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Respiratory failure and non-invasive respiratory support during the covid-19 pandemic: an update for re-deployed hospital doctors and primary care physicians

BMJ 2020; 369 doi: https://doi.org/10.1136/bmj.m2446 (Published 30 June 2020) Cite this as: BMJ 2020;369:m2446

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Re: Respiratory failure and non-invasive respiratory support during the covid-19 pandemic: an update for re-deployed hospital doctors and primary care physicians

Dear Editor,
This is a very timely, well written and informative article on the use of oxygen which is applicable to many other conditions, not just covid. The infrographic is very helpful.

Two areas need clarification; firstly venous blood gases can be used to assess respiratory failure (this approach is already widely used in many hospitals). If an initial venous gas is not informative an arterial sample can still be taken: (https://thorax.bmj.com/content/71/3/210). This approach is easier, less painful and can be performed at the same time as routine bloods.

Secondly, there are two reasons that moving to high flow nasal oxygen or CPAP is important if a patient is still hypoxic. The first, positive end expiratory pressure, leading to alveolar recruitment, is covered. However the second, the need for increasing volumes of oxygen in patients with high inspiratory flow, which can lead to air entrainment and consequent reduced FiO2, is not.

This latter situation is more common in fit healthy people who can generate high inspiratory flows due to acute respiratory disease (eg pneumonia or Covid). In this case the flow of oxygen needs to increase. CPAP can also deliver high oxygen flow, depending on the device used.

Kind regards,

Competing interests: No competing interests

15 July 2020
dominick shaw
Professor
University of Nottingham
University of Nottingham