Bioimpedance monitoring: better than chest x-ray for predicting abnormal pulmonary fluid?

Bioimpedance monitoring may aid in treating heart failure. Mean thoracic electrical impedance (Zo) is inversely proportional to thoracic fluid volume and may offer greater sensitivity for detecting thoracic fluid. OBJECTIVE. Compare bioimpedance monitoring thoracic fluid detection to that of chest x-ray. METHOD. Prospective convenience sample. SETTING. 1000 bed teaching hospital. PARTICIPANTS. Patients with suspected heart failure and shortness of breath. A single blinded radiologist interpreted chest x-rays as: normal, cardiomegaly, or abnormal pulmonary fluid. STATISTICS. General linear model with post hoc Bon Ferroni pairwise comparisons. RESULTS. 131 patients, mean age 66.8 years, 64.3% male, with an initial mean Zo=18 ohms. There was a significant difference (p<0.0002) between patients with cardiomegaly (Zo=17.5+/-5.5) or abnormal pulmonary fluid on chest x-ray (Zo=17.2+/-4.2) compared to normals (Zo=23.4+/-5.4). There was no difference between cardiomegaly and abnormal pulmonary fluid patients. CONCLUSION. Bioimpedance measurement may detect pulmonary fluid not apparent on chest radiograph. (c)2000 by CHF, Inc.