What is the function of vasopressin during cardiac arrest?

Vasopressin functions as a vasoconstrictor during cardiac arrest, particularly when used in conjunction with epinephrine. In this critical situation, vasopressin helps augment vascular tone, which can lead to increased blood flow to vital organs, particularly the heart and brain. This is crucial during cardiac arrest, where effective circulation is compromised.

In the setting of cardiopulmonary resuscitation (CPR), vasopressin can improve the chances of return of spontaneous circulation. It enhances the overall effectiveness of resuscitation efforts when paired with epinephrine, as it aids in maximizing systolic blood pressure and perfusion pressure.

In contrast to the other options, vasopressin does not function as a vasodilator, nor does it directly increase stroke volume or enhance fluid volume. Its primary role in this context is to induce vasoconstriction, thereby improving hemodynamics during a life-threatening event such as cardiac arrest.