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Incidence and Causes of Carbon Monoxide Intoxication: Results of an Epidemiologic Survey in a French Department a




Ph Gajdos M.D. , F. Conso M.D. , J. M. Korach M.D. , S. Chevret M.D. , J. C. e




Raphael M.D. , J. Pasteyer M.D. , D. Elkharrat M.D. , E. Lanata M.D. , J. L. g

Geronimi & Cl Chastang M.D., Ph.D.



Service de Réanimation Medicale Hôpital Raymond Poincare Garches , France


Consultation des Maladies Professionnelles Hôpital Cochin Paris , Paris, France


Service de Réanimation Medicale Hôpital Raymond Poincare


Departement de Biostatistique et Informatique , Medicale Hopital Saint Louis , Paris, France e

Service de Reanimation Médicale Hôpital Raymond Poincare


SAMU 92 Hôpital Raymond Poincare


Laboratoire Central Préfecture de Police , Paris, France


Departement de Biostatistique et Informatique , Médicale Hôpital Saint Louis Published online: 03 Aug 2010.

To cite this article: Ph Gajdos M.D. , F. Conso M.D. , J. M. Korach M.D. , S. Chevret M.D. , J. C. Raphael M.D. , J. Pasteyer M.D. , D. Elkharrat M.D. , E. Lanata M.D. , J. L. Geronimi & Cl Chastang M.D., Ph.D. (1991) Incidence and Causes of Carbon Monoxide Intoxication: Results of an Epidemiologic Survey in a French Department, Archives of Environmental Health: An International Journal, 46:6, 373-376, DOI: 10.1080/00039896.1991.9934405 To link to this article:

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Incidence and Causes of Carbon Monoxide Intoxication: Results of

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an Epidemiologic Survey in a French Department

Ph CAJDOS, M.D. Service de Reanimation Medicale HBpital Raymond Poincare Carches, France F. CONSO, M.D. Consultation des Maladies Professionnelles HBpital Cochin Paris, France J.M. KORACH, M.D. Service de R6animation Medicale HBpital Raymond Poincare S. CHEVRET, M.D. Departement de Biostatistique et lnformatique Medicale Hopital Saint Louis Paris, France J. C. RAPHAEL, M.D. Service de Reanimation M6dicale HBpital Raymond Poincare J. PASTEYER, M.D. SAMU 92 Hbpital Raymond Poincare D. ELKHARRAT, M.D. Service de Rbanimation Medicale HBpital Raymond Poincare E. LANATA, M.D. SAMU 92 HBpital Raymond Poincare J.L. CERONIMI Laboratoire Central Prefecture de Police Paris, France CI CHASTANC, M.D., Ph.D. Departement de Biostatistique et lnformatique MPdicale HBpital Saint Louis

ABSTRACT. The purpose of this study was to estimate the incidence, mortality, and causes of carbon monoxide intoxications in France. A survey was conducted in the department of the Hauts-de-Seine, which is represenative of the French population. Data were collected through a headquarters that had direct contact with all department emergency organizations and to a technical laboratory. During the 3-y study, 735 cases that were related to 291 events were reported. Thirty-six patients died. The average incidence of carbon monoxide intoxications was 17.5 per 100 OOO inhabitants. Poisoning was caused by fires in 36 events and by car exhausts in 12. For the remaining events, causes were determined as follows for 1 9 6 water heaters (57%), boiler (20.5%), coal stove (9%), brazier (4%), cooker (2%), heating device (1.5%), and miscellaneous (6%). The main mechanisms of intoxication were a defective device, poor ventilation, or poor evacuation of combustion gases. Carbon monoxide intoxication occurs frequently in France, and preventive actions are warranted. November/December 1991[Vol. 46 (No. 6)]


