February 2013

Winter Bulletin Online Now

The WINTER EDITION of our section Bulletin is out now, so click on the link to read great articles on sleep credentials and sleep licensure, plus an informative story on sleep deprivation and how it could be putting everyone at risk for some serious diseases.

Telemedicine Approach Found Effective

Spanish investigators publishing in the January edition of the Telemedicine Journal and e-Health report positive outcomes for the use of telemedicine to transmit data in real time from respiratory polygraphy and auto-continuous CPAP to a sleep lab. The research involved 40 patients who were divided into two groups. One group was seen in a conventional clinic while the other was tested by teleconsultation. Overall, 35 of the patients were diagnosed with obstructive sleep apnea syndrome and 16 were started on CPAP. Greater than a 90% agreement was seen between the studies stored in the polygraph and those transmitted telematically for the apnea-hypopnea index, total apneas and hypopneas, mean oxygen saturation, and time with an oxygen saturation <90%. However, CPAP compliance was higher for patients seen in the clinic, 85% vs. 75%. READ ABSTRACT

Poor Sleep Impacts a Range of Chronic Diseases

Centers for Disease Control and Prevention researchers shed new light on the relationship between poor sleep, frequent mental distress (FMD), obesity, and chronic disease in a new study published ahead of print by BMC Public Health on Jan. 29. Looking at data from 375,653 adults age 18 and older in the 2009 Behavioral Risk Factor Surveillance System they found 10.4% reported insufficient sleep every day of the month, 17% reported poor sleep for 14-29 days of the month, and 42% for 1-13 days. No sleep problems were reported by 30.6%. After adjusting the results for other factors, poor sleep was significantly associated with all six of the chronic diseases in the study (diabetes mellitus, coronary heart disease, stroke, high blood pressure, asthma, and arthritis). These associations were only modestly attenuated by FMD and, in the case of diabetes and high blood pressure, by obesity. The authors believe these findings suggest the need to include assessment of sleep quantity and quality in routine medical examinations. They also call for studies on treatments for chronic conditions to take possible effects on sleep into account. READ ABSTRACT

Length of Apneas and Hypopneas Matters Too

The severity of sleep apnea-hypopnea syndrome (SAHS) is typically assessed by the apnea-hypopnea index (AHI), but Finnish researchers believe additional parameters could help clarify both the diagnosis and health risks posed by the condition. Specifically, they note that the AHI does not take the length of each apnea and hypopnea event into account. Longer events, they argue, could lead to longer and deeper periods of oxygen desaturation. They even suggest that less frequent but longer apneas and hypopneas could be more dangerous when it comes to raising health risks than more frequent but brief apneas and hypopneas. To assess their theory, they retrospectively analyzed diagnostic ambulatory polygraphy recordings of 19 men, adding the duration of the breathing cessations and the morphology of the oxygen desaturation events into the mix. Results showed significant variation between subjects with similar AHIs. For example, only a moderate correlation was seen between AHI and the obstruction severity parameter. They believe these findings suggest “patients with similar AHI may exhibit significantly different cardiovascular stress related to the disease.” The study was published in a recent issue of the Journal of Medical Engineering & Technology. READ ABSTRACT

Determining Phenotypic Traits in OSA

New research out of Brigham and Women’s Hospital and Harvard Medical School may provide an easier way of defining mechanisms underlying OSA that could be useful in individualizing therapy in the clinical setting. Building on previous research, the investigators came up with a method for measuring several OSA traits by manipulating CPAP during sleep. Specifically, the method quantifies: 

1. Eupneic ventilation.
2. Level of ventilation at which arousals begin to occur.
3. Ventilation off CPAP (nasal pressure=0 cmH2O) when the pharyngeal muscles are activated during sleep.
4. Ventilation off CPAP when the pharyngeal muscles are relatively passive.

The technique was tested in 13 subjects and all of the measures could be made in all 13. Substantial intersubject variability was seen in the reduction in ventilation that individuals tolerated before having arousals and in the amount of ventilatory compensation that individuals could generate. Most significantly, a correlation was noted between the AHI and the difference between ventilation #2 and #3, which is a measure of the gap that must be overcome to achieve stable breathing during sleep. When a procedure to measure loop gain was added to the technique, the researchers were also able to quantify arousal threshold and upper airway gain. The study was published ahead of print by the Journal of Applied Physiology on Jan. 24. READ ABSTRACT