The increasing numbers of patients referred for evaluation of suspected obstructive sleep apnoea (OSA) places a growing burden on available sleep laboratory resources. A number of limited diagnostic systems have been developed in an effort to cope with this clinical problem. In this study, the diagnostic capabilities of one limited diagnostic system (ResCare Autoset) were compared with full polysomnography (PSG), using the Oxford SAC computerized system. Thirty six patients with suspected OSA had simultaneous studies performed both with the Autoset and Oxford PSG systems. The apnoea plus hypopnoea index (AHI) (events x h(-1)) scored by the Autoset system was compared with the AHI scored from the PSG raw tracings by an experienced sleep technician. There were highly significant correlations between the Autoset AHI and the AHI scored by the manual PSG scoring method (r=0.92; p<0.001). The positive predictive value for diagnosis of OSA for the Autoset was 86% when compared with manual PSG scoring, based on an AHI threshold for OSA of 15 events x h(-1). However, the agreement between Autoset and PSG was poor in severe cases of OSA, although not sufficiently so as to result in mistaken diagnosis in any of these cases. We conclude that the Autoset system is a sensitive and easy to use system, which facilitates screening for obstructive sleep apnoea with a reasonable degree of accuracy.

The Robin sequence is a congenital disorder characterized by micrognathia and cleft palate [1] and has been associated with a predisposition to obstructive sleep apnoea (OSA) [2][3][4]. The associated posterior displacement of the tongue (glossoptosis) results in a narrowed upper airway (UA), which favours UA collapse during inspiration [5,6]. We report a case of severe OSA in a teenage female with the Robin sequence, which was successfully treated with nasal continuous positive airway pressure (nCPAP) and in whom the OSA resolved spontaneously over a three-year period associated with changes in UA bony and soft tissue dimensions. Case reportThe patient details and initial response to nCPAP have previously been reported elsewhere [7], and are summarized as follows. A 12 yr old female with Robin sequence presented with a history of habitual snoring since infancy and witnessed apnoeas during sleep over the previous 12 months. A cleft palate repair had been performed at the age of 11 months, a tonsillectomy/adenoidectomy at the age of 5 yrs, and palatoplasty 2 yrs later to correct a speech disturbance. The patient complained of chronic fatigue and sleepiness, frequent nocturia and occasional nocturnal enuresis. Her weight was 29 kg (3rd centile) and height 150 cm (50th centile). Apart from prominent micrognathia and a resting tachycardia, physical examination was normal. A 12-lead electrocardiogram (ECG) showed sinus tachycardia (110-115 beats·min -1 ) and p-pulmonale, suggesting right-heart strain.Full overnight sleep studies using standard polysomnographic techniques [8] demonstrated severe OSA with 49 obstructive apnoeas (no airflow despite inspiratory effort) or hypopnoeas (tidal volume <50% baseline, with associated O 2 desaturation Š4%) per hour of sleep and associated oxygen desaturations to levels below 50% ( fig. 1). She had poor quality sleep with no slow wave sleep (SWS) or rapid-eye movement (REM) sleep. The OSA was effectively controlled with nCPAP (REMstar™; Respironics, Murrayville, PA, USA) at a pressure level of 14 cmH 2 O and this therapy was associated with an immediate improvement in energy and daytime sleepiness. Follow-up sleep studies and assessment on nCPAP after 6 and 18 months of continuous therapy at home showed abolition of apnoeas and hypopnoeas, normal oxygen saturation (Sa,O 2 ), and normal amounts of SWS and REM sleep with no further daytime sleepiness, nocturia or nocturnal enuresis. Her ECG had reverted to normal and nCPAP pressure was reduced to 10 cmH 2 O, without the reappearance of apnoea or hypopnoeas.After 3.5 yrs of continuous nCPAP therapy, aged 16 yrs, she had grown to 162 cm (50th centile) and weighed 50.5 kg (25th centile). She wished to try sleeping without nCPAP and, therefore, full polysomnography (PSG) was repeated after 1 week without the device. This study showed that her OSA had resolved and oxygen saturation remained >90% throughout sleep. Nasal CPAP was discontinued and a further follow-up PSG after 6 months confirmed