Vasopressin is a naturally occurring peptide hormone that regulates fluid and the cardiovascular system. In high doses, it acts as a potent non-adrenergic peripheral vasoconstrictor, causing blood vessels to narrow. Advanced Cardiovascular Life Support (ACLS) uses standardized algorithms to treat cardiac arrest and other cardiopulmonary emergencies. These protocols are periodically reviewed and updated based on the latest scientific evidence.
Vasopressin’s Prior Role in Cardiac Arrest
Vasopressin was included in the American Heart Association’s (AHA) ACLS protocols for nearly a decade, appearing in the 2005 and 2010 Guidelines. It was an acceptable substitute for the first or second dose of epinephrine, the standard vasopressor used during resuscitation.
The typical recommended dosage was a single 40 unit intravenous or intraosseous push. This was permitted for all forms of pulseless cardiac arrest, including pulseless ventricular fibrillation (pVF), pulseless ventricular tachycardia (pVT), asystole, and pulseless electrical activity (PEA). Its inclusion was based on the theory that its prolonged vasoconstrictive effects might increase blood flow to the heart and brain, offering an advantage over epinephrine.
The 2015 Guideline Revision and Rationale
The removal occurred with the publication of the 2015 AHA Guidelines Update for CPR and ECC. Vasopressin was removed entirely from the adult cardiac arrest algorithm following a thorough review of scientific literature, including meta-analyses and clinical trials.
The evidence showed that vasopressin, alone or combined with epinephrine, offered no additional benefit compared to standard-dose epinephrine. Specifically, there was no statistically significant improvement in patient outcomes, such as survival to hospital discharge or favorable neurological function.
A major objective of the update was simplifying the complex cardiac arrest algorithm. Removing a drug that lacked a measured advantage over the existing standard intervention streamlined the treatment process. This simplification reduces potential provider confusion and focuses efforts on proven interventions like high-quality chest compressions and timely defibrillation.
Status of Vasopressin in Modern ACLS Protocols
Since the 2015 revision, and reinforced by the 2020 guidelines, vasopressin has remained absent from the primary Adult Cardiac Arrest Algorithm. Its removal solidified epinephrine as the sole first-line vasopressor for all rhythms in the pulseless arrest pathway. Epinephrine is administered at a 1-milligram dose every three to five minutes throughout resuscitation.
Vasopressin is no longer recommended for routine use during cardiac arrest resuscitation, but it is not prohibited in all critical care settings. It may still be used outside the core algorithm, such as managing distributive shock states like septic shock, where its vasoconstrictive properties help raise blood pressure. In highly specific in-hospital scenarios, a combination of vasopressin, steroids, and epinephrine may be considered, but this is a specialized intervention.