Validation of the Sonomat: a contactless monitoring system used for the diagnosis of sleep disordered breathing

To evaluate the ability of the Sonomat to diagnose obstructive sleep apnea (OSA). Prospective and randomized. Sleep laboratory and home. 62 subjects; 54 with a clinical history of OSA and 8 normal control subjects. N/A. Simultaneous PSG and Sonomat recordings were made in 62 subjects; 2 were excluded due to a poor nasal flow recording in PSG. There were positive correlations between the two devices for measures of sleep time, respiratory events, and the AHI (all correlations > 0.89). Bland-Altman analysis of the AHI showed positive agreement between devices, particularly at levels around common diagnostic thresholds. The mean difference in AHI values was 1.4 events per hour, and at a diagnostic threshold of 15 events per hour, sensitivity and specificity were 88% and 91%. More than 93% of PSG defined respiratory events were identified by the Sonomat and the absence of respiratory events was correctly identified in 91% of occasions. Gender, obesity, and body position did not influence the accuracy of the Sonomat. PSG snore sensors differed in how much snoring was detected when compared to the Sonomat. These data indicate that the Sonomat was reliable and accurate for the diagnosis of OSA. The provision of audible breath sound/snoring replay permits more accurate quantification of snoring. It requires no patient attachment and can be performed in the home with minimal training.