Document 1yY7XLpzNNQ7NeaXLpwX6vemo

Vy V W CLINICAL INVESTIGATIONS Transient Hypoxemia in Firemen Following Inhalation of Smoke* Michael G. Genooesi, M.DDonald P. Tashkin, M.D.; Sawtantra Chopra, M.D.; Marshall Morgan, M.D.; and Charles McElroy, M.D. Mild to moderately severe hypoxemia was documented Jo 19 of 21 mostly asymptomatic firemen who were ex posed to dense smoke containing polyvinylchloride and other pulmonary Irritants. The hypoxemia was transient, with nearly complete reversibility within 24 hours. Sub sequent tests for pulmonary function one month later, demonstrated that this transient hypoxemia was not related to previous underlying pulmonary disease. The potential for serious complications of inhalation of smoke, particularly smoke from burning plastics, Is heightened by the frequent lark of symptoms associated with this type of exposure, despite the development of moderately severe hypoxemia in addition to carboxyhtmoglobinemia. Precautionary measures should in clude uninterrupted use of an effective breathing appa ratus by firemen exposed to smoke and to noxious fumes and temporary oxygen supplementation, even in asymp tomatic firemen, following exposure to dense smoke. T ohalation of smoke is known to cause a broad spectrum of adverse respiratory effects, from mild irritation of the upper airways to severe tra cheobronchitis, bronchospasm, pulmonary edema, and bronchopneumonia, often resulting in pulmo- For editorial comment, see page 438 nary insufficiency and death.1 The duration of the exposure to the smoke and the occurrence of the exposure in a confined space are two of the factors that help determine the severity of the pulmonary consequences of inhalation of smoke.1 Additional factors are the nature and quantity of the products of combustion of the materials consumed in the fire and the degree to which these products are inhaled along with tire smoke.1 These latter factors have assumed particular significance in recent years, with the increased use of synthetic plastic materials in the construction of buildings. The particular hazard of the toxicity of polyvinylchloride in fires has recently been discussed.4 The present report documents the appearance of *Ftom the Division of Pulmonary Disease and the Emergen cy. Service of the Department of Medicine, School of MedJTM*. University of California, Los Angeiei. Supported in part by Public Health Service grant HL ^05917. Currently at New Britain Ceneral Hospital, New Britain, Conn, and the University of Connecticut Health Center, Farmington, manuscript received April 12; revision accepted August 30. jvrpft'nr tcqueiti: Dr. Ttnhliin, Department of Medicine, "CZ-A School of Medicine, Lor Angeles 90024 moderately severe hypoxemia in firemen after expo sure to smoke from fire in an office building, in which large quantities of polyvinylchloride materials were burned. On Nov 12, 1974, a fire broke out on the eighth floor of a high-rise office building in the Century City area of Los Angeles. The fire was extensive and extremely smokey, requiring several hours to extin guish. After the fire had been brought under control, two firemen who initially had experienced a mod erately severe burning sensation in the throat and upper portion of the chest were brought to the emergency room at the University of California, Los Angeles. On arrival at the emergency room, one oi the firemen was no longer symptomatic, and the other complained only of a mild sensation of burn ing in the throat Findings from physical examina tions were normal, and chest x-ray films in the pos teroanterior and lateral projections were withfc normal limits; however, since arterial blood ga levels determined in these two firemen revealed h; poxemia and hyperventilation (arterial oxygen pre.' sure [PaOi], 68 to 72 mm Hg; and arterial carbo dioxide pressure [PaCOi], 25 to 29 mm Hg), the were hospitalized for further observation. Because of the finding of hypoxemia in these two patients, despite a relative paucity of symptoms, the Fire Department was notified, and most of the firemen