GERD occurs in up to 60% of OSA patients; comparatively, it occurs in only 20% of the general population. Several studies showed that OSA was more common in GERD patients than in the general population.
Several observations suggest close causative relationship between GERD and OSA. Nasal continuous positive airway pressure treatment for OSA improves the symptoms of GERD. Proton pump inhibitor treatment reduces the obstructive events and improves the apnea hypopnea index in OSA patients.
Several mechanisms have been suggested to explain why patients suffering from GERD develop OSA. The connection between the diaphragm and lower esophageal sphincter through the phrenoesophageal ligament is considered the mechanism of GERD in OSA patients.
Many patients with GERD have nocturnal re-flux symptoms, because sleep itself leads to proximal migration of gastric acid and aspiration into the tracheal-bronchial tree. The proximal migration of refluxed gastric contents and microaspiration of acid during sleep can cause inflammation and edema of the upper airway, as well as bronchoconstriction, thereby predisposing to OSA. The refluxed gastric acid in the distal esophagus in GERD also triggers a vagal reflex that can facilitate bronchospasm.
Nocturnal GERD is considered to have a greater risk for respiratory complications including OSA. According to previous studies, nocturnal symptoms of GERD are more common in patients with OSA and may be improved by treatment with nasal continuous positive airway pressure. A recent study also showed that having persistent nocturnal symptoms of GERD is linked to recent development of OSA symptoms.