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USE OF COAL has decreased in the household, and carbon-monoxide-rich coal gas has been replaced by natural gas, which is theoretically devoid of carbon monoxide (CO); therefore, the frequency of CO intoxications has diminished but nevertheless remains elevated.’ In Britain, 913 deaths during 1980 were attributed to CO. In the United States, CO poisoning is the leading cause of death by intoxication.’ Morbidity from CO poisoning is poorly evaluated. Thompson3 reported 101 cases of CO intoxication that occurred between 1977 and 1982 in London. Larcan4 documented 509 cases who were treated in Nancy Hospital (France) for CO intoxication during a 9-y period. In our hospital, 974 patients intoxicated with CO have been treated during the past 4 However, all the data have been provided by institutions involved in the treatment of CO intoxication; therefore, its incidence may not be reflected accurately. Therefore, the purpose of this epidemiologic study was to estimate the incidence, mortality, and current causes of CO intoxications in a French department. Methods Criteria for inclusion. Patients were included if they met one of the following criteria: (a) demonstrated a carboxyhemoglobin level (COHb) greater than 10%; (b) experienced significant signs or symptoms (i.e., impairment or brief loss of consciousness, coma, headache, vertigo, nausea, muscle weakness) while being on the same premises as the patient described in criterion (a); or (c) presented signs of CO intoxication in a situation of suspected CO intoxication, authenticated by the presence of a CO source or by detection of CO in the atmosphere. Data collection. The survey was conducted in the department of the Hauts-de-Seine. Most of the data was collected by the doctors of the Emergency Medical Transport (EMT). They had access to a central telephone that all inhabitants of the department could reach 24 hld. The doctors were also in charge of handling and coordinating all medical transports of patients and for their allocation to the various hospitals throughout the department. Furthermore, in each of the five general hospitals throughout the department, a physician was to inform the EMT of CO-intoxicated patients who may have been admitted through other channels. Also, all hospitals of the departments that bordered the Hauts-de-Seine were requested to report any patients who were referred from the Hauts-deSeine for acute CO intoxication. The local branch of the national gas company was asked to report all possible CO cases of which they were aware. The lnstitut Medico-Legal de Paris reported all deaths that resulted from CO poisoning. Registers of all centers with hyperbaric facilities were consulted. Prior to the survey, information about the purposes and modalities of the study was mailed to all general practitioners in the department. Statistical units. Two statistical units were distinguished: (1) the “case,“ i.e., the individual victim; and (b) the “event,” i.e., the episode of intoxication 374

that may have included one or several cases on the same site. Standardized forms were completed by EMT teams, which were dispatched to the site of intoxication or by the secretariat for those patients who were reported secondarily. A specialized technical crew was dispatched to the site of each intoxication so that the device involved, CO level in the combustion gas, intoxication mechanisms, and type of housing could be identified. Results From November 15, 1983 through November 15, 1986, 291 events, which included 735 cases, were reported. The initial COHb level was greater than 10% standard deviation: for 368 cases (mean COHb level 20 81, and 136 cases presented with meaningful signs or symptoms while being on the same premises as the 368 cases described above. A total of 231 patients presented with signs of CO intoxication while in a situation of suspected CO exposure, a source for which was authenticated for 203 patients, and CO was detected in the atmosphere for 28 patients. During each of the 3 y of study, the number of events was 96, 110, and 85, respectively, and the number of cases was 234, 307, and 194, respectively. The average annual incidence in the department, based on these figures, would have been 17.5 CO intoxications per 100 000 inhabitants. The incidence of CO intoxications was much higher during winter and autumn. According to the 35 boroughs of the department, the incidence ranged between 2 and 61 cases per 100000 inhabitants. The highest incidences were observed in the poorest boroughs. The type of housing is emphasized as a social parameter; in 51% of events, a house consisted of one or two rooms. The total surface of the housing was under 50 m2 in 48% of events, and it was deemed “squalid” in one-third of the events. Intoxication was accidental in 282 events and was self-inflicted in 9. Intoxication occurred in the setting of a fire in 36 events (108 cases), and in 12 events it was the result of car exhaust (18 cases). A technical survey was conducted for the remainder of instances (n =



