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

Study objectives: To evaluate the ability of the Sonomat to diagnose obstructive sleep apnea (OSA).

Design: Prospective and randomized.

Setting: Sleep laboratory and home.

Participants: 62 subjects; 54 with a clinical history of OSA and 8 normal control subjects.

Interventions: N/A.

Measurements and results: 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.

Conclusion: 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.