Injury: Smoke Inhalation

Definition
Description
Demographics
Causes and Symptoms
Diagnosis
Treatment
Prognosis
Prevention
The Future
For more information

Definition

Smoke inhalation (SI) is a health problem and potential emergency caused by exposure to the heat and smoke of a fire; to the products of cigarette smoke; or to other sources of outdoor or indoor air pollution.

Description

Smoke inhalation occurs when a person is forced to breathe in (inhale) the toxic gases and particles carried in smoke from a fire, volcanic eruption, or industrial process. Smoke can arise from natural as well as human causes, ranging from lightning strikes, wildfires, and volcanic eruptions to house or building fires, fires following railroad or aviation disasters, pipeline or factory explosions, arson and other criminal acts, and traffic exhaust. Some people also choose to inhale smoke, as when they light up a tobacco or marijuana cigarette.

Smoke inhalation damages the respiratory system in one or more of three ways. First, the hot air from a fire can damage the mouth and upper

airway. This thermal injury can be even worse if the hot air is accompanied by steam. Second, a fire can starve the body of needed oxygen, either because the fire is using up the oxygen in a closed space, or because the fire is producing carbon monoxide and other gases that interfere with the blood's ability to transport oxygen to the brain and heart. Third, smoke often contains chemicals that irritate the tissues of the lungs, causing damage that ranges from triggering the body's immune system to complete direct destruction of lung tissue.

Demographics

Smoke inhalation, rather than burn injuries, is responsible for the majority of fire-related deaths in the United States. Between 50 and 80 percent of deaths related to house fires are caused by SI rather than burns. Fires are the third leading cause of accidental deaths in all age groups in the United States. Arson is the single most common cause of house fires (26 percent), followed by faulty electrical wiring (17 percent) and faulty heating systems (16 percent).

Some persons are at greater risk of serious injury from smoke inhalation, including:

• Firefighters and emergency workers.
• People in occupations that involve making or transporting hazardous materials.

• Children, who are susceptible to airway damage because their airways are still developing and they breathe more air per pound of body weight than adults.
• Elderly persons.
• People with asthma, bronchitis, emphysema, or other disorders that affect the lungs.
• People who are heavy smokers.
• People who are under the influence of drugs or alcohol.
• Persons who are physically disabled.

Smoke Inhalation and Personal Safety

Smoke inhalation, or SI, can be a serious threat to health. The Centers for Disease Control and Prevention (CDC) recommend the following steps in case of exposure to smoke in a fire or other emergency:

• Get away from the source of the smoke as quickly as possible. If in a building, avoid smoke-filled hallways or stairwells. If there are no other ways out of the building, stay as low to the floor as possible and crawl under the smoke toward the closest exit.
• Once in an area with fresh air, rest for a few moments and take several slow deep breaths.
• Do not return to a burning home or other building until the fire has been completely extinguished and all the smoke has cleared.
• Call the doctor if someone exposed to smoke feels feverish or develops a high temperature.
• Call for emergency help at once if the person is wheezing, having trouble breathing, is vomiting, has burns on the face, or seems confused or unusually sleepy. In addition, do not let the injured person try to drive himself or herself to the hospital.

Causes and Symptoms

Smoke inhalation causes injury or death by a combination of heat damage to the tissues of the mouth and upper throat; oxygen starvation of body tissues; and chemical damage to the tissues of the lungs.

Some fires are more dangerous than others in terms of the inhalation injuries they can cause. There are several factors that affect the potential deadliness of smoke from a fire:

• Temperature of the fire. The hotter the fire, the greater the thermal injury to the upper airway.
• Location of the fire. Fires inside closed spaces, such as houses or other buildings, aircraft fuselages, railroad cars, etc. use up the oxygen that people trapped inside the space need to breathe.
• Materials being burned. Plastics, silk, and wool all release cyanide gas when burned. This gas increases the risk of damage to the central nervous system.

The symptoms of smoke inhalation include:

• Cough. The patient will usually bring up mucus, which may be either clear or black (if it contains soot or smoke particles).

• Difficulty breathing, rapid breathing, or hoarse or noisy breathing.
• Reddened eyes.
• Abnormal skin color. Patients who are oxygen-starved may have pale or bluish skin. A cherry-red color may indicate carbon monoxide poisoning.
• Soot in the nostrils or upper throat.
• Headache.
• Nausea and vomiting.
• Changes in level of mental alertness or consciousness. Patients who have been severely affected by smoke inhalation may faint, have seizures, or go into a coma.

In some cases the symptoms of smoke inhalation do not appear until a day or two after the fire. People who have been exposed to smoke but seem healthy should be observed or monitored at home for at least forty-eight hours after the fire. The doctor should be called if the person develops a hoarse voice, chest pains, long periods of coughing, or mental confusion.

Diagnosis

The diagnosis of smoke inhalation is based on a combination of the patient's history (which will be obvious if he or she has left or been rescued from a fire) and imaging or laboratory studies. Emergency rescue personnel can check the patient at the scene for evidence of facial burns, soot in the airway, and other external signs of SI. They can also measure the patient's breathing, pulse, and level of consciousness.

