Anesthesia (6)

Abstract

P.A. Mallinder, J.E. Hall, F.G. Bergin, P. Royle, D.J. Leaper: A comparison of opiate‐ and epidural‐induced alterations in splanchnic blood flow using intraoperative gastric tonometry. (North Tees Hospital, Hardwick, Stockton‐on‐Tees, Cleveland, UK) Anaesthesia 2000;55:659–665.This study assessed the ability of tonometry to measure differential effects of opiate and epidural analgesia on splanchnic blood flow. Forty patients for elective colorectal surgery were randomly allocated to receive epidural infusion or intravenous morphine. Gastric mucosal PCO2, pHi, standard pHi, PCO2 gap, and pH gap were measured after induction and on termination of surgery. These parameters were within normal limits at the end in most cases and there was no significant difference between the groups. The complication rate was similar in both groups and was not correlated with low pHi, but was correlated with blood loss. A difference in splanchnic perfusion was not demonstrated between the two groups. Comment by Octavio Calvillo, MD, PhD.This study concerns the assessment of splanchnic blood flow measured indirectly and noninvasively in patients undergoing colorectal surgery. The tonometer is a modified gastric tube terminating in a silicone balloon, which can be filled intermittently with either air or saline. With this technique, it is possible to measure gastric mucosal CO2 (PgCO2) and intramucosal pH and pH gap using a modified Henderson‐Hasellbach equation, thus indirectly providing an estimate of splanchnic blood flow. These parameters were measured after induction and upon termination of surgery in 2 groups of patients randomly allocated to receive either intravenous morphine (10 mg) or epidural bupivacaine to achieve a T5 sensory level of blockade. The authors were unable to demonstrate a difference in splanchnic perfusion as assessed with tonometry between the 2 groups.