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Carbon Monoxide Poisoning

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Carbon Monoxide Poisoning J R Army Med Corps: first published as 10.1136/jramc-73-02-02 on 1 August 1939. Downloaded from 79 CARBON MONOXIDE POISONING: A REVIEW. By BREVET LIEUTENANT-COLONEL A. E. RICHMOND, O.B.E., Royal Army Medical Corps. CARBON monoxide, together with the dioxide, occurs in the combustion of organic matter, and the less oxygen there is available the greater the proportion of carbon monoxide produced. It is colourless and odourless, and on these accounts its presence is normally only detectable by the symptoms it causes, which adds much to the risk of poisoning from it. It it also inflammable and in strong concentration may give rise to explosions. It has been recognized as a poison since ancient times, and has assumed special importance within the last half-century owing to the increased amounts of it produced consequent upon the augmented use of gas for by guest. Protected copyright. illuminating, cooking, and heating purposes, and upon the introduction of the internal combustion engine. It is the favourite means of the suicide to encompass his aim, while accidental poisoning with it frequently occurs. From a military point of view carbon monoxide intoxication is a subject which deserves the close attention and study of all military medical officers in these days of intensive mechanization, and unlimited employment of explosives; and the object of the writer is to lay before his readers in as concise and compact a form as possible those details of moment in connexion with the various aspects of this important subject. In endeavouring to attain this object references have been made to certain publications dealing with carbon monoxide poisoning. These references are clearly indicated, so that those desirous of making a more detailed study of the matter may have available the same assistance as has http://militaryhealth.bmj.com/ been at the disposal of the author and which he most gratefully acknowledges. Carbon monoxide enters the body through the lungs and by no other means. Drinker [1], in his recently published and most valuable book on the subject, quotes observations by Sendroy Liu and Van Slyke which appear to have established the affinity of carbon monoxide for hremoglobin compared with that of oxygen as being in the proportion of 210: 1. This is a sig­ nificant fact, and the ease with which the carbon monoxide is taken up by hremoglobin is the essential feature of the toxic syndrome. The oxygen-carrying capacity of the blood is in this way interfered with to a greater or less degree, and in severe cases of poisoning disastrous and on September 27, 2021 enduring states of anoxremia may arise with all their resultant adverse effects. It will be realized also that this amazing affinity of carbon monoxide for hremoglobin is an obvious explanation of the occurrence of cases of poisoning in individuals exposed to comparatively low concentrations of the gas. J R Army Med Corps: first published as 10.1136/jramc-73-02-02 on 1 August 1939. Downloaded from 80 Oarbon Monoxide Poisoning The combination of carbon monoxide with hremoglobin is very slowly reversible, and oxygen will displace it when the individual is removed from the poisonous atmosphere. This is due to the mass action of the oxygen in the air, and the process may be accelerated by the administration of pure oxygen in the usual way. Carbon dioxide exerts a benevolent influence, as this gas affects the combination of both oxygen and carbon monoxide with hremoglobin, which is less able to hold these gases as the carbon dioxide increases. Hence the importance of the administration of carbon dioxide in treatment as it acts not only by aiding the dissociation of carbon monoxide from hremoglobin, but also by stimulating the respiratory centre. When non-fatal concentrations of carbon monoxide are present in the air breathed, the partial pressure in the blood gradually reaches a state of equilibrium with that in the air, and so the blood concentration is prevented from reaching a lethal height. As an example of this, with an­ atmospheric percentage of 0·05 the maximum hremoglobin saturation with by guest. Protected copyright. carbon monoxide produced will be 40 per cent, which will be attained in practically four hours. Perhaps of special importance from a military point of view is the effect of the low barometric pressures, which may be found at great heights, on the absorption of carbon monoxide by the blood. Such influence is clearly adverse owing to the reduction in partial pressure of the oxygen due to the carbon monoxide taken up coupled with that consequent upon the low barometric reading. This will serve to emphasize the danger of subjecting persons to carbon monoxide at high altitudes. It should be noted that mice and small birds die more quickly from carbon monoxide poisoning than men, owing