Jul 07, 2021

Oximeters: Calibrating the 1st line of COVID Defense

  • health
  • calibration services

One critical factor in ensuring lower fatalities as well as providing the right treatment at the right juncture during the Covid-19 infection cycle, is close monitoring of the level of oxygen saturation in the person’s blood. Thousands of lives were lost in the second wave due to extremely high requirements of oxygen, in part because patients’ oxygen saturation levels were often ignored until artificial oxygen supplies became critical for survival. 

Reading the signs

Oximeters were an often-used tool across the country as it helped people constantly monitor the oxygen levels of the patient in a most non-invasive manner. Moreover, since it requires no expert knowledge or technical nous, it can be used by all strata of society.

When oxygen saturation, or the amount of oxygen in the human body, falls below a particular level, key organs are starved of sustenance; such lowered levels for prolonged periods often result in multiple organ failure. According to the ministry of health in India, oxygen concentration of 93% or less in adults needs urgent medical attention. If it drops below 90%, then it is considered a severe case of Covid-19.

How reliable is the oximeter?

But recent audits have called into question the accuracy of the oximeters available in the market and therefore their efficacy as the first line of defense. According to the results supplied by Godrej Calibration Services, a part of Godrej & Boyce, 15% of the oximeters available in the market gave erroneous results.

A good oximeter, according to calibration experts and industry standards, will maintain a plus or minus 2% variation. Its results are thus medically reliable. However, in a recent study conducted by the Consumer Guidance Society of India (CGSI), it was found that a few branded oximeters available in Maharashtra consistently showed wrong readings.

From a consumer perspective, this means that the results would be unreliable in Covid care and sometimes overstate or understate the need for treatment or hospitalization. CGSI collected 40 samples of oximeters sold in various parts of Mumbai, Navi Mumbai and Thane and sent them for a calibration test to a nationally accredited laboratory of Godrej Calibration in May 2021. 

These randomly collected samples were tested for their twin readings of oxygen, technically referred to as SpO2, a measure of the amount of oxygen-carrying hemoglobin in the blood relative to the amount of hemoglobin not carrying oxygen and Prbpm (the pulse rate beats per minute).

Packaged in half truths

Apart from the worrisome calibration results, significant variations in price and quality were also discovered. For instance, several oximeters were manufactured by the same firm and then priced and branded differently. The prices for the same product varied across a broad range and were often sold at 40-60% discounts on the maximum retail price (MRP). 

Many products audited did not match basic packaging standards with no details of the manufacturer, distributor, date of manufacture and MRP, in clear violation of the Packages & Commodities Rules. This poses a major impediment for consumer rights, as buyers will not be able to peg responsibility in the event of getting a faulty product.

Oximeters are over the counter electronic medical products expected to comply with BIS Standard for Oximeters: IS/ISO 80601: Part 2: Sec 61: 2011 (Reaffirmed Year: 2019) Medical Electrical Equipment Part 2 Particular Requirements for the Basic Safety and Essential Performance Section 61 Pulse Oximeter Equipment. But there has been no calibration or market regulation to ensure that the consumers do not buy erroneous equipment.

Mandating the calibration of oximeters is the need of the moment

Given the importance of oximeters as a first line of medical diagnosis among suspect Covid-19 patients, state governments should rapidly consider bringing these instruments under stricter regulations buttressed with regular inspection and audits to ensure accuracy, quality and other standards are maintained. The devices must be calibrated in the direct calibration method using a Fluke Biomedical Vital Sign Simulator (Prosim 8). An artificial finger that can simulate the functions of the human body is placed in the probe and then used to alter the rates of oxygen saturation and pulse rate. The readings are checked for accuracy according to reference standards mandated in IS/ISO 80601-2-61: 2011 & Fluke Biomedical - 1/2009 3276553 C-EN-N Rev A.

As the nation prepares for the 3rd wave, it is even more urgent that simple healthcare enablers like well-calibrated pulse oximeters, which people can use to monitor their health and be free from worry, are easily available and trusted by consumers. The government must wake up to this reality and very soon enforce strict regulations that will make calibration and standardization necessary for the use of critical medical devices like oximeters. 


From www.hopkinsmedicine.org (click to visit the website)

When diagnosing and treating patients with severe upper respiratory illnesses, fast, accurate, and reliable SpO2 measurements are critical. Accurate measurements ensure that patients who need advanced screening and care receive it promptly and prevents patients with healthy oxygen levels from undergoing unnecessary tests and treatments. Proper sensor placement is instrumental in delivering SpO2 monitoring you can count on.

From www.healthline.com (click to visit the website)

From www.thehindu.com (click to visit the website)

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