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Carbon Monoxide Poisoning

Carbon Monoxide Poisoning Graphic

Carbon monoxide poisoning can be hard to recognize when it occurs in the field. The symptoms of CO poisoning are similar to flu symptoms and can result in death. According to the CDC, carbon monoxide kills more Americans than any other acute toxicant, so it’s worth learning how to recognize and treat this medical emergency.


I don’t know about you, but my EMT lecture on CO poisoning taught that the classic sign to look out for is cherry red skin. Experience has shown me that this is not true and research shows cherry red is a very late sign of CO poisoning, often indicating the patient is near death.


This page will go over what carbon monoxide poisoning is, how it works, common sources of CO, what the symptoms of CO poisoning are and the prehospital treatment of CO poisoning.


It will also cover prevention because toxic exposure to carbon monoxide can be prevented.


What is Carbon Monoxide?

Carbon monoxide is a toxic gas produced when combustion takes place, from carbon based fuels, in a poorly oxygenated environment. 

Carbon monoxide is:

→ Colorless

→ Odorless

→ Tasteless

→ Toxic

Carbon monoxide is one carbon atom bonded with one oxygen atom. The chemical formula for carbon monoxide is CO.

When combustion takes place in the presence of adequate oxygen levels, two oxygen atoms will combine with one carbon forming carbon dioxide (CO2), instead of carbon monoxide (CO).


Some examples of carbon based fuels are:

– Gasoline

– Kerosene

– Charcoal

– Wood

– Propane

– Natural Gas


Carbon Monoxide Poisoning Physiology

To learn about how CO poisoning happens in the body let’s compare taking a normal breath to taking a breath with carbon monoxide in the air.


Breathing Room Air:

First, you inhale room air and oxygen travels down the trachea, into the lungs and into the alveoli. From there the oxygen molecules, or O2, are able to enter the bloodstream by traveling into the capillaries.


Once in the bloodstream the oxygen molecules can bind to the hemoglobin. In fact, four O2 molecules can bind to one hemoglobin protein and travel to areas of the body that need more oxygen.


This is how oxygen is successfully delivered to body tissues like your muscles and heart. 


Inspiration air in lungs diagram


Breathing Carbon Monoxide:

First you inhale room air that contains both carbon monoxide and oxygen. They travel down the trachea, into the lungs and into the alveoli. From there the CO and O2 molecules enter the bloodstream through the capillaries and both head for the hemoglobin proteins.


Carbon monoxide binds to the iron sites in hemoglobin with an affinity 200-250 times that of oxygen. This means the CO wins every time and it doesn’t release quickly like oxygen does.


Only two CO molecules will bind to each hemoglobin, which leaves two open slots for oxygen to bind. However, the CO changes the shape of the hemoglobin which traps the two bound oxygen so they can’t be released when needed.


As a result the red blood cells containing hemoglobin with CO molecules attached have a decreased oxygen carrying capacity.


Red blood cells in blood


The red blood cells travel around the bloodstream full of O2 and CO that won’t release while the body’s tissues and organs become more and more hypoxic. The body becomes starved of oxygen, beginning with the organs that have rapid oxygen use like the brain and heart. This is how carbon monoxide disrupts oxygen delivery in the body.


When the CO bind with the hemoglobin it produces COHg, called carboxyhemoglobin. The carboxyhemoglobin levels are what’s tested in the hospital to determine how severe the CO poisoning is.


CO Poisoning Symptoms

Many of the signs and symptoms of CO poisoning are a result of oxygen starvation in the different body systems.


The signs and symptoms of carbon monoxide poisoning are variable and non-specific.


Many of us were taught that “cherry red skin” is a classic sign of carbon monoxide poisoning. However, anyone exposed to these patients knows that cherry red skin rarely occurs, and when it does it will usually occur very. Often it’s a late sign that happens when the patient is nearing death.


The more common CO poisoning symptoms are hard to differentiate from the flu, gastroenteritis and other viral illnesses.


EMTs and paramedics will need to be aware of the patient’s surroundings, on scene clues, time of year and the signs and symptoms of CO monoxide poisoning to recognize this emergency in the field.


Common Signs and Symptoms of CO Poisoning

  • Headache
  • Nausea
  • throwing up symptom of CO poisoningVomiting
  • Diarrhea
  • Fatigue
  • Dizziness 
  • Weakness
  • SOB
  • Irritability
  • Confusion
  • Tachypnea


Look at the CO poisoning symptoms above and you can see why food poisoning is a common misdiagnosis for these patients. Patients are also mistaken as having flu’s and other viral illnesses.


A clue for first responders is that the patient won’t have a fever as you would expect with a viral infection. 


