Sedative properties of epidural anesthesia / 中华麻醉学杂志

ABSTRACT

Objective To investigate the potential sedative effects of epidural anesthesia and its mechanism. Methods Fifty ASA Ⅰ -Ⅱ patients aged 20-55yr, scheduled for gynecological surgery were studied. Patients whose body weight exceeded 95 kg or was less than 45kg were excluded. Alcoholics and those addicted to sedative or opiates were also excluded. The patients were unpremedicated. Before anesthesia the patients' radial artery was cannulated for continuous BP monitoring and blood sampling. ECG, BIS and HRV were continuously monitored. Epidural puncture was performed at L1-2 . A catheter was inserted in epidural space for 3-4cm in a cephalad direction. The patients were randomly divided into 3 groups epidural lidocaine group (group E, n = 15); intravenous lidocaine group (group Ⅰ , n = 15) and control group (group C, n =20). In group E the patients received an iv bolus of lidocaine 1.5mg?kg-1 followed by a lidocaine infusion at a rate of 30mg?kg-1?min-1 and an epidural bolus of normal saline 15 ml; in group C the patients received an epidural bolus of NS 15 ml only. The intravenous lidocaine infusion in group I was designed to mimic systemic absorption of lidocaine from epidural space. 20 min after epidural lidocaine or saline administration, a propofol infusion was started at a rate of 150ml/h until the patients lost consciousness, The amount of propofol infused was recorded. Blood samples were taken before propofol infusion for determination of plasma level of lidocaine. Results The amount of propofol infused when the patients lost consciousness was (1.22 ?0.25) mg?kg-1 in group E, (1.62 ?0.22) mg?kg-1 in group I and (1.85?0.41) mg?kg-1 in control group. The amount of propofol infused in group E was significantly less than that n group I and C ( P