Pre-emptive effect of pre-incisional versus post-incisional infiltration of local anaesthesia on children undergoing hernioplasty.

BACKGROUND: Although promising in experimental studies of post-traumatic pain, the concept of pre-emptive analgesia is still controversial in a clinical setting. Thus, we wanted to compare the clinical efficacy of wound infiltration with local anaesthesia before surgery with wound infiltration after hernioplasty in children.

METHODS: Fifty children aged 2-10 years scheduled for hernioplasty were randomly assigned into two groups. Group 1 (n = 28) was infiltrated before surgery with bupivacaine 2.5mg/ml, 1mg/kg after induction of general anaesthesia. After surgery they were infiltrated with the same volume of 0.9% saline. Group 2 (n = 22) was infiltrated with 0.9% saline before surgery and bupivacaine 2.5 mg/ml, 1mg/kg after surgery. The study was performed double-blindly. In both groups anaesthesia was induced with thiopenthone and maintained with nitrous oxide and halothane, adjusted to keep haemodynamic measurements stable. All children were given paracetamol 15-20 mg/kg rectally when admitted to the recovery ward. Painscore (OPS) and analgesic requirements were registered postoperatively. After 48 h the parents completed a standardised questionnaire and they were interviewed by telephone after one week.

RESULTS: The pre-incisional group needed significantly less halothane during the procedure compared with the post-incisional group (P < 0.05). The pre-incisional group also had a tendency towards faster awakening after the end of anaesthesia and a significantly lower OPS-pain score 30 min after the operation (P < 0.03). There were no differences between the two groups regarding need for additional analgesia: meperidine i.v. during the first 5 h postoperatively, and paracetamol thereafter. There were no differences between the groups regarding activity level, appetite and quality of sleep in the first week. In both groups the need for opioid analgesics was low: 54% in the pre-incisional group and 45% in the post-incisional group did not receive any opioid analgesic treatment. The children were virtually fully recovered after the first 24 h.

CONCLUSION: Perioperative infiltration with a local anaesthetic in children undergoing hernioplasty results in a smooth recovery with little need for opioids postoperatively. Apart from a lower anaesthetic requirement and a reduced postoperative pain level after 30 min in the pre-incisional bupivacaine group, there was no difference between infiltration before (pre-emptive) or after surgery.