15 Use of Bioelectric Impedance Analysis in Burn Patients: A Pilot Study

Introduction Bioelectric Impedance Analysis (BIA) is a rapid, non-invasive, and inexpensive technology based on electrical conductivity. BIA assesses body composition, fluid shifts, and phase angle, an electrical force vector where smaller values suggest cellular injury. Our objective was to use BIA to longitudinally track the clinical status of burn patients. We hypothesized that BIA would detect progressive decreases in muscle mass throughout the patient’s hospital course and that low phase angle values would correlate with severity of injury. Methods A cohort study of 10 patients from January 1, 2020 to March 13, 2020 was performed at an ABA-verified burn center. Patient and burn characteristics and laboratory data were collected. BIA measurements were performed daily for the first 10 days of admission and then twice weekly until discharge. The primary outcome was to detect changes in body composition. The secondary objectives were to detect differences between low and high-risk patients in terms of water composition and phase angle. Patients with APACHE II > 15, measured at burn unit admission, were considered high risk for burn injury related morbidity and mortality. Results BIA detected a statistically significant negative correlation between time spent hospitalized and leg lean mass (LM) (r2=0.56, P< 0.0001), right arm LM (r2=0.52, P< 0.0001) and left leg LM (r2=0.57, P< 0.0001), and positive correlation between body fat mass (BFM) and time spent hospitalized (r2=0.50, P=0.0004). Water composition (volume of extracellular water (ECW) per total body water (TBW)) negatively correlated with low-risk patients: right arm (r2=0.51, P< 0.0001), left arm (0.71, P< 0.001), thorax (0.66, P< 0.0001), right leg (0.74, P< 0.0001), left leg (0.35, P=0.002). Full body phase angle increased with low-risk patients over their hospital course (r2=0.62, P< 0.0001), while phase angle decreased with high-risk patients (r2=0.71, P=0.0006). Full body phase angle differentiated high risk patients (P< 0.0001), and phase angle of thorax differentiated between patients with and without inhalation injury (P=0.002). Conclusions Our study demonstrates that BIA measures changes in body composition and fluid shifts, identifies inhalation injury, and correlates with severity of injury in hospitalized burn patients. This pilot study included a limited number of participants with varying anatomic injuries presenting unique measurement challenges. Regardless, our preliminary data justifies a larger prospective study to confirm these results and correlate them with clinical outcomes.