Sleep.7: positive airway pressure therapy for obstructive sleep apnoea/hypopnoea syndrome.

The use of continuous positive airway pressure (CPAP) in treating symptoms associated with OSAHS is reviewed. Although it is an imperfect intervention, it continues to evolve and improve in such a way that patients who would not have been able to use this treatment even in the recent past can benefit from it today.

Repair rates of R-band, G-band and C-band DNA in murine and human cultured cells.

Repair of cyclobutane pyrimidine dimers (CPDs) in cultured neonatal human fibroblasts and in Mus spretus x M. castaneus F1 neonatal skin fibroblasts was analyzed after UVC-irradiation by cleavage with T4 endonuclease V cyclopyrimidine dimer glycosylase, alkaline-agarose gel electrophoresis, and Southern blotting. The blots were sequentially probed with 32P-labeled Alu, or B2, to preferentially illuminate R-band DNA, by L1 to preferentially illuminate G-band DNA, and by satellite DNA to illuminate C-band DNA. These three different DNA populations showed slightly different global nucleotide excision repair rates that are in the order of speed, R-band DNA > G-band DNA > C-band DNA. Fibroblasts from out-bred neonatal mice and humans showed similar band-specific repair rate ratios and the global repair rate of murine fibroblasts was almost as rapid as that of the human fibroblasts. The mass distribution of the human Alu-probed signal was further analyzed. Gel mobility data was fitted to a logistic equation to include all M(r) values. Hypothetical distributions of DNA randomly cleaved to a particular number-average molecular weight were fit to the logistic gel mobility function to determine how such a randomly cleaved distribution of a particular cleavage frequency would be displayed along the experimental gel. This revealed a rapidly repaired kinetic fraction that represented 17% of the Alu-probed signal (R-band DNA), almost none of the L1 probed signal (G-band DNA), and reflects transcription coupled repair of active genes. The remaining Alu-probed DNA showed a random distribution of UVC-induced CPDs throughout all stages of global nucleotide excision repair. The Alu-probed CPDs disappeared with an excellent fit to first order kinetics and with a half-life of seven hours.

Chiari malformation and sleep-disordered breathing: a review of diagnostic and management issues.

Chiari Malformation (CM) encompasses several patterns of congenital or acquired cerebellar herniation through the foramen magnum. This may result in brain-stem compression that impacts control of breathing and is associated with obstructive and central apneas. A high clinical suspicion for sleep-disordered breathing is needed in the care of such patients after as well as before corrective surgery. To introduce a review of CM with a focus on the relevance to sleep medicine, we present a case of a 13-year-old female who was diagnosed with CM Type 1 in the course of an evaluation of symptomatic central sleep apnea. After initial improvement following surgery there was recurrence of brain-stem compression. The only clinical expression of which was polysomnographically evident recurrence of sleep apnea.

Rates of sensor loss in unattended home polysomnography: the influence of age, gender, obesity, and sleep-disordered breathing.

OBJECTIVES: To evaluate study failure and sensor loss in unattended home polysomnography and their relationship to age, gender, obesity, and severity of sleep-disordered breathing (SDB). DESIGN: A cross-sectional analysis of data gathered prospectively for the Sleep Heart Health Study (SHHS). SETTING: Unattended polysomnography was performed in participants' homes by the staff of the sites that are involved in SHHS. PARTICIPANTS: 6,802 individuals who met the inclusion criteria (age >40 years, no history of treatment of sleep apnea, no tracheostomy, no current home oxygen therapy) for SHHS. RESULTS: A total of 6802 participants had 7151 studies performed. 6161 of 6802 initial studies (90.6%) were acceptable. Obesity was associated with a decreased likelihood of a successful initial study. After one or more attempts, 6440 participants (94.7%) had studies that were judged as acceptable. The mean duration of scorable signals for specific channels ranged from 5.7 to 6.8 hours. The magnitudes of the effects of age, gender, BMI, and RDI on specific signal durations were not clinically significant. CONCLUSION: Unattended home PSG as performed for SHHS was usually successful. Participant characteristics had very weak associations with duration of scorable signal. This study suggests that unattended home PSG, when performed with proper protocols and quality controls, has reasonable success rates and signal quality for the evaluation of SDB in clinical and research settings.

