Metabolic and Hemodynamic Responses to Early Passive Range of Motion in Sedated Critically Ill Adults

Background: Passive range of motion (PROM) is a common early mobilization technique in intensive care, especially for sedated, mechanically ventilated patients. This study aimed to evaluate the effect of early PROM on oxygen consumption (VO₂) and carbon dioxide production (VCO₂) in mechanically ventilated critically ill adults. Methods: A prospective observational cohort study was conducted in the tertiary ICU of a university hospital between May and September 2023. PROM was initiated within 24–48 hours of admission in hemodynamically stable, sedated patients (RASS: -2 to -4). An experienced physiotherapist performed a standardized 10-minute PROM protocol. VO₂ and VCO₂ were measured via indirect calorimetry before, during, and after the intervention. Cardiovascular parameters were also recorded. Results: Eighteen patients were included. Compared to baseline, VCO₂ increased significantly during PROM (mean change: +12%, p < 0.05), while VO₂ showed a modest but significant increase only at the seventh minute (+9%, p < 0.01). Both returned to near-baseline post-intervention. Systolic blood pressure increased transiently at the seventh minute (p = 0.04); other parameters remained stable. No adverse events were reported. Conclusion: Early PROM exercises in sedated, mechanically ventilated ICU patients induced a mild yet significant rise in metabolic demand, particularly reflected in VCO₂. The findings show that PROM is metabolically safe and does not cause haemodynamic instability. It accelerates the elimination of metabolic waste and can be used as part of early rehabilitation protocols.