Skip Pulse Oximetry in Bronchiolitis ?

Skip Pulse Oximetry in Bronchiolitis ?

An article was published in in the in the British Medical Journal on 8/16/2017 entitled “When technology creates uncertainty: pulse oximetry and overdiagnosis of hypoxaemia in bronchiolitis”.  This was not a study, but an editorial/opinion statement by the authors reviewing the current literature.  They believe that the overuse of pulse oximetry in bronchiolitis has led to poorer outcomes and increased healthcare costs.

What is Pulse Oximetry?

Pulse Oximetry is used medicine currently to measure the amount of oxygen in the blood.  It is accurate and non-invasive.  That means, you don’t need to get stuck with a needle to have it measured.  It is extremely useful.  People turn blue if their oxygen level drops far enough, but many factors affect the visibility of the blueness and you cannot reliably know a person’s oxygen level just by looking at their skin.  You can get a pulse oximeter off of eBay or Amazon for about $15.  I bought this one to have at home.  The device gives you the pulse rate and the percent oxygen saturation.  The numbers are different from oxygen tension and oxygen content.  You can measure the oxygen saturation one time, intermittently, or continuously.  If you look over the last link carefully, you will see how one, even a physician, might get confused interpreting the numbers.  A “normal” oxygen saturation is considered from 95 to 100%.  However, if you take frequent or continuous oxygen saturation measurements in normal people, you will find that the values can drift below the “normal” range under different conditions, even in the absence of disease or other problems.  This complicates the interpretation of the numbers and generates semantic confusion.

For example, if we connected you to continuous pulse oximeter for 24 hours, assuming you are healthy, the vast majority of the time you would have values between 95% and 100% saturation.  But during certain activities, like eating and sleeping, it might temporarily dip into the upper 80s “normally”.

Does the Overdiagnosis of Hypoxemia Lead to Increased Hospital Admission Rates?

Hypoxemia is a low level of oxygen in the blood.  Either oxygen saturation (pulse oximetry) or oxygen tension (blood gases/pO2) can be used as a proxy for oxygen content (the amount of oxygen in the blood).  The problem I have with the above premise is that it implies that one is automatically admitted to the hospital if hypoxemia is diagnosed.  To me, one must make a distinction between what is a statistical laboratory abnormality (hypoxemia/ anything under 95%), and the degree or threshold of the abnormality needed before hospital admission and/or oxygen treatment is necessary.  In an outpatient pediatric office setting, if a child presents with bronchiolitis,  we routinely measure the oxygen saturation.  If it is in the low 90s (which is abnormal, at least to our thinking), we don’t automatically admit the child.  There are numerous factors to consider, for example:

• Is the child eating
• Having persistent vomiting (unable to retain fluids and needs an IV)
• Other co-existing medical problems
• The child’s age (a young child, especially under 6 months of age or premature is at increased risk for apnea)
• Severe work of breathing (child may tire leading to respiratory failure)
• Parent’s ability to cope with their child’s illness

So, hypoxemia by itself (unless to a sufficient degree) should not be the trigger for admission.  The exact degree of hypoxemia in relation to all the other factors needs to be considered before that decision is made.

Is Bronchiolitis “Bad” ?

Bronchiolitis is extremely variable.  Many cases present like an ordinary “cold” / upper respiratory infection.  But it can be severe too, or any degree of severity in between.  You have to individualize each case.  They are not all the same.   Bronchiolitis is most commonly caused by RSV (Respiratory Syncytial Virus).

Protocol Variability:

There is considerable variability in how this condition is managed and the hospital admission criteria for it,  between and among Pediatricians, Family Practitioners, Emergency Room Doctors, and Urgent Care Doctors.  Over the last few years we have seen a shift of the care of patients first presenting to an ER or Urgent Care Center for this, instead of going to their primary doctor.  An ER doctor has ready access to order an RSV antigen test on nasal secretions from an infant or child.  The results can be made available during the visit.  Some ERs will reflexively diagnose bronchiolitis and admit a child to the hospital as a result.  This is not pulse oximetry’s fault or its overuse.  It is the improper use / interpretation of information.  If the same doctor decides to admit the child solely because he/she is hypoxemic with an oxygen saturation of 93%, it it the same kind of error.  Don’t blame the test.

Why should I be told I shouldn’t know the arterial oxygen saturation of my patient because some other doctors are misusing the results.  If my patient has an oxygen saturation of 85%, but I can’t see it on examination (in other words, his skin didn’t turn visibly blue), I want to know that.

Semantic Confusion:

The American Academy of Pediatrics has defined hypoxemia in the setting of bronchiolitis as an oxygen saturation of less than 90%.  I think this is the correct level to suggest the need for oxygen therapy.  What I object to is calling the saturations between 90 and 94% as normal.  I think it muddies the water in our thinking of the physiology of what is going on here.  Although I don’t feel it is always necessary to treat a child with oxygen if the saturation is 90%,  to call that normal risks the trap of believing it is normal (especially when training medical students  and nurses), which it isn’t.  Something is definitely wrong with the child, even if it doesn’t require oxygen treatment.

Is There Overtreatment of Bronchiolitis?

Sure there is.  But don’t put the blame on pulse oximetry.  Instead, put the blame on protocols and physicians that don’t use the information of the test appropriately.

Other Factors in “Overtreatment”

Sometimes, especially in borderline situations, a doctor will treat hypoxemia with oxygen, not because it is absolutely necessary, but to “justify” to the insurance companies the need for continued hospitalization.  These are times where the doctor believes the patient still needs to be in the hospital for monitoring or other reasons but is concerned the continued stay will otherwise be denied by the insurance company.  If the insurance company doesn’t pay, then the patient has to pay or the hospital doesn’t get  paid for the services provided.  To the extent this happens, it will appear as “overuse” or “unnecessary use” of resources upon review.

Again, this is not the fault of pulse oximetry, but instead the result of our fercockt health care system.