Signs and Sx of Severe CO Poisoning

Severe poisoning can have more obvious carbon monoxide effects, making it a bit easier to identify in the field.


  • Tachypnea
  • Pulmonary Edema
  • Respiratory Arrest
  • Hypotension
  • Altered mental statusFigure in Tri-pod position due to trouble breathing
  • Cognitive Impairment
  • Confusion 
  • Ataxia
  • Memory loss
  • Convulsions
  • Siezures
  • Chest pain
  • Heart Palpitations
  • Arrythmias
  • Myocardial Ischemia
  • Myocardial Infarction 
  • Loss of Consciousness 
  • Coma
  • Death  

Individuals who are sleeping or intoxicated can pass away from carbon monoxide exposure before exhibiting any symptoms.


Long Term Symptoms & Effects

Patients who experience chronic or severe carbon monoxide poisoning can end up with delayed and long-term symptoms. The patient can recover from the initial incident and then develop neuropsychiatric symptoms days or weeks later.

These symptoms can be subtle or severe and can get better with time or become permanent.


The long-term symptoms are serious and can include:

  • Behavior changes
  • Personality changes
  • Cognitive deficits
  • Memory loss
  • Decreased brain function
  • Headaches
  • Vision loss
  • Lack of coordination


Recognizing CO Poisoning Clues

The signs and symptoms of carbon monoxide poisoning are variable and non-specific which makes this medical emergency difficult to recognize, unless you are told by dispatch.


However, you can maintain a high level of suspicion and pay attention to clues in the field that indicate the possibility of carbon monoxide exposure. After all, the patient will be released back to their home and get exposed to the CO again if the leak isn’t recognized by a professional.


Remember that many CO poisoning symptoms look like flu symptoms. The patient may or may not also have memory issues and poor coordination. When patients present with these common issues keep an eye out for these  warning signs that there might be something else going on.


• Does the patient have flu symptoms but never had a temperature?

• Is there more than one person suffering with symptoms in the home? Did elderly, infants, chronically ill, and even pets get hit the worst?

• Poor areas during cold weather may be desperate for heat. Pay attention to symptoms and don’t be afraid to ask the patient how they are warming the home. People may bring BBQ grills or other heat sources inside. (I’ve seen homes using the four gas burners and an open oven for warmth.)

• Are all the windows and doors closed indicating poor ventilation?

• Do you see or hear generators running too close to the home?

• Check for CO detectors in the home, but keep in mind the batteries may be dead.


Keeping an eye out for extra clues can provide help to the patient and E.D. about what’s going on with your patient. For example, noting that the patient was found with all windows closed and using gas burners and oven for warmth can indicate to the E.D. the need to run a carboxyhemoglobin test. 


Sources of Carbon Monoxide Infographic


Carbon Monoxide Sources

When combustion takes place in the presence of low oxygen there is the potential to create carbon monoxide. There are some types of devices and times of year that are more likely to cause CO poisoning. For example, many carbon monoxide poisonings occur due to storms and power outages.


Many exposures to CO occur the second or third day after an outage and are caused by generators.  


Furnaces are the most common cause of CO poisoning.


In the past automobiles were more likely to cause carbon monoxide death. Government regulations were put in place that required automobiles to have a catalytic convertor and they decreased the carbon monoxide death rates by 80%.

Here are common source of carbon monoxide:

  • Automobiles
  • Generators
  • Heating systems
  • CO poisoning risk from LawnmowerStructural and wild fires
  • Gasoline engines
  • Snowblowers
  • Chainsaws
  • Furnaces
  • Boilers
  • Poorly vented chimneys
  • Kerosene space heaters
  • Charcoal Briquettes 
  • Hibachi Grills
  • Gas Clothes Dryers
  • Water Heaters
  • Propane stoves
  • Power washers
  • Boats
  • Spray paint/paint removers
  • Solvents and degreasers


Carbon monoxide from any of these sources can build up in enclosed or semi-enclosed spaces like rooms, homes or apartments. Breathing it can poison multiple people and any animals in these spaces.


→ Carbon monoxide is found in combustion fumes from automobiles, generators, heating systems, and even fires.

→ Fire fighters are at risk of carbon monoxide poisoning from structural and wild fires.


Causes of High Carbon Monoxide Levels?

Carbon monoxide can build up in enclosed, semi-enclosed and even open air locations, putting people and families at risk for injury or even death.


Generator risk of Carbon monoxide poisoning


  • Generator location – placing a generator in the garage, a shed, a basement, a carport, under the deck or too close to an open window is a factor for CO poisoning.
  • A furnace that is faulty or damaged. 
  • Using cooking appliances for heating purposes.
  • A chimney that has become partially or completely blocked.
  • Warming up the car by running it in the garage.
  • Use of gas powered tools like power washers and lawnmowers.
  • Smoke inhalation at a wild fire.
  • Using a BBQ grill in the garage.
  • Swimming near the back of a motorboat.
  • Burning a fire in an enclosed or poorly ventilated space. 


Carbon Monoxide Poisoning Treatment

For EMTs and paramedics the biggest barrier to treating carbon monoxide poisoning in patients is recognizing the problem. Treatment is fairly simple and straightforward when you are sent on a call for carbon monoxide poisoning.


However, being able to recognize on scene clues for CO exposure is the difference between being an average EMT and a good EMT.


Once you suspect or know there is carbon monoxide present, immediate action is necessary to get yourself and the patient to a safe area. Basic Life Support units (BLS) and Advanced Life Support (ALS) units will treat CO poisoning differently based on expertise, but the foundation of treatment is the same for both EMTs and paramedics.  


EMT CO Poisoning Treatment


Remove self and patient from exposure area.

Important: Are there other people inside? Evacuate.

Are there possible secondary victims? Initiate Fire Department to search area.

Administer 100% oxygen via non-rebreather mask.

Begin transport immediately.


Include the time your patient was removed from the carbon monoxide exposure and placed on oxygen in both the written and verbal reports. Doctors will need to know how long the patient has been out of the toxic environment when evaluating the patient’s carboxyhemoglobin levels.


Do Carbon Monoxide Levels Effect Pulsox Readings?

You might be wondering how all this will effect your patient’s O2 Sat reading. After all, they are basically suffocating from a lack of oxygen during severe carbon monoxide poisoning. Unfortunately, traditional pulse oximeters are of little value when measuring for CO poisoning.


The pulse oximeter can only differentiate between hemoglobin which is bound, and therefore saturated, and hemoglobin which is unbound and available to transport oxygen. The pulse oximeter can not differentiate hemoglobin bound with oxygen molecules versus carbon monoxide molecules.


Since CO loves binding with hemoglobin the pulsox will report a good oxygen saturation in CO poisoning patients. Ideally, these patients would be measured using a much more expensive CO-oximeter instead.


Paramedic CO Poisoning Treatment


Provide EMT treatments above along with the following as needed.

Assess for airway support and ventilate or intubate as needed.

Blood pressure support with Vasopressors and NS via IV may be needed. Hypotension can indicate myocardial dysfunction.

Perform 12 lead EKG, checking for CO poisoning cardiac complications.

Be ready for seizure treatments as needed.

In patients with altered mental status the Blood Glucose should be checked and corrected.


If hyperglycemia is found in a CO poisoning patient it needs to be treated immediately. Hyperglycemia has been shown to exacerbate the central nervous system damage done by CO. 


The fundamental carbon monoxide poisoning treatment is 100% oxygen via non-rebreather mask.


Oxygen administration is a necessary treatment and will likely continue until the patient’s symptoms resolve, which often takes about 4-6 hours. Oxygen therapy is proven to speed up the elimination of carbon monoxide from the body, which will decrease the longterm neurological effects of CO poisoning.


Patients with moderate to severe carbon monoxide effects will likely be treated in the hospital using hyperbaric oxygen therapy.


hyperbaric chamber carbon monoxide poisoning treatment
Hyperbaric Oxygen Chambers


Removing symptomatic individuals from carbon monoxide exposure to fresh air is not good enough because the CO atoms will stay attached to the hemoglobin and can result in longterm cognitive effects. They need treatment after exposure.


Prevention of Carbon Monoxide Poisoning


There are steps you can take to prevent carbon monoxide leaks including getting annual maintenance on your appliances, having the chimney swept annually and other routines.


Anyone who doesn’t have the financial ability to keep up the maintenance and annual checks for water heaters, furnaces, ovens, etc. every year, should at least have CO detectors placed in their home.


→ Purchase and place carbon monoxide alarms to detect problems before they become emergencies.

→ Get regular maintenance on appliances, furnaces, boilers, chimneys, etc.

→ Don’t burn charcoal in the garage or any other enclosed space.

→ Don’t warm up automobiles in a closed or open garage. The NFPA says vehicles should be removed from the garage once turned on.

→ Don’t run gas engine tools in poorly ventilated areas.

→ Keep your home well ventilated and don’t block off the air vents.

Wear a mask when working with solvent, spray paint and other products that contain methylene chloride.

During power outages don’t place generators within 20 feet of the home or near windows.

Don’t swim near the back of boats with the engine on, this includes sitting on the swim step.

→ Avoid using gas powered tools inside. If you have to use them, keep the area well ventilated and try to place the engine and exhaust units outside.

