title: Validation of Bedside Ultrasound of Muscle Layer Thickness of the Quadriceps in the Critically Ill Patient (VALIDUM Study).
abstract: In critically ill patients, muscle atrophy is associated with long-term disability and mortality. Bedside ultrasound may quantify muscle mass, but it has not been validated in the intensive care unit (ICU). Here, we compared ultrasound-based quadriceps muscle layer thickness (QMLT) with precise quantifications of computed tomography (CT)-based muscle cross-sectional area (CSA).
  
  
  
  Patients ≥18 years old with abdominal CT scans performed for clinical reasons were recruited from 9 ICUs for an ultrasound assessment of the quadriceps. CT scans of the third lumbar vertebra, performed <24 hours before or <72 hours after ICU admission, were analyzed for CSA. Low muscularity was defined as 170 cm2for men and 110 cm2for women. The ultrasound probe was maximally compressed against the skin and QMLT was measured on 2 sites of each quadriceps <72 hours of the CT scan.
  
  
  
  Mean CT-derived muscle CSA was 109 ± 25 cm2for women and 168 ± 37 cm2for men, where 58% of patients exhibited low muscularity; only 2.7% patients were underweight according to body mass index. QMLT was positively correlated with CT CSA ( r = 0.45, P < .001). Based on logistic regression to predict low muscularity, QMLT independently generated a concordance index ( c) of 0.67 ( P < .002), which increased to 0.77 ( P < .001) when age, sex, body mass index, Charlson Comorbidity Index, and admission type (surgical vs medical) were added.
  
  
  
  Our results suggest that QMLT alone with our current protocol may not accurately identify patients with low muscle mass.
authors.affiliation: 1 Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Paris
authors.affiliation: 1 Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Marina
authors.initials: M
authors.lastname: Mourtzakis
authors.affiliation: 2 Clinical Evaluation Research Unit, Kingston General Hospital, Kingston, Ontario, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Day
authors.affiliation: 2 Clinical Evaluation Research Unit, Kingston General Hospital, Kingston, Ontario, Canada.
authors.forename: Roger
authors.initials: R
authors.lastname: Leung
authors.affiliation: 1 Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Snehal
authors.initials: S
authors.lastname: Watharkar
authors.affiliation: 3 Surgery, University of Texas, Houston, Texas, USA.
authors.forename: Rosemary
authors.initials: R
authors.lastname: Kozar
authors.affiliation: 4 Food Science and Nutrition, University of Minnesota, St Paul, Minnesota, USA.
authors.forename: Carrie
authors.initials: C
authors.lastname: Earthman
authors.affiliation: 4 Food Science and Nutrition, University of Minnesota, St Paul, Minnesota, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Kuchnia
authors.affiliation: 2 Clinical Evaluation Research Unit, Kingston General Hospital, Kingston, Ontario, Canada.
authors.forename: Rupinder
authors.initials: R
authors.lastname: Dhaliwal
authors.affiliation: 1 Kinesiology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Lesley
authors.initials: L
authors.lastname: Moisey
authors.affiliation: 5 School of Nursing, University of Pennsylvania, Philadelphia, Pennsylvania, USA.|6 Clinical Nutrition Support Services, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Charlene
authors.initials: C
authors.lastname: Compher
authors.affiliation: 7 Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Niels
authors.initials: N
authors.lastname: Martin
authors.affiliation: 7 Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Nicolo
authors.affiliation: 8 Surgery, Intermountain Medical Center, Murray, Utah, USA.
authors.forename: Tom
authors.initials: T
authors.lastname: White
authors.affiliation: 9 Food and Nutrition, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Hannah
authors.initials: H
authors.lastname: Roosevelt
authors.affiliation: 9 Food and Nutrition, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Peterson
authors.affiliation: 2 Clinical Evaluation Research Unit, Kingston General Hospital, Kingston, Ontario, Canada.
authors.forename: Daren K
authors.initials: DK
authors.lastname: Heyland
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D016638:Critical Illness; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D009133:Muscular Atrophy / Q000000981:diagnostic imaging; D000067716:Point-of-Care Testing; D011446:Prospective Studies; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography / Q000379:methods*
keywords: computed tomography; critical illness; intensive care unit; muscle atrophy; muscle thickness; ultrasound