Single shot spinal anesthesia with very low hyperbaric bupivacaine dose (3.75 mg) for hip fracture repair surgery in the elderly. A randomized, double blinded study.
PURPOSE
Single shot spinal anesthesia is used worldwide for hip fracture repair surgery in the elderly. Arterial hypotension is a frequent adverse effect. We hypothesized that lowering local anesthetics dose could decrease the incidence of arterial hypotension, while maintaining quality of surgical anesthesia.


METHODS
In a randomized double blinded study, 66 patients over the age of 65 years, with hip fracture needing surgical repair, were assigned to B0.5 group 7.5mg hyperbaric bupivacaine 5mg/ml (control group), and B0.25 group 3.75mg hyperbaric bupivacaine 2.5mg/ml (study group). Sensory and motor block level, and hemodynamic parameters including blood presure, heart rate and vasopressor dose administration were registered, along with rescue anesthesia needs, the feasibility of surgery, its duration, and regression time of sensory anesthesia to T12.


RESULTS
After exclusions, 61 patients were included in the final analysis. Arterial hypotension incidence was lower in the B0.25 group (at the 5, 10, and 15min determinations), and a lower amount of vasopressor drugs was needed (mean accumulated ephedrine dose 1.6mg vs. 8.7mg in the B0.5 group, p<0.002). Sensory block regression time to T12 was shorter in the B0.25 group, mean 78.6±23.6 (95% CI 51.7-110.2)min vs. 125.5±37.9 (95% CI 101.7-169.4)min in the B0.5 group, p=0.033. All but one patient in the B0.25 group were operated on under the anesthetic procedure first intended. No rescue anesthesia was needed.


CONCLUSION
Lowering bupivacaine dose for single shot spinal anesthesia for hip fracture repair surgery in elderly patients was effective in decreasing the occurrence of arterial hypotension and vasopressor use, while intraoperative quality remained.