DiagnosticsPulseless electrical activity in cardiac arrest: electrocardiographic presentations and management considerations based on the electrocardiogram
Introduction
Pulseless electrical activity (PEA), formerly known as electromechanical dissociation, occurs in patients who have organized cardiac electrical activity without a palpable pulse. Pulseless electrical activity is physiologically defined as electrical depolarization of the heart in the absence of synchronous cardiac myocyte shortening [1]. In the setting of cardiac arrest, evidence over the past 2 decades suggests that the incidence of PEA has been increasing, whereas the occurrence of pulseless ventricular tachycardia and ventricular fibrillation has been decreasing [2], [3], [4]. Several studies have shown the incidence of PEA in-hospital to be approximately 35% to 40% of arrest events [5], [6]. For out-of-hospital cardiac arrest, the incidence of PEA is 22% to 30% [7], [8]. In addition to this alarming rise in PEA is the fact that PEA arrests are associated with a poor prognosis, with a survival to discharge rate between 2% and 5% for out-of-hospital cardiac arrest [9], [10].
Standard treatment according to the American Heart Association 2005 guidelines [11] emphasizes the need to identify and correct reversible etiologies in addition to standard resuscitation—a difficult task that is not always possible in the often hectic early minutes of cardiac arrest resuscitation. Because a wide variety of pathologies can cause a PEA arrest, it is necessary to narrow the differential possibilities of etiologies such that appropriate treatment can be applied. The electrocardiogram (ECG) is an important tool that can be used in conjunction with the history and examination to potentially determine the cause of PEA and the appropriate course of action to reverse pathologic insults. Diagnostic clues from the ECG, when interpreted in conjunction with the patient's history and examination, can be used to not only suggest the underlying etiology but also to predict the likelihood of survival. The following case studies highlight these issues.
Section snippets
Case 1
A 52-year-old woman was admitted with melena. She became unresponsive, pulseless, and apneic while awaiting an upper esophagogastroduodenoscopy. A rapid, narrow complex tachycardia with P waves was noted as the initial PEA rhythm (Fig. 1). Standard cardiopulmonary resuscitation and advanced cardiovascular life support protocols were followed. In addition to advanced life support, normal saline was rapidly infused via an intraosseous line followed by 4 U of packed red blood cells. The patient's
Discussion
Pulseless electrical activity is a particularly challenging scenario for the clinician because it can be the result of a wide spectrum of potential etiologies. Some of the various causes include significant hypoxia, profound acidosis, severe hypovolemia, tension pneumothorax, electrolyte imbalance, drug overdose, sepsis, large myocardial infarction, massive pulmonary embolism, cardiac tamponade, hypoglycemia, hypothermia, and trauma [12]. Many clinicians define PEA as myocardial electrical
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2020, ResuscitationCitation Excerpt :This group now represents almost 75% of all OHCA victims, and has a substantially poorer prognosis compared to patients with an initial shockable rhythm.1 Importantly, cardiac arrest aetiology and physiology may differ in the non-shockable group such that optimal CPR, including CCF, may also differ.16 A single prior study of this rhythm group suggested that higher CCF could possibly be associated with a higher incidence of return of spontaneous circulation (ROSC) among non-shockable OHCA victims.17