A prospective observational study of head-of-bed adjustment for patients following elective craniotomy based on cerebral autoregulation

Background: While head-of-bed (HOB) elevation is standard in neurocritical care for managing intracranial hypertension, its optimal angle for patients after elective craniotomy remains undefined. This study aimed to evaluate the effects of different HOB angles on cerebral hemodynamics, oxygenation, and cerebral autoregulation (CA) in patients during the early postoperative period following elective craniotomy. Methods: In a prospective observational study, 21 patients underwent sequential positioning at HOB 45°, 30°, 15°, and 0°. Each angle was maintained for 15 min, with multimodal data including intracranial pressure (ICP), cerebral perfusion pressure (CPP), mean flow velocity (mFV) and pulsatility index (PI) of the middle cerebral artery (MCA) M1 segment, tissue oxygenation index (TOI) and the mean flow index (Mx-a) for CA recorded during the final 5 min. Linear mixed-effects models assessed the main effects of HOB angle, baseline ICP status (Elevated: >15 mmHg vs. Normal), and baseline CA status (Impaired: Mx-a > 0.3 vs. Intact). Results: < 0.001). Conclusion: HOB significantly modulates cerebral hemodynamics after elective craniotomy. The 0° position is particularly detrimental, elevating ICP, reducing CPP, and potentially exhausting cerebrovascular regulatory reserve. Patient's baseline ICP and CA status are key determinants of their hemodynamic response. Postoperative management must extend beyond the prevention of intracranial hypertension to also include the vigilant avoidance of CA impairment.