What Smoke Can Do to Your Body
Part 2: Hyperventilation, heat exhaustion and heart attacks
Continued from August Issue
From the preceding discussion, it is obvious that the atmosphere a fire fighter breathes may be harmful to him in a variety of ways. To prevent injuries of this type, fire fighters have adopted the use of respiratory protective devices, but these devices may fail to give protection against a hazardous atmosphere for a number of reasons. In fact, the design of some of this equipment is such that it may produce respiratory problems which would not be present without the equipment! The use of respiratory protective equipment must not lull the wearer into a false sense of security.
The use of a respiratory protective device may still leave the wearer liable to injury both from hypoxia and exposure to toxic gases. Filter cannister type masks may allow the wearer to become hypoxic if they are used in an oxygen-deficient atmosphere, if the cannister resistance is too high to allow a sufficient volume of air to enter, or if the carbon monoxide absorbent is exhausted or incapable of handling a higher than usual carbon monoxide concentration. Hypoxia may occur with users of self-contained breathing apparatus if the valves are faulty, the facepiece leaks or the cylinder becomes empty.
Breathing apparatus will not prevent exposure to toxic gases if the cannister is the wrong one for the gas encountered, if the concentration of gas exceeds the maximum which can be absorbed, if the equipment leaks or if the air tanks are charged with impure air.
Self-contained breathing apparatus offers the best all-round respiratory protection available to the fire fighter at this time because it protects him against all concentrations of all types of toxic gases and smoke in addition to providing an oxygen supply. The cannister mask is quicker, lighter, and less bulky, but it offers no oxygen supply and affords protection only against some gases in certain concentrations. In today’s world of plastics, chemicals and synthetic building materials and textiles, the fire fighter should not be content with a respiratory protective device which affords only the limited protection of a cannister mask.
Learn to spot symptoms
However, no device is of value, if it is not used or if it is removed before ventilation of the structure is complete. The tendency to use breathing apparatus only when dense visible smoke is present is dangerous, for lethal concentration of carbon monoxide or other gases may be present when there is little or no visible smoke. Once a device is put to use, the wearer must realize that it is not perfect, and he can still be exposed to the hazards of oxygen-lack and toxic gases. He and his officers should be taught to recognize the early symptoms of these conditions and take appropriate action. Too often, early symptoms of difficulty are ignored until an advanced stage is reached because everyone believes the man using some type of mask is protected against all respiratory hazards.
All situations I have discussed so far threaten a fire fighter’s health either by injuring the respiratory system directly or by gaining access to some other part of the body by means of the respiratory system. Fire fighters are also subject to another group of disorders or conditions which frequently masquerade as, or are confused with, respiratory problems.
The confusion arises because these disorders appear acutely in men working in the heat, smoke and tension of the fireground, and they produce the symptoms of collapse and labored or difficult breathing so often seen in patients with respiratory problems. These disorders, however, are not the direct result of exposure of the respiratory system to smoke or gases.
The first of these disorders has the medical name of hyperventilation syndrome, or simply, breathing too much. To understand this condition, we must remember that breathing not only brings oxygen into the body but also removes carbon dioxide from the body. The removal of carbon dioxide is never complete, and normally a certain amount of this gas is present in the bloodstream, where it serves the important function of regulating the acid-base balance of the body.
By breathing too deeply or too rapidly, or both, the victim of hyperventilation syndrome exhales too much carbon dioxide from the body, and this causes the blood to become less acid and more alkaline, resulting in disordered body functions. Especially affected are the functions of the nervous system. At first, numbness of the hands, feet and face occur, but as excessive breathing continues, there may be twitching of the muscles, loss of consciousness and even convulsions.
Effect of heat
Hyperventilation syndrome in fire fighters may be the result of fear and anxiety alone, and individuals who respond in this way to the stresses and tensions of the fireground are simply unsuited to be fire fighters. Men exposed to high temperatures tend to overbreathe or hyperventilate as the body attempts to eliminate heat by means of the respiratory tract, much as a dog pants on a hot day.
