Rupture of the stomach (particularly if the stomach is distended with air) is also a rare complication. Delayed rupture of the spleen is very rare.
The most common rhythm in witnessed adult cardiac arrest is ventricular fibrillation Ventricular Fibrillation (VF) Ventricular fibrillation causes uncoordinated quivering of the ventricle with no useful contractions. It causes immediate syncope and death within minutes. Treatment is with cardiopulmonary... read more (VF); rapid conversion to a perfusing rhythm is essential. Pulseless ventricular tachycardia Ventricular Tachycardia (VT) Ventricular tachycardia is ≥ 3 consecutive ventricular beats at a rate ≥ 120 beats/minute. Symptoms depend on duration and vary from none to palpitations to hemodynamic collapse and death. Diagnosis... read more (VT) is treated the same as VF.
Prompt defibrillation is the only intervention for cardiac arrest, other than high-quality CPR, that has been shown to improve survival; however, the success of defibrillation is time dependent, with about a 10% decline in success after each minute of VF (or pulseless VT). Automated external defibrillators (AEDs) allow minimally trained rescuers to treat VT or VF. Their use by first responders (police and fire services) and their prominent availability in public locations have increased the likelihood of resuscitation.
Defibrillating paddles or pads are placed either between the clavicle and the 2nd intercostal space along the right sternal border and over the 5th or 6th intercostal space at the apex of the heart (in the mid-axillary line). Alternatively, the 2 pads may be placed with one pad over the anterior left hemithorax and the other pad on the posterior left hemithorax. Conventional defibrillator paddles are rarely present on modern defibrillators. When present, paddles are used with conducting paste; pads have conductive gel incorporated into them. One initial shock is advised as soon as a shockable rhythm is detected, after which chest compressions are immediately resumed. Energy level for biphasic defibrillators is between 150 and 200 joules (2 joules/kg in children) for the initial shock; monophasic defibrillators are set at 360 joules for the initial shock. Postshock rhythm is not checked until after 2 minutes of chest compressions. Subsequent shocks are delivered at the same or higher energy level (maximum 360 joules in adults, or 10 joules/kg in children). Patients remaining in VF or VT receive continued chest compression and ventilation and optional drug therapy Drugs for ACLS Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest, including Recognition of absent breathing and circulation Basic life support with chest compressions... read more .
Monitor and IV
Electrocardiographic (ECG) monitoring is established to identify the underlying cardiac rhythm. An IV line may be started; 2 lines minimize the risk of losing IV access during CPR. Large-bore peripheral lines in the antecubital veins are preferred. In adults and children, if a peripheral line cannot be established, a subclavian or femoral central line (see Procedure Central Venous Catheterization A number of procedures are used to gain vascular access. Most patients’ needs for IV fluid and drugs can be met with a percutaneous peripheral venous catheter. If blind percutaneous placement... read more ) can be placed provided it can be done without stopping chest compression (often difficult). Intraosseous lines (see Intraosseous Infusion Intraosseous Infusion A number of procedures are used to gain vascular access. Most patients’ needs for IV fluid and drugs can be met with a percutaneous peripheral venous catheter. If blind percutaneous placement... read more ) are preferred alternatives, especially in children, as they can be placed quickly to avoid delay in administration of the first dose of epinephrine. Femoral vein catheters (see Procedure Central Venous Catheterization A number of procedures are used to gain vascular access. Most patients’ needs for IV fluid and drugs can be met with a percutaneous peripheral venous catheter. If blind percutaneous placement... read more ) are an option because CPR does not need to be stopped and they have less potential for lethal complications; however, they may have a lower rate of successful placement because no discrete femoral arterial pulsations are available to guide insertion.
The type and volume of fluids or drugs given depend on the clinical circumstances. Usually, IV 0.9% saline is given slowly (sufficient only to keep an IV line open); vigorous volume replacement (crystalloid and colloid solutions, blood) is required only when arrest results from hypovolemia (see Intravenous Fluid Resuscitation Intravenous Fluid Resuscitation Almost all circulatory shock states require large-volume IV fluid replacement, as does severe intravascular volume depletion (eg, due to diarrhea or heatstroke). Intravascular volume deficiency... read more ), or as part of the management of cardiogenic shock after return of spontaneous circulation.
