Sleep-Related Hypoventilation 387
Sleep-Related Hypoventilation
Diagnostic Criteria
A. Polysomnograpy demonstrates episodes of decreased respiration associated with el-
evated CO2 levels. ( Note:  In the absence of objective measurement of CO2, persistent
low levels of hemoglobin oxygen saturation unassociated with apneic/hypopneic
events may indicate hypoventilation.)
B. The disturbance is not better explained by another current sleep disorder.
Specify whether:
327.24 (G47.34) Idiopathic hypoventilation:  This subtype is not attributable to any
readily identified condition.
327.25 (G47.35) Congenital centr al alveolar hypoventilation:  This subtype is a rare
congenital disorder in which the individual typically presents in the perinatal period with
shallow breathing, or cyanosis and apnea during sleep.
327.26 (G47.36) Comorbid sleep -related hypoventilation: This subtype occurs as a
consequence of a medical condition, such as a pulmonary disorder (e.g., interstitial
lung disease, chronic obstructive pulmonary disease) or a neuromuscular or chest wall
disorder (e.g., muscular dystrophies, postpolio syndrome, cervical spinal cord injury,
kyphoscoliosis), or medications (e.g., benzodiazepines, opiates). It also occurs with
obesity (obesity hypoventilation disorder), where it reflects a combination of increased
work of breathing due to reduced chest wall compliance and ventilation-perfusion mis-
match and variably reduced ventilatory drive. Such individuals usually are character-
ized by body mass index of greater than 30 and hypercapnia during wakefulness (with
a pCO2 of greater than 45), without other evidence of hypoventilation.