Cardiovascular response to passive leg movement in critically ill patients

Objective: To determine whether passive leg movement (PLM) in critically ill patients increases oxygen consumption (VO2), and, if so, the relative contributions of increases in cardiac index (CI) and oxygen extraction (O2ER). Design: Prospective, controlled study. Setting: Multidisciplinary department of intensive care in a university hospital. Patients: Sixteen ICU patients undergoing PLM as part of their standard management were divided into two groups according to the presence of cardiac disease and /or cardiac dysfunction. Outcome measures: VO2, CI oxygen extraction. Intervention: Complete hemodynamic data were obtained before and 5 minutes after starting PLM. Results: For the whole group, VO2 increased from 123±23 to 143±34 ml/min.m2 (p<0.05). In the eight patients with cardiac dysfunction, the increase in VO2 was met by an increase in O2ER (from 37.2±7.3 to 41.1±7.1 %, p<0.01) without a significant increase in CI (from 2.44±0.56 to 2.52±0.65 l/min/m2, p=ns). In the eight patients without cardiac dysfunction, the increase in VO2 was met by an increase of CI (from 3.88±0.90 to 4.36±1.00 l/min/m2, p<0.01) without a significant increase in O2ER (from 26.4±7.3 to 27.2±7.9 %, p=ns). Conclusions: Simple maneuvers like PLM can influence the hemodynamic status of ICU patients. The study of the relation between CI and O2 ER may be helpful to assess the hemodynamic response to nursing or physical therapy procedures.