Society of Cardiovascular Anesthesiologists

A Randomized Comparison of Arginine Vasopressin in Advanced Vasodilatory Shock: A Prospective, Randomized, Controlled Study

Dunser MW, Mayr AJ, Ulmer H et al. Circulation 2003;107:2313-2319

Reviewer: Julia K. Labovsky, MD
University of Chicago
Chicago, IL

Abstract:

Arginine vasopressin (AVP) has been shown to be an effective treatment of catecholamine-resistant vasodilatory shock. This study prospectively randomized 48 patients with vasodilatory shock as defined as a mean arterial pressure less than 70 mm Hg despite adequate volume resuscitation and norepinephrine (NE) requirements exceeding 0.5 mcg/kg/min to receive either NE alone or AVP (4 U/hr) in addition to NE. Causes of vasodilatory shock included systemic inflammatory response syndrome (SIRS), sepsis or cardiovascular surgery. Hemodynamic, acid/base, single organ and gastric variables were reported at one, 12, 24, and 48 hours after study enrollment. The patients who received AVP had higher mean arterial pressure (P<0.001), cardiac index (P=0.001), stroke volume index (P=0.005), left ventricular stoke work index (P<0.001), better preservation of gastrointestinal perfusion as assessed by gastric tonometry and required less NE (P<0.001). The patients who received NE alone had a higher incidence of tachyarrhythmias. There was no difference in mortality during the study time period.

Comments:

The treatment of vasodilatory shock is a task that we are often called to manage during and after cardiac surgery. While the use of NE is often effective, it is not always sufficient, especially in cases of acidosis and hypoxemia. The vasoconstrictor effect of AVP appears to be preserved during such states. This study is of interest because it compares the effect of the addition of AVP to NE to that of NE alone.

The higher cardiac index, stroke volume and left ventricular stroke work indices that occurred with the addition of AVP are certainly noteworthy. While the exact mechanism is unclear, the authors have a few hypotheses. The improved hemodynamic parameters may be a reflection of positive inotropy that occurs as result of the stimulation of V1a receptors and subsequent calcium release that has been observed in rat models. In human cardiac arrest subjects, increased coronary perfusion pressure was noted after AVP administration, which may be a result of increased systemic pressure.

Also of interest is the lower incidence of tachyarrhythmias in the patients that received AVP in addition to NE. Whether this is a consequence of a lower amount of NE administered or the possibility of better myocardial perfusion is uncertain.

The applicability of this study to the cardiac surgical population is limited, however, by the fact that the patient population also contained those with sepsis and SIRS. Furthermore, the study examined the post-operative addition of AVP. Given the findings of a higher cardiac index, a lower incidence of tachyarrhythmias and markers of preservation of gastrointestinal perfusion, it would be interesting to investigate whether these benefits would occur with the use of AVP in the intra-operative setting of the cardiac surgical patient with vasodilatory shock.

Table of Contents: