Oxygen used to be considered useful, or at least harmless, for any of the following situations, despite lack of evidence it does any good:
- Emergency departments
- Post-anasthesia care units
- Conscious sedation
- Chest pain
- Shortness of breath
- Critical Care Units
ACLS used to recommend 2-4lpm by nasal cannula for chest pain. The idea here is that if a low flow of oxygen to the heart is causing the chest pain, the oxygen "might" help.
However, there was never any science to show this. Plus, it makes no sense, because if you are getting an SpO2 reading of 98%, then you know the heart has an ample amount of oxygen. If it's not getting enough oxygen it's because of a blockage in the coronary arteries, not the supply of oxygen to the heart.
ACLS currently recommends oxygen only if the SpO2 is less than 94%. This makes much more sense to me.
Plus, most hospital-wide oxygenation protocols call for an SpO2 of 90-94%, and even 88% is often acceptable. This makes sense particularly if you look at the deoxyhemoglobin curve.
One of the main reasons why it's important not to oxygenate until the SpO2 decreases is that the use of supplemental may mask that an underlying problem may be occurring.
A patient may have decreased ventilations, but this will not be recognized because the SpO2 is already artificially maintained with supplemental oxygen. When such a patient is not on oxygen, a dip in SpO2 would be noticed at a routine check, and oxygen could be administered at this time, with appropriate measures being taken to recognize and resolve the underlying cause.
The new policies make sense, especially when you consider that oxygen is a drug with side effects and an expense. To oxygenate based on a myth that it will help but won't hurt is not good medicine.
- Blakeman, Thomas C., "Evidence for Oxygen in the Hospitalized Patient: Is more Really the Enemy of Good," Respiratory Care, October, 2013, volume 58, number 10, pages 1679-1693
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