Bilateral interpleural block for midline upper abdominal surgery.

To the Editor: Continuous interpleural block provides effective postoperative analgesia following a variety of operations with unilateral skin incisions. ~-2 We report a case where bilateral interpleural blocks combined.with light general anaesthesia were used to provide intraoperative and postoperative analgesia for midline upper abdominal surgery. A 23-yr-old male, weighing 55 kg with chronic ulcer disease, but in otherwise good health, presented for vagotomy and pyloroplasty. Premedication consisted of meperidine 50 mg and promethazine 25 mg im one hour pre-op. In the operating room ECG, automatic blood pressure cuff and pulse oximeter probe were applied and an iv infusion commenced. The patient was further sedated with fentanyl 100 I~g and midazolam 2 mg and placed in a lateral position. Following skin preparation with betadine and local anaesthetic infiltration, an interpleural catheter was placed in the seventh intercostal space at the posterior axillary line using a loss of resistance technique. The patient was turned to the opposite side and the procedure was repeated. The catheters were both introduced a distance of 4-5 cm in the interpleural space, taped in place and draped over the shoulders. After the second catheter was placed, the patient was turned supine and 30 ml of bupivicaine 0.25% with epinephrine 1:200,000 were injected on each side. General anaesthesia was then induced with thiopentone 225 mg and was followed by succinylcholine 80 mg. The trachea was intubated with a 9 mm tracheal tube and allowed to breathe spontaneously a mixture of 70% nitrous oxide in oxygen and halothane 0.3% delivered from a circle absorber system. One half-hour into the surgery the haiothane was discontinued, as it appeared unnecessary and the patient received an additional 2 mg of midazolam to prevent awareness. No additional narcotics were given. The surgeons were asked to evaluate muscular relaxation at several times throughout the case and commented that it was satisfactory. The patient's blood pressure ranged between 125/70 and 105/55 and the pulse between 60 and 80/minute. The end tidal CO2 and arterial 02 saturation remained stable and within normal limits, in spite of surgical retraction. Throughout the operation there were no signs of discomfort, light anaesthesia or sympathetic discharge. Surgery lasted 120 minutes. In the recovery room the patient's only complaint was of nasal discomfort from the nasogastric tube. A chest x-ray taken in the recovery room showed a small pneumothorax on the fight which resolved without treatment over the next few hours. The patient received four top-up injections on the ward, the timing of which depended on the availability of one of the authors. These consisted of 20 ml of bupivicaine 0.25% with epinephrine 1:200,000 on each side. We were impressed by the profound difference in analgesia before and after each injection. The patient also received two 50 mg doses of im meperidine in the first 24 hours, but no additional narcotics. Both catheters were removed on the third postoperative day and the patient made an uneventful recovery. The use of bilateral interpleural blocks has been described previously in two patients with cancer pain and fib fractures respectively. 4 Potential complications can occur such as pneumothorax and toxicity from absorption of local anesthetics. Also, the use of nitrous oxide following air to locate the interpleural space may potentially enlarge a pneumothorax. Clearly, detailed studies are required to determine the efficacy and safety of the bilateral technique as well as its effect on cardiopulmonary function.