Measuring the scale of CO poisoning

Carbon monoxide poisoning is a significant public health concern, not least because there is no accurate measure of the number of victims of carbon monoxide poisoning.

This is partly due to the lack of a single centralised database of cases. 
 

It's also because of the following factors:
 

• Low awareness of the risks and symptoms of carbon monoxide poisoning among homeowners and tenants. This means people may not be aware that they are being exposed to carbon monoxide, so do not report it or get the correct treatment.
• Low awareness of the symptoms of carbon monoxide poisoning among healthcare professionals. This can lead to the potential misdiagnosis of carbon monoxide poisoning cases.
• A lack of a reliable biomarker to diagnose cases means that even if carbon monoxide poisoning is suspected, it can be difficult to prove/diagnose.
   

In an attempt to build a clearer picture of the carbon monoxide poisoning landscape, the Trust has funded several studies.


 

In 2014 Cranfield University carried out a thorough review of the existing research relating to carbon monoxide in the UK and elsewhere.

 

The research looked at how people are affected by carbon monoxide in a variety of environments and to what degree. These included environments associated with leisure activities including boats, caravans and tents, as well as in the home, specific working environments and public spaces.
 

The outcome of this research is a report identifying gaps in research and understanding, as well as the development of systems for defining the impact of carbon monoxide and monitoring its effects in the UK in defined environments.

To read more about this review click here.



 

There are several methods of diagnosing carbon monoxide poisoning. These are outlined below.

Carboxyhaemoglobin (COHb) levels

The most common method is to measure the concentration of carboxyhaemoglobin (COHb) in a person's blood. COHb is formed when carbon monoxide binds to haemoglobin in the blood, reducing its oxygen-carrying capacity. Elevated levels of COHb indicate exposure to carbon monoxide.

A carbon monoxide blood test is the most accurate way to determine COHb levels.


 

A special pulse oximeter called a CO-oximeter can also be used. These allow for more accurate oxygen level readings in a patient with carbon monoxide poisoning.


 

Symptom Assessment

Clinical evaluation of symptoms such as headache, dizziness, confusion, nausea, and shortness of breath can help diagnose carbon monoxide poisoning. However, these symptoms can be nonspecific and overlap with other conditions.


 

Research carried out by a team at St George’s, Epsom and St Helier University Hospitals, University of Surrey and Frimley Health Foundation Trust sought to understand the number of patients presenting to emergency departments (EDs) with raised COHb levels that could be caused by carbon monoxide exposure.

The study found that patients with symptoms suggestive of carbon monoxide poisoning but no history of carbon monoxide exposure are at risk of poisoning. 

The findings suggest components of the carbon monoxide screening tool (used in the study) may be an indicator of carbon monoxide exposure over and above elevated COHb.


 

Healthcare professionals should have a high index of suspicion for carbon monoxide exposure so that this important diagnosis is not missed.

 

Read more about this study here.
 

Post-mortem Examination

In cases of suspected carbon monoxide poisoning fatalities, post-mortem and toxicological analyses can help determine the cause of death and quantify carbon monoxide levels in tissues.

Read more about the role of post-mortem examination in the diagnosis of carbon monoxide poisoning here.



 

For medical professionals, there are several 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 multiple patients are coming from the same location and 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 there may be 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 an appliance may have caused carbon monoxide poisoning.
• Alarm - is there a CO 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 several 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 also be a red flag for another incidence of carbon monoxide poisoning.

Health professionals face several challenges in diagnosing carbon monoxide poisoning.

Symptom Variability

Symptoms of carbon monoxide poisoning can vary widely among individuals and may resemble other illnesses, making diagnosis challenging.


 

Timing
Carbon monoxide poisoning can be misdiagnosed as flu or other common illnesses, leading to delayed or incorrect treatment. This is a particular issue during flu season, which also coincides with central heating season.


 

Delayed Symptoms

Symptoms may not appear immediately, leading to delayed diagnosis and treatment. This can also be misleading for medical professionals who are trying to gather a medical history.


 

Chronic Exposure

Low-level, chronic exposure to carbon monoxide can be insidious and may go undetected, as symptoms might be subtle or attributed to other causes.

The difficulty in detecting low-level exposure can therefore affect the ability to measure and understand the scale of the issue. 

It can lead to chronic health problems, including cognitive impairment, cardiovascular issues, and mood disorders.


 

The CO Research Trust believes that low-level carbon monoxide poisoning is a significant public health issue.

If you suspect you might have CO poisoning, please visit the NHS website immediately - Here

Read more about low-level carbon monoxide poisoning here.