In accidental electrical shock Electrical Injuries Electrical injury is damage caused by generated electrical current passing through the body. Symptoms range from skin burns to damage to internal organs and other soft tissues, cardiac arrhythmias... read more , rescuers must be certain that the patient is no longer in contact with the electrical source to avoid shocking themselves. Use of nonmetallic grapples or rods and grounding of the rescuer allows for safe removal of the patient before starting CPR.
In drowning Drowning Drowning is respiratory impairment resulting from submersion in a liquid medium. It can be nonfatal (previously called near drowning) or fatal. Drowning results in hypoxia, which can damage... read more , rescue breathing may be started in shallow water, although chest compression is not likely to be effectively done until the patient is placed horizontally on a firm surface.
If cardiac arrest follows traumatic injury, airway-opening maneuvers and a brief period of external ventilation after clearing the airway have the highest priority because airway obstruction is the most likely treatable cause of arrest. If cervical spine injury is suspected, jaw thrust, but not head tilt and chin lift, is advised. Other survivable causes of traumatic cardiac arrest include cardiac tamponade Cardiac Tamponade Cardiac tamponade is accumulation of blood in the pericardial sac of sufficient volume and pressure to impair cardiac filling. Patients typically have hypotension, muffled heart tones, and distended... read more and tension pneumothorax Pneumothorax (Tension) Tension pneumothorax is accumulation of air in the pleural space under pressure, compressing the lungs and decreasing venous return to the heart. (See also Overview of Thoracic Trauma.) Tension... read more , for which immediate needle decompression is lifesaving. However, most patients with traumatic cardiac arrest have severe hypovolemia due to blood loss (for which chest compression may be ineffective) or nonsurvivable brain injuries.
Drugs for ACLS
Despite widespread and long-standing use, no drug or drug combination has been definitively shown to increase neurologically intact survival to hospital discharge in patients with cardiac arrest. Some drugs do seem to improve the likelihood of restoration of spontaneous circulation (ROSC) and thus may reasonably be given (for dosing, including pediatric, see table Drugs for Resuscitation Drugs for Resuscitation* ). Drug therapy for shock and cardiac arrest continues to be researched.
In a patient with a peripheral IV line, drug administration is followed by a fluid bolus (“wide open” IV in adults; 3 to 5 mL in young children) to flush the drug into the central circulation. In a patient without IV or intraosseous (IO) access, naloxone, atropine, and epinephrine, when indicated, may be given via the endotracheal tube at 2 to 2.5 times the IV dose. During administration of a drug via endotracheal tube, compression should be briefly stopped.
The main first-line drug used in cardiac arrest is
Epinephrine 1 mg IV/IO should be given as soon as possible to patients with a nonshockable initial rhythm and may be repeated every 3 to 5 minutes. It should be given early in nonshockable rhythms, because recent evidence suggests survival is increased when it is given in the first 5 minutes of resuscitation, or for ventricular tachycardia Ventricular Tachycardia (VT) Ventricular tachycardia is ≥ 3 consecutive ventricular beats at a rate ≥ 120 beats/minute. Symptoms depend on duration and vary from none to palpitations to hemodynamic collapse and death. Diagnosis... read more (VT) or ventricular fibrillation Ventricular Fibrillation (VF) Ventricular fibrillation causes uncoordinated quivering of the ventricle with no useful contractions. It causes immediate syncope and death within minutes. Treatment is with cardiopulmonary... read more (VF) refractory to two shocks. It has combined alpha-adrenergic and beta-adrenergic effects. The alpha-adrenergic effects may augment coronary diastolic pressure, thereby increasing subendocardial perfusion during chest compressions. Epinephrine also increases the likelihood of successful defibrillation. However, beta-adrenergic effects may be detrimental because they increase oxygen requirements (especially of the heart) and cause vasodilation. Intracardiac injection of epinephrine is not recommended because, in addition to interrupting precordial compression, pneumothorax, coronary artery laceration, and cardiac tamponade may occur.
Amiodarone 300 mg can be given once if a third attempt at defibrillation is unsuccessful after epinephrine, followed by 1 dose of 150 mg. It is also of potential value if VT or VF recurs after successful defibrillation; a lower dose is given over 10 minutes followed by a continuous infusion. There is no persuasive proof that it increases survival to hospital discharge. Lidocaine is an alternative antiarrhythmic to amiodarone, with an initial dose of 1 to 1.5 mg/kg, followed by a second dose of 0.5 to 0.75 mg/kg.
