Continuous respiratory monitoring for sleep apnea screening by ambulatory hemodynamic monitor

AIM: To validate the sleep-disordered breathing components of a portable electrocardiography and hemodynamic monitor to be used for sleep apnea screening. METHODS: Sleep-disordered breathing (SDB) is associated with cardiovascular disease. Patients with existing cardiovascular disease may have unrecognized SDB or may develop SDB while under the care of a cardiologist. A screening device for SDB, easy to use and appealing to cardiologists, would assist in referral of appropriate patients for full polysomnography (PSG). A cardiac and respiratory monitor (CPAM) was attached to patients undergoing PSG and an apnea/hypopnea index (AHI) generated. The CPAM device produced respiration rate, snoring rate, individual apnea/hypopnea events and an SDB severity score (SDBSS). In addition to AHI, an expert over-reader annotated individual breaths, snores and SDB breathing events to which the automated algorithms were compared. RESULTS: The test set consisted of data from 85 patients (age: 50.5 ± 12.4 years). Of these, 57 had a positive PSG defined as AHI ≥ 5.0 (mean: 30.0 ± 29.8, negative group mean: 1.5 ± 1.2). The sensitivity and specificity of the SDBSS compared to AHI was 57.9% and 89.3%, respectively. The correlation of snoring rate by CPAM compared to the expert over-reader was r = 0.58 (mean error: 1.52 snores/min), while the automated respiration rate had a correlation of r = 0.90 (mean error: 0.70 breaths/min). CONCLUSION: This performance assessment shows that CPAM can be a useful portable monitor for screening and follow-up of subjects for SDB.