Caution Advised When Using Vasopressin Septic Shock

Vasopressin should be used with great caution for the treatment of hypotension in septic shock, according to a new international study.

Researchers at the Washington University School of Medicine (St. Louis, MI, USA) and other institutions in Iceland and Switzerland studied 32 pigs that were anesthetized, mechanically ventilated, and randomly assigned to one of four groups: Group S (sepsis) and group SV (sepsis and vasopressin) were exposed to fecal peritonitis; Group C and group V were non-septic controls. After 240 minutes, both septic groups were resuscitated with intravenous fluids; after 300 minutes, groups V and SV received intravenous vasopressin. Regional blood flow was measured in the hepatic and renal arteries, the portal vein, and the celiac trunk using ultrasonic transit time flowmetry. Microcirculatory blood flow was measured in the liver, kidney, and pancreas using laser Doppler flowmetry.

The researchers found that in septic shock, vasopressin decreased blood flow by 58% in the portal vein within an hour, and even after three hours the reduction stood at 45%. Blood flow in the liver, however, remained unchanged. The investigation also revealed that increased urine output did not necessarily reflect increased renal blood flow, and therefore may not be a useful indicator of the effects of a particular treatment. The study was published online on December 13, 2007, in the open access journal Critical Care.

"Vasopressin caused marked redistribution of splanchnic regional and microcirculatory blood flow, including a significant decrease in portal, pancreatic and renal blood flows, while hepatic artery flow remained virtually unchanged,” explained lead author Dr Vladimir Krejci, M.D., of the department of anesthesiology at Washington University medical school, and colleagues.

Vasopressin, a peptide hormone, is being developed as a new therapy for the hemodynamic support of septic shock and vasodilatory shock due to systemic inflammatory response syndrome, and has previously been shown in animal models to increase blood pressure in septic shock that fails to respond to catecholamines. However, the safety of vasopressin treatment in humans with septic shock is yet to be proven.


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