N. T. Ferguson1, B. A. Warden2, J. L. Thomas3, S. P. Stawicki4 1St. Luke’s University Health Network,Department Of Medicine,Bethlehem, PENNSYLVANIA, USA 2Temple University,St. Luke’s University Hospital Campus,Bethlehem, PENNSYLVANIA, USA 3St. Luke’s University Health Network,Department Of Radiology,Bethlehem, PENNSYLVANIA, USA 4St. Luke’s University Health Network,Department Of Research & Innovation,Bethlehem, PENNSYLVANIA, USA
Introduction: Physiologic changes associated with acute stress may render traditional markers of nutritional status unreliable in the intensive care unit (ICU), creating the need for more objective alternatives. One such alternative to traditional serum laboratory testing is the use of data from computed tomography (CT), including the psoas muscle (PM) area and density. Our goal was to determine correlations between prealbumin and CT characteristics (e.g., density-corrected psoas area or DCPA) in a cohort of ICU patients. We hypothesized that PM area, density, and DCPA will significantly correlate with prealbumin in this population.
Methods: A convenience sample of ICU patients was studied between Jan 2010 – Jul 2015. Data collected included demographics (age, gender, BMI); labs (prealbumin, albumin, total protein, lymphocyte counts); abdominal CT measurements of PM density (Hounsfield units [HU]) and area (measured in mm2). Psoas data were acquired using axial CT images at the superior aspect of L4 vertebral body. Using advanced image processing software (GE Healthcare, Chicago, Illinois), the trace tool was used to outline PM borders. Software-generated cross-sectional area / HU were recorded. Bilateral PM data were averaged for cross-sectional area and density. The primary study variable was DCPA (average PM area/average PM density), and was further categorized into “low” (≤28) and “high” (>28) based on the mean dataset value. Permitted time between the CT and nutritional labs was 72 hrs (based on the 3-d half-life of prealbumin). Clinical data were contrasted against “high” and “low” DCPA. Univariate comparisons utilized Mann-Whitney U-test, Student’s t-test, and Fisher’s exact test, as appropriate.
Results: A total of 59 ICU patients underwent abdominal CTs for a variety of indications during the study period. Average patient age was 47.3 yrs, with 41/59 (69.5%) males. Average ICU stay was 25.2 d. A total of 86 measurement pairs were analyzed. The DCPA correlated with patient weight and prealbumin levels. It did not, however, correlate with BMI, lymphocyte count, albumin, or total protein determinations (Table 1). Neither the average PM area or density alone correlated with prealbumin.
Conclusion: Although neither of its constituent variables (psoas density or area) correlated with prealbumin in this pilot study, we found that DCPA ≤28 was associated with lower prealbumin levels. This identifies DCPA as a potential marker of suboptimal nutritional status. Clinical implications of this finding require independent confirmation, further investigation, larger sample sizes and greater data granularity.
