As reported previously in ENToday, as many as 18 million Americans might have obstructive sleep apnea (OSA) with an apnea-hypopnea index (AHI) > 5.0 events per hour of sleep, according to the National Commission on Sleep Disorders Research report, Wake up America: A National Sleep Alert. The National Sleep Foundation’s 2004 Sleep in America poll found that almost one in five preschoolers and school-age children snore, which can be an indication of sleep apnea.
Insomnolence due to OSA may lead adults to sit and seethe in traffic jams, quarrel with other people, or overeat, and is suspected to increase the risk for daytime learning problems, poor school performance, daytime sleepiness, and hyperactivity in children. Effectively screening for OSA, as well as improving or resolving certain comorbidities of OSA, is becoming increasingly important for sleep-deprived adults and children.
Screening for OSA
Polysomnography (PSG) has long been considered the gold standard for the diagnosis of OSA, but its use is limited by the availability of sleep centers and the costs of the tests, stated Jordan C. Stern, MD, of the New York Otolaryngology Group in his presentation, A New Device for Home Screening of Obstructive Sleep Apnea Using Holter Oximetry, delivered at the Combined Otolaryngology Spring Meeting in April. Other screening tests have been proposed over the past 20 years, ranging from simple overnight pulse oximetry to more complex multiple channel home devices.1 Previous studies have determined that single-lead electrocardiogram (ECG) recordings from sleep study patients can detect OSA with great sensitivity and specificity in the laboratory setting.2,3,4
ENTs are confronted daily with patients presenting with the signs and symptoms of OSA, said Dr. Stern. Many patients do not want to go through the trouble of sleeping in a lab; hence, a reliable, inexpensive, portable, and easy-to-use at home screening device would be invaluable for both ENTs and their patients.
During his presentation, Dr. Stern described the use of two new devices to screen for OSA in the unattended home setting: (1) the Holter apnea monitor (continuous ambulatory ECG recording) and (2) the Holter oximeter (both continuous ECG recording and pulse oximetry). The underlying technology in both devices is the same; each consists of a small portable digital recording device connected to chest electrodes. The Holter oximeter has an additional pulse oximetry finger probe.
The Holter oximeter uses the same software to analyze the continuous ECG signal, as well as data from the continuous pulse oximetry, and produces two outputs. The first output is an epoch-by-epoch sequence of annotations of normal or sleep-disordered breathing (SDB). The second output provides an estimate of the AHI, derived from the epoch-by-epoch annotations. An estimated AHI was derived from the per-epoch classification by counting the average number of detected apnea segments per hour of sleep and automatically applying an appropriate threshold.
The Holter apnea monitor was used on 14 adult patients and the Holter oximeter on 47 adults and three children between March 2006 and January 2007 in an unattended home setting. After placing chest electrodes on patients and securing the oximetry finger probe on those using the Holter oximeter, the medical assistant instructed the patients (or parents) on the use and removal of the device. Patients were also instructed to record the time at which they went to sleep, awoke, or experienced any other events during the night.
Patients were also asked to complete a brief questionnaire regarding any discomfort related to the device. Few patients complained about sleeping with the device and none complained about it interfering with their daily life, even the children, said Dr. Stern. In fact, most patients were surprised and pleased with the ease of use and rapid test results.
When the device was returned the next day, the medical assistant obtained any other information regarding the test and inquired specifically about electrode disconnections during the test. The assistant then transferred data via a compact flash card from the Holter device to a desktop computer for analysis.
We believe that the Holter oximeter represents a very promising new method of screening for OSA in the unattended home environment, said Dr. Stern. It uses time-tested inexpensive devices to produce a reliable and sensitive measure of the AHI. Compared to other tests currently used for home screening of OSA, it has a very high reliability rate and correlates well with PSG. It could become a first-line screening tool for OSA in the adult population and is especially promising in the pediatric population, where the most common screening device has been pulse oximetry alone.
Pulse oximetry in children is problematic. The pathophysiology of OSA in children is different from that in adults, with frequent episodes of upper airway obstruction that are not associated with saturation drop.5 In children, there are large numbers of movement artifacts, due to their more restless sleep.6 These artifacts can cause low saturation recordings and a large number of false positive findings. A recent study questioned the validity of pulse oximetry in children and suggested that if it is used as a test for the diagnosis of OSA, it should be associated with additional sensors, such as motion sensors or measures of airflow.7
It’s even more difficult to get kids into a lab and get them to sleep, as their sleeping position is restricted because of the numerous electrodes and their sleep is interrupted by technicians repositioning the electrodes, said Dr. Stern. The home device is a major advance for screening kids, as it eases follow-up and retesting after treatment.
The Holter apnea device is already available and distributed under the name of Life Screen Apnea™ and the Holter oximeter will soon be available commercially, continued Dr. Stern. I do not know the price point yet, but it would be affordable and very cost-effective, probably five to 10 times less than a PSG. Right now, some insurance companies are covering the tests when submitted using the CPT code 95806.
GERD and OSA
According to the International Foundation for Functional Gastrointestinal Disorders, approximately 21% of the US population may suffer from gastroesophageal reflux disease (GERD); reflux appears to be prevalent in SDB patients.8 Some studies suggest that there is a correlation between OSA and GERD,9,10 as they share similar risk factors, as well as signs and symptoms, and that treating one condition often improves the other.11
In his presentation at COSM, The Impact of Treatment of Laryngopharyngeal Reflux on Obstructive Sleep Apnea/Hypopnea Syndrome, Michael Friedman, MD, Professor of Otolaryngology at Rush University Medical Center and Chairman of Otolaryngology at Advocate Illinois Masonic Medical Center in Chicago, stated that laryngopharyngeal reflux (LPR) is also extremely common in patients with OSA.
