Postoperative epidural analgesia in obese patients undergoing liver resection surgery

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.

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.

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.

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.