Cardiac Arrest

  • Author: Luan Lawson, MD, Brody School of Medicine at East Carolina University, Greenville, North Carolina
  • Editor: Lynda Daniel-Underwood, MD, Loma Linda University School of Medicine, Loma Linda, California
  • Last Updated: 2008


“Physician to the Resuscitation Bay Stat!” On arriving to the bay, you find EMS performing CPR on patient. EMS gives the report that they were called out for a 69 year old female complaining of general ill feeling and dizziness. EMS reports patient was stable in route until they rolled into the ED where patient became unresponsive, pulseless, and apneic.

Emergency medicine physicians must be adept at dealing with life threatening emergencies including cardiopulmonary arrest. Cardiac arrest claims over 250,000 lives a year and the majority of these events occur outside the hospital. Early initiation of cardiopulmonary resuscitation (CPR) and advanced cardiopulmonary life support (ACLS) has been shown to improve the mortality of cardiac arrest.


Upon completion of this self-study module, you should be able to:

  • Describe the BLS Primary survey
  • Describe the ACLS Secondary survey
  • List indications for defibrillation
  • List most frequent causes of Pulseless Electrical Activity
  • Interpret cardiac rhythm strips
  • Explain the appropriate diagnostic tests for cardiac arrest victims
  • Understand the role of therapeutic hypothermia

Primary Actions

As you walk into the resuscitation bay, what initial steps should be taken to evaluate and manage this cardiac arrest victim?

  • Perform BLS primary survey
  • Obtain finger stick blood sugar
  • Perform ACLS secondary survey

BLS Primary Survey

This basic approach to life support stresses early CPR and early defibrillation, but does not include advanced interventions. The goal is to support or restore effective oxygenation, ventilation, and circulation until return of spontaneous circulation or until ACLS interventions can be initiated. These actions have been shown to significantly improve the chance of survival and neurologic outcome. As each step is assessed the appropriate critical action should be performed before proceeding to the next assessment step. Remember, assess then perform the appropriate action.

  • Airway: Is the airway open? The airway should be opened using head tilt-chin lift or if trauma is suspected jaw thrust. If trauma is suspected, cervical immobilization must be maintained.
  • Breathing: Look, listen, and feel for adequate breathing. Initiate rescue breathing with bag-valve-mask ventilation if the patient is not adequately breathing. If it is difficult to compress air from the bag into the airway, reposition the head and consider using visualization and McGill forceps to remove any obstruction. BVM ventilation can be performed using a one or two person technique.
    • One Person Bag-Valve-Mask Technique: The single handed technique is more difficult to perform especially for people with smaller hands or less experience. A tight mask seal must be maintained to prevent loss of air and can be very difficult in patients with craniofacial abnormalities or facial hair. The one handed technique uses the thumb and index finger in a C configuration to grasp the body of the mask to form a seal while the third and fourth fingers grasp the ridge of the mandible. The fifth finger lifts at the angle of the mandible. The other hand compresses the bag. Dentures may be left in place while bagging to ensure a better seal with the mask and to prevent airway occlusion, but should be removed prior to intubation.
  • Two Person Bag-Valve-Mask Ventilation: The two handed rescue technique should be employed whenever possible to improve adequacy of ventilation. One person uses both hands to apply downward pressure on the mask onto the face while simultaneously lifting the ramus of the mandible. The other person uses both hands to squeeze the bag. Regardless of the technique employed, adequacy of ventilation can be assessed by inspecting the chest for rise and fall and auscultating the chest for adequate aeration. Epigastric sounds and abdominal distention suggest gastric insufflations and poor ventilation.
  • Circulation: Check carotid pulse for at least 5 seconds, but not longer than 10 seconds. If no pulse is present, cardiopulmonary resuscitation (CPR) should be initiated. Chest compressions should be performed at a rate of 80-100 per minute in adults.
  • Defibrillation: If no pulse is present, the rhythm should be assessed using a manual defibrillator or AED. Shocks should be provided as indicated and each shock should be immediately followed by CPR beginning with the chest compressions. Minimize any interruptions in chest compressions as this will rapidly decreased blood flow to the brain and heart.

