Abdominal ultrasonography as a tool to quantify adipose tissue in critically ill patients

Abstract

Adipose tissue has important roles in both healthy and disease states. Quantifying adipose tissue composition and distribution may help predict outcomes and guide management in intensive care unit patients. Computed tomography is the preferred method for measuring adipose tissue but has drawbacks, such as radiation exposure and the need to transport patients. Ultrasonography is a safer, more convenient alternative for bedside assessment of body fat composition. This review examines the relevance of adipose tissue in critical illness and describes ultrasound techniques to quantify subcutaneous, visceral, and epicardial adipose tissue depots. Standardized protocols to measure subcutaneous fat thickness at multiple sites and approaches to estimate visceral fat using the supraumbilical or xipho-umbilical lines are discussed. A technique to quantify epicardial fat thickness using transthoracic echocardiography is also presented. While more research is needed, bedside ultrasonography shows promise for monitoring adipose tissue changes and their potential associations with outcomes in critically ill patients.

Key words: Ultrasonography, critical illness, body composition, subcutaneous adipose tissue, visceral adipose tissue, epicardial adipose tissue