A randomized, prospective evaluation of noninvasive ventilation for acute respiratory failure.

We compared noninvasive positive-pressure ventilation (NPPV), using bilevel positive airway pressure, with usual medical care (UMC) in the therapy of patients with acute respiratory failure (ARF) in a prospective, randomized trial. Patients were subgrouped according to the disease leading to ARF (chronic obstructive pulmonary disease [COPD], a non-COPD-related pulmonary process, neuromuscular disease, and status postextubation), and were then randomized to NPPV or UMC. Thirty-two patients were evaluated in the NPPV group and 29 in the UMC group. The rate of endotracheal intubation (ETI) was significantly lower in the NPPV than in the UMC group (6.38 intubations versus 21.25 intubations per 100 ICU days, p = 0.002). Mortality rates in the intensive care unit (ICU) were similar for the two treatment groups (2.39 deaths versus 4.27 deaths per 100 ICU days, p = 0.21, NPPV versus UMC, respectively). Patients with hypoxemic ARF in the NPPV group had a significantly lower ETI rate than those in the UMC group (7.46 intubations versus 22.64 intubations per 100 ICU days, p = 0.026); a similar trend was noted for patients with hypercapnic ARF (5.41 intubations versus 18.52 intubations per 100 ICU days, p = 0.064, NPPV versus UMC, respectively). Patients with ARF in the non-COPD category had a lower rate of ETI with NPPV than with UMC (8.45 intubations versus 30.30 intubations per 100 ICU days, p = 0.01). Although the rate of ETI was lower among COPD patients receiving NPPV, this trend did not reach statistical significance (5.26 intubations versus 15.63 intubations per 100 ICU days, p = 0.12, NPPV versus UMC, respectively). In conclusion, NPPV with bilevel positive airway pressure reduces the rate of ETI in patients with ARF of various etiologies.

Effects of varying approaches for identifying respiratory disturbances on sleep apnea assessment.

Varying approaches to measuring the respiratory disturbance index (RDI) may lead to discrepant estimates of the severity of sleep-disordered breathing (SDB). In this study, we assessed the impact of varying the use of corroborative data (presence and degree of desaturation and/or arousal) to identify hypopneas and apneas. The relationships among 10 RDIs defined by various definitions of apneas and hypopneas were assessed in 5,046 participants in the Sleep Heart Health Study (SHHS) who underwent overnight unattended 12-channel polysomnography (PSG). The magnitude of the median RDI varied 10-fold (i.e., 29.3 when the RDI was based on events identified on the basis of flow or volume amplitude criteria alone to 2.0 for an RDI that required an associated 5% desaturation with events). The correlation between RDIs based on different definitions ranged from 0.99 to 0.68. The highest correlations were among RDIs that required apneas and hypopneas to be associated with some level of desaturation. Lower correlations were observed between RDIs that required desaturation as compared with RDIs defined on the basis of amplitude criteria alone or associated arousal. These data suggest that different approaches for measuring the RDI may contribute to substantial variability in identification and classification of the disorder.

Positive pressure therapy.

Positive airway pressure in the treatment of obstructive sleep-disordered breathing (OSDB) is reviewed. Continuous positive airway pressure (CPAP), bilevel positive airway pressure, and variable (auto-CPAP) pressure, their mechanisms of action, benefits, and complications are examined. A perspective on the future of positive airway pressure therapy for OSDB is provided.

Methods for obtaining and analyzing unattended polysomnography data for a multicenter study. Sleep Heart Health Research Group.

