INTRAVENOUS SEDATION PRIOR TO PERIBULBAR ANESTHESIA FOR CATARACT-SURGERY IN ELDERLY PATIENTS

Purpose: To investigate if pre-block iv sedation using midazolam, alfe ntanil, or a midazolam-alfentanil combination minimizes pain, reduces pain recall, and attenuates haemodynamic responses to peribulbar block ; and to determine other factors influencing oxygen saturation (SpO(2) ) following iv sedation. Methods: In a randomized, double-blind, place bo-controlled study, 120 patients, mean age 73 yr, having cataract sur gery with peribulbar anaesthesia, were randomized to receive either no rmal saline, 1 mg midazolam, 500 mu g alfentanil, or 0.5 mg midazolam plus 250 mu g alfentanil. Blood pressure (BP), heart rate (HR) and pul se oximetry readings were recorded before injection of the study drugs , immediately after completion of the peribulbar block, and 10 min aft er the block. Pain from the anaesthetic block was assessed immediately after the block and after surgery using a visual analog scale, and re call of pain was assessed by telephone on the day after surgery. Resul ts: Pain scores were low in all four groups. Midazolam-alfentanil redu ced pain perception, and all iv sedation used reduction pain recall. M idazolam reduced systolic BP; alfentanil +/- midazolam reduced HR. All iv sedation reduced SpO(2) more than did saline, but not usually to a clinically important level. Nine patients had a SpO(2) less than or e qual to 90%; all had received alfentanil with or without midazolam. It was not possible to predict oxygen saturation levels by any factors o ther than iv sedation and baseline SpO(2) levels. Conclusion: Intraven ous sedation with midazolam or alfentanil or in combination reduced pa in perception, pain recall, and haemodynamic responses from peribulbar anaesthesia. Fifteen percent of patients given alfentanil developed c linically important oxygen desaturation. The use of fine gauge needles combined with slow injection of anaesthetic solution causes minimal d iscomfort, and routine iv sedation may be unnecessary.