Don’t use tape to repair vent pipes. It can allow CO to leak through.

Check that appliance and fireplace vents are not blocked during and after snowstorms.

Check that automobile tail pipes are not blocked by snow after and during snowfall.


Vehicle in Snow clear tailpipe


Detecting carbon monoxide in the environment is simple with inexpensive detectors available to keep families safe. Carbon monoxide alarms can be purchased locally or online and many states have made them a requirement in homes, like smoke detectors.


If you’re an EMT or paramedic reading this, I highly recommend you have them installed and encourage your family to get them too. I recently bought first alert carbon monoxide detector and smoke alarm combos for family members and installed them.


I recommend installing the CO alarms for older family members in a place where they can hear the alarm if it goes off while they are sleeping.


Carbon Monoxide Alarm

Everyone should at the very least have carbon monoxide alarms placed in their homes. You can even purchase combination smoke and carbon monoxide detectors to take care of two safety issues with one device.


It is recommended that appliances, heating systems, boilers, chimneys, etc. are regularly serviced by a professional and CO detector placement is not a substitute for that maintenance.


First alerst carbon monoxide detector and smoke alarm


Where to Place Carbon Monoxide Detector

Below are general guidelines for CO detector placement, but it’s always best to follow the installation directions that come with your specific device.


How many CO detectors do I need? How many CO detectors you need depends on the size of your home and how many levels it has. Here are some tips to help you decide how many carbon monoxide detectors to place in your home.


  1. There should be at least one CO detector on each level of your home. Ex: Basement, 1st floor and 2nd floor.

  2. There should be one carbon monoxide alarm in each room somebody sleeps in, especially a room directly over the garage.


If this adds up to more alarms than you want to purchase right now, don’t give up on CO detection. Having at least one CO alarm in the house is better than having none. One CO detector will give you a way to detect if CO poisoning is happening, and you can always buy more CO detectors later.


I strongly encourage everyone to have at least one carbon monoxide detector in their apartment, house or home for safety. If you don’t want to buy online, check your local hardware store, Lowes, Home Depot or even a Target store. 


CO Detector Placement in the Room


Where you place the carbon monoxide detector in your room with depend on what kind of device you get. Always follow the manufactures directions for installation, but here are some tips to help.

Plug In Carbon Monoxide Detector – These devices are easy to place because you plug them into an open plug outlet in the room. They will be lower in the room which is safe for CO alarms. Always put batteries in for back up because many CO poisonings occur during power outages.


Battery Carbon Monoxide Detector – If outlets are valuable real-estate in your home, like they are in mine, you might want a more traditional battery operated carbon monoxide alarm. Recommendations vary for placement, but many say to place them anywhere on the wall from about 6 inches up from the floor to 6 inches down from the ceiling. CO is slightly lighter than air and dissipates around the room like air, but it can take higher levels before it pools on the ceiling.

The detector linked above is also a free-standing table top CO detector, so it can be mounted or simply placed on a shelf.


Smoke and Carbon Monoxide Detector – This is a great option if you want to take care of both smoke and carbon monoxide detection with one device. I use the First Alert Carbon Monoxide Detector and Smoke Alarm in one and my biggest challenge was placement.

Smoke alarms are recommended to be high in the room and are often placed on the ceiling, but it’s recommended not to place CO alarms on the ceiling.

I found that placing the combination smoke and CO detectors about 6 to 8 inches down from the ceiling is a good compromise that allows both alarms to do their jobs well.


If your CO detector has a digital screen, place it at eye level.

→ Place carbon monoxide detectors 15 feet away from kitchen appliances, furnaces, water heaters and fireplaces to avoid frequent false alarms.

→ Don’t place CO alarms behind curtains or furniture that can prevent CO from reaching the sensor.

→ The CO alarms are meant to work within specific humidity and temperature ranges. Don’t place them in bathrooms, direct sunlight, or near appliances that give off heat. 


Common Questions

What is carbon monoxide? It’s a colorless, odorless and tasteless gas that is created during combustion.

Does carbon monoxide rise? Carbon Monoxide is slightly lighter than air and it will diffuse evenly throughout the room like air.

Does carbon monoxide smell? No, it is an odorless gas.

Where to place a carbon monoxide detector? Carbon monoxide detector placement can be low on the wall in a plug, high on the wall or even at eye level if there is a digital screen. This is because CO spreads through the room like air. The carbon monoxide detector shouldn’t be placed near appliances which give off CO or you will end up with frequent false alarms.


Check these out for more EMT topics:


Treating Heat Exhaustion and Heat Stroke

A Guide For Auscultating Lung Sounds

35 Books for EMTs and Paramedics 



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