Sleep Apnea Associated with Stomach Acid Backflow into Throat
15-Sep-2004 12:30 PM EDT
Newswise — Medical researchers have long suspected a relationship between gastro-esophageal reflux disease (GERD) and obstructive sleep apnea (OSA), two medical conditions which can have a deleterious effect on a patient's quality of life. Now, a team of Canadian researchers has determined that there are significant relationships between laryngopharyngeal reflux (LPR), OSA, and upper airway sensory impairment.
Laryngopharyngeal reflux, or LPR, is the backflow of stomach contents up the esophagus and into the upper airway, whereas GERD includes backflow only into the esophagus. The refluxed stomach contents (refluxate) are primarily composed of acid and activated pepsin, a proteolytic enzyme needed to digest food in the stomach. The damage from this disorder can be extensive. Symptoms of laryngopharyngeal reflux include altered voice, throat clearing, vocal fatigue, and cough, and have been linked to more substantial illnesses including laryngospasm , tightening of the larynx, and glottic carcinoma. This disorder is common in the North American adult population, estimated to affect up to 35 percent of the population 40 years or older.
Obstructive sleep apnea (OSA) affects 4-9 percent of males and 1-4 percent of females in the general population. The authors of this study have identified airway inflammation, a mucosal sensory impairment in the oropharynx (pharynx posterior to the mouth), velopharynx (soft palate), and larynx (voice box) of OSA patients, using endoscopic sensory testing. Correlations between the level of laryngeal sensory impairment and apnea severity strongly suggest that this sensory impairment plays a role in the functioning of OSA.
While previous studies have shown that GERD is prevalent among patients with OSA, the authors of this study are unaware of previous evaluation of LPR in this patient population. Accordingly, otolaryngologists from several hospitals in Montreal hypothesized that LPR is prevalent among OSA patients, and that this contributes to impaired laryngeal sensation, which in turn may contribute to the pathophysiology of OSA.
A new study evaluates the prevalence of LPR in consecutive patients with OSA using the reflux finding score and assesses the relationships between the finding of LPR and the severity of both upper airway sensory impairment and OSA. The authors of "Laryngopharyngeal Reflux, Upper Airway Sensory Impairment, and Obstructive Sleep Apnea," all from Montreal, Canada, are Richard J. Payne MD, and Saul Frenkiel MD FRCS, from the Jewish General Hospital, McGill University, Montreal; Karen M. Kost MD FRCS, and Anthony G. Zeitouni MD FRCS, at the Royal Victoria Hospital, McGill University; George Sejean MD FRCS, with St. Mary's Hospital; Dr. Robert C. Sweet FRCS, affiliated with Montreal General Hospital, McGill University; and Naftaly Naor, Lourdes Hernandez MD, and R. John Kimoff MD FRCP, McGill University Health Centre. Their findings are being presented at the American Academy of Otolaryngology-Head and Neck Surgery Foundation Annual Meeting & OTO EXPO, being held September 19-22, 2004, at the Jacob K. Javits Convention Center, New York City, NY.
Methodology: This was a prospective, blinded study of 34 patients who underwent overnight diagnostic polysomnography (PSG), a sleep study, and upper airway endoscopy during the daytime for purposes of sensory testing (EST) and assessment of LPR using the reflex finding score (RFS).
A diagnosis of subject OSA was made on the basis of an AHI value â‰¥15 events per hour. Other measures of OSA severity included measures of sleep disruption (microarousal index), mean apnea and hypopnea duration, mean SaO2 during sleep, time spent <90 percent hypoxia and lowest point of hypoxia during sleep. The laryngopharyngeal reflux assessment entailed videotaping the EST. Two investigators independently determined the RFS for each subject. The mean RFS score for the subject was then calculated. A mean value for RFS > 7 confirmed a diagnosis of LPR.
Results: There were 26 males and eight females enrolled in the study. For the group overall, the mean age was 43.9 Â± 2.4 (SE) years and the mean body mass index was 26.5 Â± 0.8 kg/m2. The corresponding data for the 29 subjects with OSA were 45.4 Â± 2.3 years and 27.2 Â± 0.8 kg/m2. Key findings included:
"¢ Sleep Study findings: A majority (29/34) were found to have an AHI â‰¥ 15 events per hour indicating that 85 percent of the subjects had OSA. "¢ Laryngopharyngeal reflux assessment findings: Of the 34 subjects, 30 were found to have a mean RFS > 7, yielding an 88 percent prevalence of LPR in this subject group. The prevalence of LPR in subjects with OSA was 93 percent (26/28). "¢ Relationships between LPR, apnea severity, and upper airway sensory function: For patients with OSA, there was a significant correlation between the severity of LPR and OSA. There was also a slightly weaker but still significant correlation between RFS scores and the nadir hypoxia for the night. These findings therefore point to a strong relationship between LPR as reflected in the RFS score and apnea severity.
Conclusions: In this study, a validated endoscopic scoring algorithm assessed LPR among patients with obstructive sleep apnea and found a dramatically higher prevalence (93 percent) for LPR than that reported for the general population. Furthermore, the severity of LPR, as reflected by RFS values correlated significantly with several key measures of apnea severity, pointed to an important interaction between these two disorders. The authors confirmed that LPR severity correlated with laryngeal sensory dysfunction, but not oropharyngeal or velopharyngeal (soft palate) sensory impairment (not previously evaluated). Previous observations that laryngeal, but not oropharyngeal or velopharyngeal sensory dysfunction correlates with apnea severity were also confirmed.
Note: The American Academy of Otolaryngology—Head and Neck Surgery (AAO-HNS) represents the nation's 11,000 otolaryngologist—head and neck surgeons. These specialists diagnose and treat disorders of the ear, nose, and throat and related structures of the head and neck. Learn more about the specialty and otolaryngic disorders at the AAO-HNS Internet web site, http://www.entnet.org.