Evaluation of Changes in Intracranial Pressure in Patients Undergoing Weaning from Mechanical Ventilation Using Optic Nerve Sheath Diameter Measurement

INTRODUCTION: Aim is to investigate changes in intracranial pressure (ICP) during the weaning process by comparing continuous positive airway pressure (CPAP) and T-piece spontaneous breathing trials using serial optic nerve sheath diameter (ONSD) measurements by ultrasonography.
METHODS: This prospective, single center study included 40 mechanically ventilated adult intensive care patients undergoing weaning. Patients were allocated to either a CPAP group (n=20) or a T-piece group (n=20). ONSD, mean arterial pressure, and rapid shallow breathing index were (RSBI) measured at predefined stages during weaning and one hour after extubation. Changes in repeated measurements and correlations between sequential measurement differences and time intervals were analyzed.
RESULTS: ONSD values increased progressively during the weaning process in both groups, with a more pronounced increase observed during T-piece trials. ONSD decreased after extubation, particularly in the CPAP group. Within-group changes in ONSD were statistically significant (p<0.001). No significant differences were observed between groups regarding weaning success or RSBI changes. A significant positive correlation was identified between the change in ONSD and the duration between measurements in the T-piece group after extubation (r=0.453, p=0.045). No significant differences in ONSD were found between patients with successful and unsuccessful weaning.
DISCUSSION AND CONCLUSION: T-piece spontaneous breathing trials are associated with greater increases in ONSD, suggesting higher ICP during the weaning process. Serial ONSD measurement may be a useful non-invasive tool for monitoring ICP, particularly in patients at risk of intracranial hypertension during weaning.

Keywords: Weaning, intracranial pressure, mechanical ventilation