Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background: We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI(2)) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods: In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGF(1 alpha) (stabile metabolite of PGI(2)), TXB2 (stabile metabolite of thromboxane A(2)) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results: Following MT, arterial hypotension occurred along with a substantial PGI, release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF(1 alpha) (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same Feint in time plasma concentrations of TXB2 (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41+/-(18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P=0.001) were significantly higher in placebo-treated patients. Conclusion: Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI(2) release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A(2), presumably contributing to hemodynamic stability within 30 min after MT.