Bioelectrical Impedance in Monitoring Hyperhydration and Muscle Wasting in Critically Ill Corona Virus Disease (COVID-19) Patients: The Feasibility of Predicting Outcome

Critically ill patients often experience hyperhydration and muscle wasting, which can worsen outcomes. This study evaluated the feasibility of using bioelectrical impedance vector analysis (BIVA) to monitor hydration and muscle mass and predict outcomes in COVID-19 patients with acute respiratory distress syndrome (ARDS), including those with extracorporeal membrane oxygenation (ECMO). The study compare fluid parameters derived from BIVA with cumulative fluid balance (CFB) and assess the prognostic value of the phase angle (PA) of BIVA against established markers such an APACHE II and serum presepsin. In this prospective, blinded observational study, 61 COVID-19 patients on invasive mechanical ventilation (IMV) were included. BIVA measurements were taken within 48 h of admission, then after 7 and 14 days. Data on demographics, fluid balance, and laboratory markers were collected. BIVA was shown to be feasible in critically ill patients, with a significant correlation between hyperhydration, defined by an elevated extracellular water to total body water ratio (ECW/TBW 0.56) and overhydration (OHY 6.9 l). Decreased PA (median 3.3°) was associated with increased mortality in non-ECMO patients. Unlike CFB, which lacked statistical significance, BIVA provided a more accurate assessment of hyperhydration (p=0.0050 for ECW/TBW and p=0.0402 for OHY). In conclusion, BIVA is a practical tool for monitoring hydration, but not muscle mass, in critically ill patients. Elevated hydration status and low PA measured by BIVA are effective predictors of mortality, although ECMO use can affect accuracy. ClinicalTrials.gov ID NCT04758676 (www.clinicaltrials.gov).