Table 1.-Outcome of the Technical Survey, Which Resulted in the Identification of the Intoxication Device in 196 Cases of 215 Victims


n Water heater Heating device Coal or wood stove Boiler Cooker Brazier Miscellaneous Total



3 17 41 4

8 13 196

57 1.5 9.0 20.5 2.0 4.0 6.0 100.0



267 5

52.5 1.o 6.5 29.5 1.o 3.5 6.0 100.0

33 150 6 18 31 510

Archives of Environmental Health

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215), which enabled determination of the cause in 196 events (Table 1). There were 110 water heaters involved, and in 76 events, the apparatus lacked outlet pipes. The feeding fuel of the device involved was identified in 178 events: city gas (119 events), coal (45 events), butane (12 events), and heating oil (2 events). The percentage of CO in gases emitted by 90 of the water heaters was analyzed. The percentage was less than 1 in 26 of the water heaters, between 1 and 5 in 38, and between 5 and 15 in 26. For 63 events, this study was completed by the determination of CO concentration in the room atmosphere. When expressed in parts per million (pprn), this concentration was less than 100 ppm in 7 events, between 100 and 1 0oO ppm in 44, between 1 000 and 5 OOO ppm in 10, and more than 5 OOO ppm in 2. Several mechanisms of intoxication may have been involved. These mechanisms, as determined by the technical survey, were a defective device (n = 1251, poor ventilation (n = 511, and poor evacuation of combustion gases (n = 64). The telltale symptoms of intoxication are detailed in Table 2. Thirty-six patients died, of whom 33 were found dead on the premises, and 3 died at the hospital. Causes of intoxication for these 36 patients were a water heater (n = 19), fire (n = 81, and miscellaneous causes (n = 11). Discussion

The Hauts-de-Seine department is very organized for medical emergencies; therefore, it appeared that the department was well adapted to ensure thoroughness of data collection. Despite this favorable situation, the annual incidence of 17.5 intoxications per 100 OOO habitants is probably an underestimation. Some patients may have refused hospitalization and may not have been reported to our offke by their doctors, despite the information that had been provided to them. Diagnosis of CO intoxication was retained only for a patient whose COHb level exceeded 10% or for whom circumstances strongly favored CO intoxication. This COHb level was retained so that inappropriate inclusion of smokers, whose COHb levels are chronically between 3 and 8%, was a ~ o i d e d However, .~ the choice of such a high threshold level may have led us to overlook authentic CO intoxications in nonsmokers. In addition, the COHb plasma level is a function of time to the end of exposure. In most cases, oxygen therapy was eventually administered before CO was measured; therefore, at the time of CO measurement, patients may have had lower COHb levels than at the end of exposure and may have been excluded from the survey. Finally, the most important reason for an underestimation is that clinical signs of intoxication are polymorphic. Diagnosis may be mistaken for influenza,‘ cardiac infarction, or a s~roke.’ It i s probable that a number of CO intoxications were overlooked in our survey. Some features allow for an extrapolation of the annual incidence of CO intoxications in the Hauts-deNovembedDecember 1991 [Vo!. 46 (No. 6)]

Table 2.-Tdltale Symptoms of CO Intoxication Victims


Symptom ~~


Headache Digestive dysfunction Loss of consciousness Coma Seizures Pet morbidity Unknown Total