A single dose of vasopressin 40 units, which has a duration of activity of 40 minutes, is an alternative to epinephrine (adults only). However, it is no more effective than epinephrine and is therefore no longer recommended as a first-line drug in the American Heart Association's guidelines. However, in the unlikely case of a lack of epinephrine during CPR, vasopressin may be substituted.
A range of additional drugs may be useful in specific settings.
Atropine sulfate is a vagolytic drug that increases heart rate and conduction through the atrioventricular node. It is given for symptomatic bradyarrhythmias and high-degree atrioventricular nodal block. It is no longer recommended for asystole or pulseless electrical activity.
Calcium chloride is recommended for patients with hyperkalemia Hyperkalemia Hyperkalemia is a serum potassium concentration > 5.5 mEq/L (> 5.5 mmol/L), usually resulting from decreased renal potassium excretion or abnormal movement of potassium out of cells. There are... read more , hypermagnesemia Hypermagnesemia Hypermagnesemia is a serum magnesium concentration > 2.6 mg/dL (> 1.05 mmol/L). The major cause is renal failure. Symptoms include hypotension, respiratory depression, and cardiac arrest. Diagnosis... read more , hypocalcemia Hypocalcemia Hypocalcemia is a total serum calcium concentration 8.8 mg/dL ( 2.20 mmol/L) in the presence of normal plasma protein concentrations or a serum ionized calcium concentration 4.7 mg/dL ( 1.17... read more , or calcium channel blocker toxicity. In other patients, because intracellular calcium is already higher than normal, additional calcium is likely to be detrimental. Because cardiac arrest in patients on renal dialysis is often a result of or accompanied by hyperkalemia, these patients may benefit from a trial of calcium if bedside potassium determination is unavailable. Caution is necessary because calcium exacerbates digitalis toxicity and can cause cardiac arrest.
Lidocaine is now recommended as an alternative to amiodarone for VF or VT that is unresponsive to defibrillation and initial vasopressor therapy with epinephrine. It may also be considered after ROSC due to VF or VT (in adults) to prevent recurrent VF or VT.
Magnesium sulfate has not been shown to improve outcome in randomized clinical studies. However, it may be helpful in patients with torsades de pointes Long QT Syndrome and Torsades de Pointes Ventricular Tachycardia Torsades de pointes is a specific form of polymorphic ventricular tachycardia in patients with a long QT interval. It is characterized by rapid, irregular QRS complexes, which appear to be twisting... read more or known or suspected magnesium deficiency (ie, alcoholics, patients with protracted diarrhea).
Procainamide is a 2nd-line drug for treatment of refractory VF or VT. However, procainamide is not recommended for pulseless arrest in children and is no longer recommended by American Heart Association guidelines for treatment of post-arrest ventricular arrhythmias. However, the European Resuscitation Council includes it as an alternative to amiodarone in the treatment of ventricular tachycardia with a pulse in both adults and pediatrics per the 2021 guidelines, as some studies have shown an association with fewer major adverse events as compared with amiodarone.
Phenytoin may rarely be used to treat VT, but only when VT is due to digitalis toxicity and is refractory to other drugs. A dose of 50 to 100 mg/minute every 5 minutes is given until rhythm improves or the total dose reaches 20 mg/kg.
Sodium bicarbonate is no longer recommended unless cardiac arrest is caused by hyperkalemia, severe metabolic acidosis, or tricyclic antidepressant overdose. Sodium bicarbonate may be considered when cardiac arrest is prolonged (> 10 minutes); it is given only if there is good ventilation. When sodium bicarbonate is used, serum bicarbonate concentration or base deficit should be monitored before infusion and after each 50-mEq dose (1 to 2 mEq/kg in children).