who had been engaged in the front line of the fire were requested to report to the emergency CHEST, 71; 4. APRIL, 1977 7 . TRANSIENT HYPOXEMIA FOLLOWING INHALATION OF SMOKE 441 loom at the University of California, Los Angeles, for evaluation for possible adverse pulmonary effects of exposure to some noxious combustion products involved in the fire. J Materials and Methods Over the next ten hours a total of 19 additional firemen were seen in the emergency room. There subjects were all asymptomatic at the time of their evaluation, and none of these firemen complained of any unusual symptoms during their involvement in the fire. Routine physical examinations and chest x-ray films in the posteroanterior and lateral projections were performed in all subjects, and the findings were all normal. Approximately 4 ml of arterial blood were withdrawn following percutaneous puncture of the radial artery for determination of pH, PaCOp and PaO, using standard electrodes (acid-base digital analyser. Radiom eter model PHM 72). In addition, venous blood was col lected anaerobically for determinations of levels of carboxyhemoglobin in three subjects, using a spectrophotometric technique. Approximately one month later, all 21 firemen who were initially studied returned for further evaluation of their res piratory Status, including administration of a respiratory questionnaire* and detailed studies of pulmonary function. Results The initial arterial blood gas values of the 21 firemen evaluated arc indicated in Table 1. The values forPaOx in 14 subjects were less than or equal to 76 mm Hg and were more than two standard deviations below the predicted value (based on the data of Sorbini et alE), despite the presence of hyperventilation (PaCOr, 25 to 36 mm Hg), which should have increased the alveolar Oxygen pressure (PaOj) and consequently the PaOj. These subjects were admitted to the hospital for further observation and received supplemental therapy with oxygen for approximately two hours. Although the other seven firemen had higher values for PaOj (]> 79 mm Hg), these patients were also hyperventilating (PaCO*. 24 to 37 mm Hg), with the result that the alveolararterial oxygen pressure difference (P[A-a]Oa) esti mated by assuming a respiratory quotient of 0.8 was abnormally widened in six of these subjects. These subjects were not hospitalized. By the following morning the two firemen who Table 1 --- Arterial Blood Cot Leeelt in 21 Firemen fallotting Exjititure to Dento Smoko Group and Fireman Age, yr Within 2-10 hr of Exposure -- -... PaCO,, PaO,. pH mm Hg mm Hg Predicted PaO,, mm Hg* Approximately 20 hr after Exposure , -. -- *' - PaCO* PaO* pH mm Hg mm Hg Hospitalised l"t 3 3 4 5t 6 7 S"| 10 11 12 13 14 Group mean 1 SD 53 40 S3 44 59 48 36 30 34 30 57 44 59 40 44111 7.47 7.44 7.46 7.40 7.40 7.43 7.45 7.41 7.42 7.45 7.42 7.46 7.41 7-42 7.43 0.02 26 39 29 34 30 33 28 29 33 33 30 31 30 32 324 08 62 54 00 00 76 06 73 58 08 51 73 67 02 7 81.3 86.7 81.7 85.0 78.7 83.3 88.4 90.D 803 92.0 79.0 85.0 78.7 88.7 84.814^ 7.40 7.44 7.40 7.44 7.42 *-* 7.45 7.39 7.44 7.44 7.44 7.41 7.43 7.42 7.4210-02 35 40 35 32 38 #** 34 34 34 34 36 34 36 38 3512 77 84 84 93 87 *# 90 104 85 89 91 92 8) 85 8817 Hot hospitalised 15 15 17 18 10 20 31 Group mean 1 SD 34 43 27 37 39 27 27 81 7 7.47 7.47 7.44 7.47 7.43 7.46 750 7.4610.02 33 25 24 34 37 34 30 3115 81 83 82 82 79 102 91 8618 93.4 85.4 92.2 87.9 91.3 93.2 - 923 90.712.9 7.43 7.43 7.39 7.42 a* 7.46 7.43 7.4210.02 27 32 40 33 a* 28 35 3212 105 100 85 96 a-* 108 60 979 Total mean SD 40 12 7.44 0.03 3114 71113 86.814.9 7,4210.02 3413 9118 Predicted according to Sorbini et al*: PaO, Initially symptomatic firemen. tCarboxyhemoglobin, 15 percent saturated, tCarboxyhemoglobin, 6 percent saturated. ICarboxyhemuglobin, 5 percent saturated. 103.5 - 0.42 X age (yr) 3.75 mm Hg (SD); I'aCO, - 40 mm Hg. ucc 008722 442 GENOVESI ET Al CHEST, 71: 4, APRIL. 