PREVALENCE OF SLEEP-APNEA AMONG JAPANESE INDUSTRIAL-WORKERS DETERMINED BY A PORTABLE SLEEP MONITORING-SYSTEM

We developed a new portable sleep monitoring system and studied the pr evalence of sleep apnea syndrome among Japanese industrial workers. Th is device assessed three kinds of parameters: nasal airflow, tracheal sound and electro-cardiogram (ECG), and digitally stored the clock tim e of the onset of apnea, apnea duration and R-R intervals by a built-i n microcomputer. After monitoring, the portable sleep monitor was conn ected to a host computer, and apneic episodes, the so-called 'apnea in dex' as apneic episodes corrected by measuring time ('AI') and R-R int ervals were analyzed. In 170 inpatients referred to our sleep clinic, sleep monitoring by this device was performed simultaneously with all- night polysomnography, and the sensitivity and specificity of this dev ice was determined under different criteria of the apnea index (AI) (A I > 5, 10, 15 and 20 episodes/h) by polysomnography. In all AI criteri a, the sensitivity was more than 90%, and the specificity was also rea sonably high. Using this system, successive 2-night home sleep monitor ing was performed on 168 healthy workers in one Japanese industrial co mpany, and 159 people (140 males; 19 females) who had successful monit oring were analyzed. The percentage of persons who had 'AI' of more th an 10 episodes/h was 7.5%. There were no significant correlations betw een 'AI' and age, body weight or scores estimated by sleep questionnai res. These results suggest that even in people who are seemingly healt hy significant apneic episodes could be detected by the portable home sleep monitoring system. This system may therefore be useful in evalua ting the occurrence of sleep apnea syndrom in general populations.