Routinely, Subarachnoid block is practiced for performing operative procedures under general surgery, orthopaedic and obstetrics and gynecology below umbilicus. 100 patients ASA grade I ­ II of either sex were divided into 2 equal groups of 50 each pout which Group I were young adults (20­40 years age) and Group II were elderly patients above 60 years age. All patients were preoperatively evaluated for fitness of anaesthesia. In group I mean age was 32.42 ± 3.44 and in group II mean age was 66.40 ± 3.91 years. After intravenous access, preloading was done with 7 ml / kg Ringer lactate solution. The mean duration of operation in group I was 77.6 ± 14.6 mints and in group II was 81.0 ± 14.6 mints, there was no statistical significant difference. Mean preoperative pulse rate in group I was 87.12 ± 7.17 per min and 84.92 ± 14.6 min in group II patients. Mean arterial pressure was 90.0 ± 5.17 in group I and 91.2 ± 5.45 in group II patients with no significant difference. The maximum height of sensory blockade was significantly higher in elderly patients as compared to adult patients. Intraoperative fluid requirement was same in both groups. Intraoperative hypotension was noted in 22% of patients in group I and 34% of patients in group II and average number of patients requiring vasopressor was 2 patients in group I and 6 patients in group II. Thus incidence of intraoperative hypotension requiring immediate correction was more in elderly group as compared to adult patients. In recovery room, highest level of sensory blockade was more in group II as compared to adult group. In recovery room after application of orthostatic challenge, the changes mean pulse rate and MAP were noted at 0, 30, 60 and 90 minutes. At all time intervals percentage rise in mean pulse rate and percent fall in MAP was more significant in elderly (group II) patients at all time intervals as compared to group I patients and it was more significant at 0 and 30 minutes and even upto 90 minutes in elderly patients. The sensory level was higher and regression was slower in elderly patients as compared to adult patients. Thus orthostatic challenge test can be safely applied in elderly patients to assess its efficacy for discharging patients from recover to wards without harm to patients. 

Keywords: Spinal Anaesthesia; Differential Spread of Blockade; Higher Sensory Block In Elderly; Delayed Regression of Block; Orthostatic Challenge; Efficacy; Criteria for Early Shifting of Patients from Recovery to Wards; Curtails Load on Recovery Room.