VF or pulseless VT is treated with one direct-current shock, preferably with biphasic waveform, as soon as possible after those rhythms are identified. Despite some laboratory evidence to the contrary, it is not recommended to delay defibrillation to administer a period of chest compressions. Chest compression should be interrupted as little as possible and for no more than 10 seconds at a time for defibrillation. Recommended energy levels for defibrillation vary: 120 to 200 joules for biphasic waveform and 360 joules for monophasic. If this treatment is unsuccessful after 2 attempts, epinephrine 1 mg IV is administered and repeated every 3 to 5 minutes. Defibrillation at the same energy level or higher is attempted 1 to 2 minutes after each drug administration. If VF persists, amiodarone 300 mg IV is given. Then, if VF/VT recurs, 150 mg is given followed by infusion of 1 mg/minute for 6 hours, then 0.5 mg/minute. Current versions of automatic external defibrillators (AEDs) provide a pediatric cable that effectively reduces the energy delivered to children. (For pediatric energy levels, see Defibrillation Defibrillation Despite the use of cardiopulmonary resuscitation (CPR), mortality rates for out-of-hospital cardiac arrest are about 90% for infants and children. Mortality rates for in-hospital cardiac arrest... read more ; for drug doses, see table Drugs for Resuscitation Drugs for Resuscitation* .)
Asystole can be mimicked by a loose or disconnected monitor lead; thus, monitor connections should be checked and the rhythm viewed in an alternative lead. If asystole is confirmed, the patient is given epinephrine 1 mg IV repeated every 3 to 5 minutes. Defibrillation of apparent asystole (because it “might be fine VF”) is discouraged because electrical shocks may injure the nonperfused heart.
Pulseless electrical activity is circulatory collapse that occurs despite satisfactory electrical complexes on the electrocardiogram (ECG). Patients with pulseless electrical activity receive epinephrine 1.0 mg IV repeated every 3 to 5 minutes, followed by 500- to 1000-mL (20 mL/kg for children) infusion of 0.9% saline if hypovolemia is suspected. Cardiac tamponade can cause pulseless electrical activity, but this disorder usually occurs in patients after thoracotomy and in patients with known pericardial effusion or major chest trauma. In such settings, immediate pericardiocentesis or thoracotomy is done (see figure Pericardiocentesis Treatment Pericarditis is inflammation of the pericardium, often with fluid accumulation in the pericardial space. Pericarditis may be caused by many disorders (eg, infection, myocardial infarction, trauma... read more ). Tamponade is rarely an occult cause of cardiac arrest but, if suspected, can be confirmed by ultrasonography or, if ultrasonography is unavailable, pericardiocentesis.
Termination of Resuscitation
CPR should be continued until the cardiopulmonary system is stabilized, the patient is pronounced dead, or a lone rescuer is physically unable to continue. If cardiac arrest is thought to be due to hypothermia, CPR should be continued until the body is rewarmed to 34° C.
The decision to terminate resuscitation is a clinical one, and clinicians take into account duration of arrest, age of the patient, and prognosis of underlying medical conditions. The decision is typically made when spontaneous circulation has not been established after CPR and advanced cardiovascular life support measures have been done. In intubated patients, an end-tidal carbon dioxide (ETCO2) level of < 10 mm Hg is a poor prognostic sign.
Restoration of spontaneous circulation (ROSC) is only an intermediate goal in resuscitation. The ultimate goal is survival to hospital discharge with good neurologic function, which is achieved by only a minority of patients with ROSC. To maximize the likelihood of a good outcome, clinicians must provide good supportive care (eg, manage blood pressure, temperature, and cardiac rhythm) and treat underlying conditions, particularly acute coronary syndromes Overview of Acute Coronary Syndromes (ACS) Acute coronary syndromes result from acute obstruction of a coronary artery. Consequences depend on degree and location of obstruction and range from unstable angina to non–ST-segment elevation... read more .
Postresuscitative care includes mitigation of reperfusion injury occurring after the period of ischemia. Postresuscitative care should begin immediately after spontaneous circulation is determined. Oxygen administration should be titrated down to an SpO2 of 94% to minimize hyperoxic damage to lungs. Ventilation rate and volume should be titrated to an end-tidal carbon dioxide reading of 35 to 40 mm Hg. A fluid bolus should be administered if tolerated, as well as vasopressor infusion.
Postresuscitation laboratory studies include arterial blood gases (ABG), complete blood count (CBC), and blood chemistries, including electrolytes, glucose, BUN (blood urea nitrogen), creatinine, and cardiac markers. (Creatine kinase is usually elevated because of skeletal muscle damage caused by CPR; troponins, which are unlikely to be affected by CPR or defibrillation, are preferred.) Arterial PaO2 should be kept near normal values (80 to 100 mm Hg). Hematocrit should be maintained at ≥ 30% (if cardiac etiology is suspected), and glucose at 140 to 180 mg/dL (7.7 to 9.9 mmol/L); electrolytes, especially potassium, should be within the normal range.
