I am no expert on oxygen therapy (we do have a resident expert who I hope will chime in), however the science of o2 therapy is not exact and in fact we still do not know what the best practices are for some situations (oxygen can be harmful)
I think it is safe to say that oxygen therapy should be guided by the clinical condition of your patient and pulse oximetry. A patient with chest pain with no dyspnea and a normal spO2 probably does not need 15 liters.
This big paper from the British Thoracic Societyhttp://www.brit-thoracic.org.uk/Por...Emergency oxygen guideline/THX-63-Suppl_6.pdf (click for the PDF) on pg. 22, 26-27 does list the consequences of hyperoxemia.
The old "too much of anything" whodathunkit is probably a good one here (as with anything really); I know it's not randomized, double-blind prospective or peer reviewed in nature but I thought it'd put it in there.
In 2007 we made a change (I don't know what it was previously) and now basically it goes like this
- not everybody gets oxygen and we only give oxygen if the patient as an abnormal airway, shock, chest pain or SPO2 <95% on air (except COAD)
- 2-4lpm on a NC or 4-6lpm on a simple face mask should be fine for everybody except NRBs or nebulizer masks (8lpm) and BVMs (10lpm)
I mean in reality I think we confuse oxygenation and ventilation or rely too much on pulse oximetery or confuse hypercarbia and hyperoxemia/hyperventilation which are all very different concepts and I wouldn't trust SPO2 totally just like I don't trust somebody who has no other S&S but whos ECG says the printer says has an MI.
In reality however I would also plug that there is a psychologycal benefit of non-medically indicated oxygen at very low rates (say 1-2lpm max on a nasal cannula) for select patients; e.g. the elderly. I've found a litre of oxygen on a cannula can do wonders for nana and the family who all want us to "do something".