Position-dependent hemodynamic changes in neurosurgery patients: A narrative review

Patient positioning is one of the milestones of neurological surgery, which significantly affects the surgical outcome and requires a multidisciplinary approach. Several positions are applied in neurosurgical interventions, including supine, lateral, park bench, prone, sitting, and semi-sitting. In this regard, different positions could lead to changes in intracranial pressure (ICP) and cerebral hemodynamics. Cerebral autoregulation (CA) is a safeguard for adequate cerebral perfusion that keeps cerebral blood flow (CBF) constant in a variable range of cerebral perfusion pressures (CPP). The clinical management of the dysfunction in CBF is still challenging due to the narrow range of cerebral self-regulation, especially in neurovascular and oncological neurosurgery. Moreover, patient positioning might predispose the patient to various intra- or postoperative complications. Changes in hemodynamics and cardiovascular function as a result of patient positioning have also been reported previously. The ICP monitoring aids us in managing surgical conditions and preventing sudden complications in neurosurgery, such as venous air embolism (VAE), hypotension, and arrhythmias. Other positional-related complications in neurosurgery are cerebral bleeding, venous and paradoxical air embolism, and pneumocephalus. Therefore, the present review aims to discuss different aspects of patient positioning in neurosurgical procedures, such as its potential impacts on cerebral hemodynamics and surgical outcomes.