An audit of hypoxaemia, hyperoxaemia, hypercapnia and acidosis in blood gas specimens

Abstract

To the Editors: The emergency management of hypoxaemic patients requires clinicians to avoid the hazard of dangerous hypoxaemia due to under-treatment with oxygen, whilst also avoiding the hazards of hypercapnic respiratory failure (iatrogenic hypercapnia) and oxygen toxicity, which may be caused by over-treatment with oxygen. In the past, many clinicians acted cautiously by giving high concentrations of oxygen to all potentially hypoxaemic patients and a culture evolved that “more is better”. However, since the 1960s, it has been known that some patient groups, particularly those with chronic obstructive pulmonary disease (COPD), are especially vulnerable to uncontrolled oxygen therapy and a recent randomised study showed that mortality in this patient group was doubled when high-concentration oxygen was used compared with controlled oxygen therapy [1–4]. It has also been demonstrated that hyperoxaemia is associated with increased mortality in patients with stroke, and in survivors of cardiac resuscitation and critically ill patients in the intensive care unit (ICU) [5–7]. The British Thoracic Society (BTS) guidelines for emergency oxygen use recommend a target oxygen saturation range of 94–98% for most emergency medical patients and a lower target range of 88–92% for those at risk of hypercapnic respiratory failure …