Smoke Inhalation

Smoke inhalation occurs when a person breathes in smoke from burning material or gases during a fire. Smoke inhalation is a leading cause of mortality due to fire, causing approximately 5000 to 10,000 deaths per year in the USA alone. 1

Smoke contains a mixture of harmful chemicals and irritants, though the exact composition depends on factors such as what is being burned, the temperature of the fire and the amount of oxygen feeding the fire. Inhaling smoke can cause the airways and lungs to become irritated, swollen and blocked, and may prevent oxygen from entering the bloodstream. If this happens, respiratory failure can occur. 2 Smoke inhalation requires immediate treatment to prevent complications.

The damage to the body inflicted as a consequence of smoke inhalation is often referred to as smoke inhalation injury.

Smoke inhalation generally occurs when an individual is trapped within an enclosed space during a fire. In most cases, it causes damage through asphyxiation (lack of oxygen) and irritation of the lungs and airways. 3

Fire can use up a significant amount of oxygen from the air, leaving less available to breathe. When this happens, asphyxiation can result. The presence of carbon monoxide in the smoke can make this particularly pronounced, as carbon monoxide takes up far more room than oxygen. Carbon monoxide is contained within carbon-containing fuels such as gas, wood, coal and oil.

Oxygen combines with the hemoglobin inside red blood cells to create oxyhemoglobin. As the red blood cells circulate around the body, oxyhemoglobin provides the body’s tissues with the oxygen they need to survive.

Carbon monoxide can also bind with hemoglobin to create carboxyhemoglobin. As smoke containing carbon monoxide is inhaled, carboxyhemoglobin begins to circulate around the body, causing the tissues to become increasingly starved of oxygen. As carbon monoxide binds roughly 200 times more tightly to hemoglobin than oxygen, this can happen even if there is only a small amount of carbon monoxide present. 3

A fire can create smoke containing a variety of chemical irritants and particles, i.e. unburned or partially burned materials small enough to enter the body, with the potential to cause significant damage to the lungs and airways. Such irritants include sulfur dioxide, ammonia, hydrogen chloride and chlorine. Breathing in these irritants and particles can cause blockage of the airways, inflammation and respiratory failure.

The symptoms of smoke inhalation will depend on what exactly has been inhaled (the composition of the smoke), and the duration of smoke inhalation. General symptoms, however, include: 2 4

• Coughing and hoarseness
• Irritated sinuses
• Shortness of breath, which may lead to total respiratory failure
• Chest pain
• Headache
• Stinging eyes or vision problems
• Runny nose
• Loss of consciousness
• Cardiovascular abnormalities, including cardiac arrest

If carbon monoxide is contained within the smoke, carbon monoxide poisoning may result. Symptoms of carbon monoxide poisoning typically differ depending on the length of time an individual is exposed and how much carbon dioxide is present. They may include: 5

• A tension-type headache
• Dizziness
• Nausea and vomiting
• Convulsions
• Increased heart rate
• Stomach pain
• Shortness of breath or difficulty breathing
• Respiratory arrest
• Soot in the nostrils and/or throat

Diagnosing smoke inhalation injury will typically first involve a doctor determining the source of the smoke, how long the individual was exposed to the smoke and the medical history of the individual. After this, a number of tests can be used to investigate the severity of the damage done by smoke inhalation. Due to the need for immediate treatment of smoke inhalation, diagnostic tests will usually take place after initial treatment has been given.

Tests used to determine the severity of smoke inhalation-related injuries include: 2 6

• Blood gas test: Used to measure the amount of carbon dioxide and oxygen in the blood, allowing doctors to determine how well the lungs are functioning. Also called an arterial blood gas test if the blood sample is taken from the wrist. 7
• Blood tests: A sample of blood will be taken and tested in a laboratory for information about the functioning of the body.
• Chest X-ray: Used to look for signs of damage to the lungs and for signs of infection.
• Bronchoscopy: A bronchoscope (tube with a light and camera attached) will be passed through the throat and into the airways to allow doctors to check for damage.
• Pulmonary function tests: A variety of different tests used to measure air flow and lung size, as well as how well oxygen and other gases enter and exit the blood. 8
• Lung VQ scan: An imaging test used to measure air flow in the lungs. Also known as a lung and pulmonary ventilation and perfusion scan. 9

The person experiencing smoke inhalation should be removed from the scene and taken to a location with fresh air as soon as possible. 3 This will usually be the responsibility of firefighters. Following this, oxygen at a high flow rate should be administered via a facemask. This will help to quickly increase the amount of oxygen dissolved into the bloodstream and prevent asphyxiation.

Once the individual has been removed from the scene and taken to a hospital, a number of treatment methods may be used. These include: 1 3 6 10

• Bronchoscopy: A bronchoscopy is used for both diagnostic and treatment purposes. Using a bronchoscope, a tube mounted with a light and camera, doctors are able to identify and remove particles and secretions lodged in the airways and lungs. Pain relievers or sedatives may be administered to the individual before the procedure takes place.
• Hyperbaric oxygenation: If the individual has been exposed to high levels of carbon monoxide, hyperbaric oxygenation may be used. This involves the individual being exposed to increasingly high levels of oxygen over a period of 60 to 90 minutes from within a specially designed chamber. This will help to increase the level of oxygen in the blood.
• Medications: Various medications, including antidotes, antibiotics to help prevent infection, steroids to open the airways and medications used to manage pain, swelling and fever may also be administered.

The inhalation of smoke can cause serious short and long-term health problems and should be considered a serious injury. The lungs may become infected, swollen or fluid-filled, something that can cause respiratory failure. This can lead to severe heart and brain problems and be potentially life-threatening. In the USA, smoke inhalation is the leading cause of death for victims of fire. 11

The prevention of smoke inhalation generally involves the prevention of fire. Each year in the USA, the highest percentage of fires occur in residential properties and over half of these are cooking-related. 12

Smoke alarms are critical to the early detection of a fire and should be fitted in every home, workplace and public building on each floor. Fire alarms should be tested regularly to ensure that they work as intended.

All buildings should also have an established escape plan for use in the event of fire. This should be reviewed periodically, memorized by the inhabitants or frequent users and practiced regularly.

Other fire prevention methods include ensuring that all burning materials – such as cigarettes, candles, stoves and fireplaces – are carefully monitored at all times and thoroughly extinguished after use. Heating systems should also be checked by a professional regularly and fixed if necessary.

It may also be useful to make a habit of unplugging all electrical appliances after use and ensuring there is no build-up of lint in the home’s dryer. It is also important to ensure all flammable or combustible materials, such as lighters, matches and oils, are kept out of the reach of children at all times.

• Smoke inhalation injury