Carbon monoxide (CO) poisoning can cause a range of symptoms, from minor to severe, depending on the level and duration of exposure. In the early stages, low to moderate CO poisoning can feel similar to the flu, with headaches, dizziness, nausea, fatigue, and confusion. More severe poisoning leads to increasingly serious symptoms like chest pain, shortness of breath, impaired vision and coordination, and even unconsciousness and death.
What are the early symptoms of CO poisoning?
At lower concentrations in the early stages, the symptoms of CO poisoning are often described as “flu-like.” Common early symptoms include:
- Headache
- Dizziness
- Nausea
- Vomiting
- Fatigue
- Weakness
- Confusion
- Impaired judgment
- Difficulty concentrating
- Shortness of breath during exertion
These symptoms can feel similar to the flu, food poisoning, or other illnesses, so CO poisoning is often misdiagnosed initially. The difference is that CO poisoning symptoms tend to improve when you leave the area with the CO and get fresh air.
How do the symptoms progress with moderate CO poisoning?
As exposure continues at moderate levels, symptoms become more pronounced and serious:
- Worsening headache
- Dizziness
- Nausea and vomiting
- Racing heart rate
- Confusion and disorientation
- Visual disturbances
- Difficulty walking or impaired coordination
- Chest pain and shortness of breath
- Irregular breathing
- Ringing in the ears
At this stage, symptoms may come and go but tend to get progressively worse without treatment. A cherry red appearance of the skin is a common sign of moderate CO poisoning.
What are the symptoms of severe CO poisoning?
At high concentrations, CO is extremely dangerous and can lead to unconsciousness and death. Severe symptoms include:
- Confusion and irrational behavior
- Extreme dizziness and loss of coordination
- Weakness to the point of paralysis or collapse
- Shortness of breath and increased heart rate
- Seizures
- Unconsciousness
- Coma
- Death
The level of CO in the environment determines how quickly these symptoms set in. Even brief exposure to very high CO levels can be immediately fatal. Otherwise, severe symptoms tend to develop after several hours of moderate CO poisoning.
Are the symptoms different in children and pregnant women?
Yes, children and pregnant women are at higher risk for CO poisoning and may show symptoms more quickly. Signs to watch for include:
- Infants: lethargy, irritability, seizure
- Children: confusion, clumsiness, dizziness, weakness
- Pregnant women: headache, dizziness, confusion, nausea, shortness of breath
Chest pain and seizures can occur in children and pregnant women even with low-level exposure over an extended time. The fetus is also vulnerable, so CO poisoning during pregnancy may lead to miscarriage, low birth weight, birth defects, or fetal death.
Can CO poisoning cause long-term symptoms?
Yes, moderate to severe CO poisoning can result in delayed neurological symptoms that may persist or reoccur for weeks to years after the initial exposure. These can include:
- Memory and cognitive difficulties
- Loss of coordination
- Visual disturbances
- Headaches
- Dizziness
- Mood and personality changes
- Speech abnormalities
- Dementia
- Parkinson’s disease-like syndrome
- Sensory and motor deficits (numbness, weakness)
Severe CO poisoning can also lead to brain damage from temporary oxygen deprivation in the brain. This can have lasting effects on cognitive, emotional, and motor function.
What causes the symptoms of CO poisoning?
The symptoms of CO poisoning stem from the way carbon monoxide interferes with the ability of hemoglobin in the blood to transport and deliver oxygen throughout the body. Specifically:
- CO binds to hemoglobin 200-300 times more readily than oxygen.
- CO occupies the hemoglobin binding sites, displacing oxygen and forming carboxyhemoglobin.
- Carboxyhemoglobin does not release oxygen effectively to tissues in the body.
- The resulting lack of oxygen causes the tissues to become hypoxic and malfunction.
- The brain, heart, and other vital organs are most affected by the oxygen deprivation.
The headaches, dizziness, confusion, and cognitive issues stem from the brain’s oxygen starvation. Meanwhile, the chest pain and shortness of breath are caused by oxygen deprivation in the heart and cardiovascular system. At high levels, hypoxia can lead to seizures, coma, and death when the vital organs fail.
How do doctors test for CO poisoning?
