Which is the best pulse oximeter for home use?
Medically reviewed and
edited by Tod Cooperman, M.D. 
Last
Updated: 12/09/2021 | Initially Posted: 09/22/2020
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Answer:
Pulse oximeters, which
simply clip onto your fingertip, are non-invasive devices that can measure
blood oxygen saturation as well as pulse (heart rate). They are relatively
inexpensive (about $20) and can be purchased for home ("non-medical")
use.
Although they are not as accurate as
FDA-approved "medical" pulse oximeters, which cost much more and
undergo more rigorous testing, comparison studies indicate that some (but not
all) non-medical pulse oximeters can help signal when medical attention is
needed in conditions such as asthma and chronic obstructive pulmonary disease
(COPD). There is also evidence that non-medical pulse oximeters may improve
clinical outcomes in patients at high risk of severe COVID-19, as was shown in
a retrospective analysis of insurance records from more than 38,000 high-risk
COVID-19 patients in South Africa. Those who had been given a pulse oximeter
for home monitoring after COVID-19 diagnosis had a 48% lower likelihood of
death within 60 days of laboratory confirmation of infection compared to those
not given a pulse oximeter. Pulse oximeter readings were recorded twice daily.
If the readings fell to 90% to 94%, patients were advised to call their doctor,
and if the reading fell to below 90%, patients were advised to go to an
emergency room. The researchers attributed the mortality benefit to the fact
that those in the pulse oximeter group probably sought medical attention
sooner. This theory was supported by lower levels of C-reactive protein (a
marker of inflammation) in the pulse oximeter group upon hospital admission
compared to the control group (Nematswerani, SSRN 2021 — preprint).
A study in England also showed that COVID-19 patients
fared better with pulse oximeters. The study, which looked at medical records
of 15,621 COVID-19 patients seen at emergency rooms but not requiring immediate
hospital admission, found that those who received a pulse oximeter for home
monitoring had a 52% lower likelihood of death within 28 days after laboratory
confirmation of infection than those who did not receive a pulse oximeter.
Interestingly, those given pulse oximeters were more likely to return the
emergency department but less likely to be admitted to critical care,
suggesting that home monitoring improved early detection of low blood oxygen
saturation levels. Patients who participated in home monitoring were advised to
take three readings per day and contact their primary care provider for
readings of 93% to 95% or emergency services for readings of 92% or lower (Clarke, medRxiv
2021 -- preprint).
Best Home Pulse Oximeter
As nicely summarized in an article on MedPage
Today by Dr. Anthony Pierson, a cardiologist, a model that has
performed relatively well in studies is the Contec
CMS50DL (or a similar model the Contec
CMS50D, from Contec Medical Systems, China),
currently sold on Amazon by a
distributor (ClinicalGuard) for just $14.81. As Dr.
Pierson points out in his article, the Contec
CMS50DL has been shown to be fairly accurate at normal oxygen
saturation levels above 90% but, like similar products, it may be less accurate
below 90%. Nevertheless, based on the current evidence, the Contec CMS50DL is ConsumerLab'sTop
Pick among pulse oximeters.
Keep in mind that direct-to-consumer pulse oximeters,
including the Contec CMS50DL, do not meet
requirements for FDA-clearance, and hospital-grade pulse oximeters such as
the Philips Sensor Glove SpO2 Monitor, have been shown to
perform better in clinical testing. Nevertheless, the Contec
CMS50DL has been shown in clinical testing to have overall accuracy of
91% (compared to 60% to 86% for most other tested devices), although, as noted
above, it was more accurate at normal oxygen saturation levels than lower
levels. It other words, this device performs better when used to rule
out low blood oxygen rather than to confirm the
condition. Normally, in healthy people, blood oxygen saturation should be in
the high 90s. Measurement of less than 93% on a home device should prompt
further investigation and management of hypoxia if necessary (Smith, SAMJ 2019; Harskamp, BMJ Open Resp Res 2021).
Cautions when using a non-medical pulse oximeter at home
Be aware that some non-medical pulse oximeters have been shown to report normal
values when true values were below 90%. This could be dangerous, as it might
lead one to think that they do not require medical assistance when they
actually do. In a study of six non-medical pulse oximeters, two products that
exhibited this problem in one patient were Atlanteen
SB100 II and Beijing Choice MD300C23 (Lipnick, Anesth Analg
2016). Apps that claim to measure oxygen saturation using only
a smartphone — such as DigiDoc and another provided
by Samsung — should not be used as oximeters, as these devices have poor
accuracy (Tarassenko, Oxford COVID-19 Evidence Service, 2020).
