Maintenance of wakefulness test in military personnel with upper airway resistance syndrome and mild to moderate obstructive sleep apnea.

BACKGROUND

Sleep-disordered breathing (SDB) and the associated symptom of excessive daytime sleepiness (EDS) in military personnel has influential consequences in both the garrison and the deployed environments. The maintenance of wakefulness test (MWT) is a daytime study used to evaluate the tendency to stay awake. We evaluated consecutive patients diagnosed with mild to moderate obstructive sleep apnea (OSA) and upper airway resistance syndrome (UARS) to provide an objective measure of their EDS using the MWT.

MATERIALS AND

METHODS

All military personnel referred between February 2004 and March 2005 with a clinical evaluation suspicious for SDB were evaluated with an overnight polysomnography (PSG). After overnight PSG, military personnel with mild to moderate OSA and UARS were evaluated with a 40-min protocol MWT. Abnormal MWT was defined as sleep onset latency mean below 19.4 min (<2 SD below the mean).

RESULTS

Sixty-two military personnel met entry criteria. Fifty-nine were men. Nineteen patients (32%) were diagnosed with UARS with a mean respiratory disturbance index of 11/h (5-20/h). Forty-one (68%) of the military personnel had OSA with a mean apnea-hypopnea index of 12/h (5-29/h). As a collective group, the mean Epworth Sleepiness Scale was elevated at 13/24 (1-24). This subjective excessive sleepiness was assessed with the MWT test, which resulted in a group mean MWT sleep onset latency of 27 min (5-40 min). Eighteen soldiers (30% of the total patients) had abnormal MWTs [six patients (33.3%) with UARS and 12 (67%) with OSA].

CONCLUSION

Military personnel with mild to moderate OSA and UARS often have abnormal MWTs and therefore have a pathological tendency to fall asleep. This EDS could pose a safety hazard in those personnel, military or civilian, who operate dangerous vehicles, machinery, or carry a firearm. Military personnel with untreated SDB are also at risk for the consequences of decreased mental alertness and decreased cognitive functioning due to daytime sleepiness.