1977 I Imil initially been symptomatic recovered complete ly and the other hospitalized firemen remained asymptomatic. Repeated studies of arterial blood pas levels performed less than 21 hours after the original measurements showed improvement in paOj in all of the 13 hospitalized subjects in whom repeated measurements were made. In addition, tbe estimated P( A-a)0* improved in all five of the fire men with an initially abnormal value who were not Itospitalized but returned to the emergency room for repeated studies of blood gas levels (Table 1), The mage individual improvement in PaO? in those patients who originally had significant hypoxemia was 24.7 mm Hg, and since the values from repeated determinations of PaCOj had returned to or toward normal in most of the subjects, the mean decrease in tlic estimated P( A-a)0* was probably even greater. Although tbe values from repeated determinations of arterial PaOr were within the predicted normal limits for age in all subjects in whom repeated mea surements were made, in three of the hospitalized patients (patients 1, 9, and 10), the estimated P(Aa)0* was still slightly abnormally widened. All sub jects were released within 24 hours of hospitaliza tion. One month later, all 21 firemen were asked to com plete a detailed respiratory questionnaire and under went a repeat physical examination and a battery of pulmonary function studies. The results of these studies, which will be reported separately, showed no apparent relationship between a history of ciga rette smoking, the presence of chronic respiratory symptoms, or abnormalities of pulmonary function and tire degree of hypoxemia that developed follow ing the episode of inhalation of smoke. Because of tire possibility that the transient hy poxemia observed in these firemen was related to iultalation of noxious chemicals released during the combustion of materials burned in the fire, the chemistry laboratory of the Los Angeles Fire De partment collected representative uncombusted iamples of the same materials as those consumed in the fire and analyzed the products released during tire burning of these samples. Representative mate rials found at the scene of the fire are listed in Table 2. along with the major toxic chemical products of combustion. It is of note that several of the latter are well-known pulmonary irritants. Discussion Because of the finding of mild to moderately se vere hypoxemia in nearly all of the firemen who were in the front line of the high-rise fire in the Century City area on Nov 12, 1974, it was obvious tliat definite respiratory irritation had occurred, de- Table 2 *-- Dutn on TnxU Froriucls of Combustion Material Major Toxic Chemical Use Products of Combustion* Polyvinyl chloride Wall and floor Hydrogen chloride IV) i covering; phosgene (P); telephone cable carbon monoxide insulation Polyuretliane Upholstery Isocyanates (P) (toluene 2,4-diisocyanate); hydrogen cyanide Lacquered wood Wall covering veneer; wallpaper Acetaldehyde (P); formaldehyde (P); oxides of nitrogen (P); acetic acid Acrylic Light diffusers Acrolein (P) Nylon Carpet Hydrogen cyanide; ammonia (P) Acrilan Carpet Hydrogen cyanide; acrolein (P) Polystyrene Miscellaneous Styrene; carbon monoxide *P, Pulmonary irritant spite the general lack of respiratory symptoms. Therefore, an effort was made to discover the source of the pulmonary irritants. Plastic material contain ing polyvinylchloride was present in relatively large quantities as floor coverings (tiles), wall coverage (0.021 inch), and telephone cable (0.031 inch) in tlie burned out section of the office building (Table 2). One of the hazards of fires occurring in buildings containing materials made of polyvinylchloride is the production of a high-density smoke which may be 4 to 14 times more dense than that which develops in fires involving common constructional timber un der similar conditions.7 Vinyl-based coverings can re lease relatively high concentrations of hydrogen chloride gas when combusted. Each kilogram of polyvinylcliloride can produce, upon complete com bustion, about 0.4 kg of hydrogen chloride gas.7 The polyvinylchloride plastic starts to evolve hydrogen chloride gas at relatively low temperatures (200C to 300C). Since the fire properties of surface cover ings are known to be substrate-dependent, the gen eration of smoke and production of noxious gases, as well as the surface flammability, will depend on the material with which the polyvinylchloride or other substances are in contact.