[Ambulatory monitoring of patients with suspected sleep apnea syndrome using a thermistor sensor in comparison with nocturnal polysomnography].

Simple ambulatory monitoring methods can be used in step-by-step diagnosis of sleep apnoea syndrome to differentiate between high-risk and low-risk patients, or to exclude the syndrome for achieving more efficient utilisation of sleep laboratory facilities. The question was whether a new method using a thermistor sensor measuring respiration-conditioned thermal convection at the mouth and nose can reliably record the frequency of apnoea (ambulatory thermistor method = ATM). The study was subdivided into two sections. In phase I the respiratory impulses measured via ATM were polygraphically recorded in 20 patients simultaneously with conventional cardiopulmonary data of nocturnal polygraphy (heart rate, oxygen saturation, thorax and abdominal excursions and oronasal respiratory flow). 40 patients participated in phase II. During a first night the patients slept under ATM in their patient rooms. In the 2nd night nocturnal polygraphy was conducted with the parameters mentioned above; the results of both nights were then compared. Taking 35 phases of apnoea in one night as threshold or baseline value, a sensitivity of 100% and a specificity of 84.6% were attained in phase I, the simultaneous comparison of ATM and nocturnal polygraphy, in the recording of an enhanced nocturnal apnoea frequency by ATM. In phase 2 (1st night ATM, 2nd night polygraphy) ATM also yielded a sensitivity of 100% and a specificity of 76%. When measuring with a borderline value of 70 nocturnal phases of apnoea, ATM yielded a specificity and sensitivity of 100%, in phase 2 a sensitivity of 80.7% and a specificity of 88.5%.(ABSTRACT TRUNCATED AT 250 WORDS)