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<< Cardiac Arrest: Current Concepts, Controversies, And Evidence

Emergency Department Evaluation

The First Minute

The ED evaluation begins with a brief history obtained from paramedics, witnesses, or family members. Quickly assess the adequacy of the airway, the presence of a pulse, and the nature of any electrical activity on the heart monitor.

If an endotracheal tube is in place, the clinician should check for proper tube location. While successful intubation rates may vary among locales, one study showed that up to 25% of all endotracheal tubes inserted by medics may be misplaced (17% in the esophagus, 8% in the hypopharynx).82 Many physicians simply listen for breath sounds bilaterally and the absence of gurgling sounds over the stomach; however, this method is fallible.83 The emergency physician can also visualize tube placement using direct laryngoscopy. While the reliability of this approach in a code situation remains unknown, it seems to be a reasonable approach. End-tidal CO2 using a capnograph or a colorimetric device can be extremely useful when the result is positive. While the presence of CO2 measured by an inline device strongly supports correct placement,84 in the arrested patient, a negative value may occur with either esophageal placement or proper endotracheal intubation. The lack of end-tidal CO2 during arrest may be due to poor perfusion of the lungs or decreased CO2 production despite CPR.85 An alternative method to confirm endotracheal tube placement that does not rely on perfusion involves the esophageal detector device. This device aspirates air from the endotracheal tube using a syringe or suction bulb.86 If the tube is in the  rachea, suction is easy and the air flows freely into the syringe. If the tube is in the esophagus (which collapses during suction), air return is negligible.87

The presence of a pulse should be assessed by palpation of a central artery, such as the carotid or femoral. Pulses may be checked with CPR stopped to evaluate return of circulation and during CPR to determine adequacy of compressions. Palpation of peripheral arteries is not reliable.88


Important information includes the circumstances and timing of the arrest and resuscitation in the field. Did the patient have any preceding symptoms of chest pain, palpitations, or dyspnea? Was the arrest witnessed, and if bystander CPR was performed, was it begun immediately? Importantly, how long has resuscitation been going on? And when was an AED or defibrillation applied? What further treatments did paramedics administer?

Events just prior to the arrest are of particular interest. Determine if there was potential exposure to inhaled, injected, ingested, or external toxins, or exposure to electricity, trauma, or drowning. A history of chest, abdominal, or head pain prior to the arrest may suggest the underlying etiology. In the appropriate clinical situation, ask about risk factors for pulmonary embolism, cardiac disease, or arrhythmia. The past medical history may play an important role in resuscitation, especially if the patient was taking known cardiotoxic drugs.

Physical Examination

The initial physical examination should focus on airway, breathing, circulation, and disability (neurologic examination). In the first several minutes, determine whether breath sounds are equal and bilateral during ventilation and whether there is a pulse during CPR. A deviated trachea, distended neck veins, and unilateral decreased breath sounds indicate a tension pneumothorax.

A secondary survey should also be performed during the course of the ED evaluation. The pupils will generally lose reactivity and dilate within four minutes of untreated arrest, but this may be reversed with adequate CPR.89 Fixed and dilated pupils during CPR portend a poor outcome, but this is not absolute.90 There may be multiple confounding factors such as the administration of epinephrine, dopamine, or other sympathomimetics that tend to dilate the pupils.91 Atropine in conventional doses causes slight pupillary dilation but does not abolish light reactivity.92

Distended neck veins may suggest an obstruction to blood flow often associated with tension pneumothorax, pericardial tamponade, or massive pulmonary embolism. The presence of a vascath or upper-extremity shunt suggests chronic renal failure and the possibility of hyperkalemia.

Diagnostic Testing

Laboratory Testing

A variety of ancillary tests can help diagnose potentially reversible causes of cardiac arrest. Recognize that the patient in full arrest derives little benefit from laboratory tests that require the traditional 30 minutes to process. However, certain point-of-care tests may be of some value. Serum glucose is frequently evaluated in patients who are known to be diabetic, but it is unclear whether someone who arrests from hypoglycemia could be resuscitated by sugar alone. Arterial blood gas measurements have limited utility during cardiac arrest because they don’t correlate with the mixed venous and tissue acid-base status.93 Electrolyte abnormalities are an important cause of or contributing factor in many cardiac arrests.94 Derangements of potassium, magnesium, and calcium are particularly important and may require emergent treatment—yet once again, treatment may be based on clinical suspicion (in the case of an arrested dialysis patient who had missed several dialysis sessions) rather than as a result of testing. A retrospective study that examined the utility of mandatory electrolyte measurements for inpatient cardiac arrest showed little clinical usefulness.95

Electrocardiagram And Chest X-Ray

The ECG may be helpful to diagnose electrolyte derangements in patients with impending arrest, but in one study the sensitivity of emergency physicians in diagnosing hyperkalemia above 6.5 mmol/L was only about 60%.96 Similarly, the diagnosis of serum calcium derangements based on the ECG QT interval has also been found to have limited utility.207 The post-arrest ECG is essential in the evaluation of MI and perhaps complex dysrhythmias.

For patients with return of spontaneous circulation, the chest x-ray may be helpful to assess a variety of findings, including the heart size, pulmonary inflation and congestion, and the location of various tubes and central lines, if any. During arrest the chest film is unlikely to be of much value. Tension pneumothorax is a clinical diagnosis, and using a chest film to determine endotracheal tube position can introduce lethal delays and misdiagnosis.


Cardiac ultrasound has a number of uses in the setting of cardiac arrest. The most important for the emergency physician is to diagnose abnormal pericardial fluid and pericardial tamponade using transthoracic echocardiography.97 Tamponade can also be treated using ultrasound-guided pericardiocentesis.98 Transthoracic echocardiography can also assess for cardiac contractions in PEA. Evidence of organized cardiac contractions is termed pseudo-electromechanical dissociation and should prompt a search for reversible causes such as hypovolemia, pericardial tamponade, tension pneumothorax, or massive pulmonary embolism.99 If hypovolemia is suspected, ultrasound can be used to investigate the major abdominal vessels and to perform the FAST (focused abdominal sonography in trauma) examination to search for intraabdominal hemorrhage.100 Echocardiographic findings of disorganized myocardial contractions in the setting of presumed asystole suggest fine VF instead, and immediate defibrillation is indicated.101 For physicians with advanced echocardiographic skills, the cardiac ultrasound can evaluate the thoracic aorta and aortic valve as well as identify the presence of regional cardiac wall motion abnormalities. Transesophageal echocardiography (TEE) may be particularly useful for diagnosing thoracic aortic disease and pulmonary embolism.208 Despite the potential difficulty in obtaining an emergent TEE, this diagnostic modality may be considered, if available.

End-Tidal CO2 And Echocardiography

The presence of cardiac motion on ultrasound in patients in cardiac arrest is predictive of survival. In one study of 136 patients in cardiac standstill by echocardiography, none survived to leave the ED regardless of their initial cardiac rhythm.102 In another ED-based study, 11 of 41 patients (27%) with and two of 61 patients (3%) without sonographic evidence of cardiac activity during the resuscitation survived to hospital admission. However, cardiac ultrasound added no additional independent prognostic information to end-tidal CO2 measurements where a cutoff value of 16 mmHg was found to be optimal (all patients with a value lower than 16 mmHg died).103 It is interesting to note that all echocardiography in both of these studies was performed by emergency physicians, and the majority felt it was an easy procedure.103

In another prospective, observational study of 150 patients, investigators found that an end-tidal CO2 level of 10 mmHg or less after 20 minutes or more of CPR had a 100% sensitivity and specificity for death.104 The confidence intervals, however, were large.



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