Doctors can use several methods to confirm CO poisoning:
- Blood tests: Measure carboxyhemoglobin levels in the blood, with levels above 3% indicating CO exposure.
- Breath test: Detect exhaled CO gas to estimate blood carboxyhemoglobin levels.
- Skin color: Cherry red skin discoloration indicates carboxyhemoglobin levels above 10-15%.
- Pulse CO-oximetry: Monitors blood oxygen saturation and heart rate as indications of hypoxia.
- Neuropsychological tests: Assess cognitive function and changes indicating neurological damage.
Doctors also consider reported symptoms, with a headache being the most common early symptom. A careful history of potential CO exposure provides important clues, along with physical examination findings like confusion and lack of coordination.
What is the treatment for CO poisoning?
Treatment involves removing the person from CO exposure and providing supplemental oxygen to restore normal oxygen levels. Other treatment approaches include:
- 100% oxygen via face mask or hyperbaric oxygen therapy in a specialized chamber.
- Monitoring of vital signs and blood carboxyhemoglobin levels.
- Treatment of any seizures or cardiac abnormalities.
- Neuropsychological evaluation to assess for cognitive deficits.
- Long-term cognitive and motor rehabilitation as needed.
In severe cases, treatment in an intensive care unit may be required along with breathing support through a ventilator. Resulting brain damage, heart problems, and other complications also need to be managed after initial treatment.
What are the main causes of CO poisoning?
The most common sources of dangerous CO exposure include:
- Gas appliances and heating systems with incomplete combustion or inadequate ventilation
- Blocked chimneys or exhaust vents on furnaces, water heaters, stoves, etc.
- Portable gas or charcoal grills used indoors
- Gasoline engines in indoor areas (mopeds, generators, etc.)
- Running vehicles in attached garages
- Gas or kerosene space heaters indoors
- Certain industrial equipment exhausts
- Tobacco smoke
- Building fires
Faulty or misused gas appliances are responsible for most household CO poisonings. Fuel-burning devices and engines should never be used indoors or in enclosed areas where dangerous CO can accumulate and be inhaled.
How can you prevent CO poisoning?
Safety tips for avoiding CO poisoning include:
- Installing CO detectors on every level of the home according to manufacturer instructions.
- Having furnaces, heaters, chimneys, flues, and exhaust vents inspected annually by professionals.
- Never using gas ranges, grills or generators indoors.
- Never idling vehicles in the garage, even with the garage door open.
- Opening windows when using kerosene space heaters indoors.
- Avoiding use of gas stoves for heating purposes.
- Knowing symptoms of CO poisoning and seeking medical attention if they appear.
Proper appliance maintenance, ventilation, and use of CO detectors can prevent many poisonings. Being aware of symptoms and quickly getting out of the environment if CO leakage is suspected can also save lives.
What is the prognosis after CO poisoning?
The prognosis depends on the degree and duration of exposure. Mild, brief low-level exposures may cause flu-like symptoms that resolve fully. However, the prognosis worsens with moderate to severe poisoning, including:
- Moderate poisoning can take weeks to months for recovery, and may result in lasting neurological deficits.
- Severe poisoning often causes coma along with damage to the brain, heart, and other organs, which can be permanent.
- Delayed post-hypoxic leukoencephalopathy syndrome can occur weeks later, causing progressive neurological deterioration.
- Up to 6% of people acutely poisoned die from CO exposure.
- Survivors of serious poisoning have a higher risk of cognitive impairment, personality changes, movement disorders, and brain damage leading to dementia.
Repeated low-level CO exposure such as from an occult leak can also lead to chronic symptoms and health issues. Educational and neuropsychological deficits are particular concerns for poisoning in children. Overall, the prognosis depends strongly on the duration and intensity of exposure.
Conclusion
Carbon monoxide poisoning can produce flu-like symptoms initially but lead to potentially fatal brain and heart damage at higher concentrations. Early warning signs like headache, dizziness, and confusion are important to recognize so that exposure can be removed. CO detectors, proper ventilation, and safe operation of fuel-burning appliances are key to preventing poisoning. While mild exposures may cause temporary symptoms, severe poisoning carries significant risk of permanent neurological deficits or death in certain cases.