A 45-year-old male patient is being transported by air after collapsing at a construction site on a hot day. Upon assessment, he is found to be disoriented, with a core temperature of 40.5°C (105°F), hot dry skin, and no sweating. What is the most immediate action you should take?
Monitor the patient's vital signs continuously.
Provide supplemental oxygen.
Administer IV fluids to prevent dehydration.
Start active cooling measures.