It has been a minute, y’all. I graduated medical school and moved to Chicago to begin Family Medicine residency! A blog post about this transition is incoming, but not too soon…so don’t hold your breath.
Speaking about breathing…
I recall a few things about the height of the pandemic, where worldwide tensions were high, and my last three brain cells were tripping over each other in the midst of generalized anxiety, excessive board exam review, and uninformed stock trading on Robinhood. I tuned into CNN, where Chris Cuomo would surface from his basement isolation lair during his early COVID infection, informing the world of his fevers and rigors. He would reference his pulse oximeter monitor—a recommendation from his personal doctor—and report despairingly about the hours of decreased oxygen saturation. As the virus stung the immune systems of the immunocompetents and the healthies (I’m making up new words here, deal with it.), thousands of people bought pulse oximeters, perhaps by their doctors’ recommendations or their own personal desires. Cough, cough, cough…Let’s clamp this onto my index finger…hmm 99%…Yeah I think that’s fine... You may have been fine, but looking back, I’m not so sure if these were fine recommendations.
Pulse oximetry is both interesting and important. I and most others would even characterize it as vital, making it quite fitting to be called a vital sign, alongside your heart rate, blood pressure, respiratory rate and temperature. We use pulse oximeters to assess for hypoxemia, which is a condition where there is not enough oxygen circulating in the blood. When there is not enough oxygen in the blood, we get concerned that your tissues and organs are not getting perfused well enough to perform their important functions, and even worse, these tissues can start failing. What leads to hypoxemia? Most likely, hypoxemia is caused by defects in your lungs to ventilate effectively—the oxygen from the outside world is just having a hard time making it into the blood because your lungs suck. Perhaps it’s an issue that attacks you pretty quickly, such as a pneumonia brewing up at the base of the lungs, or even a chronic issue such as Chronic Obstructive Pulmonary Disease, where the smallest performing sections of the lungs, called alveoli, are busted over several years of tobacco smoking.
Hypoxemia seems like a big deal, so why am I bewildered that doctors would recommend a pulse oximeter for patients dealing with a respiratory disease?
Pulse Oximetry is a number, not necessarily a representation of the overall clinical picture.
Anyone who has had formal medical training has heard the phrase “treat the patient, not the number.” At face value, the mantra gestures to trainees to not perseverate over a single abnormal lab value. Clinically, it helps inform the doctor that the post-surgical patient with the 150/95 blood pressure requires more effective pain medicine rather than an additional blood pressure medication.
When left to her own devices at home, Ashley (our token layperson) with a number shown on her digital pulse-ox sees a number and assumes her clinical picture. 95% blood saturation during an active COVID infection sounds pretty bad to her. It’s 11 at night. What is she to do?
This is just the beginning of the quandary. The COVID infection was the first time Ashley was wearing that pulse-ox. What is her baseline? Maybe Ashley has chronic obstructive sleep apnea and is de-conditioned. Perhaps 95% is her normal. Ashley doesn’t feel too terrible, but deoxygenated blood sounds pretty bad. Should she go to the ER?
You got supplemental oxygen?
Got milk? I don’t know about you, but I’m going to have to make some serious calls to secure a filled oxygen tank for home use. I’ll admit: I don’t have the street cred to buy myself an oxygen tank, but I will also raise the alarm and declare that Ashley certainly doesn’t have the street cred nor does she have a clue about the correct use of supplemental oxygen. I’m not trying to be demeaning here. Rather, I’m trying to synthesize the following points: if the true oxygen saturation was bad enough, Ashley would feel symptoms (shortness of breath, use of her accessory breathing muscles, blueness of her skin, altered mental status, etc) that would make it necessary for her to report to the ER. Thereafter, supplemental oxygen would be administered. Ashley can’t do this at home because the source of hypoxemia needs to be identified and improvement of her clinical status needs to be monitored. Even if Ashley finessed her way into obtaining supplemental oxygen at home and experienced amelioration of her symptoms, there is a chance that Ashley could over-do her oxygenation. It is well-researched that administration of oxygen decreases the body’s inherent drive to increase its ventilatory rate in the face of hypoxia.₁
A large, randomized controlled-trial supports my gripes
Listen, listen, listen. Hindsight is 20/20, right? Many experts in the beginning of the pandemic thought that pulse-ox monitoring was important because patients may experience drops in saturation right before they deteriorate. However, a large clinical trial out of the Perelman School of Medicine of the University of Pennsylvania found that the use of pulse-ox monitoring at home was not anymore effective than just calling the patients you were concerned about and asking them, “Hey Ashley, how are you feeling today? Are you short of breath?”₂
At the end of the day, I’m sure there are millions of worse ways to burn $20, but I am afraid that recommendations for the widespread use of pulse oximeters at home were poorly informed, as they lacked actionable plans for patients in the unmonitored, home settings.
Not medical advice.
Ezra Guttmann, DO
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