Oxygen and inhalers

doi:10.1136/bmj.333.7557.34

BMJ 2006;333:34-36 (1 July), doi:10.1136/bmj.333.7557.34

Practice

ABC of chronic obstructive pulmonary disease

Oxygen and inhalers

Graeme P Currie, specialist registrar, J Graham Douglas, consultant

Respiratory Unit, Aberdeen Royal Infirmary, Aberdeen.

The first 150 words of the full text of this article appear below.

Oxygen

Administering oxygen for chronic obstructive pulmonary disease(COPD) is not without risk and it should be properly prescribed—interms of flow rate and mode of delivery—like any otherdrug. Giving high concentrations of oxygen to hypoxaemic patientswith hypercapnia can result in individuals losing their hypoxicdrive to breathe, with development of CO₂ retention, respiratoryacidosis, and even death.

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The oxyhaemoglobin dissociation curve showing the relation between partial pressure of oxygen and haemoglobin saturation

However, in acute and chronic ventilatory failure, oxygen supplementationis essential to maintain adequate delivery of oxyhaemoglobinto organs such as the heart, kidneys, and brain. Many patientswho are chronically hypoxic are able to cope satisfactorilywith an oxygen saturation of arterial blood of around 90%. However,at saturations below this, the oxygen dissociation curve rapidlysteepens, and a sharp fall in oxygenated haemoglobin occurswith reduction in oxygen supply to vital organs.