* Polyvinylchloride also produces moderate amounts of phosgene and high concentrations of carbon monoxide.4,1 In addition to polyvinylcliloride, the fire proper ties of which have been the most intensively studied, other plastics and synthetic materials, including acrylics, Acrilan, and nylons, were involved in the present fire (Table 2). On overheating, these sub stances can decompose and emit acrolein, ammonia. CHEST, 71: 4. APRIL, 1977 TRANSIENT HYPOXEMIA FOLLOWING INHALATION OF SMOKE 443 and oxides of nitrogen, all of which are capable of causing pulmonary injury,*1*11 especially under con ditions of poor ventilation, when the local concentra tions of these irritating substances are increased. Although the firemen all used a self-contained breathing apparatus while fighting the fire in the Century City area, some admitted that they re moved the breathing masks for short periods of time when they visually estimated that the smoke condi tions were not hazardous. The fact that these fire men nearly all exhibited hypoxemia and hyper ventilation two to ten hours after exposure to the fire is of particular interest, since all but one of the firemen were essentially asymptomatic, and all had normal chest x-ray films and normal findings on physical examinations. The short-term changes in blood gas levels undoubtedly represented subclinical respiratory irritation, most likely from noxious chemicals inhaled at the scene of the fire, resulting in abnormalities in gas exchange and stimulation of airway or pulmonary receptors, or both, with in creased alveolar ventilation. Less than 24 hours later, oxygenation had improved in all subjects, al though residual mild widening of the P(A-a)Oj in three subjects may have reflected either underlying chronic obstructive pulmonary disease (two of the three subjects were regular smokers and were the only firemen who complained of chronic cough) or the residual effects of respiratory irritation, or both. Although studies have not been performed in large numbers of firemen to determine the presence and extent of arterial hypoxemia after exposure to smoke from an ordinary fire, we have demonstrated that significant hypoxemia does occur in asympto matic firemen without underlying respiratory disease or pulmonary functional impairment after exposure to smoke containing pulmonary irritants produced by the combustion of plastics and other synthetic materials. Although the hypoxemia which developed was often moderately severe, it was fortunately short-lived; however, a longer duration or a greater intensity of exposure to the same irritants, or both, might have resulted in less readily reversible pulmo nary changes. Moreover, the concomitant occur rence of carboxyhemoglobinerma secondary to the inhalation of carbon monoxide would be expected to magnify the impairment in oxygen transport result ing from hypoxemia, thereby increasing the risk of development of acute cardiac or cerebral complica tions of curtailed delivery of oxygen to the tissues. A significantly higher resting level of carboxyhemoglobin has been found in Oklahoma City firemen, even during fire-free intervals, compared with a matched group of nonfiremen.!1 That these findings probably have clinical significance is suggested by 444 GENDVES1 ET AL tiie demonstration of a high incidence of ischemic response to a standard near-maximal exercise test in Los Angeles firemen, when compared to a comparable group of llonfi^emen.,, Consequently, preven tive measures, such as the uninterrupted use of an effective breathing apparatus should be scrupulously observed by firemen exposed to smoke and noxious fumes, particularly from burning polyvinylchloride and other plastics, and temporary oxygen supple mentation should be considered as a precautionary therapeutic