Does Oxygen Addiction Exist?
Ok, I know, the joke’s on me. We’re ALL addicted to oxygen, after all it’s in 21% of the air we breathe (if this is not the case, please check your location, you may be on the wrong planet). We all need oxygen physiologically, but I’m talking about psychologically. There are those patients that know, I mean absolutely know, that oxygen seems to make their dyspnea better, even though a check of their pulse oximetry shows an oxygen saturation of one-hundred percent even when exercising. So back to my question, does this mean that they are psychologically addicted to oxygen, or does the supplemental oxygen actually fulfill an as yet unknown physiologic purpose?
Ever since two studies in the early 80’s (one which showed an overall increased survival with oxygen use, and another which showed a benefit with continuous oxygen over nocturnal use), supplemental use of oxygen for people with low oxygen levels has been considered standard of care. The current cutoff for an acceptable level of oxygen in a stable patient is, in general, eighty-nine percent (though there are always exceptions, let’s be clear, that I am talking about ambulatory oxygen in otherwise stable patients, and not about a hospitalized patient who is having a heart attack). For the most part, insurance companies will not pay for ambulatory oxygen therapy unless it is documented that their oxygen hits the magic number of 88, as we know that’s when the hemoglobin saturation curve starts to fall down a steep cliff. Or perhaps it’s because that’s when the Dr. Brown’s Delorean takes off. Either, one, I can’t quite remember.
Anyway, as I was saying, there is no known benefit to using oxygen when the measured levels are normal. And come to think of it, I don’t know of any data showing beneficial effects of its use in those with COPD whose oxygen saturation drops only with exertion (a common scenario where it is prescribed). Yet, many patient often insist on the continuation of oxygen even after it is explained that it is no longer medically necessary. To date I know of no study that shows beneficial effects of adding ambulatory oxygen to people with normal oxygen levels. One study compared forced air with oxygen in people with normal oxygen levels and found no reductions of subjective dysnea. Currently, the LOTT study is underway to see if ambulatory oxygen may be beneficial in patients with COPD and low-normal levels of oxygen. In addition, there are possible negative effects of oxygen, including the possibility of carbon dioxide retention, potential oxygen toxicity, and the hazards of transporting and storing the stuff. Not to mention the dangers of having inflammable substance being used by a smoker.
However, in my experience, patients who really feel that the oxygen is helping them with dyspnea do not care about these ideas, and are resentful about their physician talking about discontinuing it. Given that there is no data to continue the use of supplemental oxygen in those with normal oxygen levels, does their insistence in fact represent a form of addiction? I often see patients who refuse oxygen because of their misconception that their body will ‘get used to it’ and that they will not be able to get off of it. Thus far, I have brushed aside these concerns as there is no known physiologic basis for this. I wonder if perhaps I should consider the possiblity that their bodies might not get used to it, but their brains might.