ACLS Secondary Survey

The ACLS secondary survey involves more advanced, invasive techniques. It is critical to consider the differential diagnoses to appropriately identify and treat the underlying cause of cardiac arrest.

  • Airway: The airway of the unconscious patient should remain patent by use of the head tilt-chin life, jaw thrust, oropharyngeal airway, or nasopharyngeal airway. Endotracheal intubation is the most effective and definitive method of providing adequate ventilation and oxygenation. Endotracheal intubation should not delay delivery of defibrillation in patients with a shockable rhythm.
  • Breathing: The adequacy of oxygenation and ventilation should be confirmed by assessing the rise and fall of the chest, auscultation of equal breath sounds, absence of breath sounds over the epigastrum, monitoring end-tidal CO2 using capnometry or capnography. False readings may result from prolonged cardiac arrest and ingestion of carbonated beverages. The endotracheal tube should be secured and a chest radiograph obtained to ensure correct position relative to the carina. Remember that a chest x-ray does not ensure endotracheal intubation. Pulse oximetry should always always be monitored.
  • Circulation: Intravenous (IV) or intraosseous (IO) access should be obtained and the patient should be placed on a cardiac monitor to assess the patient’s cardiac rhythm and appropriate drugs should be given based on ACLS guidelines. All IV medications and blood may also be administered via intraosseous access. Several medications can be given via the endotracheal (ET) tube as well, if IV or IO access has not been established. The optimal dosing of drugs administered endotracheally has not been established, but 2-2 1/2 times the IV route is generally accepted.

NAVEL: ACLS Drugs Safe for Endotrachael Administration

  • Naloxone
  • Atropine
  • Vasopressin
  • Epinephrine
  • Lidocaine

Differential Diagnosis for Cardiac Arrest

Consider, identify, and treat potential reversible causes.

  • Hypovolemia
  • Hypoxia
  • Acidosis
  • Hypothermia
  • Tension pneumothorax
  • Cardiac tamponade
  • Electrolyte abnormality
  • Overdose
  • Trauma
  • Acute Coronary Syndrome
  • Obtain history and events surrounding arrest
  • Perform physical exam that may give clues to cause of arrest
  • Perform appropriate diagnostic studies
  • EKG: More than one-half of arrests in the US are cardiac in origin and the EKG can offer evidence of cardiac ischemia, various toxin exposure, or hyperkalemia.
  • ABG: shows the acid-base and oxygenation status of the patient
  • Serum electrolytes
  • Chest X-ray
  • Bedside ultrasound may be used to evaluate cardiac activity or the presence of pericardial effusions.
  • Postresuscitation care or termination of efforts


You perform the BLS primary survey. Airway is opened using head tilt-chin lift. The patient continues to be apneic with no evidence of breathing. Patient is ventilated with bag valve mask. No carotid pulse can be palpated during 7 seconds. Patient is placed on monitor and the following rhythm strip is handed to you:

The above rhythm demonstrates ventricular tachycardia. Almost all episodes of sudden cardiac death initiate from a ventricular tachydysrhythmia. Successful resuscitation is dependent on rapid defibrillation. Improved survival is related to witnessed arrest with initiation of bystander CPR, initial shockable rhythm, and rapid defibrillation and initiation of ACLS by a trained professional within 10 minutes of onset.

Once pulseless VT or VF is identified, the patient should be immediately defibrillated using 200J on a biphasic defibrillator or 360J on a monophasic defibrillator. ACLS recommends chest compressions should be interrupted only for ventilation, rhythm checks, and shock delivery since even a 5-10 second pause in compressions reduces the probability that the shock will terminate VF/pulseless VT.

You defibrillated your patient once with a monophasic defibrillator at 360J. How should you proceed?

