Management

Acute onset of hypocarbia can cause cerebral vasoconstriction and though, in the past, there was a vogue for hyperventilating head injured patients so reducing CBF, the current practice is to maintain normal/low normal levels of PCO₂. This is because acute decline in CBF flow can cause symptoms of dizziness, mental confusion, syncope and seizures.

One positive of hypocarbia is the rise in PO₂ as oxygen replaces the CO₂ expired. This interrelationship is represented by the alveolar gas equation (AGE):

Where FiO₂ is the inspired oxygen concentration.

This principle is utilised by free divers who hyperventilate prior to their descent thus replacing the CO₂ with O₂ allowing more protracted breath holding.