It is the summer season, and patients with signs and symptoms of heat-related illness present in the ED. Which patient needs attention first?

An elderly person complains of dizziness and syncope after standing in the sun for several hours to view a parade.

A marathon runner complains of severe leg cramps and nausea. Tachycardia, diaphoresis, pallor, and weakness are observed.

A previously healthy homemaker reports broken air conditioner for days. Tachypnea, hypotension, fatigue, and profuse diaphoresis are observed.

A homeless person, poor historian, presents with altered mental status, poor muscle coordination, and hot, dry, ashen skin. Duration of exposure is unknown.