Effects of a combined nerve block on intraoperative stress and postoperative immune function in elderly patients subjected to total hip replacement: study protocol for a randomized controlled trial

Background: Anesthesia, surgery, and other nociceptive stimuli affect stress and hemorheological indices, impact physiological function, decrease immune function, and thereby influence recovery of hip joint function in elderly patients who undergo total hip replacement. Previous anesthesia methods for hip replacement in elderly patients include general, lumbar puncture, or epidural anesthesia alone. A combined nerve block is more suitable for total hip replacement in the elderly because of the safety and reliability of the method. In this study, we hypothesized that a combined nerve block is superior to any previous anesthesia method alone for total hip replacement in the elderly. Specifically, we hypothesized that intraoperative stress, hemorheological indices, postoperative immune function, and incidence of postoperative complications would be more favorable using a combined nerve block compared with previous anesthesia methods. Methods/Design: This is a prospective, single-center, randomized controlled, open-label trial, which will be performed at Qinghai University Affiliated Hospital, China. A total of 120 elderly patients scheduled to undergo total hip replacement will be randomly assigned to undergo a combined nerve block (involving lower lumbar plexus, sciatic nerve, and paraspinal nerve L 1-2 ) (experimental group, n = 60), or general anesthesia (control group, n = 60). All patients will be followed up at 3 months. The primary outcome is serum cortisol concentration during surgery, as a measure of intraoperative stress. Secondary outcomes include serum cortisol concentration prior to anesthesia, and prior to and immediately after surgery; blood glucose level prior to anesthesia, and prior to, during, and after surgery, used to evaluate stress during different times. In addition, immune function-related indices including absolute leukocyte count, absolute neutrophil count, interleukin-1, interleukin-6, tumor necrosis factor-α, and T-lymphocyte subset levels prior to anesthesia, immediately after surgery, 1, 3, 7 days, and 3 months after surgery, will be used to evaluate patients' immune function after surgery. Hemorheological indices including electrocardiogram, pulse, systolic pressure, diastolic pressure, heart rate, blood gas analysis prior to anesthesia, and during and after surgery will be used to investigate changes in blood-related indices. Lastly, incidence of adverse events 1, 3, 7 days, and 3 months after surgery will be used to evaluate postoperative complications. Discussion: This study will investigate the effects of a combined nerve block versus general anesthesia on intraoperative stress and postoperative immune function in elderly patients who undergo total hip replacement. This study will provide objective evidence for selection of anesthesia method for total hip replacement in the elderly, with the aim of reducing intraoperative risks and postoperative complications. Trial registration: ClinicalTrial.gov identifier: NCT02884388; registered on 19 August 2016. Ethics: This trial has been approved by Ethics Committee, Qinghai University Affiliated Hospital, China (approval number QHY1017D) and will be performed in accordance with the Declaration of Helsinki, formulated by the World Medical Association. Informed consent: Signed informed consent will be obtained from the patients or their relatives.