In my experience, hyperventilation in fire fighters is most commonly a delayed reaction following smoke exposure. These men apparently hold their breath or reduce their breathing during exposure in an effort to avoid breathing the smoke. Since a period of overbreathing normally follows an episode of breath holding, these men collapse from hyperventilation after they emerge into fresh air.
Hyperventilating individuals should not be given oxygen from a resuscitator, since this will only increase their breathing. They will recover quickly, however, if made to rebreathe their own exhaled air from an ordinary paper sack or rubber breathing bag, since this procedure will restore the carbon dioxide content of their blood to normal.
Another cause of collapse and difficult breathing may be confused with a true respiratory problem is heat exhaustion. These men lose enough water through perspiration to faint due to reduced blood volume, the condition commonly called shock. As has been mentioned, hyperventilation accompanies heat exposure and contributes to the patient’s difficulties.
The diagnosis and treatment of heat exhaustion can be difficult for the physician, but most of these cases are preventable if men working under conditions of high temperature will drink adequate quantities of water and learn to pace their activities so that they don’t attempt to do too much at once.
Heat is capable of damaging the respiratory system directly, but such injuries are rare in fire fighters. The respiratory tract can be burned by the inhalation of steam but not by the inhalation of dry, hot air or even flames because of the low specific heat of dry gases. Steam burns of the lungs resemble chemical burns of the lungs produced by pulmonary irritant gases but are much less common. In fact, I have never seen a steam burn of the lungs of a fire fighter, although I have seen them in fire victims. The possibility of producing steam bums of the lungs of trapped persons should be considered when using fog to extinguish interior fires because this procedure produces large amounts of steam.
The last condition which may masquerade as a respiratory problem or injury in a fire fighter is a heart attack. The collapse, chest pain and difficulty in breathing produced by an acute coronary occlusion can be easily confused with the symptoms of respiratory disorder, and the conditions of tension, heat, smoke and the necessity of heavy physical work which brings on heart attacks are the same ones which result in respiratory casualties. It may be genuinely difficult to tell the imposter from the real disease in some cases so that it is a good idea to have an electrocardiogram made on fire fighters who collapse on the fireground, especially if they are over 40 years of age or are known to have conditions which predispose to heart attacks, such as obesity or high blood pressure.
With so many respiratory and related disorders to confront us, what can be done to prevent fire fighters from sustaining this type of injury? I believe that now, today, we should provide every man with self-contained breathing apparatus and train him to use it properly. Once the equipment is available, it should be used regularly. The man who does not use the equipment should be looked upon as a fool rather than a hero who can “really get in there and take a beating.” The fire fighter today is exposed to an increasing number of toxic gases which make the “hero” approach too dangerous.
I believe that we should have closer cooperation between the medical profession and the fire fighter so that the knowledge now available about the causes of respiratory disorders and the methods of preventing and treating them can be more generally applied.
For the future, we should encourage research in several areas. Medicallyoriented research needs to be done on the composition of fire smoke and gas, the nature of the toxic agents present and their effects on human beings following both acute and chronic exposure. New and improved methods of treating exposed persons should be developed. The results of this research should be made available to physicians through their regular channels of information, such as medical journals and textbooks. At the present time, the medical literature contains almost nothing on these subjects, even though the technical literature of the fire service contains some excellent information.
There is also a need for medical and engineering research with a view toward developing self-contained breathing apparatus that is lighter and less bulky. If possible, this apparatus should be built into the fire fighter’s helmet and clothing so that it is constantly available.
I have presented a long and rather complicated list of respiratory problems and related conditions which may affect fire fighters. The important thing is that we cannot be content to label every man who collapses on the fireground as being “overcome by smoke.” Those of us who are responsible for the health of fire fighters must look beyond the smoke for the true causes of respiratory and related disorders so that we will be better able to prevent and treat this type of injury.