A 58-year-old man presents to a rural emergency department with fever, rigors and confusion. He is hypotensive at 82/48 mmHg, heart rate 118/min, respiratory rate 28/min and oxygen saturation 93% on room air. His lactate is 4.5 mmol/L and you diagnose septic shock likely due to pneumonia. Retrieval to a tertiary centre will take several hours. According to the Australian Sepsis Clinical Care Standard and remote practice manuals, which action is the highest priority and should occur within the first hour after recognition?