MSFinals-5806

A 50-year-old woman is brought to the Emergency Department after falling down the stairs at home. She complains of ‘rib pain’ and is moved to the resus room from triage, as she was unable to complete full sentences due to shortness of breath. Sats on room air were 92%. You are asked to see her urgently as the nursing staff are concerned about her deterioration.
On examination, she appears distressed; blood pressure is 85/45, heart rate 115 bpm, respiratory rate 38 and sats 87% on air. Her left chest does not appear to be moving very well, and there are no audible breath sounds on the left on auscultation.
What is the most appropriate next step in immediate management of this patient?