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Internal Medicine

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A 78-year-old man with known COPD (Global Initiative for Chronic Obstructive Lung Disease grade III, group D) is admitted with worsening dyspnoea and increased sputum volume and purulence for the past 3 days. He is fully conscious and not confused or agitated. His temperature is 37.8°C, SpO2 is 96%, he is tachycardic (110 beats per min) but normotensive, tachypnoeic with a respiratory

rate of 30 breaths per min, and there is widespread wheeze on auscultation. A chest radiograph shows hyperinflated lung fields but no new consolidation. Laboratory examination results include C-reactive protein 45 mg·L−1 and neutrophils 12×109 cells per L. Arterial blood gases on arrival are as follows: pH 7.28, PaCO2 76 mmHg, PaO2 122 mmHg and bicarbonate concentration 33 mmol·L−1


What is the most appropriate form of management?

  • 0%Endotracheal intubation and mechanical ventilation

  • 0%NIV

  • 0%High-flow nasal cannula oxygen therapy

  • 0%Optimal medical treatment and close monitoring


D B T
I K

@Everyone The arterial blood gases show acute hypercapnic respiratory acidaemia due to decompensated chronic type 2 respiratory failure. The high PaO2 suggests recent administration of oxygen with an unrestricted inspiratory oxygen fraction (FIO2), most probably by the emergency services prior to his arrival at hospital.


High levels of inspired oxygen can lead to hypercapnia due principally to ventilation–perfusion mismatching and loss of hypoxic pulmonary vasoconstriction. In this situation, initial management should be optimal medical therapy including controlled oxygen therapy to achieve a target saturation of 88–92%, bronchodilators and systemic corticosteroids. NIV should be started when pH <7.35 and PaCO2 >49 mmHg persist despite these measures and this should be assessed by repeat arterial blood gas estimation, typically after an interval of approximately 1 h.

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