The Cardiopulmonary Effects of Vasopressin Compared With Norepinephrine in Septic Shock

Background: Vasopressin is known to be an effective vasopressor in the treatment of septic shock, but uncertainty remains about its effect on other hemodynamic parameters. Methods: We examined the cardiopulmonary effects of vasopressin compared with norepinephrine in 779 adult patients with septic shock recruited to the Vasopressin and Septic Shock Trial. More detailed cardiac output data were analyzed for a subset of 241 patients managed with a pulmonary artery catheter, and data were collected for the first 96 h after randomization. We compared the effects of vasopressin vs norepinephrine in all patients and according to severity of shock (< 15 or >= 15 mu g/min of norepinephrine) and cardiac output at baseline. Results: Equal BPs were maintained in both treatment groups, with a significant reduction in norepinephrine requirements in the patients treated with vasopressin. The major hemodynamic difference between the two groups was a significant reduction in heart rate in the patients treated with vasopressin (P < .0001), and this was most pronounced in the less severe shock stratum (treatment x shock stratum interaction, P = .03). There were no other major cardiopulmonary differences between treatment groups, including no difference in cardiac index or stroke volume index between patients treated with vasopressin and those treated with norepinephrine. There was significantly greater use of inotropic drugs in the vasopressin group than in the norepinephrine group. Conclusions: Vasopressin treatment in septic shock is associated with a significant reduction in heart rate but no change in cardiac output or other measures of perfusion.