Background-The gold standard diagnostic test for obstructive sleep apnoea (OSA) is overnight polysomnography (PSG) which is costly in terms of time and money. Consequently, a number of alternatives to PSG have been proposed. Oximetry is appealing because of its widespread availability and ease of application. The diagnostic performance of an automated analysis algorithm based on falls and recovery of digitally recorded oxygen saturation was compared with PSG. Methods-Two hundred and forty six patients with suspected OSA were randomly selected for PSG and automated oV line analysis of the digitally recorded oximeter signal. Results-The PSG derived apnoea hypopnoea index (AHI) and oximeter derived respiratory disturbance index (RDI) were highly correlated (R = 0.97). The mean (2SD) of the diVerences between AHI and RDI was 2.18 (12.34)/h. The sensitivity and specificity of the algorithm depended on the AHI and RDI criteria selected for OSA case designation. Using case designation criteria of 15/h for AHI and RDI, the sensitivity and specificity were 98% and 88%, respectively. If the PSG derived AHI included EEG based arousals as part of the hypopnoea definition, the mean (2SD) of the diVerences between RDI and AHI was -0.12 (15.62)/h and the sensitivity and specificity profile did not change significantly. Conclusions-In a population of patients suspected of having OSA, oV line automated analysis of the oximetry signal provides a close estimate of AHI as well as excellent diagnostic sensitivity and specificity for OSA. (Thorax 2000;55:302-307)

Anterior mandibular positioners (AMPs) have become increasingly popular as alternatives to continuous positive airway pressure for the treatment of obstructive sleep apnea. However, widespread acceptance of AMP is limited by an efficacy rate of 50-80% and an inability to predict which patients will respond to therapy. We evaluated 23 patients with obstructive sleep apnea (respiratory disturbance index [RDI] >/= 15 h(-1)) with a remotely controlled mandibular positioner (RCMP), a temporary oral appliance that can advance or retract the mandible in a process analogous to changing the mask pressure during a continuous positive airway pressure titration study. We hypothesized that the elimination of respiratory events and significant nocturnal oxygen desaturation during an RCMP overnight study would predict AMP efficacy, as defined by an absolute reduction in RDI to less than 15 h(-1), a relative reduction in RDI of more than 30% from baseline, and a subjective improvement in symptoms. AMP compliance was 82%, and therapeutic efficacy was 53%. Among compliant patients, the positive and negative predictive value of an RCMP study in predicting AMP treatment success was 90% and 89%, respectively. An overnight RCMP study is highly predictive of AMP response.

Objective: To investigate the impact of oxygen on sleep and breathing in patients with interstitial lung disease (ILD) in Mexico City, at 2,240 m of altitude. Participants: Nineteen ILD patients with a mean FVC of 58 ± 17% pred. (SD) and a mean PaO₂ of 51 ± 6 mm Hg were recruited from a pulmonary clinic in a tertiary referral center. In addition, 14 normal control subjects, matched for age and gender, were studied. All patients underwent two consecutive full polysomnographies (PSG), one breathing room air and one breathing supplementary oxygen through nasal prongs, in random order. Controls were studied for one night breathing room air. Results: The mean oxygen saturation (SaO₂) in ILD patients was 82.3 ± 9.1% during sleep on air and 94.8 ± 2.9% on oxygen (p < 0.001). In controls it was 92.9 ± 1.9% (p < 0.001). Sleep efficiency was similar in patients and controls (75 vs. 82%, p > 0.05) and did not change with oxygen (77%). Arousal index was 12.4 ± 6.9·h^–1 in ILD patients breathing room air and 12.9 ± 9.1·h^–1 breathing oxygen while in controls it was 11.4 ± 5.4·h^–1. Breathing frequency (f) during sleep was 24.7 ± 4.2 in ILD patients and decreased breathing oxygen to 22.5 ± 3.6 (p < 0.001) but was still higher than in controls (15.6 ± 2.7; p < 0.001). Similarly, the heart rate (HR) in ILD and controls was 79 ± 12 and 68 ± 8, respectively (p < 0.001), and decreased to 68 ± 4 when patients breathed oxygen (p < 0.001). Conclusions: Oxygen substantially decreases HR and f, but does not normalize the f in ILD patients. The impact of hypoxia on sleep efficiency and arousal index was not demonstrable in our patients acclimatized to moderate altitude.