A comparison of opiate- and epidural-induced alterations in splanchnic blood flow using intra-operative gastric tonometry

Several methods are available to measure splanchnic blood flow and gut isch aemia. Tonometry is most practical for peri-operative use. Epidural blockad e from T-5 to T-11 causes mesenteric arteriovenous vasodilation and may inc rease splanchnic blood flow. This study assesses the ability of tonometry t o measure differential effects of opiate and epidural analgesia on splanchn ic blood flow. Forty patients for elective colorectal surgery were randomly allocated to receive epidural infusion or intravenous morphine. Gastric mu cosal PCO2, pHi, standard pHi, PCO2 gap and pH gap were measured after indu ction and on termination of surgery. These parameters were within normal li mits at the end in most cases and there was no significant difference betwe en the groups. The complication rate was similar in both groups and was not correlated with low pHi, but was correlated with blood loss. We were unabl e to demonstrate a difference in splanchnic perfusion, as assessed by gastr ic tonometry, between the two groups.