Gastric Reflux High in Patients with Sleep Disorders

Newswise — Obstructive sleep apnea (OSA), gastroesophageal reflux (GERD, an abnormal amount of reflux of stomach acid up through the lower sphincters and into the esophagus), and laryngopharyngeal reflux (LPR, when reflux travels all the way up through the upper sphincter and into the back of the throat) may have dangerous consequences if they persist undiagnosed or untreated. All are treated by the otolaryngologist—head neck surgeon. The relationship between gastric acid reflux and sleep disordered breathing has been examined in previous research. However, only a single study has concentrated on the relationship between proximal pharyngeal reflux and OSA.

Consequently, researchers in Atlanta have initiated a study to examine the prevalence of GERD and LPR in patients diagnosed with breathing-related sleep disorders. The authors of “Gastroesophageal Reflux and Laryngopharyngeal Reflux in Patients with Sleep-Disordered Breathing,” are Sarah K. Wise MD and John M. DelGaudio MD, both from the Department of Otolaryngology-Head and Neck Surgery, The Emory Clinic; and Justin C. Wise PhD, at the Department of Psychology, Georgia State University, all in Atlanta, GA. This study was supported by a grant from the Investigator-Sponsored Studies Program of AstraZeneca Corporation. The findings are to be presented at the 109th Annual Meeting & OTO EXPO of the American Academy of Otolaryngology—Head and Neck Surgery Foundation, being held September 25-28, 2005, at the Los Angeles Convention Center, Los Angeles, CA.

Methodology: Thirty-seven patients undergoing evaluation for snoring or sleep disordered breathing participated in this study. Any participants taking acid suppressive medications were instructed to discontinue the use of these medications for at least seven days prior to undergoing PSG (overnight sleep study) and pH probe studies (the negative logarithm of the hydrogen ion concentration, used as a scale for expressing acidity and alkalinity. Exclusion criteria included failure to suspend acid suppressive medications or inability to tolerate pH probe testing. Participants completed the Epworth Sleepiness Scale, the Reflux Symptom Index, and rated their snoring on a zero to 10 scale (zero = no snoring, 10 = worst snoring). Patient height and weight were recorded, and body mass index (BMI) was calculated.

Dual-sensor pH probes with laryngopharyngeal (LP), and distal esophageal electrodes were utilized for 24-hour pH measurement. The distal esophageal electrode was at the tip of the catheter, and the LP electrode was located fifteen to 18 cm proximal to the esophageal electrode.

As part of this study, participants also underwent traditional PSG. Every effort was made to schedule pH probe and PSG studies during the same 24-hour period. PSG reports included total study respiratory disturbance index (RDI), REM sleep RDI, low oxygen saturation, and arousal index. RDI, also known as apnea-hypopnea index, is the combined number of apneas and hypopneas per hour.

Results: Thirty-seven patients, 11 females, 26 males, with complaints of snoring or breathing-related sleep disturbances participated in this study. Patients ranged in age from 25 to 67 years, with a mean age of 47 years. Mean body main index was 32, with a range of 21.7 to 61.9. Eight patients reported a history of reflux. Twenty-five patients (67.6 percent) underwent overnight PSG and pH probe simultaneously. The remaining 12 participants had the two studies performed on separate nights due to technical difficulties with either the pH probe or PSG, or due to participant scheduling conflicts.

Twenty-eight study participants were diagnosed with obstructive sleep apnea or OSA following overnight PSG. The nine remaining participants, with an RDI of five or less, were classified as simple snorers. Patients diagnosed with OSA had a range of RDI values from 5.1 to 167.6, with a mean RDI of 38.9. However, due to one outlier in the severe OSA group, the distribution was skewed, resulting in a median RDI of 24.8. Thirteen patients were classified as mild OSA (RDI 5.1-20), four patients as moderate OSA (RDI 20.1-40), and eleven patients as severe OSA (RDI >40.1). The lowest oxygen saturation recorded was 58 percent in a patient in the severe OSA group. Arousal index ranged from 3.6 to 90.9 events per hour, with a mean of 34.8 events across both snorers and OSA patients. Arousal index correlated significantly with RDI (r = .86, p < .01).

By 24-hour dual sensor pH probe, 21 of the 37 patients (56.8 percent) were diagnosed with GERD using the criteria of >4 percent of total study time below pH 4 at the distal esophageal probe. For patients diagnosed with GERD, the mean number of esophageal episodes below pH 4 was 168.5 (range 51-355), the mean number of esophageal episodes below pH 4 occurring in the supine position was 45.1 (range 1-140), and the mean percent of study time below pH 4 was 10.9 percent (range 4.3-28.8 percent). Twenty-three patients (62.2 percent) were diagnosed with LPR by the criteria of seven or more LPR events per 24-hour study or an RAI greater than 6.3. For patients diagnosed with LPR, the mean number of pharyngeal episodes below pH 4 was 20.9 (range 3-61), the mean number of pharyngeal episodes below pH 4 occurring in the supine position was 3.2 (range 0-20), and the mean RAI was 81.2 (range 1.2-1438.9).

Mean score on the Epworth Sleepiness Scale was 12.1 out of 24, with a range of three to 22. Pearson correlation analyses indicated that there was no significant correlation between patient scores on the Epworth Sleepiness Scale and OSA severity, presence of GERD, or presence of LPR in this study. Scores on the 0-10 Snore scale ranged from 4 to 10, with a mean of 7.6 out of 10 possible points. Pearson correlation analyses did not identify a significant correlation between Snore ratings and OSA severity, presence of GERD, or presence of LPR. Finally, the mean score on the Reflux Symptom Index in this patient sample was 11 out of 27 possible points, with a range of one to 25. Again, there was no significant correlation between Reflux Symptom Index score and OSA severity, presence of GER, or presence of LPR by Pearson correlation analyses.

Conclusions: The authors found no significant difference in GERD symptoms between patients with OSA and those with simple snoring. Furthermore, the severity of OSA did not have a significant association with GER symptoms.

The authors did identify a high prevalence of both GER and LPR in patients undergoing evaluation for sleep disordered breathing. However, in the current study, no significant correlations existed between pH probe parameters and PSG parameters. Previous research has shown benefit in sleep measures following pharmacologic treatment for gastric acid reflux, and conversely, CPAP has provided subjective and objective improvement in measures of reflux. The increased incidence of GERD and LPR in the sample of SDB patients may only be viewed as a coexistence of these two entities at the current time, rather than a causative or interrelated association. Future investigations may reveal correlations between gastric acid reflux and SDB that have not yet been identified.