Lumbar Skeletal Muscle Index Derived from Routine Computed Tomography Exams Predict Adverse Post-extubation Outcomes in Critically Ill Patients

Purpose: To evaluate the effect of a skeletal muscle index derived from a routine CT image at the level of vertebral body L3 (L3SMI) on outcomes of extubated patients in the surgical intensive care unit.

Materials And Methods: 231 patients of a prospective observational trial (NCT01967056) who had undergone CT within 5days of extubation were included. L3SMI was computed using semi-automated segmentation. Primary outcomes were pneumonia within 30days of extubation, adverse discharge disposition and 30-day mortality. Secondary outcomes included re-intubation within 72h, total hospital costs, ICU length of stay (LOS), post-extubation LOS and total hospital LOS. Outcomes were analyzed using multivariable regression models with a priori-defined covariates height, gender, age, APACHE II score and Charlson Comorbidity Index.

Results: L3SMI was an independent predictor of pneumonia (aOR 0.96; 95% CI 0.941-0.986; P=0.002), adverse discharge disposition (aOR 0.98; 95% CI 0.957-0.999; P=0.044) and 30-day mortality (aOR 0.94; 95% CI 0.890-0.995; P=0.033). L3SMI was significantly lower in re-intubated patients (P=0.024). Secondary analyses suggest that L3SMI is associated with total hospital costs (P=0.043) and LOS post-extubation (P=0.048).

Conclusion: The lumbar skeletal muscle index, derived from routine abdominal CT, is an objective prognostic tool at the time of extubation.