A randomized controlled trial comparing haemodynamic stability in elderly patients undergoing spinal anaesthesia at L5, S1 versus spinal anaesthesia at L3, 4 at a tertiary African hospital.|
Mung’ayi, Vitalis; Mbaya, Karen; Sharif, Thikra & Kamya, Dorothy
Background: Spinal anaesthesia is a routinely used anaesthetic technique in elderly patients (> 60 years) undergoing operations
involving the lower limbs, lower abdomen, pelvis and the perineum. Spinal anaesthesia has several advantages over
general anaesthesia including stable haemodynamic variables, less blood loss, less post-operative pain, faster recovery time
and less post-operative confusion. 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
Objective: To determine the difference in haemodynamic stability between elderly patients undergoing spinal anaesthesia at
L5, S1 interspace compared to those at L3, 4.
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 and 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 68.8% 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).. 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 sensory block 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. The intervention
group had better outcomes with significantly less episodes of hypotension. 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.
Haemodynamic stability; spinal anaesthesia