Bioimpedance cardiac output measurements in patients with presumed congestive heart failure.

Abstract

To describe preliminary ED experience with thoracic electrical bioimpedance (TEB) for evaluation of patients with complaints suggestive of congestive heart failure (CHF). A 6-month, prospective, observational study was performed using a convenience sample of patients with signs and symptoms consistent with CHF. Patients were excluded if they had received medication prior to arrival in the ED, if they were obese, and if they had unstable vital signs. They also were excluded if they were combative, refused to sign consent, or had invasive lines that did not allow for TEB lead placement. Patients also were excluded if the study could not be completed because the patient was taken from the department for a diagnostic test, or if there were no good follow-up records available 6-12 months after the patient's visit. The patient's physician was blinded to the output of the TEB monitor. Cardiac output (CO), stroke volume (SV), end-diastolic volume (EDV), thoracic fluid index (TFI), and acceleration index (ACI) were recorded at 5-minute intervals. Results were evaluated for the time intervals 0-5 minutes, 30-35 minutes, and 60-65 minutes. Seven patients were included in the study. The echocardiographic diagnoses were hypertrophic cardiomyopathy (2 cases), dilated cardiomyopathy (2 cases), ischemic cardiomyopathy (1 case), right ventricular hypertrophy (1 case), and pericardial effusion (1 case). Significant changes were seen in all cardiac parameters, with variance from individual to individual. Significant differences in TEB variables exist between patients who appear similar on initial examination in the ED. Changes noted on TEB may help to further elucidate physiologic differences. The clinical use of TEB-based hemodynamic measurements to guide presumed CHF patient management remains speculative.