Excessive Daytime Sleepiness in Chronic Obstructive Pulmonary Disease
The common occurrence of excessive daytime sleepiness (EDS) in patients with obstructive sleep apnea remains perhaps the most enigmatic aspect of what has been called the obstructive sleep apnea syndrome (OSAS). Initial speculation related EDS to the most obvious cause, ie, sleep deprivation, since it had been noted that these patients have numerous arousals from sleep secondary to obstructive apneic events. In a subsequent study from our laboratory, it was found that patients with equivalent sleep disruption (matched on the basis of the number of upper airway obstructions per unit time) had markedly different subjective complaints of EDS. This study documented the fact that patients with complaints of EDS had a significantly greater degree of nocturnal oxyhemoglobin desaturation than those who were without subjective daytime sleepiness.
Since patients with chronic obstructive pulmonary disease (COPD) are known to have chronic daytime and nocturnal hypoxemia, and poor nocturnal sleep, they would appear to be a population of considerable interest in assessing a relationship between hypoxemia and daytime sleepiness. Furthermore, Calverley and colleagues have shown that oxygen administration during sleep to patients with COPD improves their nocturnal oxygenation and their sleep pattern. Clinically, patients with COPD do not appear to have the degree of daytime sleepiness commonly exhibited by patients with OS AS, despite the presence of chronic hypoxemia. The present study addresses the issue of the relationship between daytime sleepiness and chronic hypoxemia by evaluating overnight sleep/ respiratory patterns and objective daytime sleepiness via the multiple sleep latency test (MSLT) in COPD patients with chronic hypoxemia.
cialis professional online