Case summary

A 75-year-old woman was admitted from a routine orthopaedic outpatient clinic to the emergency department with severe hypoxia. She had recently undergone a right elbow replacement (approximately 2 weeks previously), having sustained a displaced supracondylar fracture of the distal humerus following a fall. Her previous medical history included asthma, hypertension, cervical spondylosis and long-standing large but stable left-sided diaphragmatic (hiatus) hernia (figure 1A). There was no evidence of prior smoking history, chronic obstructive pulmonary disease, or obesity. On initial assessment, she appeared in extremis with marked respiratory (though not haemodynamic) compromise, distended abdomen and reduced chest expansion with audible high-pitched bowel sounds throughout the left lung field. Arterial blood gas analysis (performed on 15 L non-rebreathe mask) revealed significant decompensated hypercapnic respiratory failure (pH 7.27, pCO₂ 13.1 kPa, pO₂ 13.2 kPa) with associated hypokalaemia (K⁺ 1.9 mmol/L) but normal lactate (1.0 mmol/L). Urgent chest radiography showed extensive …