PULSE OXIMETRY AND PULSE OXIMETERS IN THE POST-COVID ERA
Between Valuable Monitoring, False Diagnostic Certainty, and the Epidemic of Device-Induced Anxiety
Scientific, technological, regulatory, clinical, operational, EMS, critical care, and tactical medicine review updated for 2026
By DrRamonReyesMD ⚕️
EMS Solutions International
INTRODUCTION
Few medical technologies have experienced such explosive global expansion as pulse oximetry.
For decades, pulse oximeters were primarily found in:
- operating rooms,
- intensive care units,
- emergency departments,
- ambulances,
- air medical transport,
- military medicine,
- critical care environments.
The COVID-19 pandemic radically changed this reality.
Millions of pulse oximeters entered homes worldwide.
What was once considered professional monitoring equipment became available through:
- supermarkets,
- pharmacies,
- convenience stores,
- online marketplaces,
- e-commerce platforms,
- discount retail chains.
The intention was understandable.
Early identification of respiratory deterioration could potentially save lives.
However, the democratization of pulse oximetry occurred much faster than public understanding of its limitations.
The result was a phenomenon rarely discussed in medical literature before the pandemic:
The mass medicalization of isolated physiological data.
Millions of individuals began interpreting numerical values without understanding:
- signal quality,
- measurement limitations,
- device accuracy,
- physiological variability,
- clinical context,
- sources of error.
Consequently, healthcare systems around the world witnessed a surge in:
- unnecessary consultations,
- anxiety-driven emergency visits,
- self-diagnosis,
- false alarms,
- delayed recognition of genuine illness.
Ironically:
The problem is not pulse oximetry.
The problem is the interpretation of pulse oximetry.
WHAT DOES A PULSE OXIMETER ACTUALLY MEASURE?
One of the most common misconceptions is that pulse oximeters directly measure oxygen in the blood.
They do not.
Pulse oximetry estimates arterial oxygen saturation (SpO₂) by analyzing differences in light absorption between oxygenated and deoxygenated hemoglobin.
The technology relies upon:
The Beer-Lambert Law
combined with complex signal-processing algorithms.
The displayed number is therefore:
An estimation.
Not a direct measurement.
The gold standard remains:
Arterial Blood Gas Analysis (ABG)
which directly measures oxygen tension and gas exchange parameters.
Therefore:
Pulse oximetry is an exceptional monitoring tool.
It is not a definitive diagnostic test.
THE SIXTH VITAL SIGN
Pulse oximetry has often been referred to as:
The Sixth Vital Sign
because of its ability to rapidly detect:
- hypoxemia,
- respiratory compromise,
- clinical deterioration,
- perioperative complications.
Its impact on patient safety has been comparable to the introduction of:
- blood pressure monitoring,
- electrocardiography,
- capnography.
However:
A vital sign is not a diagnosis.
THE MOST COMMON CLINICAL ERROR
Every emergency physician has encountered some variation of the following scenario:
A patient arrives stating:
“My pulse oximeter says my oxygen level is 84%.”
Yet examination reveals:
- normal speech,
- no dyspnea,
- normal respiratory rate,
- normal skin coloration,
- no accessory muscle use,
- stable hemodynamics.
Hospital-grade monitoring subsequently demonstrates:
- SpO₂ 98–99%,
- stable pulse waveform,
- normal physiological parameters.
In many of these cases:
The patient was not hypoxemic.
The measurement was wrong.
The technique was wrong.
Or both.
THE PROBLEM WITH CONSUMER-GRADE PULSE OXIMETERS
Not all pulse oximeters are created equal.
There is a profound difference between:
Professionally validated medical devices
and
Low-cost consumer products.
Manufacturers such as:
- Masimo,
- Nellcor,
- Nonin,
- Philips,
- GE Healthcare,
- Mindray,
have invested decades in algorithm development and validation studies.
These systems are designed to compensate for:
- motion artifact,
- poor perfusion,
- signal distortion,
- optical interference,
- physiological variability.
Conversely, many inexpensive devices sold through retail channels have limited publicly available validation data.
Some may perform reasonably well.
Others may not.
The difficulty is that consumers often cannot distinguish between the two.
SIGNAL QUALITY MATTERS MORE THAN THE NUMBER
Perhaps the most overlooked concept in pulse oximetry is signal quality.
A saturation value means very little if signal acquisition is poor.
Professional monitoring systems routinely evaluate:
- plethysmographic waveform quality,
- pulse strength,
- signal consistency,
- perfusion indicators.
A wide, rhythmic, stable waveform generally suggests reliable arterial signal detection.
A flat, erratic, or unstable waveform should immediately raise questions regarding measurement validity.
This is one reason why professional systems provide much more information than a single saturation number.
THE PERFUSION INDEX (PI)
Modern pulse oximeters increasingly provide:
Perfusion Index (PI)
which estimates the strength of pulsatile blood flow at the sensor site.
Low PI values frequently occur in:
- shock,
- vasoconstriction,
- hypothermia,
- dehydration,
- peripheral vascular disease.
A low PI often predicts reduced reliability of SpO₂ measurements.
Yet many users have never heard of the parameter.
TECHNICAL FACTORS THAT DISTORT READINGS
Pulse oximetry accuracy may be affected by:
Poor Peripheral Perfusion
- shock,
- severe dehydration,
- vasoconstriction.
Cold Extremities
Cold fingers frequently produce false readings.
Motion Artifact
- tremors,
- Parkinson disease,
- anxiety-related movement.
Nail Polish
Particularly:
- black,
- blue,
- dark green.
Artificial Nails
Ambient Light Interference
Sensor Misplacement
Edema
Cardiac Arrhythmias
Carbon Monoxide Exposure
Methemoglobinemia
In many of these situations, displayed values may be misleading.
