This week's question

A 25-year-old man is brought to the emergency department by paramedics after being pulled from a cold lake, where he had been submerged for approximately one minute following a fall from a boat. He was reportedly conscious on retrieval and has been breathing spontaneously throughout transport, though bystanders report a brief period of coughing and spluttering at the scene. On arrival he is alert and orientated with GCS 15. Observations are: temperature 35.6°C, heart rate 92 bpm, blood pressure 118/76 mmHg, respiratory rate 18/min, and SpO2 97% on room air. Chest auscultation is clear bilaterally, and there is no stridor, wheeze or accessory muscle use. He denies chest pain or dyspnoea and asks to go home. Which of the following represents the most appropriate next step in his management?