to the fact that their volume of breathing per minute compared with the total volume of their blood is greater than in the case of man, and it is stated that the average man ought to be able to remain in an atmosphere with a given concentration of carbon http://militaryhealth.bmj.com/ monoxide twenty times as long as a canary~ It appears to have been definitely established that carbon monoxide inhaled in small amounts over periods of time has the power to increase the red cells and the amount of hremoglobin in the individual [2]. The augmentation of the erythrocytes is thought to be due in the early stages to contraction of the spleen, but it would seem that later true -new red cell formation definitely occurs in the bone-marrow. Finally, the fact must not be lost sight of that on cessation of respiration the excretion of carbon monoxide also ceases, and that evidence of it in the blood may be found for months or even years afterwards. on September 27, 2021 DANGEROUS PERCENTAGES OF CARBON MONOXIDE. In considering this aspect of the subject with which we are dealing, realization of the fact that given concentrations of carbon monoxide in the atmosphere will not affect every individual equally is essential. Not only J R Army Med Corps: first published as 10.1136/jramc-73-02-02 on 1 August 1939. Downloaded from A. E. Richmond 81 do individuals vary in their reactions to this gas, but other modifying influences in the situation are also frequently present. It is also important to realize that dangerous precentages of carbon monoxide will never be reached in open spaces owing to the rapid diffusion of the gas, and that risks from it only arise in enclosed spaces, or in semi­ enclosed in which ventilation is inadequate or stagnation of air exists. Individual susceptibility depends to some extent upon age, and Drinker emphasizes that the very young and very old are at greater risk than others. " The Medical History of the War" [3] states that young men were more susceptible to carbon monoxide than those over 40, due apparently to their greater elasticity of chest wall and deeper inspiration. Although there may be some doubt as to the influence exerted by sex, there appears to be no question that pregnant women are more liable to fall victims to poisoning by carbon monoxide than others. Such abnormal bodily conditions as anffimia, heart disease, asthma, chronic bronchitis, alcoholism and narcotism have a material and detri­ by guest. Protected copyright. mental effect in carbon monoxide intoxication, while of prime importance is the extent of any bodily activity taken in the poisoned atmosphere. In this connexion Drinker quotes certain experiments by Sayers, Meriwether and Yant, [4] which illustrate the effect of rest and strenuous exercise respectively on carbon monoxide absorption. These investigations showed that persons at rest breathing 0·02 per cent of the gas developed 16 to 20 per cent hffimoglobin saturation with mild subjective symptoms at the end of six hours. On the other hand, an individual exercising strenuously in 0·025 per cent of carbon monoxide had 14 to 16 per cent saturation in one hour with moderate subjective symptoms. These experiments serve to emphasize the consideration we must give to the degree of activity of the soldier or anybody else in an atmosphere containing carbon monoxide, if we are to assess correctly the extent of the risk. http://militaryhealth.bmj.com/ As regards atmospheric conditions, low barometric pressure is a factor of considerable moment, and the intake of carbon monoxide at the low pressures of great altitudes will have infinitely more rapid and serious results than would be the case at normal heights. Hence the great necessity for efficient safeguards against the inhalation of exhaust gases of aeroplanes while in flight. High temperatures and humidities also accelerate the rate of combination of the gas with hffimoglobin. Varying susceptibilities of animals and birds as compared with man must also be given passing thought as they are of importance in the selection of test creatures for experimental and other work. In this connexion Drinker on September 27, 2021 quotes Anson, Barcroft, Mirsky and Oinuma [5] as showing that carbon monoxide has an effect on animals, etc., in the following descending order of potency: Dog, horse, cat, man, fowl, mouse, rat, tortoise, sheep, lizard, frog, and rabbit. Similarly, in the case of smaller -animals and birds Burrell, Seibert and Robertson [6] concluded that the following was the order of J R Army Med Corps: first published as 10.1136/jramc-73-02-02 on 1 August 1939. Downloaded from 82 Oarbon Monoxide Poisoning degree of susceptibility: Canary, mouse, chicken, small dog, pigeon, sparrow, guinea-pig, and rabbit. Finally, we must not lose sight of the fact that carbon monoxide varies in its effects according as to whether it is alone or in combination with other gases.
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