Effects of head direction during prone position on postoperative delirium in elderly patients undergoing thoracolumbar spine surgery: a study protocol for a randomised controlled trial

Introduction: Prone positioning with head rotation can influence cerebral haemodynamics, potentially affecting cerebral perfusion and oxygenation. Elderly patients with impaired brain perfusion and oxygenation are at an increased risk of developing postoperative delirium (POD). Despite this, few studies have explored whether head orientation during prone positioning contributes to POD in older adults, an aspect often overlooked by clinicians. This study aimed to evaluate the impact of head orientation during prone positioning on the incidence of POD in elderly patients undergoing thoracolumbar spine surgery.

Methods and analysis: This study is a single-centre, randomised, single-blind trial, with the assessors blinded to the intraoperative head position. Eligible participants are patients aged ≥65 years undergoing elective thoracolumbar spine surgery. A total of 500 patients will be randomly assigned to either the prone position with the head centred, or the prone position with the head deviated. The primary outcome is the incidence of POD, measured using the 3 min Diagnostic Interview for Confusion Assessment Method (3D-CAM) until postoperative day 5. Secondary outcomes include the severity of POD assessed by the Memorial Delirium Assessment Scale (MDAS), postoperative cognitive impairment evaluated using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA), intraoperative regional cerebral oxygen saturation (rSO₂), changes in vertebrobasilar artery and middle cerebral artery haemodynamics, and plasma levels of calcium channel-binding protein S100 subunit beta (S100B) and neuron-specific enolase (NSE).

Ethics and dissemination: Ethical approval was obtained from Yancheng No. 1 People's Hospital Ethics Examination Committee (2023-K-120-01). The findings will be disseminated through presentations at annual conferences and publications in scientific journals.

Trial registration number: ChiCTR2300078839.