A 59-year-old man with a urinary tract infection becomes increasingly unwell on the ward. He is febrile at 39.2 degrees Celsius, hypotensive at 85/50 mmHg and tachycardic at 125 per minute. Lactate is 4.0 mmol per litre and urine output has fallen. You suspect sepsis. According to UK practice, which immediate intervention is part of the Sepsis 6 bundle to be delivered within 1 hour?