Increased incidence of postoperative nausea and vomiting without additional analgesic effects when a low dose of intravenous fentanyl is combined with a caudal block.

BACKGROUND

The use of opioids is known to increase the incidence of postoperative nausea and vomiting (PONV). In spite of this, administration of low doses of an opioid during anaesthesia is common practice, even if a regional anaesthetic technique is used. This study was designed to estimate the effects of intraoperative intravenous administration of fentanyl on PONV in paediatric daycase surgery.

METHODS

PONV and pain were evaluated in 29 boys during the first 24 h after daycase penile surgery. Anaesthesia was standardized. The patients were allocated to two groups. Fentanyl 1 micro g.kg-1 i.v. or placebo was administered in a randomized, double-blind design. A caudal block with ropivacaine 2 mg.ml-1, 0.5 ml.kg-1 was performed preoperatively and topical lidocaine gel 20 mg.ml-1 was applied over the wound area immediately after surgery.

RESULTS

The total incidence of PONV in hospital and at home during the first 24 h was 36% (5/14) when fentanyl was used, whereas no PONV was reported when placebo was given (P < 0.05). The median time to first administration of analgesics after the caudal block was approximately 6 h. It did not differ between groups. Intraoperative fentanyl did not result in any reduction in pain scores nor the incidence of pain. Fentanyl caused apnoea in one-half of the cases and decreased the breathing rates during the first 10 min of surgery.

CONCLUSIONS

Intraoperative use of i.v. fentanyl 1 micro g.kg-1 combined with a regional anaesthetic block is associated with an increased incidence of PONV without any significant contribution to the postoperative pain relief.