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Wednesday, June 27, 2012

Pulm. fibrosis patients can tolerate low PO2s

So recently we had an end stage pulmonary fibrosis patient in respiratory distress and with an SpO2 of 77.  The blood gas revealed a PO2 of 47, and it was determined by the respiratory therapist that this patient needed oxygen or she was going to die.

Her doctor wrote an order to never exceed 4lpm by nasal cannula.  This meant that my hands were tied, and there was nothing I could do without calling the doctor.  So I did, and he said, "Draw an ABG and call me with the results."

It should be noted here the patient was a DNR patient and was a hospice patient.  Yet by no means are those abbreviations indications for not treating the patient. 

So I called the doctor back with the results, and he said, "Good.  I'm satisfied with those numbers."

Why was he satisfied with these numbers?  Every ounce of common wisdom in my head told me this patient needed oxygen.  My coworkers thought the same. 

 An RT student of mine took up the task of writing a report on this patient.  She discussed it with her RT teacher, who said, "So if a hospice patient had a pillow over his head, does that mean you don't make an effort to remove the pillow?"

The student later approached the patient's doctor to get an explaination of why he decided a PO2 of 77 was adequate for this patient.

The doctor said, "We are not trying to cure the patient.  We just want to make her comfortable."

To me that was an unsatisfactory answer.  It reminded me once again of the pillow analogy.  Yet I explained to the student that in medicine there are usually more than one option for one situation, and in many cases both options are correct.  The doctor is not necessarily wrong here, it's more that we RTs would give her oxygen.

My initial thought was he didn't want to oxygenate because the patient smoked 30 years ago.  I thought perhaps he was afraid more oxygen would cause her to stop breathing.  Yet during previous visits she was on an NRB for several days and never stopped breathing. 

So I discussed this with the sagatious Jane Sage.  She provides us with the following explaination for the doctor's behavior:

Most people with end stage pulmonary fibrosis are used to a low oxygen level.  In fact, it may surprise you to learn that pulmonary fibrosis is not an oxygenation problem.  Most of these patients are used to running around with PO2s in the 40s and even 30s.  Their oxygen levels dropped gradually so such PO2s are normal for them.  If you or me had a PO2 that low we'd be in severe respiratory distress.

Yet since their PO2 levels dropped so gradually, their bodies produced lots of extra red blood cells to search for more oxygen.  So checking a sat on these patients isn't even going to do any good.  With so many RBCs, there's going to be many hemoglobin molecules that are not carrying an oxygen molecule.  It will be normal for an SpO2 to be in the 80s, or even 70s.  That's nothing to panic about with these patients.

Yes oxygen might make these patients more comfortable, and personally I'd oxygenate this patient.  I hope this helps.  Jane Sage.

Thanks Jane.  Once again we appreciate your wisdom.


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