The use of transthoracic electrical bioimpedance in assessing thoracic fluid status in emergency department patients.

Baseline transthoracic electrical bioimpedance (Z) was measured in 26 seriously ill emergency department (ED) patients in order to determine the usefulness of this noninvasive method of assessing thoracic fluid (TF) status. Patients were divided, on the basis of clinical and radiographic information, into three groups: group A (11 patients), with clinically normal TF status; group B (12 patients), with elevated TF status; and group C (3 patients), with decreased TF status. The mean Z values measured in each group were: 26.5 ohms in group A, 21.8 ohms in group B, and 37.4 ohms in group C (differences significant at P less than .02). Using a cutoff Z value of 24.0 ohms would have predicted group B individuals with a sensitivity of 92% and a specificity of 79%. In eleven patients, impedance measurement would have added information that confirmed diagnostic suspicions or suggested the diagnosis earlier than would otherwise have occurred. In five patients, real-time changes in Z were potentially useful in guiding and monitoring the results of therapeutic interventions or changes in clinical condition. This study demonstrates that Z measurement and real-time monitoring can be a useful and noninvasive means of assessing TF status in ED patients. However, it may be most helpful in those patients whose TF status is changing or unstable.