THE RACIAL BIAS CONTROVERSY
One of the most important discoveries in recent years involved pulse oximeter performance across different skin pigmentation groups.
Sjoding and colleagues demonstrated that some devices may overestimate oxygen saturation in individuals with darker skin pigmentation.
This phenomenon can potentially result in:
Occult Hypoxemia
where true hypoxemia remains undetected.
Publication:
Sjoding MW et al.
DOI:
10.1056/NEJMc2029240
This finding prompted regulatory reviews by:
- FDA,
- healthcare systems,
- device manufacturers,
- academic institutions.
The issue remains under active investigation.
COVID-19 AND THE RISE OF "HAPPY HYPOXIA"
The pandemic popularized the concept of:
Happy Hypoxia
Patients exhibited:
- markedly reduced oxygen saturation,
- surprisingly mild subjective respiratory distress.
This phenomenon dramatically increased public interest in home pulse oximetry.
Pulse oximeters became household devices.
Yet a second phenomenon emerged simultaneously:
Obsessive self-monitoring.
Many individuals began checking oxygen saturation:
- every few minutes,
- multiple times per day,
- on different fingers,
- comparing family members.
In some cases, anxiety became the primary pathology.
THE DANGER OF FALSE REASSURANCE
False alarms receive substantial attention.
False reassurance is often more dangerous.
A normal SpO₂ does not exclude:
- pulmonary embolism,
- early sepsis,
- acute coronary syndromes,
- evolving respiratory failure,
- impending clinical deterioration.
Patients should be evaluated clinically.
Not numerically.
PULSE OXIMETRY IS NOT CAPNOGRAPHY
Modern emergency medicine increasingly integrates:
- pulse oximetry,
- capnography,
- respiratory rate,
- clinical examination.
Capnography frequently detects ventilatory compromise before pulse oximetry changes occur.
For this reason, devices such as:
EMMA Emergency Capnometer
have become increasingly valuable in:
- EMS,
- HEMS,
- critical care transport,
- tactical medicine,
- prolonged field care.
TACTICAL MEDICINE AND OPERATIONAL CONSIDERATIONS
In tactical environments, pulse oximetry remains useful but must be interpreted cautiously.
Operators may present with:
- hypovolemia,
- cold exposure,
- vasoconstriction,
- shock,
- environmental stress.
All can distort readings.
Experienced tactical clinicians understand:
Pulse oximetry supplements clinical judgment.
It never replaces it.
THE POST-COVID EPIDEMIC OF DIGITAL HEALTH ANXIETY
The pandemic created a new phenomenon:
Digital Physiological Hypervigilance
Millions of individuals continuously monitor:
- oxygen saturation,
- heart rate,
- blood pressure,
- temperature.
We now possess more physiological data than ever before.
Yet data does not automatically create understanding.
The unintended consequences include:
- anxiety disorders,
- unnecessary consultations,
- healthcare system overload,
- medico-legal disputes,
- misinterpretation of normal physiological variation.
THE ROLE OF REGULATORY OVERSIGHT
The COVID era also highlighted the importance of device regulation.
Healthcare professionals should distinguish between:
- FDA-cleared medical devices,
- CE-marked medical devices under MDR frameworks,
- consumer wellness products,
- unvalidated devices of uncertain origin.
Regulatory oversight does not guarantee perfection.
However, it significantly improves confidence in device performance.
CONCLUSION
Pulse oximetry remains one of the most important technological advances in modern medicine.
It has undoubtedly saved countless lives.
However:
A pulse oximeter is not an arterial blood gas.
A pulse oximeter is not a diagnosis.
A pulse oximeter is not a physician.
Most pulse oximetry-related problems observed since the COVID-19 pandemic are not failures of the technology itself.
They are failures of interpretation.
The combination of:
- poorly understood devices,
- variable quality equipment,
- obsessive monitoring,
- lack of clinical context,
has generated a new category of healthcare utilization.
The principle taught in emergency medicine remains unchanged:
“Treat the patient, not the monitor.”
And in pulse oximetry specifically:
“A number without clinical context has limited value.”
Pulse oximetry is an extraordinary tool.
But it remains exactly that:
A tool.
Not a diagnosis.
Not a prognosis.
And certainly not a substitute for sound clinical judgment.
DrRamonReyesMD ⚕️
EMS Solutions International
Updated 2026
REFERENCES
FDA Pulse Oximeter Accuracy and Limitations
https://www.fda.gov/medical-devices/safety-communications/pulse-oximeter-accuracy-and-limitations-fda-safety-communication
Sjoding MW et al. Racial Bias in Pulse Oximetry Measurement
DOI: 10.1056/NEJMc2029240
Valbuena VSM et al. Assessment of Racial and Ethnic Differences in Oxygen Supplementation Among ICU Patients
DOI: 10.1001/jamainternmed.2021.6338
Jubran A. Pulse Oximetry
DOI: 10.1183/09031936.00027803
EMS Solutions International – Pulse Oximetry Collection
https://emssolutionsint.blogspot.com/2019/06/oximetria-todas-las-publicaciones.html
EMS Solutions International – Happy Hypoxia and COVID-19
http://emssolutionsint.blogspot.com/2020/12/espana-investigadores-explican-la.html
EMS Solutions International – Masimo Pulse Oximetry Systems
https://emssolutionsint.blogspot.com/2019/06/oximetros-masimo-servicios-medicos-de.html
EMS Solutions International – Pulse Oximetry as the Sixth Vital Sign
https://emssolutionsint.blogspot.com/2010/12/oximetria-de-pulso-sexto-signo-vital.html
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