PULMONARY FUNCTION TESTING IN MILITARY PERSONNEL:

A PRELIMINARY STUDY1

Lieutenant Robert Bason, MSC USNR and

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)7 W PULMONARY FUNCTION TESTING IN MILITARY PERSONNEL:

A PRELIMINARY STUDY

Lieutenant Robert Bason, MSC USNR and

Commander David R. Stoop, MSC USNXIBureau of Medicine and Surgery

MF51.524.005-7027BA1X

Approved by Released by

Ashton Graybiel, M. D. Captain N. W. Allebach, MC USNAssistant for Scientific Programs Commanding Officer

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28 May 1975ISTH _I TION STATEMENT__ _ D

APPIV'Odfor Public releaoieDistribution Un.mit.d

NAVAL AEROSPACE MEDICAL RESEARCH LABORATORYP"NSACOLA, FLORIDA

1. .

SUMMARY PAGE

L

THE PROBLEM

The military community is made up of a very diverse group ofindividuals representing a random sample from all walks of life andgeographical locations. Although these individuals are supposedlyhealthy, an increasing number of them are later being diagnosed ashaving irreversible early obstructive ventilatory mechanics. While themagnitude and scope of the problem is largely unknown since it has notbeen adequately researched, the problem, nevertheless, is believed tobe significant and alarming by general medical officers and flightsur•. -ons.

The present report is part of a larger study aimed at detectingcardiopulmonary disease among military personnel. This report describesthe pulmonary function data obtained on these people.

FINDINGS

1. Pulmonary functions decreased progressively and significantlywith age, an observation that is in keeping with other studies.

2. The single most important feature of this study was the high"mechanics observed in the 20-24 year age group. Whereas most studiessuch as this reflect disease statistics in patients already symptomatic,this investigation reveals a significant percentage (23.5%) of the yetasymptomatic young age group who have the beginning of a long-termprocess.

3. The early obstructive ventilatory mechanics observed in the20-24 year age group were not related to smoking habits.

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0i,INTRODUCTION

An alarming increase in the death rate from pulmonary insufficiencyhas occurred over the past few years. For example, the Public Health

k Service in 1966 reported over 25,000 deaths due to chronic bronchitisand emphysema. This represented a 25% increase over the previous year (1).

In 1967, the Social Security Administration paid ninety million dollarsIV. in benefits to people affected with the two diseases. This represented

7% of all disability payments and made pulmonary obstructive diseaseK, second only to heart disease.

The military community is made up of a very diverse group ofindividuals representing a random sample from all walks of life andgeographycal locations. Although these individuals are supposedlyhealthy, an increasing number of them are later being diagnosed as havingirreversible early obstructive ventilatory mechanics. While the magnitudeand scope of the problem is largely unknown since it has not beenadequately researched, the problem, nevertheless, is believed to besignificant and alarming by general medical officers and flight surgeons.

The present report is part of a larger study aimed at detectingcardiopulmonary disease among military personnel. This report describesthe pulmonary function data obtained on these people.

METHOD

The subjects involved in this study comprised incoming Naval AviationCadets and designated aviators at Naval Air Station, Pensacola.

Routine spirometry was done using a Sanborn 211 and the Med-ScienceWedge Spirometer 370. Expiratory and inspiratory curves were alsorecorded on magnetic tapes for computer analysis. While standing, thesubject inhaled maximally from room air through a three-way valve, thenexhaled with maxomal force and speed into the wedge spirometer. A paperrecording demonstrated the validsty of the curve. Final analysis oftotal volume, forced expiratory volumes (one second, two seconds andthree seconds) and flow rates (maximal 200-1200 and 25-75%) rested withthe computer (2, 3). All values were reported in BTPS uncorrected forresting conditions. Nose clips were used.

Each subject ptzformed three trials and the best trial, i.e., theone with the highest forced vital capacity was used in the statisticalanalysis.

All anthropometric measurements were made according to standardtechniques and are described in an earlier report (4).

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The subjects were divided into three age groups: 20-24 year oldgroup, 25-34 year old group and the 40-49 year old group. There wereno subjects between the ages of 35-39. Each age group was furtherdivided into "normals" and those who were diagnosed as having pulmonarydisease, according to the criteria set forth in Table 1.

RESULTS

Pulmonary functions for the "normal" and " diseased" groups areshown in Figure 1 and summarized in Table II.

As can be seen from this figure, all of the pulmonary functionsregardless of diagnostic group exhibited identical trends, i.e., a :Jprogressive decrease with age with a more precipitous drop in the 40-49year old group. This value was significantly lower (p .05) than theother two age groups for all pulmonary functions for both the "normals"and the "diseased" groups. As would be expected, those subjects diagnosedwith pulmonary disease had significantly (p .01) lower overallpulmonary functions than the "normals" for each age group.

Anthropometric measurements are summarized in Table III and someare graphically displayed in Figure 2. No significant differenceswere observed between identical age groups for any of the variablesS measured. Chest circumference measured during maximum expiration and"inspiration tended to increase with age beyond the 25-34 year old groupfor both the "normals" arJ "diseased" groups. This increase, however,was not statistically significant.

