EVALUATION OF TRANSTHORACIC BIOELECTRICAL-IMPEDANCE ANALYSIS IN MONITORING LUNG WATER DURING DIURESIS

Objective: To evaluate if noninvasive monitoring of lung water by tran sthoracic bioimpedance analysis adds useful information to standard cl inical parameters while diuresing patients with edematous lungs. Desig n: Prospective, observational study. Setting: University tertiary care teaching hospital. Patients and interventions: Fifty-one healthy cont rols had right chest transthoracic BIA measured to determine normal ri ght chest resistance and right lung resistivity. Fourteen hospitalized fluid-overloaded patients with edematous lungs were subsequently eval uated by serial right transthoracic BIA measurements before and after four days of diuresis. Measurements and main results: Although right t ransthoracic resistances were significantly higher in healthy women th an men, there were no significant between-sex differences in calculate d right lung resistivities. Combined male and female right lung resist ivities were normally distributed. Natural log conversion of chest res istivity (named t-BIA) yielded a mean of 6.54 +/- 0.23, with a coeffic ient of variation of 3.5%. Hospitalized patients had right lung t-BIAs significantly lower than normals before diuresis (6.22 +/- 0.48; p < 0.01). After diuresis, these rose into the normal range (6.40 +/- 0.51 ). Eight patients (57%) had an increase in chest resistivity, i.e., dr ier lungs and weight loss. Four patients (29%) who lost weight had wet ter lungs and two patients (14%) who gained weight had drier lungs. Ch est resistivity changes did not correlate with changes in body weight, chest exam or fluid balance. Conclusion: During diuresis, t-BIA measu red changes in lung water add useful additional information to standar d clinical parameters by both monitoring the dynamic changes that occu r during treatment and by helping to establish meaningful therapeutic endpoints.