Comparison of the Effects and Complications of Unilateral Spinal Anesthesia Versus Standard Spinal Anesthesia in Lower-Limb Orthopedic Surgery

Abstract

Objective :The aim of this prospective, randomized, parallel group study was to evaluate vital parameters , sensory and motor block during unilateral subarachnoid block and to compare it with that produced by standard bilateral spinal anaesthesia. Side effects and complications were also noted and compared.Methods: 100 ASA I-II patients scheduled for one leg surgery. Dural puncture was performed by 25-G spinal needle with patients lying in the lateral position and the side to be operated on dependent. Patients then randomly received 8 mg of 0.5% hyperbaric bupivacaine injected over 80 sec with needle hole orientated towards the dependent side (Unilateral, n = 30), or 15 mg of the same solution injected over 6 sec with needle bevel cranially directed (Control, n = 30). Only patients of the Unilateral group remained in the lateral position for 15 min. Blood pressure, heart rate were measured before spinal block (baseline) and then at 5, 15, 30 and 45 min; while sensory and motor blocks were evaluated at 15, 30 and 45 min on both sides.Results:Patients characteristics in terms of age and weight were comparable in both the groups All blocks were fully effective. Mean blood pressure was significantly lower in the bilateral group. Heart and respiratory rates did not differ between the groups. There was no statistically significant difference in mean time for onset, peak of sensory block in two groups. But there was statistically significant difference in two segment and complete regression of sensory block. Regression of sensory block was prolonged in group A as compared to group B (P<0.0001).There was no statistically significant difference in onset of motor block in two groups. But there was statistically significant difference in regression of motor block. There was delayed regression of motor block in group A as compared to group B (P<0.01).There was significant prolongation of analgesia in Group A where first rescue analgesic was required after 9 hours of subarachnoid blockade. Patients in Group B required rescue analgesic at 7 hours after subarachnoid blockade. There was statistically significant difference in duration of analgesia in two groups. Postoperative analgesia was significantly prolonged in Group A as compared to Group B.The total number of side effects (hypotension, bradycardia, apnoea) requiring intervention was similar in both groups.Conclusion: The use of 8 mg of 0.5% hyperbaric bupivacaine slowly injected through a directional needle provided a spinal block relatively restricted to the operative side with minimal effects on cardiovascular homeostasis. Unilateral spinal anaesthesia is safe. The dose of bupivacaine is lower and haemodynamic stability is better. The technique is more time consuming, compared to standard spinal anaesthesia and the patient's cooperation is essential.