When indicated, coronary angiography should be done emergently (rather than later during the hospital course) so that if percutaneous coronary intervention (PCI) is needed, it is done as soon as possible. The decision to do cardiac catheterization Cardiac Catheterization Cardiac catheterization is the passage of a catheter through peripheral arteries or veins into cardiac chambers, the pulmonary artery, and coronary arteries and veins. Cardiac catheterization... read more after resuscitation from cardiac arrest should be individualized based on the electrocardiogram (ECG), the interventional cardiologist's clinical impression, and the patient's prognosis. However, guidelines suggest doing emergency angiography for adult patients in whom a cardiac cause is suspected and who have
ST-segment elevation (STEMI), or new left bundle branch block (LBBB) on the ECG
Some researchers advocate liberal use of cardiac catheterization after ROSC, doing the procedure on most patients unless the etiology is clearly unlikely to be cardiac (eg, drowning) or there are contraindications (eg, intracranial bleeding).
Only about 10% of all cardiac arrest survivors have good central nervous system function (cerebral performance category [CPC] score 1 or 2—see table Cerebral Performance Category Scale Cerebral Performance Category Scale (Adult)* ) at hospital discharge. A CPC score of 1 is indicative of good cerebral performance (patient is conscious, alert, able to work but may have mild neurologic or psychologic deficit). A CPC score of 2 is indicative of moderate cerebral performance (patient is conscious, able to do activities of daily living [ADLs] and work in a simple environment). Hypoxic brain injury is a result of ischemic damage and cerebral edema (see pathophysiology of cardiac arrest Pathophysiology Cardiac arrest is the cessation of cardiac mechanical activity resulting in the absence of circulating blood flow. Cardiac arrest stops blood from flowing to vital organs, depriving them of... read more ). Both damage and recovery may evolve over 48 to 72 hours after resuscitation.
Maintenance of oxygenation and cerebral perfusion pressure (avoiding hyperventilation, hyperoxia, hypoxia, and hypotension) may reduce cerebral complications. Both hypoglycemia and hyperglycemia may damage the post-ischemic brain and should be treated.
In adults, targeted temperature management (maintaining body temperature of 32 to 36° C) is recommended for patients who remain unresponsive after spontaneous circulation has returned (1, 2 Postresuscitative care references Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest, including Recognition of absent breathing and circulation Basic life support with chest compressions... read more ). Cooling is begun as soon as spontaneous circulation has returned. Techniques to induce and maintain hypothermia can be either external or invasive. External cooling methods are easy to apply and range from the use of external ice packs to several commercially available external cooling devices that circulate high volumes of chilled water over the skin. For internal cooling, chilled IV fluids (4° C) can be rapidly infused to lower body temperature, but this method may be problematic in patients who cannot tolerate much additional fluid volume. Also available are external heat-exchange devices that circulate chilled saline to an indwelling IV heat-exchange catheter using a closed-loop design in which chilled saline circulates through the catheter and back to the device, rather than into the patient. Another invasive method for cooling uses an extracorporeal device that circulates and cools blood externally then returns it to the central circulation. Regardless of the method chosen, the goal is to cool the patient rapidly and to maintain the core temperature between 32° C and 36° C for 24 hours after restoration of spontaneous circulation. Currently, there is no evidence that any specific temperature within this range is superior, but it is imperative to avoid hyperthermia.
Numerous pharmacologic treatments, including free radical scavengers, antioxidants, glutamate inhibitors, and calcium channel blockers, are of theoretic benefit; many have been successful in animal models, but none have proved effective in human trials.
Blood pressure support
Current recommendations are to maintain a mean arterial pressure (MAP) of > 65 mm Hg and systolic blood pressure > 90 mm Hg. In patients known to be hypertensive, a reasonable target is systolic blood pressure 30 mm Hg below prearrest level. MAP is best measured with an intra-arterial catheter. Use of a flow-directed pulmonary artery catheter for hemodynamic monitoring has been largely discarded.
