July 2010

Specialty Practitioner of the Year Nominations Due Aug. 31
Know a fellow section member who goes above and beyond, either for the section or on the job? Then nominate him or her for our 2010 Specialty Practitioner of the Year award. Nominations are due by Aug. 31 and may be made via our online NOMINATIONS FORM.

Auto Bi-Level Algorithm Found Effective
A new study out of the Swedish Medical Center in Seattle, WA, compared a new auto-adjusting bi-level algorithm to the standard method for prescribing bi-level therapy in patients with obstructive sleep apnea (OSA), finding good results for the new method. The research was based on data obtained on 22 subjects who underwent sleep studies on two consecutive nights. The mean apnea-hypopnea index (AHI) was 6.2 ± 5.4 events per hour for the auto-adjusting bi-level mode vs. 8.3 ± 5.8 events per hour for the standard bi-level mode. The difference in median pressure was -3.8 cm H2O ± 3.6 in favor of the auto-adjusting bi-level mode. The maximum pressure was significantly higher in the auto-adjusting bi-level mode as well, 16.0 cm H2O vs. 14.1 cm H2O. “The auto-adjusting bi-level mode provides a potentially reliable alternative for sleep clinicians faced with prescribing bi-level PAP for non-compliant patients,” write the authors The study appeared in the July 6 Epub edition of Sleep & Breathing. READ ABSTRACT

Sleep Stage Transition Dynamics Change with OSA
Massachusetts General Hospital researchers believe stage transition analysis to characterize sleep continuity could be used to improve predictive phenotyping of fragmented sleep. But extended monitoring, most likely in the patient’s home, may be required because a single night contains insufficient transitions. The investigators arrived at those conclusions after analyzing hypnograms from the Sleep Heart Health Study, using three stage designations: wake after sleep onset (WASO), non-rapid eye movement (NREM) sleep, and REM sleep. A control group was compared to patients with mild or severe OSA. Among the results:

• WASO, REM sleep, and NREM sleep bout durations exhibited multi-exponential temporal dynamics.
• The presence of OSA accelerated the “decay” rate of NREM and REM sleep bouts, resulting in instability manifesting as shorter bouts and increased number of stage transitions.
• For WASO bouts, previously attributed to a power law process, a multi-exponential decay described the data well. Simulations demonstrated that a multi-exponential process can mimic a power law distribution.

The study appeared in the June issue of PLoS One. READ ABSTRACT

Heated Humidification Reduces Nasal Symptoms for CPAP Patients
Greek investigators publishing in the July 1 Epub edition of the European Respiratory Journal find adding humidification to nasal CPAP treatment can mitigate some of the nasal symptoms experience by OSA patients. They randomized 20 patients to CPAP plus humidification for three weeks or CPAP plus sham humidification. After three weeks, the two groups switched treatments. Nasal symptom score; nasal resistance; nasal lavage interleukin-6, interleukin-12, and tumour necrosis factor-a; and nasal mucosa histopathology were assessed at baseline and after each treatment arm. Heated humidification was linked to decreased nasal symptomatology, resistance and lavage cytokines, and attenuation of inflammatory cell infiltration and fibrosis of the nasal mucosa when compared with the sham treatment. READ ABSTRACT

OSA and Stroke
Is OSA an independent risk factor for stroke? That’s the question Mayo Clinic researchers asked through the development of a “structured critically appraised topic,” an evidence-based methodology in which clinical and content experts reviewed a large observational cohort study. Their findings suggest the answer is yes. Among the results:

• The unadjusted analysis revealed that OSA (AHI >5) was associated with stroke or death from any cause.
• The adjusted OSA analysis retained a statistically significant association with stroke or death.
• In separate unadjusted analyses, OSA was associated with death and stroke with relative risks of 1.68 and 5.16, respectively.