The risks and benefits of
epinephrine given during
cardiopulmonary resuscitation (
CPR) are controversially discussed. Animal experiments revealed beta-receptor-mediated adverse effects of
epinephrine such as increased myocardial oxygen consumption, ventricular
arrhythmia, ventilation-perfusion defects, and
cardiac failure in the postresuscitation phase. In clinical studies, high-dose vs. standard-dose
epinephrine was unable to improve
resuscitation success. During
CPR in patients, endogenous
arginine vasopressin (AVP) levels were increased and surviving vs. non-surviving patients had significantly higher AVP levels. This may indicate that the human body discharges AVP during life-threatening situations as an additional vasopressor to
catecholamines in order to maintain cardiocirculatory homeostasis. In different experimental
CPR models, AVP compared with
epinephrine given during
CPR significantly improved vital organ blood flow, coronary perfusion pressure, resuscitability, and long-term survival. During prolonged
CPR with repeated drug administration, AVP but not
epinephrine maintained coronary perfusion pressure on a level that ensured return of spontaneous circulation. Also, AVP can be administered successfully in the intravenous dose into the endobronchial tree, and also intraosseously. When given during
CPR, AVP induces a transient splanchnic hypoperfusion, and an increase in systemic vascular resistance, both of which normalized spontaneously; furthermore, an oligo-anuric state was not observed. In two clinical studies, AVP vs.
epinephrine improved 24-h survival during out-of-hospital
CPR, and comparable
CPR outcome during in-hospital
CPR. The new
CPR guidelines of both the American Heart Association and the European
Resuscitation Council assign a given
CPR intervention into classes of recommendation [class 1 (definitely recommended), class 2 A (intervention of choice), class 2B (alternative intervention), class X (neutral), or class 3 (not recommended)]. For
CPR of adults with
shock-refractory
ventricular fibrillation, 40 units AVP or 1 mg
epinephrine is recommended (class 2B); patients with
asystole or pulseless electrical activity should be resuscitated with
epinephrine. AVP is not recommended for adult
cardiac arrest patients with
asystole or pulseless electrical activity; or pediatric
cardiac arrest patients due to a lack of clinical data. Until definitive data about AVP vs.
epinephrine effects during
CPR are available, the present state of knowledge should be interpreted that two vasopressors are available for use instead of one.