Evaluation of obstructive sleep apnea: Considerations and caveats

The past quarter century has seen an evolution in the concept of sleep-disordered breathing. Before that time, the state-dependent (wake v sleep) nature of respiratory physiology and pathology was not recognized. The pickwickian, or obesity-hypoventilation, syndrome had been identified, but was not appreciated to be the waking consequence of sleep-altered respiration. Most sleep laboratories were research facilities, under the purview of psychologists and psychiatrists, focusing on sleep deprivation or dream (rapid eye movement [REM] sleep) research. Within 10 years of the initial description of obstructive sleep apnea in 1965, the development of clinical facilities for sleep disorders had begun. The prevalence of obstructive sleep apnea was a major impetus to the development of the clinical sleep disorders center. With the advent of a variety of surgical treatments for obstructive sleep apnea, otolaryngologists became an important part of the sleep disorders evaluation and treatment team. Initially, sleep-disordered breathing seemed simple: apnea was either obstructive or central in nature. However, as monitoring techniques became more sophisticated, and as more diverse patient populations were studied, it became apparent that pathologies of respiratory physiology during sleep were complicated phenomena requiring complex monitoring techniques interpreted by experienced clinicians. The intent of this article is to emphasize the spectrum of sleep-disordered breathing, pitfalls in monitoring techniques, and caveats in data interpretation. The fact that sleep-disordered breathing is diagnosable and treatable in the vast majority of cases, despite the devastating consequences before diagnosis and treatment, mandates awareness of the availability of sleep disorder centers staffed by experienced specialists.