Lung Recruitment and PEEP Effects on Intracranial Pressure in Cranial Surgery

High positive end-expiratory pressure (PEEP) levels required to achieve clinical benefits may increase ICP and reduce cerebral perfusion pressure (CPP) in patients at risk of intracranial hypertension. However, individualizing ventilation parameters is essential for each patient. Among protective ventilation strategies, PEEP is key to preventing alveolar collapse. The PEEP level that minimizes alveolar collapse while avoiding overdistension of the pulmonary parenchyma is known as the Best PEEP. This study aims to evaluate the application of Best PEEP in cranial neurosurgery.

In general anesthesia for neurosurgery, mechanical ventilation is the standard approach. However, mechanical ventilation can induce pulmonary parenchymal injury through various mechanisms, including volutrauma, barotrauma, and atelectrauma. These correspond to lung damage caused by high tidal volumes, elevated airway pressures, repetitive alveolar collapse, and reopening. Protective ventilation strategies include limiting tidal volume (Vt), applying positive end-expiratory pressure (PEEP), and performing alveolar recruitment maneuvers (ARM). Historically, both ARM and higher levels of PEEP have been avoided in neurocritical patients, including those undergoing neurosurgery, due to concerns about their potential impact on intracranial pressure (ICP) and cerebral perfusion pressure (CPP). As postoperative pulmonary complications can significantly alter the prognosis of surgical patients, increasing hospital stay and healthcare costs, and, in neurocritical patients, compromising cerebral oxygenation, protective ventilation strategies may play a critical role in patients undergoing neurosurgery. Their historical exclusion from studies lacks demonstrated physiological justification. Here, the investigators aim to evaluate the impact of intrathoracic pressure on ICP in neurosurgical patients.