measure in even asymptomatic firemen following any intense exposure to smoke. Additional studies, including measurements of arterial blood gas levels and carboxyhemoglobin determinations, are required to ascertain the short-term pulmonary ~ effects of exposure to the products of combustion of different types of materials used in the construction of buildings. ACKNOWLEDGMENT: We appreciate the full cooperation and assistance of the Los Angeles Eire Department; the help ful advice of Dr. 11. J. Barnard of the Department of Kinesiol- ogy. University of California, Los Angeles, in the preparation of the manuscript; and the technical assistance of Mr. Barn1 Calvarcse and Mr. Charles Harper. References 1 Webster JA, McCabe MM, Karp M: Recognition awl management of smoke inhalation. JAMA 201:287-290. 1907 2 Lloyd EL, MacRae WR: Respiratory tract damage in bums: Case reports: Review of the literature. Br J Anaesth 43:365-373,1971 3 Thomas DM: The smoke inhalation problem, fn Proceed ings of the Symposium on Occupational Health and Haz ards of the Fire Service, Notre Dame University, 197). Washington, DC, Internationa) Association of Fire Fight ers, 197], p 21 4 Dyer RF, Esch VH: Polyvinylchloride toxicity fn fires: Hydrogen chloride toxicity in fire-lighters. JAMA 235: 393-397,1976 5 Medical Research Council's Committee on the Aetiology of Chronic Bronchitis: Standardized questionnaire on respiratory symptoms. Br Med J 2:1605, I960 6 Sorbinl CA, Gross! V, Solinas E, ct ah Arterial oxygen tension in relation to age in healthy subjects. Respiration 25:3-13,196S 7 Ezriel N: PVC: Its known and expected behaviour in fire. Fire Int 39:40-47,1973 8 Waksman D, Ferguson JB: Fire tests of building interior covering systems. Fire Technology, (Aug) 1974, pp 211220 9 Sumi K, Tsuehiya Y: Toxic gases and vapours produced at fires. Can Bldg Digest, (Dec) 1971, p 144 10 Watters P: Effects of smoke on the body. Fire, (June) 1970.pplS.16 11 Simmons JH, Coleman RL: Firefighters* occupational ex posure to carbon monoxide. J Occup Med 16:543-516, 1974 12 Barnard RJ, Cardner CW, Disco NV, ct ah Near maxi mum ECG stress testing and coronary artery disease risk factor analysis in Los Angeles City firemen. J Occup Med 17:693-695.1975 j VCC 008724 CHEST, 71: 4, APRIL 1977 Respiratory Status of Los Angeles Firemen' One-Month Follow-Up after Inhalation of Dense Smoke j Donald P. Tushkin, M.D.; Michael C. Cenovesi, M.D." Sfwtantra Chopra, M.D.; Anne Coutson; and Michael Simmons A standardised respiratory questionnaire and detailed pulmonary function tests were administered to 21 Los Angeles firemen one month following exposure to the combustion products of polyvinylchloride, which had produced transient hypoxemia in 19 of the firemen. The results of these studies were compared with those ok reined in a sample of nonfiremen residing in the Los Angeles area who were matched by computer with the firemen for anthropomorphic characteristics and smok ing status. The frequency of respiratory symptoms, the results of splrometric and plethysmographlc studies, and the single-breath nitrogen washout were similar in the firemen, compared with the matched sample, whereas closing volume was higher in the matched controls. These findings suggest that although fighting fires may result in acute pulmonary Injury secondary to discrete episodes of inhalation of smoke, it does not appear to predispose to the development of chronic respiratoiy symptoms or chronic functional respiratory impairment. T>ecent publications have suggested an increased prevalence of chronic nonspecific respiratory disease in Boston firemen' who also developed a greater decrement in measurements of pulmonary function when compared with a similar group of For editorial comment, see page .438 men matched for age, smoking habits, and ethnic background.* Analysis of data on pulmonary func tion in Boston firemen also revealed a slightly lower ventilatory capacity in nonsmokers in all age cate gories, compared with age-adjusted predicted values for healthy nonfiremen, although these differences were not statistically significant.