September 2010

You Have Till Monday to Do This
Last year it was Tom Smalling. This year it will be ? Get your nominations in for SPECIALTY PRACTITIONER OF THE YEAR . Last chance.

AARC International Respiratory Congress: Lots of Great Presentations for Sleep Specialists
Thanks to the proposals made by many of us in the Sleep Section, this year’s AARC Congress, Dec. 6–9 in Las Vegas, NV, will be full of great lectures and speakers devoted to our specialty. So if you’ve yet to check out the ADVANCE PROGRAM, click over now and page through the agenda, then register for the meeting today. With 25+ CRCEs, it’s the best educational value you’ll find all year long.

Nocturnal GER and OSA
Australian researchers who studied the relationship between obstructive sleep apnea (OSA) and nocturnal gastroesophageal reflux (nocturnal GER) events and symptoms—including the effect of CPAP treatment on the two—find no direct relationship between upper airway obstruction and nocturnal GER events. Instead, the investigation found:

• Baseline lower esophageal sphincter (LES) barrier pressure (P (b)) was low in these patients.
• When patients were off CPAP, there were 2.7 ± 1.8 nocturnal GER events per hour and 70 ± 39 obstructive respiratory events per hour.
• While upper airway obstruction did not alter P (b), CPAP tended to increase the nadir P (b) during LES relaxation (LESR) and decreased the duration of LESR.

The authors conclude, “The relatively low P (b) in these OSA patients raises the possibility of weakening of the gastroesophageal junction from repetitive strain associated with obstructed breathing events. The favorable effect of CPAP on nocturnal GER is possibly due to an increase in nadir P (b) and decrease in the duration for which the LES relaxes during swallow-induced and transient LESR.” The study appeared in the Aug. 14 Epub edition of Sleep & Breathing. READ ABSTRACT

OSA Prevalence High in Therapy-Resistant AF Patients
A new study out of Germany suggests patients with a recurrence of paroxysmal atrial fibrillation (AF) after two or more pulmonary vein (PV) isolation procedures are significantly more likely than those without a recurrence to suffer from OSA. The research compared outcomes for patients with therapy-resistant symptomatic paroxysmal AF with those seen in patients who were successfully treated by one PV isolation. Eighty-seven percent of patients with therapy-resistant AF were diagnosed with OSA, compared to 48% in the control group. What’s more, OSA was more severe in the resistant AF group, as indicated by a significantly higher apnea-hypopnea index, 27 ± 22 versus 12 ± 16. “The extraordinarily high prevalence of sleep apnea in patients with recurrent paroxysmal AF supports its presumable role in the pathogenesis of AF and demands further controlled prospective trials,” write the authors. “Moreover, OSA should inherently be considered in patients with therapy-resistant AF.” The research was published in the Aug. 17 Epub edition of the Journal of Interventional Cardiac Electrophysiology. READ ABSTRACT

Diaphragm Muscle Activity and Lung Volume at Sleep Onset: Comparing Obese OSA Patients with Healthy Controls
Researchers publishing in the Aug. 19 Epub edition of the Journal of Applied Physiology set out to determine whether expiratory diaphragmatic activity (eEMG(DI)) is greater during wakefulness in obese OSA patients versus healthy-weight controls without OSA, and to compare eEMGDI and end-expiratory lung volume (EELV) changes at sleep onset. Results showed:

• eEMG(DI) expressed as the percent of maximal activity was not significantly different between groups during wakefulness, but the OSA patients experienced a greater fall in eEMG(DI) following sleep onset and a greater decrease when respiratory events accompanied sleep onsets.
• The decrease in EELV by the third post sleep onset breath was small, with the decrease significantly greater in OSA patients over time.
• There was a greater decrease with more severe events, with EELV decreasing by 89.6 ± 14.2 ml at the onset of apneas in the OSA group.

The authors believe these findings show that diaphragm tone and EELV decrease following sleep onset, with greater falls at transitions accompanied by respiratory events, possibly contributing to an increased propensity for upper airway collapse in OSA patients at sleep onset. READ ABSTRACT

Few OSA Patients Undergo Surgery to Correct the Condition
Surgery is rarely performed for OSA in the United States, report University of California, San Francisco researchers who identified OSA procedures from two large national databases covering the years 2000–2006. In 2006, approximately 35,263 surgeries were performed, including 33,087 palate, 6561 hypopharyngeal, and 1378 maxillomandibular advancement procedures. Mean costs were about $6000 per admission. Inpatient surgical volumes decreased over the study period, but the researchers were unable to discern trends in total volumes. Overall, only 0.2% of adults with OSA underwent a surgical procedure. The study appears in this month’s Otolaryngology and Head and Neck Surgery. READ ABSTRACT