Metabolic and hemodynamic responses to early passive range of motion in sedated critically ill adults

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.

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). A physiotherapist performed a standardized 10-minute PROM protocol. VO₂ and VCO₂ were measured via indirect calorimetry before, during, and after the intervention. Statistical analyses were conducted using a repeated-measures ANOVA, with the average level before and after the measurement, as well as the peak level of VCO₂ during the intervention. Cardiovascular parameters were also recorded.

Twenty-three patients were included. PROM exercises showed a significant quadratic trend in VCO₂; F = 6.686, p = 0.017 and a borderline quadratic trend in VO₂ (F = 4.320, p = 0.050). Heart rate decreased significantly compared to baseline (P = 0.043). No significant change in blood pressure levels was observed.

Early PROM exercises in sedated, mechanically ventilated ICU patients induced a quadratic trend in VCO₂ and VO₂, indicating a temporary and reversible metabolic response. PROM does not cause any hemodynamic instability. It accelerates the elimination of metabolic waste and can be used as part of early rehabilitation protocols.