Smoking habits of the two groups might conceivably differ enough toinfluence lung functions. However, in this study, 56Z of the "normal"group were smokers, and 57% of the "diseased" group were smokers.

Furthermore, there were no differences in either the quantity or theduration of smoking. In the 20-24 year old group, the "normals" smokedan average of 15 cigarettes per day for an average of 5 years while the"diseased" group averaged 14 cigarettes per day for 5.4 years. In the40-49 year old group the "normals" smoked an average of 18 cigarettesper day for 20 years while the "diseased" group averaged 7.5 cigarettesper day for 8 years. This "diseased" group, however, had only a samplesize of two and one of these was a nun-smoker.

DISCUSSION

Tt has been known that the pulmonary functions decrease progressivelyand significantly with age. The decreases observed in this study are inkeeping with the observations made by others (5-8). This decrease islargely attributed to a loss of lung elastic recoil and seems to occursometime after 34 years of age. The tendency toward increased chest

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V Table 1

Criteria Used to Establish Restrictive and Obstructive Pulmonary Disease

i MEASUREMENT 0AGE9 DIAGNOSIS AýS DIAGNOSIS ITRRTTO

0- - 9ITRRTTO

•EV'F S• ',,J-? 75 Normal 70 NormalFVG 76 OPD* 470 OPD A. All trials are considered in the

S.......Diagnosis.FEV_2 Sec.% 94 Normal go9 Normal B . All predicted normal values are based

FVC 94 OPD 4.90 OPD on age, sex, and heijht.

