Central Neurogenic Hyperventilation

True CNH is exceedingly rare; the exact incidence is unknown.

In pts with neurologic injury, it is most often associated with pulm dysfunction or shunting (aspiration, pneumonia, pulm edema, and baseline disease).

Primarily seen in comatose pts.

No association with age or gender.

A diagnosis of exclusion in neurologic disorders and in cases of hyperventilation; life-threatening causes of hyperventilation (hypoxemia, ischemic bowel, and acidosis) must be ruled out.

Primary diagnostic criteria are hyperventilation that persists during sleep; low PaCO ₂ , high PaO ₂ , and absence of drug or metastatic causes.

Associated primarily with brainstem inflammation and brainstem tumors with inconsistent involvement of midbrain, pons, and/or medulla.

CNS lymphomas and astrocytomas are the most common tumor types with gliomas, lymphomatoid granulomatosis, and medulloblastoma; also reported in metastatic tumors.

May result from seizure activity that stimulates the ventilatory response.

May be associated with acute intermittent porphyria.

Effects of GA unknown.