Effects of Trunk Postural Change on CO2 Removal Efficiency in ARDS Patients: Quasi-experimental Study

OBJECTIVES: The trunk inclination from semirecumbent to lying supine improves lung mechanics and reduces end-expiratory lung volume in Acute Respiratory Distress Syndrome (ARDS) patients. Besides, it can improve the ventilatory ratio and PaCO2, although the effects and mechanisms are not entirely elucidated. Therefore, this study aimed to evaluate the effects of trunk tilt from 45° to 10° on CO2 removal efficiency. DESIGN: Quasi-experimental study. SETTING: A medical ICU in Chile. PATIENTS: Twenty-two patients with ARDS. INTERVENTION: Patients in pressure-controlled ventilation underwent three 60-minute steps in which trunk inclination was changed from 45° (baseline) to 10° (intervention) and back to 45° (control) in the last step. Respiratory mechanics, arterial blood gas analysis, dead space by volumetric capnography, and electrical impedance tomography were recorded.