Impact of bupivacaine dose on haemodynamics in elderly hip surgery: a randomized controlled trial

Elderly patients with hip fractures are at high risk of hypotension during spinal anaesthesia, and lowering the intrathecal local anesthetic dose may help reduce haemodynamic instability. We therefore compared two low-dose spinal anaesthesia protocols in patients ≥ 65 years with hip fractures, and secondarily evaluated the relationship between preoperative perfusion index (PI), haemodynamic variables, patient satisfaction, and discharge time. Patients aged 65 years and older scheduled for surgery for hip fracture were included in this prospective, randomized controlled study. Patients were divided into two groups based on the spinal anaesthesia protocol: group B5 received 5 mg of 0.5% hyperbaric bupivacaine, and group B7.5 received 7.5 mg of 0.5% hyperbaric bupivacaine. The lower dose (5 mg) was chosen to reduce the risk of hypotension in frail older adults, while the higher dose (7.5 mg) served as a comparator reflecting conventional dosing. All patients underwent pre- and intra-operative ASA standard non-invasive monitoring, PI measurements were performed and recorded. The baseline PI was determined as the average of three values measured at five-minute intervals. All patients received a PENG (pericapsular nerve group) block prior to spinal anaesthesia to improve analgesia before positioning, facilitate comfort during lateral decubitus placement, and reduce perioperative opioid requirements. Block success was assessed by confirming adequate sensory loss to pinprick on the operative side. Spinal anaesthesia was performed in the lateral decubitus position to promote a preferential unilateral block on the operative side, aiming to limit sympathetic spread and minimize haemodynamic instability. The allocated bupivacaine dose was administered, and the surgical procedure was started once adequate anaesthesia was confirmed. There was no difference in demographics between the groups. The incidence of hypotension was significantly higher in Group B7.5 compared to Group B5 (76.4% vs. 26.4%, p < 0.001), and ephedrine use was also greater in Group B7.5 (15.29 ± 11.27 mg vs. 2.65 ± 3.53 mg, p < 0.001) Bromage scale and dermatomal regression occurred earlier in group B5. Dermatomal level reached the highest level in group B7.5. There was no significant difference in the preoperative PI value used to predict hypotension after spinal anaesthesia between and within groups. Discharge time was shorter in group B5. We found that 5 mg 0.5% hyperbaric bupivacaine caused less hypotension than 7.5 mg 0.5% hyperbaric bupivacaine and provided adequate spinal anaesthesia in elderly patients undergoing hip fracture surgery, consequently resulting in significant clinical outcomes by reducing the length of hospital stay. Preoperative PI score was not significant in predicting hypotension. https://www.clinicaltrials.gov/ NCT05896631.