ACLS currently recommends that only 1 shock is delivered which changed from their previous recommendations of 3 shocks. CPR starting with compressions should be immediately initiated after the shock without performing a pulse or rhythm check for 2 minutes (5 cycles) of CPR. In patients without an advanced airway, each cycle consists of 30 compressions and 2 ventilations. After 2 minutes of CPR, the rhythm should be rechecked, but the interruption in CPR should not exceed 10 seconds.

You cannot palpate a pulse and are given the following rhythm strip. What should you do next?

The rhythm strip demonstrates ventricular fibrillation (VF). The patient should be immediately shocked with the same amount of energy used previously. CPR should again be initiated immediately after the shock is delivered and should continue for 2 minutes. Once IV/IO access has been established, epinephrine 1mg should be administered every 3 to 5 minutes or vasopressin 40 U may be substituted one time for the first or second dose of epinephrine. You should continue CPR for 2 minutes until the pulse and rhythm is checked again. If the patient remains in VF, you should consider giving antiarrhythmics including amiodarone or lidocaine. Magnesium may be given for torsades de pointes.

Despite the above interventions, the patient remains pulseless. The next rhythm check reveals the following rhythm:

What is this rhythm and how should you proceed?

Without a pulse, this represents PEA (pulseless electrical activity). Both asystole and PEA are treated using the same ACLS algorithm. The ability to resuscitate the patient is dependent on effective CPR and the ability to identify any reversible etiologies of the arrest. Epinephrine 1mg should be administered every 3-5 minutes, but Vasopressin 40 U can be substituted for the first or second dose of epinephrine. No vasopressor medications have been shown to improve the survival rate for PEA, but are recommended to improve aortic diastolic blood pressure and coronary artery perfusion. Atropine 1mg IV/IO should be considered for asystole or slow PEA and may be repeated every 3 to 5 minutes for a total of 3 doses. Patients with PEA and asystole have poor outcomes, but the identification of the underlying etiology is extremely important and the common causes should be reviewed, treated, or excluded during the resuscitation.

Despite 30 minutes of resuscitation efforts, your patient remains pulseless and the following rhythm is obtained:

This rhythm strip demonstrates asystole. Routine transcutaneous pacing for asystole has not been shown to improve survival. The duration of the cardiac arrest is the most important prognostic factor. Studies have shown that resuscitation efforts are unlikely to be successful after 20 minutes of combined BLS and ACLS. It is appropriate to consider cessation of resuscitation efforts at that time.

Therapeutic Hypothermia

The survival rate of out of hospital cardiac arrest remains very poor despite years of prehospital advanced life support. Of those patients who develop return of spontaneous circulation after cardiac arrest, less than one-half of them will survive until hospital discharge. A large proportion of these victims will suffer anoxic brain injuries. Initiation of mild hypothermia (cooling to 32-34 C) has been demonstrated to decrease the 6 month mortality rate and lead to improved functional recovery at hospital discharge. ACLS 2005 guidelines recommend that unconscious patients with return of spontaneous circulation should be cooled to 32-34 C for 12-24 hours when VF was the initial rhythm.

The Inclusion Criteria for Therapeutic Hypothermia include:

  • Patients resuscitated after out-of-hospital witnessed arrest with VT/VF as initial rhythm
  • Resuscitation initiated by EMS within 5-15 minutes of arrest
  • No more than 60 minutes from collapse to return of spontaneous circulation (ROSC)
  • Persistent coma after ROSC
  • Adult age
  • Endotracheal intubation and mechanical ventilation

And the Contraindications to Therapeutic Hypothermia include:

  • Severe cardiogenic shock (SBP<90 mmHg) despite fluids and inotropes
  • Cause of coma other than cardiac arrest (overdose, CVA)
  • Pregnancy
  • Known coagulopathy
  • Life-threatening arrhythmias
  • Initial temperature <30 C
  • Preexisting DNR status
  • Pediatric patients

Additional References

Link to the following for additional information on Advanced Life Support from the American Heart Association: