Carbon monoxide poisoning

The silent killer

CarolinaFireJournal - BRADLEY DEAN
10/18/2009 -

Through the development of technology, pulse oximetry has become a standard vital sign for prehospital providers. Why then do we not pay attention to the data and studies and avoid the use of them on the fire scene or in the monitoring and treatment of burn and smoke inhalation patients?


Carbon monoxide is not recognized because the signs and symptoms are similar to those of other illness...

A pulse oximeter measures the saturation of hemoglobin. Hemoglobin is normally saturated with oxygen, so that is what we expect. Hemaglobin has a greater affinity for carbon monoxide than oxygen, saturating the hemoglobin leading the provider into a false reading of hemoglobin saturation. Newer technology has been developed to assist us with monitoring Carbon Monoxide in the patients that have been potentially exposed to this deadly, yet silent killer. Before we discuss the benefits of the advances, we must understand the general pathophysiology of carbon monoxide.

Carbon monoxide poisoning is the most common exposure poisoning in the United States. This odorless, colorless gas can cause sudden illness and death. The gas is produced from a variety of sources such as vehicles, camp stoves, burning charcoal and wood, gas ranges, heating systems, and poorly vented chimneys. Structure fires provide another common source of CO exposure for both the victim and firefighters.

During the summer we typically do not think about this because we think about it occurring during the winter due to more people spending time inside trying to stay warm. It is important to remember that carbon monoxide poisoning can be experienced throughout the year, especially during the hurricane season when houses can lose electricity and result to generator use.

Carbon monoxide toxicity causes a significant impairment of oxygen delivery and utilization at the cellular level. It competitively competes with oxygen for the receptor sites on hemoglobin in the red blood cell. Hemoglo bin has 200 times the affinity for carbon monoxide than oxygen. Exposure to carbon monoxide increases during exposure to the environment of combustion. As this occurs the level of carbon monoxide attached to the blood, known as carboxyhemoglobin, increases. This then renders the red blood cell incapable of transporting oxygen throughout the body. When the red blood cell loses the ability to transport oxygen, the body can not survive without medical intervention.

This exposure and buildup of carbon monoxide has serious adverse effects on all of the body systems. The body needs oxygen, and this critical element has now been displaced by carbon monoxide. One of the largest systems affected is the central nervous system. As a person is exposed and oxygen is displaced, common symptoms such as headaches, confusion and dizziness begin to manifest. Should the level of carbon monoxide continue to increase, the person may have seizures or even go into a coma.

A second manifestation of exposure to carbon monoxide may produce profound effects, which would present such symptoms as chest pain, dysrhytmias, myocardial ischemia and even ventricular fibrillation. This is extremely important when considering that firefighters may already be at risk for a cardiac event. Typically, if a firefighter dies in the line of duty, they will have elevated levels of carbon monoxide.

Overall, carbon monoxide is not recognized because the signs and symptoms are similar to those of other illness, which may lead to a misdiagnosis by medical providers. Prehospital providers need to be aware of these symptoms and how they may present with patients experiencing elevated levels of carboxyhemoglobin, and carefully scrutinize the environmental issues for a correct diagnosis. The symptoms include the following; flu-like illness, fatigue, chest pain, lethargy, depression, nausea, vomiting, headaches, abdominal pain, drowsiness, and ultimately coma. These signs and symptoms vary widely with the level of carbon monoxide exposure.

The lungs work to eliminate carbon monoxide, but this may take some time. The half-life of carbon monoxide is three to four hours, which means that it will take that amount of time to reduce the amount by one-half. The use of high concentration oxygen will reduce the halflife to 30-90 minutes. This is with 100 percent oxygen which can only be achieved through a tight fitting sealed mask, not a non-rebreather. A non-rebreather only really de livers 65 to 70 percent oxygen because of the design of the mask. The use of a non-rebreather will reduce the halflife to 90-120 minutes.

The organs within the body with the highest oxygen consumption such as the brain and heart suffer the most profound problems. The condition is often misdiagnosed due to the generality and broad varying symptom complaints. Complaints often become attributed to a viral illness such as the flu in the winter months, or allergies, or allergy medications in the spring and summer.

A pulse oximeter can not be used to determine if a patient has been exposed to carbon monoxide. The pulse oximeter displays what appears to be a normal oxygen saturation, because it is saturated with oxygen, but that oxygen is in a non usable state, and the pulse oximeter can not determine if it is oxygen or carbon monoxide.

In order to determine the percent of carbon monoxide in the blood, one would need to use the new technology of Pulse CO-oximetry. This can determine both the percentage measurement of carbon monoxide saturation that is bonded to the hemoglobin as well as that of oxygen.

The population group that is at greatest risk for carbon monoxide exposure are the very young and the very old. This is due to the changes in their physiology. Pregnant women, and most importantly the fetus are at an increased risk for adverse outcomes from carbon monoxide exposure due to the fetal circulation. Fetal hemoglobin has an even higher affinity for carbon monoxide than that of the adult. Other increased risk populations include those with respiratory compromise, since they have a decreased ability to oxygenate their system. Firefighters are always at increased risk and should be evaluated while in rehab during firefighting operations. The utilization of a Pulse COoximeter is simple, accurate and very fast. This will allow you to monitor firefighters, and use high-concentrations of oxygen to help treat for the effects of carbon monoxide poisoning. Often they do not realize that they have been exposed, and you can not afford not to realize this potentially silent killer. This should be one of the standard vital signs taken during rehab operations.

There are some other simple devices on the market that can assist providers in scrutinizing their environment. There are simple CO detectors that are small enough to clip onto the handle of a “jump bag.” Since the bag is taken in on every call this device can constantly monitor the environment where personnel will be working. Should the patient be exposed to this “silent killer,” and be presenting with a medical problem it could simply be overlooked. Most of these detectors are set to alarm at relatively low levels that are considered safe for short periods of time. When the device alarms it does so at an annoying, but not deafening level (approximately 95db). This should give providers enough warning to evacuate the immediate area and remove any patients or potential victims that are present. The fire department can then work to locate the source and begin immediate ventilation and correction of the problem.

I encourage every agency to purchase CO-oximeters, and CO detectors to go on the strap of the jump bag for constant monitoring of the environment. These devices are life saving, and can avert a huge workman’s compensation claim for a department when personnel are potentially exposed to this “silent killer”.

Avoiding Hazards

Here are some simple statements that can be jazzed up and placed onto department brochures for safety notices for generators since we are heading into the seasons when generators are used most often.

To Avoid Carbon Monoxide Hazards

  • Use generators outdoors and away from windows, doors, and vents.
  • Follow manufacturer’s instructions.
  • Install carbon monoxide (CO) alarms indoors. To Avoid Electrical Hazards
  • Keep the generator dry by operating on a dry surface under an open, canopy-like structure.
  • Touch the generator only with dry hands.
  • Plug appliances directly into generator or use a heavyduty outdoor-rated extension cord.
  • Connect generator to building wiring only by a qualified electrician or utility company.
  • Prevent plugging a generator into a wall outlet, which may cause an electrocution risk to utility workers and others.
To Avoid Fire Hazards
  • Turn off generator and let it cool before refueling.
  • Store fuel outside of main area in a properly labeled and non-glass container.
  • Store fuel away from any fuel-burning appliance. Before the next storm, check the manufacturer’s instructions and ensure the generator works properly. Following these simple tips can increase survival rates dramatically.


Bradley Dean currently works as one of the Assistant Regional Emergency Response and Recovery Coordinator for the Triad Region of North Carolina through Wake Forest University Baptist Medical Center Trauma Department. He is a faculty member for the EMS Programs at Alamance Community College, a paramedic with Davidson County Emergency Services and a volunteer with Thomasville Rescue, and Holly Grove Fire Department.
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