Reflux from GERD or LPR leads to nighttime arousals, which increase daytime somnolence, said Dr. Friedman. Repeated reflux often leads to tissue swelling, which may result in airway obstruction. Reflux may also cause vagal reflexes that bring about sleep apnea.
To determine whether treatment of LPR could improve OSA, Dr. Friedman reported on a prospective clinical trial in a tertiary care center that was done in two phases. In Phase I, 81 patients with signs and symptoms of OSA underwent a complete history and physical that included questions related to LPR and GERD symptoms, a PSG, a 24-hour wireless esophageal pH study, a snoring and Epworth Sleepiness Scale survey completed by both the patient and a family member, and a quality-of-life (QOL) survey.
We chose to use a wireless esophageal pH monitor rather than a transnasal pH catheter, which has to go down the patient’s nose and into the esophagus, causing greater discomfort, said Dr. Friedman. This new technology involves placing a sensor-about the size of a capsule-in the esophagus via endoscopy and attaching it to the esophagus with a small pin. The sensor transmits data, such as the frequency, duration, and degree of stomach acid reflux in the upper esophagus, to a collection device that the patient wears on a belt. Eventually the sensor dislodges and passes through the digestive tract. Most patients find that this procedure interferes less in their activities of daily living than using the catheter.
Based on the tests, 71.4% of the patients had positive pH studies and 10.4% reported no signs or symptoms of LPR, indicating occult disease. Patients who tested positive for LPR were enrolled in Phase II and treated with esomeprazole magnesium, 40 mg QD, for two months. After two months, the PSG, pH study, QOL survey and subject data collection were repeated.
During the study, we did not use CPAP and BiPAP, even though they are a fairly simple and effective treatment for OSA, because the purpose of this study was to evaluate whether the elimination of LPR, as an isolated treatment, could improve OSA, said Dr. Friedman.
In the 32 patients participating in Phase II, snoring levels decreased from 8.7 ± 2.1 to 6.9 ± 2.6 (p09), daytime sleepiness decreased from 14.4 ± 3.5 to 11.2 ± 2.5 (p21), AHI from 33.5 ± 21.6 to 30.1 ± 12.3 (p12), and minimum O2 saturation increased form 85.7 ± 8.3 to 87.1 ± 5.0 (p16).
Although no patients were cured by proton-pump inhibitor therapy alone, the study identified the following important points. First, LPR and OSA are common comorbid conditions; the incidence of LPR in patients with OSA in this study was 71.4%. Second, treatment of LPR had a significant impact on the reduction of AHI, snoring, and daytime sleepiness, and it also improved minimum oxygen saturation.
This was the first study to focus on patients with negative upper esophageal monitoring indicating the elimination of LPR. In patients with both conditions, adequate treatment of LPR with esomeprazole was effective in reducing the subjective and objective findings of OSA and is an important adjunct in the overall management of OSA.
References
- Pang K, Terris D. Screening for obstructive sleep apnea: an evidence-based analysis. Am J Otolaryngol 2006;27(2);112-8.
- de Chazal P, Penzel T, Heneghan C. Automated detection of obstructive sleep apnea at different time scales using electrocardiogram. Physiol Meas 2004;25(4):967-83.
- Shouldice RB, O’Brien LM, O’Brien C, et al. Detection of obstructive sleep apnea in pediatric subjects using surface lead electrocardiogram features. Sleep 2004;27(4):784-92.
- de Chazal P, Heneghan C, Sheridan E, et al. Automated processing of the single lead electrocardiogram for the detection of obstructive sleep apnea. IEEE Trans Biomed Eng 2003;50(6):686-96.
- American Thoracic Society. Standards and indications for cardiopulmonary sleep studies in children. Am J Respir Crit Care Med 1996;153(2):866-78.
- Scholle S, Zwacka G. Arousals and obstructive sleep apnea syndrome in children. Clin Neurophysiol 2001(6);112:984-91.
- Kirk VG, Bohn SG, Flemons W, et al. Comparison of home oximetry monitoring with laboratory polysomnography in children. Chest 2003;124(5):1702-8.
- Wise SK, Wise JC, DelGaudio JM. Gastroesophageal reflux and laryngopharyngeal reflux in patients with sleep-disordered breathing. Otolaryngol Head Neck Surg 2006;135(2):253-7.
- Kasasbeh A, Kasasbeh E, Krishnaswamy G. Potential mechanisms connecting asthma, esophageal reflux, and obesity/sleep apnea complex-a hypothetical review. Sleep Med Rev 2007;11(1):47-58.
- Morse CA, Quan SF, May MZ. Is there a relationship between obstructive sleep apnea and gastroesophageal reflux disease? Clin Gastroenterol Hepatol 2004;2(9):761-8.
- Green BT, Broughton WA, O’Connor JB. Marked improvement in nocturnal gastroesophageal reflux in a large cohort of patients with obstructive sleep apnea treated with continuous positive airway pressure. Arch Intern Med 2003;163(1):41-5.
©2007 The Triological Society