Blood flow restriction combined with passive mobilization (BFRp) has emerged as a potential method to reduce muscle mass loss during critical illness. Although BFR has shown safe cardiovascular and respiratory responses in other populations, its effects in critically ill patients remain unclear. Objective: To analyze the impact of a BFRp session on vascular compliance and hemodynamic and respiratory responses in critically ill patients. Methods: A cross-controlled clinical trial was conducted with eight comatose patients randomized to receive either BFRp or passive mobilization (PM). Both groups underwent five sets of five minutes of lower-limb passive mobilization. In the BFRp group, 85% of the total vascular occlusion pressure was applied during mobilization. Assessments occurred before (T0), during (T1), and 10 minutes after the session (T3). Heart rate (HR), cardiac output (CO), cardiac index (CI), stroke volume (SV), and mean arterial pressure (MAP) were monitored via transthoracic electrical bioimpedance, along with respiratory rate (RR) and peripheral oxygen saturation (SpO₂). Arterial compliance was evaluated using tonometry at T0, immediately after the session (T2), and six hours later (T4). Results: BFRp elicited greater hemodynamic and respiratory responses from T0 to T1, with a return to baseline at T3, whereas isolated PM showed no significant changes. Arterial compliance decreased immediately after BFRp, indicated by increased PWV, but returned to baseline thereafter. Conclusion: In critically ill patients, BFRp induces slightly greater cardiorespiratory and vascular compliance responses than PM, remaining within safe limits and spontaneously returning to baseline. Future studies should investigate its long-term effects in early mobilization

Postdoctoral researcher at the Ribeirão Preto Medical School of the University of São Paulo, working in the Respiratory Assessment Laboratory. She is also a Collaborating Professor in the Specialization Course in Physiotherapy in the Intensive Care Unit at the São José do Rio Preto Medical School, Brazil. She previously served as a tenured Professor of Clinical Physiotherapy and Exercise Physiology at the Industrial University of Santander (Colombia). Her past roles include Clinical Supervisor in Cardiorespiratory Physiotherapy at Paulista University and ICU Physiotherapy Coordinator in Brazil. Her research focuses on cardiorespiratory physiotherapy and early mobilization in hospital and ICU settings.