Spinal anaesthesia with hyperbaric bupivacaine. Effects of age on neural blockade and pharmacokinetics.

Effects of ageing were studied on the neural blockade and the pharmacokinetics after subarachnoid administration of 0.5% bupivacaine 3 ml in 8% glucose in two groups of 15 male patients, between 20 and 55 yr and older than 55 yr, respectively. The blockade was performed with the patient in the sitting position. Two minutes after the injection the patient was placed in the supine position. The time to maximum cephalad spread and the upper level of analgesia increased with advancing age, whereas the time to onset of motor blockade decreased with advancing age. Effects of age on the total duration of analgesia and motor blockade could not be demonstrated. Age had no effect on the peak plasma concentration of bupivacaine. The time to peak concentration and the terminal half-life increased, whereas the total plasma clearance decreased with advancing age.