Unilateral pupillary dilation accompanied by a decreased level of consciousness may signify impending cerebral herniation; if these signs occur, take the following actions to decrease intracranial pressure:

- Administer 250 ml of 3 or 5% hypertonic saline IV/IO bolus.

OR

- Give 30 mL 23.4% hypertonic saline SLOW IV/IO push over 10 minutes followed by a saline flush. Repeat in 20 minutes if no response (max 2 doses). Monitor IV site and discontinue if signs of extravasation.
- Elevate the casualty’s head 30 degrees if patient is not in shock and tactically feasible.
- Hyperventilate the casualty.
- Hyperventilate at 20 breaths per minute.
- Capnography should be used to maintain the end-tidal CO2 between 32-38 mmHg.
- The highest oxygen concentration (FIO2) possible should be used for hyperventilation.
- Do not hyperventilate the casualty unless signs of impending herniation are present. Casualties may be hyperventilated with oxygen using the bag-valve-mask technique.