Effect of epidural blockade on indicators of splanchnic perfusion and gut function in critically ill patients with peritonitis: a randomised comparison of epidural bupivacaine with systemic morphine

Objectives: (a) To measure gastric tonometry values in critically iu patien ts with peritonitis and to assess the impact of epidural analgesia on these values. (b) To assess the impact of epidural analgesia on gastro-intestina l motility by abdominal ultrasound and paracetamol absorption. (c) To obser ve any change in clinical outcome that may result from the use of epidural analgesia in such patients. Design: A double-blinded, prospective. randomised and controlled study of g eneral intensive therapy unit (ITU) patients. Patients: Twenty-one patients admitted with peritonitis and adynamic small bowel following abdominal surgery were randomly allocated to receive either intravenous morphine or epidural bupivacaine for analgesia. Measurements and results: Gastric intramucosal pH (pH(ig)) and the mucosal: arterial PCO2 gradient (Pg-PaCO2) were measured at admission and after 24 h of analgesia. Analysis of mean changes in tonometry values showed a rise i n Pg- PaCO2 and a fall in pH(ig) in the morphine group and a significant di fference between groups in the Pg-PaCO2 trends (p = 0.024). Significant imp rovements in the ultrasound appearance of the small bowel were observed in the epidural group (p = 0.0037, Mann-Whitney U test of median changes in a locally developed scoring system). There were no significant differences be tween the groups in any of the variables derived from the paracetamol absor ption test (n = 10); both groups showed persistently delayed gastric outflo w throughout the study period. Conclusions: Epidural analgesia resulted in improvements in gastric mucosal perfusion and the ultrasound appearance of the small bowel, indicating pot ential clinical benefit in a group of patients in whom epidural catheterisa tion is traditionally contraindicated.