Sleep Apnea, Central and Mixed

Incidence USA is 3–12% of middle-aged adults (which has increased fourfold in last 15 y, presumably due to increase in obesity). The M:F ratio is 2–2.5:1; obstructive or mixed.

Risk increases with male sex, upper middle age (55–64 y), obesity, and Hx of snoring with impaired daytime performance.

In elderly, risk is 2× higher for African Americans.

Increased risk of central and mixed (central and obstructive) apnea. In mixed SAS, obstructive apnea component can mask central apnea.

Risk for respiratory depression also in intubated, tracheotomized, and awake pts.

Increased risk with sedative-hypnotic narcotics, postop with any form of pain relief.

See medical records for previous problems.

Look for related medical disorders (e.g., cor pulmonale, cardiac arrhythmias, erythrocytosis, disordered cognition, daytime somnolence).

Apnea possible even several h postop, especially after epidural anesthesia.

When administering O ₂ , think of possible dependence of ventilation on hypoxic drive.

Central sleep apnea implies failure of respiratory rhythmogenesis. In SAS pts, at least 30 periods of apnea, defined as cessation of airflow for ≥10 sec, are found during normal nocturnal sleep.

Obstructive sleep apnea relates to a failed or inadequate respiratory activation of upper airway muscles, resulting in lack of airflow.

In central apnea, hypoventilation persists despite relief of obstruction.

Central apnea is unaccompanied by any respiratory effort, in contrast to obstructive sleep apnea.

Related to central alveolar hypoventilation syndrome, also known as Ondine curse.

Central: Familial basis is evident in some cases; possible relation to neurologic disorders (e.g., encephalitis in childhood, damaged respiratory centers, autonomic neuropathy in diabetes)

Mixed: Has obstructive component. Upper airway narrowing superimposed on coexistent abnormality of neurologic control or function of upper airway muscle tone or ventilatory control.

Associated with obesity and nasal obstruction (polyps, rhinitis, deviated septum, acromegaly, hypothyroidism, Htn).