Research: Tests for carbon monoxide poisoning shouldn't be used
Berlin, Germany: According to a systematic review and meta-analysis published at the European Emergency Medicine Congress, pulse oximetry is an unreliable approach for identifying persons who are suffering from carbon monoxide poisoning and it should not be used for this reason.
One of the leading causes of poisoning-related fatalities worldwide is carbon monoxide. Oxygen can be used to cure it effectively. However, due to the symptoms of carbon monoxide poisoning being similar to those of common illnesses like the flu, it can be challenging to diagnose.
More research is reportedly required in order to develop a quick and accurate approach to diagnosing carbon monoxide intoxication.
An odourless, colourless gas known as carbon monoxide can be created when fuels burn in an area with inadequate ventilation, such as in a gas stove or boiler that is broken or not maintained properly. When someone is exposed to carbon monoxide, it passes through their lungs and into their bloodstream. The body may become oxygen-starved due to carbon monoxide attaching to haemoglobin, the molecule that typically transports oxygen throughout the body.
A blood test that gauges the percentage of haemoglobin that is linked to carbon monoxide can identify carbon monoxide poisoning.
The new findings were presented by Dr Mathilde Papin from the emergency department at Nantes University Hospital in France. She said: "If we suspect carbon monoxide poisoning, we want to be able to treat patients quickly with oxygen in the ambulance or in the emergency room, and that means we need a test that can be done immediately onsite. A blood test is reliable, but not practical."
Pulse oximetry is a quick and simple test that uses a sensor that is often put on the fingertip of the patient to detect their pulse and calculate the percentage of their blood that is oxygenated (called oxygen saturation). Patients with lung problems including asthma or chest infections are monitored using this method.
The presence of carbon dioxide in a patient's blood, which is replacing the oxygen in their blood, may also be indicated by a reduced degree of oxygen saturation. The use of pulse oximetry to test for carbon monoxide poisoning, according to Dr Papin, has produced conflicting results in both clinical practice and research.
Dr Papin and her associates carried out a systematic review and meta-analysis to get a clearer picture. They looked for all prior clinical trials that included both adults and children and compared pulse oximetry with blood tests in patients or healthy volunteers, and they discovered 19 such trials. In order to assess the efficacy of the two testing methods, the researchers were able to aggregate the findings from 11 different investigations, which included information on more than 2000 individuals.
This shows that 77% of the time, pulse oximetry was able to accurately detect positive instances (also known as "sensitivity" or "true positive rate"). The true negative rate, also known as "specificity," was able to accurately identify negative situations 83% of the time. It had an 86% overall accuracy rate.
"At 23%, the false negative rate with pulse oximetry is too high for accurately triaging patients with suspected carbon monoxide poisoning," Dr Papin stated before Congress. This technique is insufficiently accurate and ought not to be applied in therapeutic settings.
The researchers are now planning to assess a different strategy for quicker measurement of carbon monoxide levels in the microscopic blood arteries (capillaries).
Professor Youri Yordanov from the St Antoine Hospital emergency department, APHP Paris, France, is Chair of the EUSEM 2022 abstract committee and was not involved in the research. He says: "After systematically assessing all the available evidence on the topic, this research team suggests that using pulse oximetry as a tool for diagnosing carbon monoxide poisoning is not a reliable method for this purpose. Other screening methods need to be developed and evaluated, and in the meantime, we must rely on a combination of symptoms, evaluating the likelihood of exposure to carbon monoxide and blood tests."
