Diagnosis of Carbon Monoxide Exposure

Emergency Departments

Emergency Departments are often the first opportunity for diagnosis of carbon monoxide poisoning.

In 2015 the Department of Health estimated that around 4,000 people attending Accident and Emergency departments each year in the UK are diagnosed with carbon monoxide poisoning.

You can read more about the Department of Health study.

When we begin to experience winter temperatures, home heating systems get switched on, often for the first time in 6 months. The risk of carbon monoxide poisoning increases, and emergency departments begin to see an increase in cases.

However, accurate numbers are difficult to determine because the signs and symptoms of carbon monoxide poisoning are very similar to other common illnesses and are easily misdiagnosed.

This is exacerbated by the fact that the heating season coincides with flu season.

A research project carried out by St George’s, Epsom and St Helier University Hospitals, University of Surrey and Frimley Health Foundation Trust has sought to reduce misdiagnosis so that patients can be treated appropriately and not sent back to the site of exposure before it is safe to do so.

You can read more about this study here.

Below Professor Heather Jarman speaks about the challenges faced by clinicians when faced with a possible carbon monoxide poisoning diagnosis.

Latest Research

The CO Research Trust has recently awarded grant funding to further a project to improve the education of junior doctors in carbon monoxide diagnosis.

Following on from a project developed using a standardised methodology at University Hospital Aintree (UHA) in 2021/22, this latest project will expand this successful intervention.

This piece of work aims to simultaneously develop the education of junior doctors, and utilise the specific intervention of tagging patient notes to prompt the use of the carbon monoxide COMA acronym.

Read more about the project here.

What is COMA?

For medical professionals, there are a number of red flags that they might look for to help confirm a diagnosis of carbon monoxide poisoning. They can be remembered by using the acronym COMA.

  • Co-habitees - is anyone else in the house affected (including pets)? If there are multiple patients coming from the same location who have similar complaints, then this might be a red flag for carbon monoxide poisoning.
  • Outdoors - do the symptoms improve when out of the house, building or office? If the answer is yes, then it’s possible there is a carbon monoxide leak in the house, building or office.
  • Maintenance - are the heating and cooking appliances properly maintained? If the answer is no, then it is possible that an appliance has caused carbon monoxide poisoning.
  • Alarm - is there a carbon monoxide alarm present and has it been activated?

There are also two other indicators that medical professionals should look for when assessing for carbon monoxide exposure. These are outlined below.

  • No fever - carbon monoxide poisoning does not cause a temperature, so if a patient is presenting with a number of flu-like symptoms, but does not have a fever, then this might be a red flag for carbon monoxide poisoning.

  • History of exposure - If the patient has a history of carbon monoxide exposure this might be a red flag for another incidence of carbon monoxide poisoning.

However, even if carbon monoxide exposure is suspected, it is very difficult for medical professionals to confirm the diagnosis.

Useful links

The UK Government website - Guidance on Carbon monoxide: toxicological overview - https://www.gov.uk/government/...