Edema in critically ill patients leads to overestimation of skeletal muscle mass measurements using computed tomography scans.

Affiliation

Baggerman MR(1), van Dijk DPJ(2), Winkens B(3), Schnabel RM(4), van Gassel RJJ(5), Bol ME(6), Bakers FC(7), Olde Damink SWM(8), van de Poll MCG(5).
Author information:
(1)Department of Intensive Care Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; School for Nutrition and Translational Research in Metabolism
(NUTRIM), Maastricht University, Maastricht, the Netherlands; Department of Intensive Care Medicine, Laurentius hospital, Roermond, the Netherlands. Electronic address: [Email]
(2)School for Nutrition and Translational Research in Metabolism
(NUTRIM), Maastricht University, Maastricht, the Netherlands; Department of Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands.
(3)Department of Methodology and Statistics, Maastricht University, Maastricht, The Netherlands; Care and Public Health Research Institute
(CAPHRI), Maastricht University, Maastricht, the Netherlands.
(4)Department of Intensive Care Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands.
(5)Department of Intensive Care Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; School for Nutrition and Translational Research in Metabolism
(NUTRIM), Maastricht University, Maastricht, the Netherlands; Department of Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands.
(6)Department of Intensive Care Medicine, Maastricht University Medical Centre, Maastricht, the Netherlands; School for Nutrition and Translational Research in Metabolism
(NUTRIM), Maastricht University, Maastricht, the Netherlands.
(7)Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, The Netherlands.
(8)School for Nutrition and Translational Research in Metabolism
(NUTRIM), Maastricht University, Maastricht, the Netherlands; Department of Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands; Department of General, Visceral and Transplantation Surgery, RWTH University Hospital Aachen, Aachen, Germany.

Abstract

OBJECTIVES: Changes in muscle mass and quality are important targets for nutritional intervention in critical illness. Effects of such interventions may be assessed using sequential computed tomography (CT) scans. However, fluid and lipid infiltration potentially affects muscle area measurements. The aim of this study was to evaluate changes in muscle mass and quality in critical illness with special emphasis on the influence of edema on this assessment. METHODS: Changes in skeletal muscle area index (SMI) and radiation attenuation (RA) at the level of vertebra L3 were analyzed using sequential CT scans of 77 patients with abdominal sepsis. Additionally, the relation between these changes and disease severity using the maximum Sequential Organ Failure Assessment (SOFA) score and change in edema were studied. RESULTS: SMI declined on average 0.35%/d (±1.22%; P = 0.013). However, SMI increased in 41.6% of the study population. Increasing edema formation was significantly associated with increased SMI and with a higher SOFA score. Muscle RA decreased during critical illness, but was not significantly associated with changes in SMI or changes in edema. CONCLUSION: In critically ill patients, edema affects skeletal muscle area measurements, which leads to an overestimation of skeletal muscle area. A higher SOFA score was associated with edema formation. Because both edema and fat infiltration may affect muscle RA, the separate effects of these on muscle quality are difficult to distinguish. When using abdominal CT scans to changes in muscle mass and quality in critically ill patients, researchers must be aware and careful with the interpretation of the results.