[The effect of age on the spread of spinal anesthesia using isobaric 2% mepivacaine]

In the elderly, anaesthesia and surgery are associated with higher perioperative mortality and morbidity as compared to younger patients. There is some evidence that spinal anaesthesia may improve the postoperative state of elderly patients. A prospective study was performed to elucidate the effects of age on the characteristics of spinal anaesthesia with isobaric 2% mepivacaine. METHODS. Forty-six patients aged between 17 and 39 years and 48 elderly patients aged between 76 and 87 years having operations on the lower extremities or lower abdomen were investigated. All patients received 4.5 ml plain mepivacaine 2% (90 mg) as a subarachnoid injection in the L3-4 interspace in the sitting position. The patients were turned supine immediately after the injection. Time of onset, extent and duration of analgesia, motor block, and cardiovascular responses were assessed. The segmental level of sensory loss was tested using the pin-prick method. RESULTS. It was found that the time to maximal motor blockade was significantly decreased in the older age group compared to the younger group (7.9 vs 11.5 min). In the older group, the time to maximum spread was significantly shorter (11.4 vs 13.6 min). A significantly higher sensory block was obtained in the older group (T8 vs T10). The mean duration of analgesia or motor blockade did not differ significantly (200.7 vs 192.8 min). There were no unacceptably high degrees of spinal blockade. In the older group there was a tendency to a greater decrease in systolic arterial pressure as compared to preanaesthetic values (23.7% vs 16.3%) and greater falls in diastolic blood pressure were observed in the older group (22.1% vs 14.4%). A greater volume of lactated Ringer's solution was necessary in the older group (14.8 vs 10.3 ml/kg). Postspinal headache was encountered in 3 patients in the younger group and 2 in the older group. DISCUSSION. It is concluded that there was a tendency for greater spread of spinal analgesia with isobaric 2% mepivacaine in the elderly. The clinical significance of this finding is limited. In elderly patients hypotension is more common than in younger patients, but might not be related solely to age or extent of the neural blockade.