Author: Mathew Alex / Editor: Thomas MacMahon / Reviewer: Jia Luen Goh / Code: PhC2, PhC4, PhP1, SLO1, SLO3 / Published: 03/01/2024

A 30-year-old man is rushed to your resuscitation area, having been found collapsed on the street one warm evening. He is confused and disorientated, with blue lips. His cardiovascular and respiratory examination is unremarkable, and his peripheries are warm.

His observations show a heart rate of 110/min, respiratory rate of 15/min with normal effort, oxygen saturations of 84% on room air, blood pressure of 122/74 mmHg. His oxygen saturations increase to 86% on 15L/O2 via a non-rebreather mask.