Hypotension after spinal block( SB) is dependent on pre-operative autonomic balance, hypertension, hydration, and SB level. in hypertensives the autonomic sympathetic activ¬ity before the spinal blockade may have limited capability for predicting hypotension. levobupivacaine is more cardiostable than racemic bupivacaine. The present study is designed to assess the haemodynamic effects of subarachnoid block with either 0.5% hyperbaric bupivacaine or 0.5% isobaric levobupivacaine

60 patients(40-60years) posted for elective orthopaedic operations under SB were in¬cluded into the study. Patients with DM or autonomic instability were excluded.Group B- (n=30) were administered 3ml of heavy bupivacaine and Group L(n=30) received 3ml of isobaric levobupivacaine in intrathecal space. 25 ugs of fentanyl was added to all spinal injectates. Demographic characteristics, preoperative pharmacotherapy, cardiac status and haemodynamics were compared before and after SB between the two groups

There was no significant difference between the groups with respect to demographics, cardiac status and antihypertensive therapy. Z score (baseline SBP) revealed normal distribution.The median maximal height of sensory block was T10( 8-11) in B and T6( 5-9) in L group. [p 0.023]. The SBP and DBP changes were statistically significant in Group L (SBP=143.07±21.04 preblock to 100.15±25.35 post block, p0.04/ DBP= 87.30±18.12 preblock to 81.60± 19 postblock, p0.05) . The HR change were statistically not significant( 5.14% in B vs 8.77% in L) .

Isobaric levobupivacaine provides adequate SB for lower limb orthopaedic surgeries. However, there is an increased possibility of higher blocks with addition of fentanyl. The drug should be cautiously used in hypertensive patients, where excessive decrease in BP can disturb the autoregulation further