define thresholds of abnormality in children.
Arterial blood gas measurements while the in dividual is awake are usually normal, but
some individuals can have waking hypoxemia or  hypercapnia. This pattern should alert the
clinician to the possibility of coexisting lung disease or hypoventilation. Imaging procedures
may reveal narrowing of the u pper airway. Cardiac testing ma y show evidence of impaired
ventricular function. Individuals with severe no cturnal oxygen desaturation may also have el-
evated hemoglobin or hematocrit values. Vali dated sleep measures (e.g., multiple sleep la-
tency test [MSLT], maintenance of wake fulness test) may identify sleepiness.
Functional Consequences of 
Obstructive Sleep Apnea Hypopnea
More than 50% of individuals with moderate  to severe obstructive sleep apnea hypopnea
report symptoms of daytime sleepiness. A twof old increased risk of occupational accidents
has been reported in association with sympto ms of snoring and slee piness. Motor vehicle
crashes also have been reported to be as mu ch as sevenfold higher among individuals with
elevated apnea hypopnea index values. Clinicians should be cognizant of state govern-
ment requirements for reporting this disorder , especially in relati onship to commercial
drivers. Reduced scores on measures of health -related quality of life are common in individ-
uals with obstructive sleep apnea hypopnea, wi th the largest decrements observed in the
physical and vitality subscales.
Differential Diagnosis
Primary snoring and other sleep disorders. Individuals with obstructive sleep apnea
hypopnea must be differentiat ed from individuals with primary snoring (i.e., otherwise