Hypercapnia-induced cerebral oedema in a patient with COPD exacerbation: a rare and under-recognised entity.

Chaudhary S, et al. BMJ Case Rep 2017. doi:10.1136/bcr-2017-221568 Description A 56-year-old Caucasian woman with severe chronic obstructive pulmonary disease (COPD) on home oxygen presented with a severe exacerbation. Vitals included a blood pressure of 111/73 mm Hg, a pulse of 102/minute, respiratory rate of 13/minute and O2 saturation of 84% on oxygen of 2–3 L/minute by nasal cannula. She was lethargic, confused and was wheezing. She was placed on bi-level positive airway pressure (BiPAP) but her mentation continued to deteriorate. White cell counts were normal. Chest X-ray showed hyperinflated lungs but no infiltrates. Arterial blood gases revealed severe hypercapnic respiratory acidosis with a pH of 7.26, pCO2 of 100.1 mm Hg, pO2 of 187 mm Hg and bicarbonate of 47 mmol/L. In spite of BiPAP, her acidosis worsened with a pCO2 of 131 mm Hg. She was intubated for acute hypercapnic respiratory failure. Although her deteriorating mentation correlated with CO2 narcosis, it was judicious to perform neuroimaging like cerebral CT to rule out other causes of acute mental decompensation, particularly cerebrovascular accidents. Given this context, a CT of the head without contrast was performed which was negative for haemorrhage or ischaemia but revealed effacement of sulci, hypodense white matter, and vastly decreased size of lateral ventricles and basal cisterns consistent with cerebral oedema