Effusion after interpleural analgesia.

To the Editor: Interpleural regional analgesia for postoperative pain relief is simple, safe and effective. 1-2 Pneumothorax is the most common complication.l-3 Following an elective cholecystectomy in a 29-yr-old healthy human but before extubation of the trachea, the patient was turned to the left side, and an interpleural catheter was placed using the saline infusion technique. 4 General anaesthesia was then discontinued, 20 ml of 0.5% bupivicaine with epinephrine (51~g.ml -l) were injected and the patient had good pain relief. Nine hours later, when a top-up dose was needed, aspiration of the catheter yielded about 9 ml of hazy, red-tinged fluid. This was sent for examination and the top-up dose was withheld. Overnight the patient received meperidine and promethazine for pain relief. Re-aspiration of the catheter the next day produced no aspirate and interpleural analgesia was continued for a further 48 hr uneventfully using plain bupivicaine. Examination of the aspirated fluid showed an RBC count of 60,660. ixl -l and WBC count of 360.1~1-1 (differential leucocyte count from concentrated centrifuge was neutrophils 50%, lymphocytes 13%, monocytes 31%, eosinophils 3% and bands 3%). The mechanism of this effusion is unclear. It could have been a reactionary pleural effusion to the catheter or to sodium metabisulphite and anhydrous citric acid which are added as antioxidants when epinephrine is added to bupivicaine. Subsequent use of plain bupivicaine produced no such effusion. Although no direct cause and effect relationship could be established from this case report, yet it highlights the need for vigilance.