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Is it time to change the approach to oxygen therapy in the breathless patient?
  1. Richard Beasley1,
  2. Sarah Aldington2,
  3. Geoffrey Robinson2
  1. 1Medical Research Institute of New Zealand, Wellington, New Zealand and University of Southampton, Southampton, UK
  2. 2Medical Research Institute of New Zealand, Wellington, New Zealand
  1. Correspondence to:
    Professor Richard Beasley
    Medical Research Institute of New Zealand, P O Box 10055, Wellington, New Zealand; Richard.Beasley{at}

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The need to highlight the risks of high flow oxygen in clinical teaching

In a recent commentary we argued that the traditional representation of the haemoglobin oxygen dissociation curve developed by physiologists may be disconcerting for clinicians because of the prominence of the steep slope of oxygen desaturation with falling oxygen tension.1 We proposed that a different alignment may be preferable for clinicians in demonstrating its beneficial characteristics, enhancing both the “pick up” of oxygen despite cardiorespiratory disease and the “drop off” of oxygen to the tissues despite falling oxygen saturation (fig 1). It was hoped that, through a different perspective of the haemoglobin oxygen dissociation curve, it might be possible to overcome the ingrained practice of doctors, nurses and paramedics to prescribe high flow oxygen to breathless patients who do not necessarily have arterial hypoxaemia.2–4 However, such a change of long established practice would also require a recognition of the risks of inappropriate high flow oxygen therapy.5,6

Figure 1

 Left: Traditional representation of the oxyhaemoglobin dissociation curve with the “slippery slope” (SS). Right: Oxyhaemoglobin dissociation curve realigned to demonstrate its two key characteristics: (a) haemoglobin maintains high levels of saturation despite marked reductions in oxygen tension, and (b) oxygen tension remains relatively stable as oxyhaemoglobin saturation declines. These characteristics result in (a) the pick up of oxygen by haemoglobin being maintained despite reduced oxygen tension, and (b) delivery of oxygen to the tissues being maintained despite progressively falling oxyhaemoglobin saturation. Figure reproduced with permission from Beasley et al.1

The potential adverse pulmonary effects of high flow oxygen therapy were recognised soon after its widespread use in clinical practice. High flow oxygen was shown to result in worsening ventilation-perfusion mismatch due to absorption atelectasis and inhibition of reflex pulmonary vasoconstriction.7,8 These effects may …

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