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pulse oximeter for health monitoring?

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SiliconWizard:

--- Quote from: JBeale on March 29, 2020, 08:52:44 pm ---The question I had in mind, is whether periodic measurements from a cheap pulse oximeter can be used to detect reduced pulmonary function, for example, due to viral inflammation, before things get critical.  Eg. could you use it in the same way people use a fever thermometer. to check for indications of possible disease.  Esp. if you suspect the condition you're trying to detect does not always cause a fever.

--- End quote ---

As you figured, those cheap sensors are not that accurate to begin with.

But even with the kind of sensors used for medical monitoring, the moment SpO2 falls below a threshold which is a hazard, the time left to act is very short.
During surgeries or for patients in ICU, when the SpO2 is at an alert level, there's only a VERY short time to act before there could be irreversible damages...

Conversely, monitoring the SpO2 just to figure out if someone isn't breathing right, or is in short apnea (as you tested), but not in any critical condition, just doesn't really work in the general case. Just as you saw with your limited experimenting, it varies a lot depending on each individual and exact condition.

A related idea would be to use pulse oximetry to monitor sleep apnea, but it doesn't really work. Monitoring inhaled air pressure is still much more effective for that.

alanambrose:
Well I thought too that the £20/$25 pulse oximeters must be cheap-ass inaccurate consumer stuff.

But actually I compared my non-name consumer one against a Nonin professional device:

https://www.nonin.com/products/8500/

... and they essentially came up with the same numbers. Sometimes you can be pleasantly surprised...

So, I'm happy to use it to help monitor my asthma and potentially the breathing impacts from the virus. I'm using >94% normal; <90% be concerned - and I'm expecting to be feeling quite short of breath in the latter case.

Alan

taydin:
I think just looking at the oxygen concentration would be incomplete. The pulse is also very important. It could be that the lungs starting to fail, but the heart is compensating by pumping more blood and further stressing the lungs. If this scenario, the oxygen concentration would be fine, but at what cost? At the cost of stressing the heart and the lungs.

JBeale:
It is my understanding the weight of opinion in this thread has been that pulse oximeter monitors are not useful for early detection of COVID-19.

There is an article in yesterday's NY Times by Dr. Richard Levitan, who has been practicing emergency medicine for 30 years, and teaching airway procedure for 20 years.
Based on his experience after 10 days in Bellevue (NYC) treating COVID-19 patients, he observes this disease behaves in unusual, if not unprecedented ways.
Notably, he found patients can have low SpO2 readings without realizing it; something not normally true. Accordingly, he has a different opinion about pulse oximeters. 


--- Quote from: https://www.nytimes.com/2020/04/20/opinion/coronavirus-testing-pneumonia.html ---Even patients without respiratory complaints had Covid pneumonia. The patient stabbed in the shoulder, whom we X-rayed because we worried he had a collapsed lung, actually had Covid pneumonia. In patients on whom we did CT scans because they were injured in falls, we coincidentally found Covid pneumonia. Elderly patients who had passed out for unknown reasons and a number of diabetic patients were found to have it.

And here is what really surprised us: These patients did not report any sensation of breathing problems, even though their chest X-rays showed diffuse pneumonia and their oxygen was below normal. How could this be?

We are just beginning to recognize that Covid pneumonia initially causes a form of oxygen deprivation we call “silent hypoxia” — “silent” because of its insidious, hard-to-detect nature.

... Patients requiring intubation because of acute hypoxia are often unconscious or using every muscle they can to take a breath. They are in extreme duress. Covid pneumonia cases are very different.

A vast majority of Covid pneumonia patients I met had remarkably low oxygen saturations at triage — seemingly incompatible with life — but they were using their cellphones as we put them on monitors. Although breathing fast, they had relatively minimal apparent distress, despite dangerously low oxygen levels and terrible pneumonia on chest X-rays.

--- End quote ---

trophosphere:

--- Quote from: JBeale on April 21, 2020, 06:54:42 pm ---It is my understanding the weight of opinion in this thread has been that pulse oximeter monitors are not useful for early detection of COVID-19.

There is an article in yesterday's NY Times by Dr. Richard Levitan, who has been practicing emergency medicine for 30 years, and teaching airway procedure for 20 years.
Based on his experience after 10 days in Bellevue (NYC) treating COVID-19 patients, he observes this disease behaves in unusual, if not unprecedented ways.
Notably, he found patients can have low SpO2 readings without realizing it; something not normally true. Accordingly, he has a different opinion about pulse oximeters. 


--- Quote from: https://www.nytimes.com/2020/04/20/opinion/coronavirus-testing-pneumonia.html ---Even patients without respiratory complaints had Covid pneumonia. The patient stabbed in the shoulder, whom we X-rayed because we worried he had a collapsed lung, actually had Covid pneumonia. In patients on whom we did CT scans because they were injured in falls, we coincidentally found Covid pneumonia. Elderly patients who had passed out for unknown reasons and a number of diabetic patients were found to have it.

And here is what really surprised us: These patients did not report any sensation of breathing problems, even though their chest X-rays showed diffuse pneumonia and their oxygen was below normal. How could this be?

We are just beginning to recognize that Covid pneumonia initially causes a form of oxygen deprivation we call “silent hypoxia” — “silent” because of its insidious, hard-to-detect nature.
--- End quote ---

--- End quote ---
.e
Other circumstances can result in people having asymptomatic low oxygen saturation such as having history of Atelectasis, COPD not in exacerbation, Chronic Heart Failure, Congenital/Acquired Cardiac defects resulting in shunting, Hemoglobinopathies, Obesity Hypoventilation, and even just after Smoking. I admit and see patients in the hospital and you would be amazed at how many patients have an episode of asymptomatic hypoxia during their stay.

Suffice it to say, asymptomatic hypoxia is not specific for Covid-19. Rather, it would be just about as useful as finding someone with an elevated temperature.
 
I think the general thought is that a finding of asymptomatic low oxygen saturation is not a specific finding just for Covid-19 - it's not specific.

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