Title

A randomised controlled trial comparing haemodynamic stability in elderly patients undergoing spinal anaesthesia at L5,S1 versus spinal anaesthesia at L3,4 at The Aga Khan University Hospital, Nairobi

Date of Award

5-25-2012

Document Type

Dissertation

Degree Name

Master of Medicine (MMed)

Department

Anaesthesia (East Africa)

Abstract

Background: Spinal anaesthesia is a routinely used anaesthetic technique for elderly patients undergoing operations involving the lower limbs, lower abdomen, pelvis and the perineum. Spinal anaesthesia has several advantages over general anaesthesia and these include stable haemodynamic variables, less blood loss, less post operative pain, faster recovery time and less post operative confusion. However, despite these advantages, the sympathetic blockade induced by spinal anaesthesia can result in hypotension, bradycardia, dysrhythmias and cardiac arrests.

Conventionally, spinal anaesthesia is performed at the level of L3,4 interspace; with a reported incidence of hypotension in the elderly ranging between 65% and 69%. A possible strategy for reducing spinal induced hypotension would be to minimize the peak block height to as low as possible for the planned procedure.

The purpose of this study was to investigate the decrease in mean arterial pressures and change heart rates from baseline values (haemodynamic stability) of elderly patients undergoing spinal anaesthesia performed at the level of L5, S1 compared to the conventional level at the L3, 4 interspace.

Objective: To determine the difference in haemodynamic stability between elderly patients undergoing spinal anaesthesia at L5, S1 interspace compared to elderly patients undergoing spinal anaesthesia at L3, 4.

Study design: A randomized single blinded controlled trial

Methods: Thirty two elderly patients scheduled for lower limb or pelvic surgery under spinal anaesthesia were randomized into 2 groups (control group and intervention group) using a computer generated table of numbers.

Control group; received 2.5 mls 0.5% hyperbaric bupivacaine injected intrathecally at the L3, 4 interspace

Intervention group; 2.5mls 0.5% hyperbaric bupivacaine injected intrathecally at the L5, S1 interspace

Results: The two groups had similar baseline characteristics in age, sex, body mass index and use of anti-hypertensive medications. There was 68.75% proportion of hypotension in the control group and 75% in the intervention group. The difference was not found to be statistically significant (p= 0.694). During the study period, there were 106 episodes of hypotension, out of which, 65 were in the control group and 41 in the intervention group (p=0.004). This difference was statistically significant.Linear regression analysis of the decrease in mean arterial pressures (MAP) showed a higher decrease in MAP in the control group (p 0.018). There were more crystalloids used in the control group (1006mls ± 374) than in the intervention group (606mls ±211) with a p< 0.0001. There was no difference in the amounts of vasopressors used between the two groups (p=0.288).There was no difference in the change in heart rates,conversion to general anaesthesia, use of supplementary intravenous fentanyl and the peak maximum block level achieved. The time to peak maximum level was 9.06min and 13.07min in the control group and intervention groups, respectively (p<0.0001).

Conclusion: Among this population, there was no difference in the proportion of those with hypotension between the elderly patients who received their spinal anaesthesia at L3,4 and those who received spinal anaesthesia at L5,S1. There were significantly less episodes of hypotension in the intervention group. It took a longer time to achieve a maximum peak sensory block in the intervention group. Performing spinal anaesthesia at the level of L5,S1 was found to provide an adequate sensory block for a wide range of pelvic, perineal and lower limb surgeries.

The study was registered under Pan African Clinical Trials Registration number PATCR 201109000311318

This document is available in the relevant AKU library

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