Clinicians providing conscious sedation should be cognizant of the possibility of OSA syndrome. The prevalence of OSA in patients presenting for surgery has been estimated at 1% to 9%, although it may be more common but undiagnosed in certain populations.2 Medications such as midazolam and fentanyl may provoke obstructive apneas or hypopneas. While central hypoventilation, or central apnea, is characterized by a decreased central effort to breathe, the hallmark of obstructive apnea is obstruction at the palato glossopharyngeal level. Often, the apneas can be mixed. Falling oximetry, continued effort to breathe, and paradoxical movements of the chest and abdomen after relatively modest doses of midazolam and fentanyl are suggestive of underlying OSA rather than aspiration pneumonitis, hemorrhagic shock, or sepsis.
2. Young T, Evans L, Finn L, Palta M. Estimation of the clinically diagnosed proportion of sleep apnea syndrome in middle-aged men and women. Sleep 1997;20:705–6
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