Normal_FEV 3 Sec.% > 97 Normal • 94 M~ormal

FVC 97 OPD 4 94 OPD The predicted normal for each measurementmust be achieved 'n one of the trials to

~~~~~~e ... ..... .... rceive a diagnosis of normal.14EFR Consistent with-Restrititve Disease. 0V=t1

(200-1200 ml 1 7000 Normal t 4000 Normal I capacity)...:flow rate ml/secý 4 7000 OPD 4 4000 OPD !

KALE This diagnosis is made when all trials fall ;

400 Nra 00 Nra below 80% of predicted vital capacity.

FEMALE 4000 OPD 4. 4000 OPD Consiltent with Obstructive Pulmonary Disease.S..... .. ... (FVC Is 2, 3, Sec.%,"MEFR, MMIF)

N.. tUF ... This diannosis is made whe n the predicted(2 6: flow 'Z 3400 Normal 2000 Normal value fails to be achieved in any of the

rate n~il/ sec) -C 3400 OPD <2000 OPD measurements in all trialIs.

t.•I.

Cr ite r Consistent wUth RestrtatbR i and Obstructiveormal 20 Normal APulmonary Dises is diagnosed When the abov

F/ALE 73000 OPD 20U0 OPD criteria for sis diagnoses are fulfilled.

FV - 2Sec80 Normal 90Formula used to prednct the vtal capacity.

F VC* 3so.% ~ 9 Normal Ž9 ~ ml Nra

(X of predicted) 4 80 ConsTstent with Restrictive In hale cc t 27.63-(0.112xnoma x ht. cmVital capac7ty Disease In Femle cc h 21.78-(0.101x gen x ht. cm

• OPD Obstructive Pulmonary tvsease.Forced Vital Capac4ty

6.0 . NORMALS____ PULMONARY DISEASE

5.5 6.0

>- 5.0 5,.-

S4.5 4.0

> 4.0 3.0o-

~3.520

3.0 .0 -

9.05.

8. uo 4 .0

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ULL

20-24 25-34 40-49 20-24 25-34 40-49

AGE GROUP (YEARS)

Figure 1

Lung Vo!l.ume Measurements by Age Groups

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Anthropometric Measurements by Age Group

6

NIcircumference, observed in this study, suggestive of larger closingvolumes would tend to support a loss of elastic recoil. The steep falloff in pulmonary functions in the older age group is in agreement withthe work of Hutchinson (9) and Berglund (10).

The reason for the significant differences in pulmonary functionsbetween the "normal" and the "diseased" group is unclear. There are a

number of factors which could be responsible for these differences.These would include anthropometric differences, smoking habits, motivation,geographic location and early respiratory illness to name a few. Thedifferences could also be a fortuitous finding in a single study.

It is unlikely that anthropometric measurements were responsible forthe differences in pulmonary functions. As was shown in Table III, therewere no significant differences in any ot the anthropometric measurementsobtained.

Smoking habits of the two groups might conceivably differ enough toinfluence lung functions. However, in this study, 56% of the "normal"were smokers and 57% of the "diseased" group were smokers. Furthermore,there was no difference in either the quantity of the duration of smoking.This is not a contradiction to vhrtually all other studies that have shownlung impairment among cigarette smokers (11-15). A comparison of smokersand non-smokers in this study did in fact show lower overall pulmonaryfunctions for smokers than non-smokers, however, the differences were notsignificant. What this does say, however, that since both the "normal"and the "diseased" groups had approximately the same percentage ofsmokers who smoked the same amount and for the same duration, smokingshould have influenced the two groups equally and therefore, dhould nothave been a contributing factor for the observed differences.

It is difficult to ascertain the role that motivation or impropertechnique played in accounting for the differences. Each group performedthree trials and the best of the three trials was used in reporting thedata. Furthermore, it is highly unlikely that motivation and propertechnique or the lack of it would have been limited to just one groupand not the other.

It was not determined whether geographic location, i.e., environmentalconditions or early respiratory illness could have been responoible forthe observed difference. It is also unlikely because of the large samplesize, that this was a fortuitous event occurring in a single study.

The single most important feature of this study was the highincidence, for whatever reasons, of early obstructive ventilatory mechanicsobserved in the 20-24 year old age group. Whereas most studles such as

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current investiration reveals a significant percentage (23.5%) of theas yet asymptomatic young age group who have the beginnirSs of a long-term process. This is quite alarming in such a young age group thatsupposedly represents the "cream of the crop" in health. It is furtherdeemed important to note that rather than search retrospectively forthe early signs of chronic obstructive airway disease, that moreinformation such as provided herein be sought first of all to ascertainwhether the observed pulmonary function values obtained in this studyfor the 20-24 year old group are real, i.e., not a chance finding in

N a single study; if it is real to account for it and discuss its impacton physical performance especially with regard to aviators flying highperformance aircraft and finally to validate the criteria for earlyobstructive ventilatory mechanics and possible reversible changes ashas been suggested in the literature (16). These young people areclearly the people at risk for future complications and the earlier theyare identified the better chance there likely will be of interruptingthe otherwise inexoresole course.

In this regard, the Aviation Medicine Division of the Naval AerospaceMedical Research Laboratory is presently undertaking a long-term pulmonaryfunction study in hopes of identifying early obstructive pulmonarymechanics in young aviators.

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F]EPERNCES1. Health Consequence of Smoking. 1968 Supplement. Public Health

Service Review. Washington, D. C. 1968.

2. Anon., Program methodology for spirometry. Washington, D. C.:Instrumentation Field Station, Heart Disease, Department of Health,Education and Welfare, 1965.

3. Shonfeld, E. M., Kerkes, J., Radmacher, C. A., et al, Methodology

for computer measurements of pulmonary function curves. Dis.

Chest, 46:427, 1964.

4. Sberman, A., Mitchell d R. E.l, A., Thousand Aviator

Study: Methodology. Monograph 11. Pensacola, Fla.: Naval4 OeaSchool oA Aviation Medicine, 1965.

5. Kaltreiaer, N. L., Fray, W. W., and Hyde, H. W., Effect of age on

pulmonary capacity and its subdivision. Am. Rev. Tuberc., 37:662,1938.

6. Briscoe, W. A., Lung volumes. Effect of age in lung volumes.In: Fenn, W. B. and Rahn, H. (Eds.), Handbook of Physiology.Vol. II, Section 3: Respiration. Washington, D. C.: AmericanPhysiology Society, 1965. P 1360.

S7. Comroe, J. H., Jr., Forster, R. E. II, Dubois, A. B., Briscoe, W. A.9and Carlsen, E., The Lung: Clinical Physiology and Pulmonary

Function Tests, Second Ed. Chicago: Year Book Medical Publishers,Inc., 1965. Chap. 9, pp 212-213.

8. Kory, R. C., Callahan, R., and Hollis, G. B., The Veterans Admin-istration-Army Cooperative Study of Pulmonary Function I.Clinical Spirometry in Normal Men. Am. J. Med., 30:243, 1961.

9. Hutchinson, J., On the capacity of the lung and on the respiratoryfunctions: with a view of establishing precise nnd easy method ofdetecting disease by spirometer. Trans. Med. Chir. Soc. London,29:137, 1846.

10. Berglund, E., Birath, G., BJure, J., et al, A spirometric study in

normal subjects 1. Forced expirograms in subjects 7 and 70 yearsof age. Acta. Med. Scand., 173: 187, 1963.

11. Hollis, G. B., Kory, R. C., and Syner, J. C., The Veterans Adminiq-tration-Army Cooperative Study ef Pulmonary Function II. The

Lung Volume and Its Subdivision in Normal Men. Am. J. Med.,41:96, 1961.

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12. Abraham, S. K., and Riker, J. B., The variable effect of smokingon pulmonary function. Chest, 63:655, 1973.

13. Edelman, N. H., Mittan, C., Norris, N. H., et al, The effects ofcigarette smoking upon spirometric performance of communitydwelling men. Am. Rev. Resp. Dis., 94:421, 1966.

14. Hensler, N. H., and Giron, D. J., Pulmonary physiological measurementsin smokers and non-smokers. JAMA, 186:885, 1963.

.15. Wilson, R. H., Meador, R. S., Jay, B. E., et al, The pulmonarypathologic physiology of persons who smoke cigarettes. N. Eng.I J. Med., 262:956, 1960.

SI16. McFadden, E. R., and Linden, D. A., A reduction in maximum mid-expiratory flow rate. A spirographic manifestation of smallairway disease. Am. J. Med., 52:725, 1972.

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