Blood pressure support includes
IV crystalloid infusion (normal saline or lactated Ringer's)
Inotropic or vasopressor drugs with a goal of maintaining systolic blood pressure of at least 90 mm Hg and MAP of at least 65 mm Hg
Rarely intra-aortic balloon counterpulsation
Patients with low MAP and low central venous pressure should have IV fluid challenge with 0.9% saline infused in 250-mL increments.
Although use of inotropic and vasopressor drugs has not proved to enhance long-term survival, older adults with moderately low MAP (70 to 80 mm Hg) and normal or high central venous pressure may receive an infusion of an inotrope (eg, dobutamine started at 2 to 5 mcg/kg/minute). Amrinone or milrinone are alternatives that are rarely used (see table Drugs for Resuscitation Drugs for Resuscitation* ).
If this therapy is ineffective, the inotrope and vasoconstrictor dopamine may be considered. Alternatives are epinephrine and the peripheral vasoconstrictors norepinephrine and phenylephrine (see table Drugs for Resuscitation Drugs for Resuscitation* ). However, vasoactive drugs should be used at the minimal dose necessary to achieve low-normal MAP because they may increase vascular resistance and decrease organ perfusion, especially in the mesenteric bed. They also increase the workload of the heart at a time when its capability is decreased because of postresuscitation myocardial dysfunction.
If MAP remains < 70 mm Hg in patients who may have sustained a myocardial infarction (MI), intra-aortic balloon counterpulsation should be considered. Patients with normal MAP and high central venous pressure may improve with either inotropic therapy or afterload reduction with nitroprusside or nitroglycerin.
Intra-aortic balloon counterpulsation can assist low-output circulatory states due to left ventricular pump failure that is refractory to drugs. A balloon catheter is introduced via the femoral artery, percutaneously or by arteriotomy, retrograde into the thoracic aorta just distal to the left subclavian artery. The balloon inflates during each diastole, augmenting coronary artery perfusion, and deflates during systole, decreasing afterload. Its primary value is as a temporizing measure when the cause of shock is potentially correctable by surgery or percutaneous intervention (eg, acute MI with major coronary obstruction, acute mitral insufficiency, ventricular septal defect).
Post-return of spontaneous circulation arrhythmia treatment
Although ventricular fibrillation Ventricular Fibrillation (VF) Ventricular fibrillation causes uncoordinated quivering of the ventricle with no useful contractions. It causes immediate syncope and death within minutes. Treatment is with cardiopulmonary... read more (VF) or ventricular tachycardia Ventricular Tachycardia (VT) Ventricular tachycardia is ≥ 3 consecutive ventricular beats at a rate ≥ 120 beats/minute. Symptoms depend on duration and vary from none to palpitations to hemodynamic collapse and death. Diagnosis... read more (VT) may recur after resuscitation, prophylactic antiarrhythmic drugs do not improve survival and are no longer routinely used. However, patients manifesting such rhythms may be treated with procainamide, lidocaine (see Other drugs Other drugs Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest, including Recognition of absent breathing and circulation Basic life support with chest compressions... read more ), or amiodarone (see First-line drugs First-line drugs Cardiopulmonary resuscitation (CPR) is an organized, sequential response to cardiac arrest, including Recognition of absent breathing and circulation Basic life support with chest compressions... read more ).
Postresuscitation rapid supraventricular tachycardias occur frequently because of high levels of beta-adrenergic catecholamines (both endogenous and exogenous) during cardiac arrest and resuscitation. These rhythms should be treated if extreme, prolonged, or associated with hypotension or signs of coronary ischemia. An esmolol IV infusion is given, beginning at 50 mcg/kg/min.
Patients who had arrest caused by VF or VT not associated with acute MI are candidates for an implantable cardioverter-defibrillator (ICD). Current ICDs are implanted similarly to pacemakers and have intracardiac leads and sometimes subcutaneous electrodes. They can sense arrhythmias and deliver either cardioversion or cardiac pacing as indicated.
Postresuscitative care references
1. Bernard SA, Gray TW, Buist MD, et al: Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med 346:557–563, 2002. doi: 10.1056/NEJMoa003289
2. Nielsen N, Wetterslev J, Cronberg T, et al: Targeted temperature management at 33°C versus 36°C after cardiac arrest. N Engl J Med 369:2197–2206, 2013. doi: 10.1056/NEJMoa1310519
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American Heart Association 2020 CPR and ECC Guidelines: These guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) are based on the most recent review of resuscitation science, protocols, and education.
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