Respiration and acid-base balance of blood after diffuse experimental brain injury.

Diffuse brain injury in rabbits was caused by injecting olive oil and saline into one internal carotid artery. In this report, the fourth of a series, the effects of this experimental brain injury on respiration and acid-base balance of blood are analyzed. The animals that withstood the injury best were those that had a lower pre-traumatic pCO2; the animals that suffered a rise in intracranial pressure and succumbed to the injury quickly did so in spite of pronounced hyperventilation after the injury. Arterial pCO2 immediately before the injury was the only significant prognostic factor in this analysis. Respiratory rate only dropped immediately before respiratory arrest and death. The findings concerning pCO2 tally with results after experimental ligation of a cerebral artery, but less so with results after other types of experimental brain injury. This emphasizes again that conclusions drawn from one type of brain injury must not be extrapolated to other types.