Obstructive sleep apnea (OSA), the repetitive collapse of posterior oropharynx during sleep resulting in hypoxia and/or arousals from sleep, is the most common form of sleep disordered breathing and a common chronic respiratory disorders among middle-aged adults. OSA can lead to significant health problems, such as worsened cardiometabolic disease and cognitive impairment, which can increase morbidity and mortality.1
The gold standard for OSA diagnosis is polysomnography (PSG), although home sleep studies can be performed for select patients. OSA diagnoses are based on the number of times per hour of sleep a patient’s airway narrows or collapses, reducing or stopping airflow, scored as hypopnea or apnea events, respectively. An Apnea-Hypopnea Index (AHI) score of 5 to 14 events/hour is considered mild OSA, 15 to 30 events/hour moderate OSA, and ≥ 30 events/hour severe OSA.2
Treatment commonly includes positive airway pressure (PAP) but more than one-half of patients are not adherent to continuous PAP (CPAP) treatment after about 90 days.3 Efficacy of treatments vary as a function of disease severity and etiology, which—in addition to the classic presentation of obesity with large neck/narrowupper airway—includes craniofacial abnormalities, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck.
Background
The American Academy of Sleep Medicine (AASM) estimates that 10% to 17% of adults in the United States have OSA.4 Compared with civilians, the military population generally is younger and healthier. Service members have access to regular health care with yearly physical examinations, exercise scheduled into the workday, and mandatory height/weight and fitness standards. Because obesity is a major risk factor for OSA, and the incidence of obesity is relatively low in the military population (estimated at 18.8% in 2021 vs 39.8% among all US adults aged 20 to 39 years), it might be expected that incidence of OSA would be correspondingly low.5,6 However, there is evidence of a rapidly increasing incidence of OSA in military populations. A 2021 study revealed that OSA incidence rates increased from 11 to 333 per 10,000 between 2005 and 2019 across all military branches and demographics, with the highest rate among Army personnel.7 An earlier study revealed a 600% increase in OSA incidence among Army personnel between 2003 and 2011.8
Several factors likely contributed to this increase, including expanding obesity and greater physician awareness and availability of sleep study centers. Rogers and colleagues found that 40% to 50% of incident OSA diagnoses among military personnel occur within 12 months of separation, suggesting that the secondary gains associated with military disability benefits might motivate OSA evaluation.9 It is possible that secondary gain is a factor because an OSA diagnosis can range from a 0% to 100% disability rating, depending on the severity.10 This disability claim is based on evidence that untreated OSA can negatively affect long-term health and mission readiness.8 For example, untreated OSA can lead to hypertension, which contributes to a long list of adverse health and wellness consequences. Most importantly for the military, OSA has been shown to increase daytime sleepiness and reduce cognitive performance.10
The current first-line treatment for OSA is CPAP, which improves symptoms of daytime sleepiness, hypertension management, and daytime alertness.11 Despite its efficacy, nonadherence rates range from 29% to 83%.12-15 Nonadherence factors include lifestyle changes, adverse effects (eg, nasal congestion), and lack of education on proper use.11 Lifestyle changes needed to increase the likelihood of successful therapy, such as regular sleep schedules and proper CPAP cleaning and maintenance, are difficult for military personnel because of the nature of continuous or sustained operations that might require shift work and/or around-the-clock (ie, 24-hour, 7 days a week) task performance. Traveling with CPAP is an added burden for service members deployed to combat operations (ie, added luggage, weight, maintenance). Although alternate treatments such as oral appliances (ie, custom dental devices) are available, they generally are less effective than CPAP.2 Oral appliances could be a reasonable alternative treatment for some patients who cannot manage their OSA with behavioral modifications and are intolerant or unable to effectively use CPAP. This could include patients in the military who are deployed to austere environments.
Surgically implanted hypoglossal nerve stimulator (HGNS) treatment may provide long-term health benefits to service members. After the device is implanted near the hypoglossal nerve, electrical stimulation causes the tongue to move forward, which opens the airway in the anteroposterior dimension. The most important consideration is the mechanism of airway collapse. HGNS is not effective for patients whose OSA events are caused by circumferential collapse of other airway muscles. The cause of airway collapse is ascertained before surgery with drug-induced sleep endoscopy, a procedure that allows visualization of conformational changes in the upper airway during OSA events.