Effects of passive cycling on cerebrovascular reactivity in acute brain injured patients: A pilot study

Early mobilization benefits critically ill patients, but concerns persist, especially in neurologic intensive care unit patients with acute brain injuries. This study assesses early mobility's impact on cerebrovascular autoregulation (CA) and systemic hemodynamics.

This single-center retrospective study focused on adult neurologic intensive care unit patients undergoing passive cycle ergometry. Data were collected from December 2020 to April 2022. Physical therapists conducted sessions using a standardized protocol, monitoring mean arterial blood pressure (MAP) and intracranial pressure (ICP). The Pressure Reactivity Index (PRx) was calculated as a measure of CA. Statistical analysis included mixed models and repeated measures ANOVA.

Eleven patients undergoing continuous physiologic monitoring and early mobility were included, primarily with subarachnoid hemorrhage or intracranial hemorrhage. Median time to protocol initiation was 4 days, with two patients discontinuing due to hemodynamic disturbances. Over a total of 11-hours of neuromonitoring data, passive cycling demonstrated a significant reduction in heart rate (HR), MAP, and ICP across different rotations per minute (RPM) settings compared to baseline. No significant alterations in PRx or cerebral perfusion pressure (CPP) were noted at various RPM levels. However, a significant difference in PRx emerged between patients who completed the protocol and those who did not, particularly at 10 RPM.

This study offers preliminary insights into the impact of early mobility on CA in acute brain injured patients. While passive cycling demonstrates promise in preserving cerebral hemodynamics, its tolerability may not be uniform across all brain-injured patients. These findings highlight the need to determine optimal early mobilization timing and intensity in this population, emphasizing the necessity for larger prospective studies to validate these findings and inform clinical practice.

This manuscript complies with all instructions to the authors. All coauthors meet the authorship requirements and have reviewed and approved the contents of the manuscript. The manuscript has not been published totally or partly, accepted for publication, or under editorial review for publication elsewhere. We have no conflicts of interest to disclose. STROBE checklist was reviewed prior to the submission of this paper. The manuscript adheres to ethical guidelines and was approved by Cleveland Clinic's institutional research board for retrospective study. There is no funding to disclose for this study.