In the initial head injury ventilator settings, what was the tidal volume used?

• A. 750 mL
• B. 500 mL
• C. 600 mL
• D. 1000 mL

Answer: (A)

In head injury, keeping arterial CO2 in the normal range is crucial because it directly affects cerebral blood flow and intracranial pressure. The initial ventilator setting uses a tidal volume that delivers enough air per predicted body weight to ensure adequate CO2 elimination, but without causing lung injury from overdistension. This moderate, per-weight approach prevents CO2 buildup that could raise ICP, while avoiding volutrauma from excessively large breaths. If the tidal volume were too small, CO2 would accumulate and ICP could rise; if it were too large, the risk of lung injury and other lung mechanics issues increases, which can complicate the patient’s overall condition.