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The direct perfusion of surgical wounds with local anaesthetic solution.

The direct perfusion of surgical wounds with local anaesthetic solution Messrs Thomas, Lambert and Lloyd Williams (Annals, July 1983, vol 65, p 226) present observations of this technique and cite its early descriptions in the literature of the 1950s. More recently Samarji (1) reported a series of 142 patients having upper abdominal surgery and compared intramuscular methadone, 0.5%/ bupivacaine in the rectus sheath and epidural analgesia; he concluded that 'chest infection and complications were significantly lower' in the rectus sheath group and recommended the technique for patients with 'existing airway disease'. No results of lung function measurements were given and pain assessment was based on the patient's ability to sit up, take deep breaths and to cough. The report concluded that pain relief was complete in the rectus sheath group. We have recently completed a similar study to that of Thomas et al. and wish to comment on their methodology and results. The precision of their mean vital capacity values and postoperative papaveretum requirements is reduced because males and females are included; it is well recognised that standardisation with respect to sex is essential in studies of this type (2). Furthermore, the timing of vital capacity measurements during days 1, 2 and 5 is not indicated; these measurements are known to be influenced by physiotherapy and prior opiate administration (3). Spirometry and assessment of pain immediately before wound perfusion and again at an interval of 30 minutes after perfusion would allow a more definitive evaluation. Standardisation could be improved by withholding papaveretum during the preceding 3 hours. Although they conclude that their claims of pain relief with saline and 0.5% bupivacaine are based upon clinical impression, their demonstration of a statistically significant reduction in postoperative papaveretum requirements in these two groups compared to the control group who received papaveretum only is convincing albeit subject to patient demand and nursing discretion. In our study of 50 patients with subcostal incisions whose wounds were perfused in a similar manner with either 0.5% bupivacaine or normal saline, we measured FEV1, FVC and visual analogue pain score (4) twice daily for 3 days after operation. We found that in the bupivacaine group FEV1 and FVC were improved after perfusion compared with measurements made immediately prior to perfusion (P< 0.01). There were significant improvements in visual analogue scores in both groups (P<0.01) which supports the claim by Thomas et al. of an apparent analgesic effect of saline perfusion. We agree that saline had no effect on FEV1 or FVC. Assessment of pain need not be the sophisticated measurement they suggest and the linear visual analogue score is simple to use and suitable for any District General Hospital. Whether wound perfusion is better than narcotics or epidural block in reducing postoperative hypoxaemia or improving functional residual capacity remains to be established but we agree that its analgesic efficacy and safety justify wider application and evaluation. IAIN D LEVACK MD FFARCS Senior Registrar in Anaesthetics Royal Infirmary Edinburgh G S ROBERTSON MD FFARCS Consultant Anaesthetist Aberdeen Royal Infirmary