335 223 116 22



8 14 17

46 30 16 3 1 2 2



Seine department to the French population. This department includes a large population (i.e., 1 4OOOOO), which is diverse in terms of socioeconomy and of density (469-22 199 inhabitantsfkml). Such an extrapolation would yield at least 8 OOO victims of CO intoxication per year in France. The severity of intoxication is reflected by mortality, which, in our study, reached 5%. This figure accords with information in previous reports. In the United States, 1 500 persons per year die from accidental CO intoxication, and an addition 2 300 die from selfinflicted CO poisoning.’ In England and in Wales, 1 365 deaths were attributed to CO poisoning in 1985,’ and between 1974 and 1980, CO poisoning accounted for 5% of the deaths in children.” In our study, the main source of CO was gas-fueled water heaters. Other causes, e.g., gas or coal-fueled boilers, wood or coal stoves, motor exhausts, and fires, occur more frequently in the United States and United Kingdom.2.7.9,11.12 Examination of the installations revealed the various mechanisms of these intoxications; in the majority of cases, a defective device caused incomplete combustion of gas and overproduction of CO. In many instances, the consequences of CO production were exacerbated by poor evacuation of combustion gas and by the lack of ventilation. Some of the water heaters in our survey produced CO concentrations that exceeded 1 OOO ppm after only a few minutes of operation. Such concentrations are 20 times the level permitted by the labor Legislation, and consciousness is usually impaired after a 10-min exp~sure.’~ In Denmark, Mi~kaelsen’~ reported such effects for 16% of the water heaters he had checked. This study supports the fact that CO intoxication occurs frequently in France, and it accounts for a high incidence of morbidity and substantial mortality. The well-known causes of these intoxications persist despite preventive measures, e.g., replacement of overused devices, regular maintenance of all devices, and emphasis on safety. It is, therefore, important that information campaigns be conducted regularly for the p u b lic, especially for the lower socioeconomic group of the population. 375

********** This study was supported by a grant of the French Health Ministry. Submitted for publication September 22, 1990; revised; accepted for publication March 24, 1991. Requests for reprints should be sent to: P.H. Cajdos, M.D., Service de Reanimation Medicale, HBpital Raymond Poincare, 104, bd Raymond Poincare, 92380 Garches, France.

********** References

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1. Anonymous. Carbon monoxide, an old enemy forgot. Lancet 1981; 2:75. 2. llano AL, Raffin TA. Management of carbon monoxide poisoning. Chest 1990; 97:165-69. 3. Thompson N, Henry ]A. Carbon monoxide poisoning: poisons unit experience over five years. Human Toxicol 1983; 2:335-38. 4. Larcan A, Lambert H. Aspects epidemiologiques, clinicobiologiques et therapeutiques actuels de I'intoxication oxycarbonee aigue. Bull Acad Nat Med 1981; 165:471-78.

5. Raphael JC, Elkharrat D, Jars-Guincestre MC, Chastang CL, Chasles V, Vercken JB, Gajdos PH. Trial of normobaric and hyperbaric oxygen for acute monoxide intoxication. Lancet 1989; 2:414-18. 6. Fort L, Criggs P. Carbon monoxide poisoning in North Carolina. MC Med J 1987; 48:317-21. 7. Grace TW, Platt FW. Subacute carbon monoxide poisoning. Another great imitator. JAMA 1981; 246:1698-1700. 8. Anonymous. Carbon monoxide intoxication. A preventable environmental health hazards. NMWR 1982; 31:529-31. 9. Meredith T, Vale A. Carbon monoxide poisoning. Br Med J 1988; 296r77-78. 10. Craft AW. Circumstances surrounding deaths from accidental poisoning 1974-1980. Arch Dis Child 1983; 58:544-46. 11. Baker SP, Fisher RS, Masemore WC, Sopher IM. Fatal unintentional carbon monoxide poisoning in motor vehicles. Am J Public Health 1972; 62:1463-67. 12. Roberts RM. Carbon monoxide poisoning and fire-associated deaths. Lancet 1981; 2:816. 13. Stewart RD. The effect of carbon monoxide on humans. Ann Rev Pharmacol 1975; 15:W-23. 14. Mickaelsen KT, Taudorf K. Danger of gas water heaters. Lancet 1983; 2:229.

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Archives of Environmental Health

Incidence and causes of carbon monoxide intoxication: results of an epidemiologic survey in a French department.

The purpose of this study was to estimate the incidence, mortality, and causes of carbon monoxide intoxications in France. A survey was conducted in t...
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