Measurement of acute edema shifts in human burn survivors--the reliability and sensitivity of bioimpedence spectroscopy as an objective clinical measure.

Improvements in treatment for acute burn edema have stalled in comparison with other areas of burn care. Designing acute edema treatment studies in humans is hindered by the lack of objective, sensitive methods of measurement in the burn population. Bioimpedence spectroscopy (BIS) is a noninvasive method of measuring fluid volumes in the body. The aim of this study was to examine the reliability and sensitivity of BIS in the measurement of acute edema shifts in burn survivors, including assessment across different wound conditions. BIS measurements were collected in triplicate from 21 burn patients in total. Phase I (n = 13) examined BIS under three different dressing conditions. Phase II (n = 8) considered only patients with dressings intact. Sensitivity (minimum detectable difference [MDD]) was examined with total body water, extracellular fluid (ECF), and intracellular fluid volume measurements. BIS demonstrated excellent reliability across all dressings conditions, including when open wounds were present (intraclass correlation coefficient = 0.975-1.00, 95% confidence intervals = 0.938-1.00). Clinically useful levels of sensitivity, or MDD, were calculated. BIS MDD for total body water (open wounds) = 360 ml, ECF (open wounds) = < or = 10 ml, ECF (new dressings) = 540 ml, and intracellular fluid (open wounds) = 310 ml. BIS analysis is clinically applicable for real-time, noninvasive monitoring of whole-body fluid shifts in acute burn survivors with < or = 30% TBSA.