To evaluate the ability of internal thoracic impedance (ITI) monitors to predict cardiogenic pulmonary edema in patients at risk.Design and Setting:
Prospective, controlled multicenter study.Patients:
We examined 328 consecutive patients admitted for cardiac conditions. Of these 265 patients aged 27–83 years with no clinical signs of pulmonary edema, extracardiac respiratory failure or pacemakers comprised the study cohort.Intervention:
Monitoring of the lung's electrical impedance was used for predicting cardiogenic pulmonary edema since accumulation of blood and fluid decreases impedance values.Measurements and results:
Impedance of the lung is the main feature of ITI measured by the RS-207 monitor: decreased ITI prior to the clinical signs of cardiogenic pulmonary edema was used as the prediction criterion. The clinical signs used for confirmation of its prediction were dyspnea, cyanosis, pulmonary rales, crepitations, arterial hypoxemia, and radiographic evidence of pulmonary congestion in chest radiographs. Clinicians were blinded to the results of ITI measurements and radiologists were blinded to both ITI and clinical data. Thirty-seven patients developed cardiogenic pulmonary edema while being monitored. ITI decreased by more than 12% of baseline in all of them; this occurred at 30 min or longer (26 patients) and at 60 min or longer (11 patients) before the appearance of clinical signs. ITI fell by less then 10.1% of baseline in all 228 patients who did not develop the edema.Conclusion:
Monitoring ITI is suitable for early prediction of cardiogenic pulmonary edema, before the appearance of the clinical signs.