Effects of bupivacaine or levobupivacaine on cerebral oxygenation during spinal anesthesia in elderly patients undergoing orthopedic surgery for hip fracture: a randomized controlled trial

BACKGROUND: Bupivacaine and levobupivacaine have similar pharmacokinetic and pharmacodynamic characteristics, and are used regularly in spinal anesthesia. Whether potential differences in their hemodynamic and anesthetic profiles could determine a differential risk of complications in elderly subjects, is controversial. The main objective was to compare the effects of intrathecally administered levobupivacaine (LB) versus bupivacaine (B), on regional cerebral O(2) saturation during spinal anesthesia, cognitive status and neurological complications in elderly patients undergoing surgery for hip fracture. METHODS: This was a randomized, controlled, single blind study. 58 patients aged 70 or older undergoing surgery for hip fracture with spinal anesthesia were allocated with a 1:1 ratio to receive LB or B, combined with fentanyl 15 μg, by intrathecal route. The primary outcome was the proportion of intraoperative time with regional cerebral desaturation (≥20% reduction in regional cerebral oxygen saturation from baseline), monitored by near –infrared spectroscopy. Secondary endpoints included hemodynamic parameters, level of sensory and motor block, changes in Short Portable Mental Status Questionnaire (SPMSQ), and neurological complications. RESULTS: The mean percentage of intraoperative time with desaturation in the B group was 6.1% (SD: 17.5) and 4.7% (SD: 11.9) in the left and right hemisphere respectively; in the LB group the mean was 4.8% (SD: 11.4) in the left hemisphere and 2.4% (SD: 8.3) in the right one. No statistically significant differences were found between treatment groups. The level of sensory block at the start of surgery was lower for LB than for B (Th10 vs Th8, p:0.047) and motor block at 15 min was lower for LB (2.5 vs 3, p:0.009). No differences in postoperative SPMSQ were observed. Neurological complications such as confusional state, agitation or disorientation were reported in 50% of patients in the B group and 21.4% of patients in the LB group, p = 0.05. CONCLUSIONS: No statistically significant differences in regional cerebral oxygen saturation or hemodynamic parameters were observed between both treatment groups. Bupivacaine and levobupivacaine differed in sensory and motor block achieved. While no differences were observed in cognitive impairment measured by the SPMSQ between treatment groups neurological complications reported by the physician were more frequent with bupivacaine. TRIAL REGISTRATION: European Union Clinical Trials Register (EudraCT 2013–000846 -20) (April 9th, 2013). ClinicalTrials.gov (NCT01960543) (September 23rd, 2013).