* From these find ings, the authors1'* concluded that the occupation of fighting fires constitutes a significant risk factor for the development of chronic pulmonary disease and pulmonary functional impairment, although more re cent data obtained in a subgroup of the same cohort of firemen suggests that factors of selection may have confounded the earlier findings.4 An earlier study of 4,379 Los Angeles firemen indi cates that they experience, on the whole, substan tially lower age-adjusted death rates than their peer 'From tlie Divisions of Pulmonary Disease and Epidemiol ogy, the Schools of Medicine and Public Health, University of California, Los Angeles. Supported in part by Public Health Service grant HL 05917. "`Currently at New Britain General Hospital, New Britain, Conn, and the University of Connecticut Health Center, Farmington. Manuscript received July 19; revision accepted August 30. tepn'nt requests: Dr. Tashkin, Deportment of Medicine, VCU School of Medicine, Lot Angeles 90024 CHEST. 71: 4. APRIL 1977 group selected either nationwide or from Los Angeles (observed deaths/expected deaths X 100 55 and 69, respectively).* A decrement in general health should be reflected to some extent in higher mortal ity. A substantially lower mortality in Los Angeles firemen is, therefore, at variance with the suggestion of a higher prevalence of chronic nonspecific res piratory disease and impaired pulmonary function due to exposure to fighting fires. We recently studied 21 Los Angeles firemen, 19 of whom developed transient acute hypoxemia fol lowing exposure to a fire in a high-rise office build ing, in which large amounts of polyvinylchloride were combusted.* These same firemen were reevalu ated one month following the fire to ascertain any possible effects on pulmonary function as a result of this episode of inhalation of smoke. In the light of previous studies suggesting impairment in pulmo nary function as a consequence of fighting fires,1'* we were surprised to find that our group of Los An geles firemen had relatively few respiratory symp toms, as well as remarkably normal pulmonary func tion, compared with published predicted values. Therefore, we matched these firemen by computer with nonfiremen residing in the Los Angeles area to ascertain whether or not differences could be de tected in respiratory symptoms and pulmonary func tion, controlling for variables other than fighting fires, including age, sex, race, cigarette smoking, and geographic and climatic differences. We now report our findings, RESPIRATORY STATUS OF LOS ANGELES FIREMEN 445 5 j *S J * J i* i *i ucc 008725 I H,-'1>"'W1 >< >1)0 qurstiomuirv and the absolute values for i|iiii.ity (urn (ion obtained in each of these21 firemen were Uo tvmpared with those reirotly obtained in individuals lttj,i... Ui the Los Anyclcs li.isin who were administered the ^h- interview and tests of pulmonary function in a mobile lilmralnry as part of a population study on chronic obstructive expiratory disease.1" These individuals were matched by nmpuler proitram us closely as possible to the firemen for age saw, and tobacco-siunking history; individuals with a hisos ol hazardous occupational exposure were excluded. The validity' of this comparison is supported by studies of validation previously performed in our laboratory, which vhuwvd good agreement (r = O.S2 to 0.91) lietsveen ipirortric values obtained by a mobile field laboratory in the population from which the matched sample was drawn and sIhm; obtained by our lalroratory in a 1 percent probability vamplr of randomly selected individuals from die same popuUtiuit-1* Values obtained in the matched sample were adpitied for the slight differences observed between the field and validation laboratories using appropriate regression equa tions.1" Differences between the results from studies of pulannary function in the firemen and their matched controls were tested for statistical significance using Student's (-test lot paired data; mean differences were considered significant (nr proliabihty values less than 0.05. Results Physical examination of the 21 firemen showed no abnormalities with respect to the heart and lungs. The smoking history and the respiratory symptoms of both the firemen and the matched sample of nonfiremen arc indicated in Table 1, Seven firemen were currently regular cigarette smokers, three were oc casional smokers (less than one cigarette per day per year), six were former smokers (had discontinued smoking for at least the previous year), and five were nonsmokers. Only two of the 21 firemen in tins re port complained of cough on most days for three months per year for two or more years, and only one of these subjects had associated production of spu tum. One additional patient raised phlegm more than three months out of the year for more than two years but did not admit to cough. Only one fireman complained of definite wheezing (on more than 19 days per year) unassociated with dyspnea, and no fireman reported shortness of breath on exertion. Of the matched group of nonfiremen, two gave a sig nificant history of cough, and both of these individ uals had associated phlegm. One of the matched controls had wheezing without shortness of breath, and two others complained of exertional dyspnea. The results .of studies of pulmonary function in the 21 firemen and their matched controls are shown Table 2 -- Data on Pulmonary Function 'Fireman/Matched Control liretnc and Male!i FVC ueT FEF25FEV, ;FEV,/FVC 75% Thoracic Gaw/Vt, Gaa L/sec/cm Raw, cm Volume, BjO/L H)0/L/seo L Db. percent of pre <dicted ** Breath Nitrogen Washout, percent CV/VC% Observed Predicted 1 86/95 2 119/125 3 97/118 4 101/110 5 120/120 e 109/101 7 113/117 8 121/130 9 101/SI ID 97/110 11 100/113 12 W/95 13 117/102 14 117/113 IS 122/101 1C 123/117 17 122/115 18 '127/IIS !!> 101/109 20 120/117 21 92/102 Mean 110/110 SD 12/12 84/92 100/123 99/118 92/124 125/112 103/101 119/109 116/130 89/76 106/103 76/97 96/93 107/83 103/108 112/117 114/120 112/109 98/108 96/m 10S/103 91/108 102/107 12/14 117/105 90/106 115/109 96/122 106/100 100/108 111/101 98/107 93/100 113/102 83/93 111/106 104/86 93/104 94/125 100/111 95/103 81/102 96/109 94/110 101/114 100/106 10/9 103/64 68/124 120/99 75/142 132/65 95/94 139/151 91/135 60/138 122/78 44/64 106/99 74/35 75/46 87/138 107/142 93/82 56/88 87/106 92/117 103/121 92/101 25/34 0.18/0.07 0.28/0.20 0.22/0.20 0.20/0.21 0.27/0.30 0.19/0.13 0.19/0.30 0.25/0.21 0.08/0.32 0.21/0.13 0.17/0.24 0.26/0.28 0.15/0.20 0.20/0.24 0.15/0.20 0.21/0.26 0.27/0.09 0.09/0.29 0.28/0.23 0.21/0.26 0.25/0.31 0.21/0.22 0.06/0.07 1.70/2.94 1.26/1.32 1.85/1.55 1.47/1.97 1.03/0.93 1.53/2.68 1.61/1.58 1.54/1.90 3.85/0.90 1.52/2.34 1.71/1.03 1.41/1.08 2.57/1.96 1.76/0.89 2.22/1.82 1.62/1.13 0.90/2.90 3.00/0.95 1.27/1.30 1.2S/1.13 1.20/1.74 1.73/1.62 0.69/0.66 3.28/5.05 2.85/3.82 2.56/3.27 3.25/2.45 3.66/3.61 3.44/2.82 3.31/212 2.64/2.57 3.28/3.63 3.13/3.38 3.53/4.08 2.72/3.34 2.61/2.56 3.00/4.76 2.98/2.76 2.99/3.39 4.09/3.83 3.87/3.65 2.78/3.32 3.86/3.37 3.39/1.86 3.19/3.31 0.43/0.79 83 90 100 86 105 86 108 106 94 110 89 100 130 100 103 140 124 109 100 95 118 104 15 07/1.5 0.2/0.1 0.1 /0.2 0.1/0.1 0.6/1.5 0.2/0.5 0.1/0.1 0.1/1.0 1.0/2.0 0.1/0.1 1.0/1.0 1.0/0.I 0.1 /0.1 0.1 /0.1 0.1/l.S 0.2/0.5 0.1/0.1 02/17 0.1/0.2 0.1/0.1 0.1/0.1 0.3/0.6 0.3/0.6 36/14 0/22 0/16 12/16 23/14 19/8 0/13 0/44 0/9 0/17 0/38 19/6 0/28 0/1 0/18 8/14 0/11 0/14 0/7 0/12 20/4 7/16 11/10 19 15 19 16 22 18 13 11 13 10 21 16 22 15 9 16 10 14 . 11 10 10 15 4 "Predicted values for FVC, FEV,, and FEF25-75% are based on regression equations of Morris et al;>* and predicted values for FEVj/FVC, Dsb, and CV/VC are based on regression equations of Bcrglund et el,1* of Kory et al,** of Hammer and Meade ** reported by Coles.1* and of Buist and Ross," respectively. "VeinTM of Dsb were not obtained in matched aample. CHEST. 