- Ventilating too fast reduces blood flow to the brain.
As harmful as hypoxia is in TBI, hypocapnea from excessive ventilation is harmful as well. A higher respiratory rate decreases the amount of CO2 in the blood, which triggers cerebral vasoconstriction and less oxygen delivery. Hyperventilation of head injuries has been associated with poor outcomes.
When assisted ventilation is necessary in isolated head injuries, follow your local protocols regarding use of end-tidal CO2 (EtCO2) monitoring for a head-injured patient.
Shock from multisystem trauma can also cause a low EtCO2 reading, in which case it should not be used to guide ventilation. If capnography is not available, or if the patient may be in shock from other injuries, ventilate adults at 10 breaths per minute. There is one exception…