A 67-year-old man is admitted with community-acquired pneumonia. Two hours later, the nurse calls you because he looks more unwell. Observations: temperature 38.6°C, respiratory rate 28/min, oxygen saturation 92% on air, pulse 120 bpm, blood pressure 88/52 mmHg, new onset confusion. The nurse has correctly calculated his NEWS2 as 7. What is the single most appropriate immediate action?