Clinical studies evaluating the use of
phenylephrine in
septic shock are lacking. The present study was designed as a prospective, crossover pilot study to compare the effects of
norepinephrine (NE) and
phenylephrine on systemic and regional hemodynamics in patients with
catecholamine-dependent
septic shock. In 15
septic shock patients, NE (0.82 +/- 0.689 microg x kg(-1) x min(-1)) was replaced with
phenylephrine (4.39 +/- 5.23 microg x kg(-1) x min(-1)) titrated to maintain MAP between 65 and 75 mmHg. After 8 h of
phenylephrine infusion treatment was switched back to NE. Data from right heart catheterization, acid-base balance, thermo-
dye dilution
catheter, gastric tonometry, and renal function were obtained before, during, and after replacing NE with
phenylephrine. Variables of systemic hemodynamics, global
oxygen transport, and acid-base balance remained unchanged after replacing NE with
phenylephrine except for a significant decrease in heart rate (
phenylephrine, 89 +/- 18 vs. NE, 93 +/- 18 bpm; P < 0.05). However, plasma disappearance rate (
phenylephrine, 13.5 +/- 7.1 vs. NE, 16.4 +/- 8.7% x min(-1)) and clearance of
indocyanine green (
phenylephrine, 330 +/- 197 vs. NE, 380 +/- 227 mL x min(-1) x m(-2)), as well as
creatinine clearance (
phenylephrine, 81.3 +/- 78.4 vs. NE, 94.3 +/- 93.5 mL x min(-1)) were significantly decreased by
phenylephrine infusion (each P < 0.05). In addition,
phenylephrine increased arterial
lactate concentrations as compared with NE infusion (1.7 +/- 1.0 vs. 1.4 +/- 1.1 mM; P < 0.05). After switching back to NE, all variables returned to values obtained before
phenylephrine infusion except
creatinine clearance and gastric tonometry values. Our results suggest that for the same MAP,
phenylephrine causes a more pronounced hepatosplanchnic vasoconstriction as compared with NE.