Effects of epinephrine, norepinephrine and phenylephrine on regional and microcirculatory blood flow during sepsis

Backgrounnd and goal of study

The use of alpha-adrenergic substances for treatment of hypotension in sepsis might deteriorate splanchnic regional and microcirculatory blood flow. The aim of this study was to measure microcirculatory blood flow (MBF) continuously and simultaneously in multiple abdominal organs during administration of epinephrine, norepinephrine and phenylephrine in peritonitis induced sepsis.

Materials and methods

Pigs (20–25 kg, n = 9) were anaesthetised and ventilated. Cardiac index (CI) was measured with thermodilution. Superior mesenteric artery (SMA) flow was measured using ultrasound transit time flowmetry. MBF was measured in gastric, colon and jejunal mucosa, jejunal muscularis, the pancreas, the liver and the kidney using a multi-channel Laser Doppler flowmeter. Peritonitis was induced by instillation of autologous feces in the peritoneal cavity. After 240 min of peritonitis, intravenous colloids were given to transform hypodynamic shock into normodynamic shock. Each animal received a continuous infusion of epinephrine (Epi), norepinephrine (Nor) and phenylephrine (Phe) in a random order. A separate baseline was taken before administration of each drug. The infusion rate was adjusted to obtain MAP between 20% and 30% above baseline for at least 10 min. After stopping the infusion MAP and CI were allowed to return within 10% of baseline. Additional intravenous fluids were given when needed.

Results

MAP was 66 ± 5 mmHg before epinephrine, 70 ± 4 mmHg before norepinephrine and 69 ± 5 mmHg before phenylephrine.

Conclusions

Epinephrine and norepinephrine appeared to divert blood flow away from the splanchnic circulation, in particular from the small intestine. In contrast, SMA flow and MBF of the intestine remained unchanged during administraton of phenylephrine. As phenylephrine is a pure alpha-adrenergic agonist, the beta-adrenergic properties of epinephrine and norepinephrine might play a role in the redistribution of blood flow when administered in sepsis.

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