This paper reviews the data collection, processing, and analysis approaches developed to obtain comprehensive unattended polysomnographic data for the Sleep Heart Health Study, a multicenter study of the cardiovascular consequences of sleep-disordered breathing. Protocols were developed and implemented to standardize in-home data collection procedures and to perform centralized sleep scoring. Of 7027 studies performed on 6697 participants, 5534 studies were determined to be technically acceptable (failure rate 5.3%). Quality grades varied over time, reflecting the influences of variable technician experience, and equipment aging and modifications. Eighty-seven percent of studies were judged to be of "good" quality or better, and 75% were judged to be of sufficient quality to provide reliable sleep staging and arousal data. Poor submental EMG (electromyogram) accounted for the largest proportion of poor signal grades (9% of studies had <2 hours artifact free EMG signal). These data suggest that with rigorous training and clear protocols for data collection and processing, good-quality multichannel polysomnography data can be obtained for a majority of unattended studies performed in a research setting. Data most susceptible to poor signal quality are sleep staging and arousal data that require clear EEG (electroencephalograph) and EMG signals.

Split-night studies for the diagnosis and treatment of sleep-disordered breathing.

We examined the effect of split-night polysomnography on compliance with positive pressure via a mask for the treatment of obstructive sleep-disordered breathing. A comparison of objective compliance (hours/day) at the first meter read from the positive-pressure device (4-6 weeks after set-up) in patients who had a successful split-night positive-pressure titration vs. patients who had traditional full-night positive-pressure titration was performed. Patients were matched for age, sex, and severity of the obstructive sleep-disordered breathing. Twelve patients were matched with controls who underwent full-night polysomnography. There were no significant differences between the split-night patients and the full-night patients with regard to age, sex, body mass index, and pretreatment Epworth Sleepiness Score. In addition, there was no significant difference between apnea-hypopnea index and the desaturation-event frequency for both groups pre- and post-treatment. The average daily use of continuous positive airway pressure (CPAP) at the time of the first meter reading in the group that underwent full-night positive-pressure titrations as opposed to split-night titrations was 5.2 hours/day +/- 2.2 vs. 3.8 hours/day +/- 2.9, respectively (p = 0.29). The Epworth Sleepiness Scale on the initial clinic visit (as an index of patient-perceived impairment) did not predict compliance at 4-6 weeks. The time at the final positive pressure did not correlate with compliance. Acceptance of positive pressure in the split-night patients ranged from 62 to 67%.

Previous tonsillectomy as prognostic indicator for success of uvulopalatopharyngoplasty.

Factors that determine a successful outcome following uvulopalatopharyngoplasty (UPPP) for obstructive sleep apnea (OSA) are not well defined. This study was undertaken to determine if prior tonsillectomy is predictive of a lower response rate to UPPP. A retrospective review of a cohort undergoing UPPP alone or in combination with nasal septoplasty for OSA was undertaken. Preoperative and postoperative polysomnograms were obtained to evaluate the severity of the OSA. The sample was a consecutive series of 79 patients with OSA. Clinical evaluation was performed by both an otolaryngologist and a pulmonologist. Surgical treatment in this group of 79 patients included 52 UPPP and 27 UPPP in patients with prior tonsillectomy. Concurrent septoplasty was undertaken in 17 patients. Criteria for outcome were based on comparison of preoperative and postoperative polysomnograms (i.e., apnea index, respiratory disturbance index change, and lowest saturation). A response to therapy was defined as a reduction in apnea index greater than 50%. A success was defined as apnea index less than 5, reduction of respiratory disturbance index greater than 50%, and nadir saturation greater than 82%. In 79 patients with OSA, 78% responded and 37% reflected therapeutic successes. Patients with history of prior tonsillectomy were less likely to have therapeutic improvement following UPPP. In 52 patients without previous tonsillectomy, 88% responded and 52% had a successful outcome. Of those with previous tonsillectomy, 59% responded and 7% had a successful outcome. The status of previous tonsillectomy is an important prognostic indicator in the success of UPPP for the treatment of OSA. We speculate that the presence of palatine tonsils allows the removal of an extra measure of oropharyngeal tissue, thereby improving the likelihood of success for UPPP.