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The impact of treating OSA on renal function decline is controversial. Previous studies usually included small samples and did not consider specific effects of different CPAP modalities. The aim of this study was to evaluate the respective influence of fixed and autoadjusting CPAP modes on estimated glomerular filtration rate (eGFR) in a large sample of patients derived from the prospective European Sleep Apnea Database cohort.

Single-night disease misclassification of OSA due to night-to-night variability may contribute to inconsistent findings in OSA trials.

The occurrence and mechanisms of nocturnal hypoxemia in precapillary pulmonary hypertension (PH) are not clearly defined.

This French, multicenter, randomized double-blind controlled trial tested the hypothesis that pressure reduction during exhalation (C-Flex; Respironics; Murrysville, PA) would improve continuous positive airway pressure (CPAP) compliance, comfort, and quality of life.

To examine the possible relationship between systemic HT and SAS we compared 21 hypertensive (HT+) and 29 normotensive (HT–) patients for morphologic characteristics, sleep disturbances and respiratory events monitored during a full night polysomnography. There was no significant difference between HT+ and HT–patients with respect to age, weight, BMI, sleep stage distribution and disorganization, apnea-hypopnea index (number of episodes per hour of sleep) and duration (minutes per hour of sleep) nor O2saturation indices: mean nocturnal and minimum O2saturation. We conclude therefore that HT in SAS patients is not directly related to morphologic characteristics, sleep disturbances and breathing abnormalities.

To assess the accuracy of the respiratory inductive plethysmograph (RIP) during sleep in obese patients with obstructive sleep apnea (OSA), we monitored 13 patients with OSA during wakefulness and nocturnal sleep with simultaneous measurements of tidal volume from RIP and integrated airflow. Patients wore a tightly fitting face mask with pneumotachograph during wakefulness and sleep. Calibrations were performed during wakefulness prior to sleep and compared with subsequent wakeful calibrations at the end of the study. Patients maintained the same posture during sleep (supine, 11; lateral, two) as during calibrations. There were no significant differences in calibrations before sleep and after awakening. The mean error in 13 patients undergoing RIP measurements of tidal volume during wakefulness was – 0.7 ± 3.4 percent while that during sleep was 2.1 ±14.9 percent (p<0.001). The standard deviation (SD) of the differences between individual breaths measured by RIP and integrated airflow was 9.8 ±5.5 percent during wakefulness and 25.5 ±18.6 percent during sleep (p<0.001). During both wakefulness and sleep, errors in RIP tidal volume were not significantly correlated with body mass index. In 12 patients with at least 10 percent time in each of stages 1 and 2 sleep, SD was greater in stage 2 sleep compared with wakefulness and stage 1 (p<0.001). In three patients who manifested all stages of sleep, SD was greater in REM sleep than in wakefulness and all stages of non-REM sleep (p<0.001). In three patients who manifested all stages of sleep, SD was greater in REM sleep than in wakefulness and all stages of non REM sleep (p<0.001). This was associated with paradoxic motion of the rib cage in two patients during REM. We conclude that, despite increased errors in individual breath measurements during sleep, more marked during stages 2 and REM sleep, RIP is clinically useful to measure ventilation quantitatively in obese patients with sleep apnea. The criterion of a decrease of 50 percent in tidal volume assessed by RIP is appropriate to define hypopneas in such patients.

To evaluate the reliability of pulse oximetry during exercise, we studied 101 patients primarily with chronic pulmonary diseases. Three devices were used on different patients. Radial arterial blood was sampled at rest and maximal exercise simultaneously to pulse oximetric determination. Measured blood oxygen saturation was significantly different from noninvasive saturation at rest and also at exercise for each device. Nevertheless, changes in pulse oximetry from rest to exercise were significantly correlated with measured saturation for all three devices. Direction of changes in saturation from rest to exercise was correctly evaluated by transcutaneous oximetry in all but six instances where changes were less than 4 percent. Although measured and transcutaneous saturations are significantly different, we conclude that pulse oximetry reliably estimates changes in arterial saturation between rest and exercise for a clinical purpose. None of the three tested devices was better compared with the others in estimating saturation changes at exercise.