Diagnosis of sleep-related breathing disorders by visual analysis of transthoracic impedance signals in pacemakers

Minute ventilation sensors of cardiac pacemakers measure ventilation by means of transthoracic impedance changes between the pacemaker case and the electrode tip. We investigated whether this technique might detect sleep-related breathing disorders. In 22 patients, analog waveforms of the transthoracic impedance signal measured by the pacemaker minute ventilation sensor over the course of a night were visualized, scored for apnea/hypopnea events, and compared with simultaneous polysomnography. Analysis of transthoracic impedance signals correctly identified the presence or absence of moderate to severe sleep apnea (apnea/hypopnea index, AHI >20 h(-1)) in all patients (receiver operating characteristics, ROC=1.0). The ROC for AHI scores of > or =5 h(-1) and > or =10 h(-1) showed an area under the curve of 0.95, P