Sedation with target-controlled propofol infusion during shoulder surgery under interscalene brachial plexus block in the sitting position: report of a series of 140 patients

BACKGROUND AND OBJECTIVE: The aim of this study was to assess target-controlled propofol infusion as a technique of sedation for shoulder surgery under interscalene brachial plexus block in the sitting position and to evaluate the effect of sedation on hypotensive/bradycardic events during this procedure. METHODS: One hundred and forty patients undergoing elective shoulder surgery in the sitting position under interscalene brachial plexus block (with 30 mL of ropivacaine 0.75%) were prospectively enrolled. All patients were premedicated with hydroxyzine 1 mg kg(-1), none received beta-blockers. No patients were given atropine except for the patients who experienced a vasovagal event either during the block procedure or intravenous catheter placement. The target-controlled propofol infusion was started immediately after positioning the patient on the operating table. The initial target concentration was 1 microg mL(-1). The infusion rate was adjusted every 15 min by increasing or decreasing the target concentration by 0.2 microg mL(-1) steps to maintain the patient rousable to verbal commands (score of 3 on Wilson sedation scale). The following parameters were assessed: minimal, maximal, optimal target concentration, respiratory and haemodynamic parameters, total propofol dose, additional alfentanil needs, occurrence of hypotensive/bradycardic events, complications. Results are mean +/- SD. Statistical analysis used t-test and chi2-tests. RESULTS: The optimal propofol target concentration was 0.8 mug mL(-1). No respiratory complications or conversion to general anaesthesia was reported. Two patients experienced transient and inconsequential intraoperative agitation. The incidence of hypotensive/bradycardic events during the procedure was 5.7% (eight patients). CONCLUSION: Target-controlled propofol infusion (0.8-0.9 microg mL(-1)) following hydroxyzine premedication is a safe and effective technique for sedation when combined with interscalene brachial plexus block during shoulder surgery in the sitting position.