McMillen: It’s crucial we know when to head for ER

Submitted photo ##
Most pharmacies carry inexpensive oximeters like this one.
Submitted photo ## Most pharmacies carry inexpensive oximeters like this one.

How sick am I? 

With the case of the coronavirus, that’s crucial to know. It’s the only way to keep our health care system from being swamped by patients who don’t actually require hospitalization.

Fortunately, there is a cheap, simple and accurate self-help tool widely available to the home user — the oximeter. You can pick one up for less than $40 through pharmacies, online vendors and big box stores.  

The most urgent practical issue we’re facing is that mortality in all three age clusters — 20 to 40, 40 to 60 and over 60 —  increases almost 10-fold when the healthcare system becomes overwhelmed. So, in addition to spreading out the curve through social distancing, droplet prevention and handwashing, one other action is of great importance — going to the hospital only when you’ve become severely ill.

Self-treatment recommendations essentially boil down to: If you begin suffering fever and respiratory symptoms, stay home taking Tylenol and fluids unless the illness becomes severe.

This is not terribly helpful advice in some respects. As a patient on the first day of an influenza infection, or even a bad head cold, I feel pretty sick. So do most others, I imagine.

So how does someone who doesn’t have my 17 years of medical education and 37 years of practice experience know whether he’s just flu-sick or facing an impending critical illness?

In critical care education and training, we refer to the thresholds that define that decision as “sentinel events.” Increased respiratory rate (normally running 14 to 24), mental status change or confusion, and metabolic acidosis (requiring a laboratory test) are very useful predictors of worsening sepsis, raising the risk of multiple organ failure.

A patient with a respiratory rate of 30 is far more likely to be deteriorating, thus becoming critically ill, than a patient with a respiratory rate of 20. Mental status change is an admittedly vague term, but reflects worsening of an illness so impending organ failure is actually changing the brain’s neurotransmitters.

Increased respiratory rate is called “tachypnea.” It can stem from the accumulation of fluid in the lungs, making faster breathing necessary to compensate for less-efficient exchange of carbon dioxide for oxygen. It can also stem from the need to blow off carbon dioxide to compensate for the onset of metabolic acidosis, which occurs when the body’s cells are failing to get enough oxygen or to function properly at the most fundamental level. And metabolic acidosis triggers respiratory alkalosis in turn.

For nearly 20 years, small portable finger oximeters have been available at pharmacies and big box retailers such as Walmart for $20 to $40. These days, they are also available through online retailers such as Amazon.

The oximeter is an adaptation of technology used in operating rooms and intensive care units for nearly 40 years.

These little clothespin-like devices beam a light of specific wavelength through one’s finger. If the oxygen-carrying hemoglobin protein in your bloodstream is fully saturated, the wavelength of the light changes and the sensor on the other side of the finger will read “99%.” 

For most things in life, 90% is a pretty good number. But a finger oximetry reading of 90% correlates with blood oxygen in the low 60s. And that’s a sign of really big trouble.

The sensor also reads your heart rate. A rate of 60 to 100 is normal, but something on the high side isn’t uncommon in the first day or two of a viral illness.

You want to drink fluids to stay hydrated, but not overdo it. You want to control your temperature with Tylenol or some other  acetaminophen formulation.

As respiratory infections worsen, fluid accumulates in the spaces in the lung between where the air goes in and out (the alveoli), and where the blood passes through capillaries to pick up oxygen. So if someone with an illness is breathing faster and faster to keep their oxygen saturation above 90%, they are probably deteriorating

As oxygenation becomes worse, patients may have difficulty speaking a sentence without taking a breath. They need to head to the emergency room.

For most of my career, medical practice has focused on the sickest of the sick in the intensive care unit. But I do continue to follow my patients after they recover and are discharged.

I have found finger oximetry to be a very useful tool in advising viral respiratory patients over the phone whether they need to come in or not. I believe greater use of finger oximetry by the general public in the next few months, with backup communication with caregivers by phone, e-mail or text message, would be helpful in keeping the worried-but-stable sick at home so hospitals can treat those with critical needs.

Why so mild in some, so virulent in others?

Despite years of participating in the Society of Critical Care Medicine’s education and information meetings, and 37 years in the practice of critical care, I am confused about coronavirus. Given the flux of the current pandemic, my opinions change daily.

Given my own uncertainty, it doesn’t surprise me that patients are so confused and therefore anxious. Fortunately, the scientific and medical community is doing an extraordinary job of informing both the public and health care professionals as information evolves, and is getting phenomenal assistance from print, online and video media.

We know the coronavirus is small and “novel,” that it is unlike any prior viral infection seen in humans. That means we have little protection against it from prior infections, which is the basis of immunization. And it’s one of the reasons coronavirus is so contagious and morbid.

It’s an RNA virus, not a DNA virus, and much of our current antiviral pharmacology targets DNA viruses. However, several drugs with potentially positive pharmacology rationales are being tested in a very rapid way, and information is being exchanged globally.

The biggest question before us is, “Why is this virus so virulent in some young, healthy patients and fairly mild in others?” This question has been a fixture of public health discussions ever since the 1918-20 Spanish flu pandemic, which proved fatal to many young, previously healthy patients.

Is it protein on the virus surface, the way the virus inserts itself into a healthy respiratory cell, the body’s immune response to the viral infection, an over-response triggering cytokine release syndrome or reactivation of some other illness or virus such as cytomegalovirus?
Unfortunately, we still have no answer.

Dr. Marvin A. McMillen serves as chief of perioperative care at a community teaching hospital in Western Massachusetts. He is both a researcher and board-certified practitioner in internal medicine, surgery and critical care. He is married to Victoria Bergreen of McMinnville.


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