Accuracy of Noninvasive Intracranial Pressure Monitoring in Patients with Subarachnoid Hemorrhage

Abstract

Background: Subarachnoid hemorrhage (SAH) can lead to elevated intracranial pressure (ICP), which poses significant risks of morbidity and mortality. Monitoring ICP is crucial for the early detection and management of these complications in patients with aneurysmal SAH (aSAH). Traditional invasive ICP monitoring techniques, while effective, carry risks associated with infection and other complications. The Schmidt method, a noninvasive ICP monitoring technique, has emerged as a potential alternative to provide reliable measurements without the inherent risks of invasive methods. Methods: From January 2018 to December 2023, the authors performed both invasive (intraventricular catheters) and noninvasive (Schmidt method) ICP monitoring in patients with aSAH and Hunt and Hess (H and H) scores of 3–5. Patients requiring emergent craniotomy, with serious medical comorbidities or coagulopathies, or with noncompliance were excluded from the study. The accuracy and efficacy of the Schmidt method were evaluated by comparing the results of noninvasive monitoring with the results of invasive ICP monitoring. Results: Out of 238 cases with aSAH referred to our neurosurgical center, 105 had H and H scores of 3–5. Noninvasive ICP monitoring using the Schmidt method was performed in 86 cases (48 females, 38 males; mean age 68 ± 8 years). The mean ICP measured by the invasive method was 15.2 ± 6.2 mmHg, whereas the mean ICP measured by the noninvasive method was 16.6 ± 5.4 mmHg. The calculated root mean square error was 3.6 mmHg, and the average Pearson correlation between the estimated and real waveforms was 0.96. Conclusion: The findings of this study suggest that the application of the Schmidt method is a reliable and accurate approach for the assessment of ICP in patients with SAH, potentially eliminating the need for invasive ICP monitoring and reducing the associated risks.