[Ambulatory monitoring of patients with suspected sleep apnea syndrome using a thermistor sensor in comparison with nocturnal polysomnography]. / Ambulantes Monitoring bei Patienten mit Verdacht auf Schlafapnoesyndrom mittels eines Thermistorsensors im Vergleich zur nächtlichen Polygraphie.

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)

[Ambulatory monitoring of frequency of apnea in patients with suspected sleep apnea syndrome. Comparative studies using a thermistor sensor]. / Ambulantes Monitoring der Apnoefrequenz bei Patienten mit Verdacht auf Schlafapnoesyndrom. Vergleichende Untersuchungen mit einem Thermistorsensor.

To record and evaluate the number and duration of nocturnal apneas, and easy method is needed in an outpatient setting. New methods such as recording the tracheal sounds, heart frequency, and O2 saturation, are now available. Recording of thermal convection by Thermistor has not been performed on an outpatient basis so far. Hence, we developed a method by which a thermistor was placed on a mask to record the nasal and oral flow. A specially developed computer hardware evaluates date, time, period, number and mean values of the apneas. The parameters were compared with the conventional methods of recording apneas (thoracic and abdominal movement. O2 saturation, heart frequency and 3 thermistors at mouth and nose). 20 patients, mean age 53.1 +/- 1.6 years, were examined. In 12 patients the apnea frequency was between 0 and 50 apneas per night, in 8 between 50 and 550. Patients with an apnea frequency of more than 50 per night (polygraphy) could be identified with the thermistor method. Our results show that the method is sensitive in respect of the oral and nasal flow. The method seems valid to differentiate between normal persons and patients with increased risk of apnea syndrome.

[Comparative studies on the effect of nasal CPAP, theophylline and oxygen in patients with sleep apnea syndrome]. / Vergleichsuntersuchungen zur Wirkung von nCPAP, Theophyllin und Sauerstoff bei Patienten mit Schlafapnoesyndrom.

In patients with sleep apnea-syndrome nasal CPAP-therapy is the method of choice. The apnea phases are practically completely eliminated. However some patients with SAS don't accept CPAP-therapy. In this group Theophylline or O2-therapy respectively is discussed. We examined therefore 21 patients (55.8 +/- 9 years) with sleep-apnea syndrome and an apnea-index of 39 +/- 19.9 during 4 consecutive nights (diagnosis, nCPAP-therapy, O2-therapy by 21/min, by nasal prongs and Theophylline 375-400 mg in the evening and calculated apnea-index, the longest apnea and the lowest O2-saturation. On CPAP the number of apneas was practically reduced to 0. On Theophylline there was a relevant reduction of the apnea frequency. On O2-therapy only few patients with non-compliance Theophylline-therapy can be of some benefit in patients with moderate sleep-apnea syndrome. However the apnea-index cannot be normalized.

Monitoring at home.

To reduce time committment and expense in the diagnosis of sleep apnea it is necessary to develop simplified monitoring techniques. The monitoring systems to detect apneas should have high sensitivity, good reproducibility, be inexpensive and practical to use. The following methods have been suggested: inductance plethysmography, capnography, flow measurements by thermistors, tracheal sound recording, static charge sensitivity bed, oximetry, activity monitoring, detection of snoring. Some devices to registrate breathing have been combined with oximetry and other methods. The results have been validated by polysomnography and show rather good correlations. However, there exists no information on the time and cost savings of a step wise diagnosis of sleep apnea.