71: 4. APRIL, 1977 RESPIRATORT STATUS OF LOS ANGELES FIREMEN 447 i I DCC 008726 ;3 jgOff 1 nB % a5 S3 jjpJM . | , 3 H 8 H 1 n n } 1 i ! ! " , Matejuals and Methods Twenty-one firemen who had developed transient hypox emia following exposure to fire in an office building in Los Angeles were studied approximately one month after the fire. Studies consisted of administration of a detailed respiratory questionnaire modified from the Medical Research Council of Crcat Britain's questionnaire on respiratory symptoms,1 physical examination, and studies of pulmonary function. The Utter consisted of the following: spirometric studies using a 13.5-L water-sealed spirometer (Warren E. Collins, Inc.), with calculation of forced vital capacity (FVC), forced ex piratory volume in one second (FEV|), and mean forced expiratory flow during the middle half of the FVC (FEF257SS); determinations of airway resistance (Raw) and thoracic gas volume using a 600-L constant-volume whole-body piethysmograph (Warren E. Collins, Inc.),*-* with calculation of specific airway conductance (Caw/VL = 1/Raw/thoradc gas volume); measurements of single-breath nitrogen wash out between 750 and 1550 ml of the FVC and closing volume (CV), using a method modified from that of Anthonisen et al;> and single-breath diffusing capacity for carbon mon oxide (Db). Spirometric studies were performed lir e trials with tire subject standing with nose clips in p|Jt-. The breath used for analysis was that associated with il greatest FEV| if the FVC was within 10 percent o! the grf;, est FVC. Maneuvers for determining CV were performed triplicate, and the values obtained from satisfactory tracing (expiratory vital capacity [VC] within 5 percent of the in. spiratory VC and expiratory flow rates less than 05 L/kt were averaged. Plethysmographic measurements were per. formed in quintuplicate, and the results were averaged. Spirometric indices. CV, and Dsb were expressed as a per. cent of published predicted values.1*'* Spirometric indirm and Dsb were considered normal if greater than 80 percer: of the predicted value, except for FEF25-75S, which wa considered normal if greater than 70 percent of the predictevalue. The lower limit of normal for Caw/VL was considerr to be 0.15 L/sec/cm HaO/L, based, on data previously ol tained in our laboratory. The upper limit of normal for i! single-breath nitrogen washout was considered to be 1.8. The CV was considered normal if it did not exceed two stan dard deviations above the predicted valuo of Buist and Ross' for nonsmoking men. Table 1 -- Hitiorical Dara In 21 Firemen end Their Matched Co'ilroh Firenian/Matched Control Years as Fireman Fireman Occupation of Matched Control 1 2 3 4 5 6 7 8 B 10 U 12 13 14 15 16 17 18 20 31 Mean SD 26 Technician 14 Technician 28 Technician 17 Skilled laborer 28------ Machine operator 25 Skilled laborer S Skilled laborer 5 Skilled laborer 13 Technician 3 Lesser professional 28 Administrative personnel 12 Farmer 33 Major professional 11 Skilled laborer 2 Skilled laborer 18 Skilled laborer 3 Administrative personnel 12 Clerical/sales S Machine operator 4 Semiprofessionni 6 14 , t ,, 10 Age, yr 53/53 40/43 52/49 44/41 59/58 48/48 36/37 30/28 34/34 26/22 57/53 44/44 59/59 40/40 24/24 43/41 27/29 37/36 29/28 27/25 27/30 40/39 12/11 Height, cm 175/175 178/180 178/178 190/1B5 179/180 189/188 176/173 175/175 180/180 188/188 190/180 168/170 173/173 189/188 175/173 182/178 182/180 172/173 183/185 I80/1S0 187/191 180/180 7/6 Smoking History* Current Occasional Former Former Cough +/0 0/0 0/0 0/0 Former 0/0 Current 0/+ Never 0/0 Current 0/+ Current Never +/0 0/0 Occasional 0/0 Current Former 0/0 0/0 Former 0/0 Occasional 0/0 Former 0/0 Never 0/0 Current Never 0/0 0/0 Never Current .. *-- 0/0 0/0 Wheeling >19 day* Short nr Phlegm per year of Brest +/0 0/0 0/0 0/0 0/0 0/0 0/6 0/0 0/+ 0/0 0/0 0/0 0/0 0/0 0/0 0/+ 0/0 0/0 0/0 0/0 0/0 0/+ 0/+ 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 +/0 0/0 0/0 0/0 0/0 0/0 0/d- 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 +/0 0/0 . - 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 . . , ... -- ..a *a. *See text for explanation of smoking history. Smoking hi-tory a-m Ainu- for each fireman ami his matched control. 446 TASHKIN ET AL CHEST, 71: 4, APRIL. 1977 UCC 008727