After the patient has been taken to the hospital, he or she will usually be given a chest x-ray to check for lung damage; an electrocardiogram to make sure that the heart is functioning adequately; and blood tests to measure the amount of oxygen in the blood or the presence of chemical byproducts of smoke inhalation. The doctor may also use a bronchoscope (a flexible lighted tube that allows the passages into the lungs to be examined and have fluid removed) to look for damage to the respiratory system. In a few cases the patient may be given a CT scan to assess possible brain injury.

Treatment

Treatment is based on the severity of the patient's injuries, as SI can range from minor irritation of the tissues lining the airway to an immediate threat to life. The most important emergency measure is keeping the airway open

and supporting the patient's breathing. The patient will be given oxygen through a mask or a tube inserted down the throat. The patient may also be given brochodilators, which are medications that relax the tissues in the airway and help to open up the breathing passages. Patients who have inhaled large amounts of carbon monoxide may be put in a hyperbaric oxygen (HBO) chamber, a special room in which the patient is given pure oxygen at two to three times normal atmospheric pressure.

Treatment of SI may also include suctioning of excess fluid from the lungs by means of a bronchoscope. This instrument can be used for treatment as well as diagnosis of SI.

Patients with mild symptoms from SI are usually kept in the emergency room for observation after treatment for four to six hours. They are advised to return to the hospital at once if their symptoms return or worsen. Those who were exposed to fire in a closed space for longer than ten minutes, have coughed up black mucus, have facial burns, are coughing severely, or have difficulty swallowing are usually admitted directly to the hospital for further treatment.

Prognosis

The prognosis of recovery from smoke inhalation depends on a number of factors, including the patient's age, previous health, the length of time one was exposed to the smoke, and whether he or she was burned in addition to inhaling smoke. The mortality rate from smoke inhalation by itself is about 7 percent; however, the mortality rate is about 29 percent for patients who suffer burns as well as SI.

Some people may have chronic shortness of breath or permanent scarring of the lungs following smoke inhalation. These long-term problems are particularly likely to develop in people who smoked, or had asthma or other lung disorders before being exposed to smoke from a fire.

Prevention

The CDC recommends the following measures to reduce the risk of illness or death from smoke inhalation:

• Install fire, smoke, and carbon monoxide detectors in the home and check them regularly. The absence of a smoke detector increases the risk of death in a fire by about 60 percent.
• Follow local air quality reports; listen for news reports about smoke or outdoor air pollution.

• If the local air quality index indicates that people should stay indoors, indoor air should be kept as clean as possible. Keep doors and windows closed. In hot weather, run the air conditioner with the fresh-air intake closed.
• Do not add to indoor air pollution by smoking or by burning wood in fireplaces when outdoor air quality is poor.
• Make an escape plan for the home to be followed in case of fire. Practice the escape route with the family, including evacuating pets.

The Future

The United States has one of the highest rates of fire fatalities in the developed world—about 2.3 deaths per 100,000 population. A majority of these deaths are due to SI rather than burns. In addition to installing and properly maintaining smoke detectors and alarms, better methods of screening patients for injury from smoke inhalation are needed. One ongoing difficulty with emergency treatment of fire victims is the present lack of tests that are sensitive enough to identify patients who develop delayed reactions to smoke inhalation.

SEE ALSO Asthma; Bronchitis; Carbon monoxide poisoning; Emphysema; Smoking

WORDS TO KNOW

Arson : The intentional setting of a fire in a building or other property. Arson is a criminal act in the United States.

Bronchodilator : A type of medication that relaxes the tissues of a congested or smoke-damaged airway, thus making it easier for the patient to breathe.

Bronchoscope : A flexible lighted tube that can be inserted into the passages leading to the lungs for examination or treatment.

Hyperbaric oxygen (HBO) : Oxygen that is delivered to a patient in a special chamber at two to three times normal atmospheric pressure.

Inhalation : The part of the breathing cycle in which a person takes in air from the outside.

For more information

BOOKS

Barraclough, Sue. Fire Safety. Chicago: Heinemann Library, 2008.

Donahue, Jill Urban. Contain the Flame: Outdoor Fire Safety. Minneapolis: Picture Window Books, 2008.

WEB SITES

Centers for Disease Control and Prevention (CDC). Emergency Preparedness and Response: Wildfires. Available online at http://www.bt.cdc.gov/disasters/wildfires/ (updated April 29, 2007; accessed May 28, 2008).

eMedicine Health. Smoke Inhalation. Available online at http://www.emedicinehealth.com/smoke_inhalation/article_em.htm (accessed May 28, 2008).

National Heart, Lung, and Blood Institute (NHLBI). How the Lungs Work.Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/hlw/hlw_all.html (accessed May 28, 2008). This page includes an animation with voiceover that describes the respiratory system and its role in the exchange of oxygen and carbon dioxide in the body. The animation takes about three minutes to play.