ABSTRACT
A 34-year-old patient, with a past history of intravenous drug abuse, presents with a 7-day history of progressive shortness of breath. On examination, he is pyrexial and has clear dyspnoea and tachycardia. His blood pressure is reduced at 90/60 mmHg. Oxygen saturation when breathing 40% oxygen is reduced at 86%, and he is sweating. His full blood count shows
