Postoperative epidural analgesia in obese patients undergoing liver resection surgery.

Aim: To investigate the relation of body mass index (BMI) with postoperative pain scores and volume of local anaesthetic (LA) administered epidurally in patients undergoing liver resection surgery.

Methods: Retrospective data from 167 patients who had epidural analgesia (EA) for liver resection surgery were analysed: 123 with BMI < 30kgm-2 and 44 with BMI > 30kgm-2.

Results: Total volume of intraoperative bolus of epidural analgesia (EA) was not different between the BMI more than 30 kgm-2 and BMI less than 30 kgm-2 groups (p less 0.05). Mean rate of infusion (8.2±2.7 ml/h vs. 7.9±1.9 ml/h, p=0.0018), pain scores immediately after extubation of the trachea (0.91±0.9 vs. 0.55±0.7, p=0.017) and that before removal of epidural catheter (0.7±0.55 vs. 0.7±0.95, p=0.015) were higher in the BMI > 30kgm-2 group when compared with the BMI ≤ 30kgm-2 group. However, there was no significant difference between the numbers of segments blocked.

Conclusion: The patients with BMI more than 30 kgm-2 undergoing liver resection experienced more postoperative pain on the day of surgery and before epidural catheter removal than patients with BMI less than 30 kgm-2, despite a higher rate of epidural infusion. Further studies are necessary to confirm these findings in order to determine adequate local anaesthetic dosing for thoracic epidural analgesia in obese patients.