When using a pulse oximeter, be aware that it works by
transmitting light through your fingertip. Factors that can affect
reading accuracy include poor circulation, skin thickness, skin temperature
(cold fingers), and current tobacco use (FDA 2021). Anything that
obstructs the light, such as fake nails or nail polish, can cause
an error or false reading. In addition, pulse oximeters may give false readings
in people with darker skin: Two large studies found that normal
readings in people with oxygen saturation less than 88% (which is below normal)
occurred almost three times as often in black people compared to white people
(11.7% vs. 3.6%, respectively) (Sjoding, N Engl J Med 2020).
Additional issues that can affect
readings, as noted in the user manual for the Contec CMS50DL device, are weak
pulse, low body temperature, major bleeding,
and use of certain drugs (including staining drugs such as
methylene blue or vasoconstricting drugs such as dopamine, procaine,
prilocaine, lidocaine, and butacaine).
Among people with severe anemia and low
blood oxygen levels, pulse oximeters may underestimate the amount of oxygen in
the blood. Fortunately, this error may lead to more timely treatment. On the
other hand, among people with normal blood oxygen levels, even severe anemia
has no effect on pulse oximeter readings (Chan, Respir Med 2013).
Consequently, pulse oximeters can't be as a tool to detect anemia.
To get
the most accurate reading, the FDA recommends the
following:
·
Follow the manufacturer's instructions for use.
·
When placing the oximeter on your finger, make sure your hand is
warm, relaxed, and held below the level of the heart. Remove any fingernail
polish on that finger. [Note: According to the WHO, the probe may be turned sideways to take a
measurement from a finger with polish in emergency situations.
However, removing polish or potentially using another site (such as a toe) is
preferred.]
·
Sit still and do not move the part of your body where the pulse
oximeter is located.
·
Wait a few seconds until the reading stops changing and displays
one steady number.
The readings alone don't tell the whole story on how you are doing. As noted by
the CDC, trouble breathing,
persistent pain or pressure in the chest, new confusion, inability to wake or
stay awake, and bluish lips or face are emergency warning signs that you should
seek medical care immediately. At best, these devices can provide another
warning sign -- that oxygen levels are low, but they should not be relied upon
for accurate measurements.
6
Comments
Jeanne23159
August 11, 2021
As an
RN, I have had good luck with turning the machine over and reading through the
finger pad if a person had on fake nails or polish. If someone is extremely
obese, this could be problematic, but I have tried it both ways on people with
normal nails, as a little test, and got the same readings. Sideways reading
sounds quite awkward to me.
Sandra
Collins
August 12, 2021
Thank you!!! I have gel nails and going on a trip. Did not want
to remove them. The finger pad is a great idea
Jef21622
December 20, 2020
Pulse
Ox differences for people of color have been noted going back to 1998. Shameful
this hasn't been addressed or solved by now.
https://pubmed.ncbi.nlm.nih.gov/18048893/
https://pubs.asahq.org/anesthesiology/article/102/4/715/7364/
https://onlinelibrary.wiley.com/doi/pdf/10.111
Ted21501
December 2, 2020
We
spend time in mountain cabins at high elevations (6000 - 10,000 feet) where the
altitude causes a large drop in oxygen saturation. We need a meter that is
accurate in the 80% to 90% range, and are willing to spend $100 - $200. Any
suggestions?
William22466
April 21, 2021
Though I am a physician, I cannot claim expertise, but I am a
pathologist who subspecializes in blood diseases and coagulation (hemato-pathology). When a person moves to high altitude,
they develop higher blood counts, but most importantly, their oxygen carrying
capacity of the blood increases. Especially important is that hemoglobin (the
protein that carries oxygen inside red blood cells) has a "dissociation
curve" that shifts, allowing the oxygen to more easily leave the
hemoglobin and go into tissues. These changes allow the body's cells to get
more oxygen to compensate for the lower amounts in the air at high altitude.
These changes take time to develop, usually a matter of a couple of weeks, but
begins to happen fairly quickly. With pulse oxymeters
relying on the more "red" color of
transmitted light, that shows only the amount of oxygen being carried in the
blood, the effect on the numbers seen on a pulse oxymeter
may, OR MAY NOT, be helpful in high altitude situations. A more knowledgeable
person than I am may be able to answer that question better. The only thing
that is certain is that a person who is developing lung dysfunction in a
COVID-19 infection would be a much greater danger when travelling to high
altitudes, and this would be less likely if the person has already been living
at high altitudes for awhile.
Jeanne23160
August 11, 2021
Excellent information William! Thank you.
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