Approach Considerations
Continuous cardiac monitoring is useful during attempts at resuscitation to determine rhythm and effects of intervention. Endotracheal intubation is indicated during resuscitation. Central venous access or intraosseous access may be needed for vascular access.
Prehospital Care
In an analysis of the records of 17,238 out-of-hospital cardiac arrest (OHCA) adult patients who achieved prehospital return of spontaneous circulation, researchers in one study investigated the relationship between cardiopulmonary resuscitation (CPR) duration and post-OHCA outcomes. They prospectively recorded data in a nationwide, Japanese database between 2011 and 2012. The critical prehospital CPR duration producing more than 99% of survivors with Cerebral Performance Category (CPC) 1-2 was 42 minutes in patients with initial asystole. [17]
In a study of the relationship between the duration of prehospital CPR by emergency medical services (EMS) personnel and post-OHCA outcomes, investigators analyzed the records of 12,877 pediatric patients who experienced OHCAs. The investigators recorded data in a nationwide Japanese database between 2005 and 2012. In patients with initial asystole, the prehospital EMS-initiated CPR duration beyond which the chance for 30-day survival with Cerebral Performance Category (CPC) 1 to 2 diminished to < 1% was 46 minutes. [18]
The only two drugs recommended or acceptable by the American Heart Association (AHA) for adults in asystole are epinephrine and vasopressin. Atropine is no longer recommended for young children and infants since 2005, and for adults since 2010 for pulseless electrical activity (PEA) and asystole. In spite of full vagolytic doses of atropine (0.03 mg/kg) and high-dose epinephrine (0.20 mg/kg), or the use of vasopressin 40 units (U), few patients survive to leave the hospital neurologically intact.
Atropine is no longer recommended in young children and infants in asystole but can be considered in adults with slow pulseless electrical activity (PEA) rhythms.
Vasopressin therapy
If spontaneous circulation has not been restored, administering intravenous (IV) vasopressin 40 U for the first 2 doses or followed by epinephrine given at the physician's discretion has showed some promising if not mixed results.
Wenzel et al reported that more patients who were administered vasopressin survived to hospital discharge than those on epinephrine, although the neurologic status of the patients at discharge was not clearly stated. [19] Further analysis suggested a tendency for a worse neurologic outcome in those who received both vasopressin and epinephrine, many of whom ended up in a vegetative state.
Of the 528 patients with asystole in the study, 12 patients in the vasopressin group survived to discharge compared with 4 in the standard therapy group. [19] In this study, the odds ratio stated may not be statistically significant, and there was also a nonstatistically significant trend toward worse results for ventricular fibrillation (VF) and PEA. [19]
In a larger comparison study between epinephrine alone and epinephrine with vasopressin 40 U, Gueugnaiud and colleagues found that there were no significant differences between groups in terms of return of spontaneous circulation, survival to hospital discharge, 1-year survival, or good neurologic recovery among survivors at hospital discharge. [20]
The advanced cardiac life support (ACLS) 2010 guidelines allow vasopressin 40 IU IV as a 1-time dose treatment option in VF and asystole. This treatment can be given either before epinephrine or after the first dose of epinephrine.
Transcutaneous pacing
Transcutaneous pacing (TCP), even when used immediately, has not altered meaningful survival (ie, functional lifestyle) significantly. [13, 21] However, when no metabolic deficit exists, such as in a cardiac arrest preceded by a conduction or impulse generation disorder (ie, primary asystole), immediate use of TCP may be lifesaving.
Emergency Department Care
Mainstays of treatment in the emergency department are providing oxygenation and ventilation via endotracheal intubation and circulation via cardiopulmonary resuscitation (CPR), attempts at transcutaneous or transvenous pacing (that have some small potential to be fruitful in primary asystole that has just occurred), and administration of pharmacologic agents.
There has been a case report of a long but successful resuscitation from asystole of a patient who was hyperkalemic secondary to renal failure. [22] The treatment included calcium chloride to reverse the physiologic effects of hyperkalemia and insulin and glucose to lower serum potassium levels. However, this therapy cannot be recommended routinely for all cases of asystolic arrest.
Some of common reasons to stop or withhold resuscitation efforts include the following:
-
The patient has a do not resuscitate (DNR) status
-
There is a threat to the safety of rescuers
-
There is family or personal information that precludes resuscitation efforts, such as having living will or advance directive
-
Rigor mortis is present
Electrical defibrillation
Electrical defibrillation should not be applied indiscriminately to the patient in asystole. This is not only fruitless, but also detrimental, eliminating any possibility of recovering a rhythm. Asystole following electrical defibrillation has an even worse outcome than that in a patient whose first documented rhythm was asystole. [23] One caution is that, following defibrillation, a brief spurious asystole can occur using manual monitoring through the defibrillator paddles. This does not occur with the rhythm monitoring leads or hands-off monitor pads. If not taken into consideration, it could lead to a delay in defibrillation, when indeed VF is present.
Admission to Intensive Care Unit
The intensive care unit is the appropriate disposition for the occasional patient who survives bradyasystolic cardiopulmonary arrest and requires further treatment and diagnostic evaluation. In the past decade, survivors who achieved electrical and hemodynamic stability but remained comatose and were modestly cooled to 32-34°C for the first 24 hours showed improvement in overall neurologic outcome. [24] The studies were conducted on prehospital arrests with ventricular fibrillation as the presenting rhythm, but results could be generalized to bradyasystolic survivors. [24]
Testori et al reports an odds ratio of 1.84 for good neurological outcome when bradyasystolic patients with a return of spontaneous rhythm are cooled, especially when the time interval, collapse to return of spontaneous circulation, is brief. [25] Given the prognosis is so poor after cardiac arrest, attempting hypothermia on all adult patients with cardiac arrest, regardless of presenting rhythm, is reasonable.
Prevention of Asystole
Primary asystole may be prevented by the appropriate use of a permanent pacemaker in those patients who have high-grade heart block or sinus arrest. Prevention of secondary asystole requires early recognition and treatment of the preceding event.
-
Rhythm strip showing asystole.
-
Rhythm strip showing ventricular fibrillation.
