Hepato-splanchnic and pancreatic blood flow during administration of vasopressin in septic shock

Background and goal of study

The use of vasopressin for treatment of hypotension in sepsis might deteriorate splanchnic regional and microcirculatory blood flow. The aim of this study was to measure regional blood flow and microcirculatory blood flow (MBF) continuously and simultaneously in multiple abdominal organs during administration of Ornithin-8-Vasopressin in peritonitis-induced sepsis.

Materials and methods

Pigs (20–25 kg, n = 32) were anaesthetised and ventilated. Cardiac index was measured with thermodilution. Blood flow was measured in the superior mesenteric and hepatic artery as well as in the portal vein using transit time flowmetry. MBF was measured on the surface of the liver and pancreas, using a multichannel Laser Doppler flowmeter. Peritonitis was induced by instillation of autologous faeces in the peritoneal cavity. After 240 min of peritonitis, intravenous colloids were given to transform hypodynamic shock into hyperdynamic septic shock. After 300 min of peritonitis, 0.06 IU/kg per hour of Ornithin-8-Vasopressin was administered continuously as an intravenous infusion. Four groups of animals were investigated: Group C (n = 8) served as control; Group V (n = 8) received only ornithin-vasopressin; Group S (n = 8) was exposed to peritonitis and fluid resuscitation; Group SV (n = 8) received ornithin-vasopressin after peritonitis and fluid resuscitation.

Results and discussion

Baseline measurements were taken at T = 300 min (before ornithin-vasopressin). Results are presented as percent of baseline. P < 0.05 was considered significant. Mean arterial blood pressure increased during infusion of vasopressin by 25% (P < 0.05) in the groups V and SV (P > 0.05), while it remained constant in the other two groups. Cardiac output decreased by 30% in the groups V and SV (P < 0.05) and remained constant in groups C and V. Blood flow in the superior mesenteric artery and in the portal vein decreased by 25% in group V (P < 0.05) while there was no change in group C, and by 50% in group SV (P < 0.05), which was significantly more compared with a decrease of 25% in group S. Blood flow in the hepatic artery increased by 120% (P < 0.05) in group V and by 50% (P < 0.05) in group SV, while there was an increase by 25% in group C and a 20% decrease in group S. MBF of the liver decreased gradually in groups S and SV to 15% (P < 0.05) below baseline after 180 min in both groups. MBF of the liver decreased during infusion of vasopressin in nonseptic animals (Group V) by 30% (P < 0.05) while it remained constant in nonseptic controls (Group C). MBF of the pancreas decreased by 20% (P < 0.05) in groups C and S, while it decreased 35–40% (P < 0.05) in groups S and SV.

Discussion and conclusions

1) During the infusion of ornithin-vasopressin, blood flow in the superior mesenteric artery and the portal vein decreased. 2) Increased blood flow in the hepatic artery during administration of ornithin-vasopressin suggests that the hepatic arterial buffer response was involved. 3) MBF in the liver decreased during administration of ornithin-vasopressin in nonseptic animals in contrast to the septic group. 3) Ornithin-vasopressin appeared to decrease significantly MBF in the pancreas in both septic and nonseptic animals. 4) In this model, increasing arterial blood pressure with ornithin-vasopressin did not result in an increase of microcirculatory blood flow in any of the organs studied.