Muscle wasting in intensive care patients: ultrasound observation of the M. quadriceps femoris muscle layer.

OBJECTIVE Patients in intensive care exhibit a high degree of loss of muscle mass. Appropriate instruments are needed to document muscle wasting in these patients. The aim of this pilot study was to describe muscle wasting in patients in the intensive care unit. DESIGN Two-fold study setting: prospective longitudinal and cross-sectional single-blind. PATIENTS A total of 118 patients in the intensive care unit (length of stay 1-98 days; male:female ratio 88:30; age 55 +/- 17 years) were included in a two-fold study setting. METHODS Muscle layer thickness of the M. quadriceps femoris was documented using ultrasound measurement at well-defined points. Seventeen pilot-patients were measured twice; at baseline and after 28 days. In another group of 101 patients, muscle layer thickness was determined once after a random length of stay. The results of both groups were compared and correlated. RESULTS In both groups, M. quadriceps femoris thickness showed a significant negative correlation with length of stay in the intensive care unit (p < 0.01). Furthermore, muscle wasting in intensive care patients could be described using a logarithmic function. CONCLUSION Loss of muscle mass shows a negative correlation with length of stay, and seems to be higher during the first 2-3 weeks of immobilization/intensive care unit stay. Ultrasound is a valid and practical measurement tool for documenting muscle mass (e.g. muscle layer thickness) as part of the daily routine at an intensive care unit.