Document 6w8dk7onp4K8dr8jJXLOv2YV9

Technical Manual 77-1 W. J. HARLEY, M.D. PULMONARY function TESTING in occupational fedicine Edward P. Horvath, Jr. May 1977 NAVY ENVIKMENTAL HEALTH CENTER 3333 VINE STREET CINCINNATI, OHIO 45220 APC 003537 Approved for public release; distribution unlimited. PULMONARY FUNCTION TESTING IN OCCUPATIONAL MEDICINE Edward P. Horvath, Jr. LCDR, MC USNR Released by Thomas N. Markham Captain, MC USN Commanding Officer 17 May 1977 Navy Environmental Health Center 3333 Vine Street Cincinnati, Ohio 45220 I TABLE OF CONTENTS I. Introduction II. Technique III Selection and Calculation ofSpecific Tests A. FVC 3 B. FEVX C. FEV1/FVC% D. FEF25_75% IV. Interpretation of Baselineand Follow-up Spirograms V. Instrument Specifications VI Specific Types of Spirometers VII. Conclusion Selected References Appendix A ' Tables and Figures PAGE 1 1 2 3 4 4 6 8 9 10 11 12 14 APC 003539 PULMONARY FUNCTION TESTING IN OCCUPATIONAL MEDICINE I. INTRODUCTION The routine assessment of ventilatory capacity for pre-employment evaluation and periodic medical surveillance is becoming an increasingly common practice in occupational medicine. Combined with a careful his tory and physical examination, such pre-placement screening can identify the job applicant with pre-existing functional impairment or unusual susceptibility to airborne substances. Follow-up studies can facilitate the early detection of respiratory impairment at a stage when corrective measures may still be beneficial. The utility of screening spirometry has been recognized by the federal government. The passage of the Federal Coal Mine Health and Safety Act and the Occupational Safety and Health Act have lead to an increase in pulmonary function evaluation. Nonetheless, not all employers have established screening programs or even identified workers at risk. Occupational Safety and Health Administration (OSHA) standards for general industry currently require such screening only for exposure to asbestos and coke oven emissions. However, Criteria Documents formulated by the National Institute of Occupational Safety and Health (NIOSH) assure it will eventually be required for numerous other substances as well. Presently, the U.S. Navy has mandated pulmonary function studies for asbestos, berrylium and isocyanates, but it too can be expected to adopt any future OSHA regu lations. Facilities that have instituted screening programs are beset by a multitude of problems. Technicians have been inadequately trained and tests are performed or calculated incorrectly. Spirometers may be inaccurate or technically unsatisfactory. Within any large organiza tion methodology may lack standardization, rendering difficult the comparison of results obtained at different locations. Information derived under these circumstances may be worse than no information at all. II. TECHNIQUE Much attention has been focused on the specific tests of pulmonary function and the type of spirometer, but relatively little thought has been given to the single most important factor in successful spiro metry - the skill and training of the technician. As Dr. Hans Weill stated in an article appearing in the September, 1973 issue of Journal of Occupational Medicine, "the personality, patience and perserverance of the pulmonary function technician will often determine the difference between a successful and unsuccessful program of pulmonary function ex amination." Such technician training can be accomplished at special courses, or through the direction of a knowledgable physician or senior 1 APC 003540 technican, preferably in a well-equipped pulmonary function laboratory. During the actual performance of spirometry, meticulous attention to detail is essential. The procedure should be explained to the patient in simple terms. A statement that you wish to test "how hard and how fast he can breathe" may not be physiologically precise, but it may be the only explanation necessary. At least one hour should have elapsed between the subject's last smoke or the administration of aerosolized bronchodilators. Pulmonary function studies should not be performed within two hours of the main meal. They should be postponed if the subject is acutely ill from any cause or has experienced an upper or lower respiratory tract infection during previous three weeks. The subject should then be instructed to remove any tight clothing or dentures. He should sit or stand in front of the spirometer. The chin should be slightly elevated with the neck sliohtlv extended. Under normal circumstances there is little difference in pulmonary function values whether the patient is standing or sitting. An exception is the grossly obese subject where the sitting value may be significantly lower. The use of a nose clip is recommended. The subject should then be instructed to take the deepest possihlp inspiration from a normal breathing pattern, close his mouth firmly around the mouth piece and without further hesitation blow into the apparatus as hard, fast and completely as possible. Common errors at this point include failing to maintain an air tight seal around the mouth piece, pursing the lips as with a musical instrument or obstruct ing the mouth piece with the tongue. USAfter two practice attempts, three further tracings shouId be re corded and assessed for acceptability. the technican believes the patient has not made a full inspiration prior to the forced expiration, has not put forth a maximal effort, (or) has not continued expiration for at least five seconds (or until an obvious plateau in the volume-time curve has occurred) that particular tracing should be repeated. At tempts marred by coughing should also be rejected. (Fig. 1 ). The variation between the largest and smallest forced vital capacity (FVC) of the three satisfactory tracings should not exceed 10%. (Fig. 2 ). From the three satisfactory tracings, the forced vital capacity and forced expiratory volume in one second (FEV^ should be measured. The largest FVC and FEV should be used in the analysis regardless of the curve(s) on which they occur. For example: in the calculation of FEV^/FVC%, the FEV1 and FVC need not be from the same curve. III. SELECTION AND CALCULATION OF SPECIFIC TESTS Numerous criteria are available to assist one in the choice of ap propriate pulmonary function tests. Briefly, the ideal test should be able to distinguish "normal" from "abnormal" with sensitivity, safety and reproducibility. The test should be effort independent, or if not, 2 APC 003541 subject motivation should be assessable by a trained observer. None of the usual spirometric tests available are "ideal" in the sense described, but certain indices have proven useful. These include the forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory volume in one second as a percent of the total forced vital capacity .FEV /FVC%), and forced expiratory flow during the middle half of the FVC (FEF25 75%* * FVC (Forced Vital Capacity) The FVC is the maximal volume of air which can be exhaled force fully after a maximal inspiration. (Fig. 3 ). For all practical purposes, the VC (vital capacity without forced effort) and the FVC are identical in most individuals. In patients with severe bronchopulmonary disease, however, the FVC is often smaller than the VC because of ex piratory slowing, air trapping and hyper-inflation. In the absence of airways obstruction, an abnormal FVC is seen in "restrictive" disease those conditions characterized by a decrease in lung volume. Extrapulmonary factors can contribute to the inability to achieve a full inspiration including chest wall deformities (kyphoscoliosis) or re spiratory muscle weakness (polio, muscular dystrophy). Actual replace ment of lung tissue by tumor or inflamatory exudate decreases lung volume thereby lowering the FVC. Stiffening of the lungs by either excess fluid or fibrosis interferes with full inspiration. Pulmonary fibrosis can be due to connective tissue disease (rheumatoid arthritis, lupus erythematosis) or the pneumoconioses (asbestosis, silicosis, bervlliosis). It can also exist without apparent cause (idiopathic pulmonary fibrosis). With regard to the early detection of pneumo coniosis, the FVC is of variable utility. In asbestosis, the FVC has been regarded as the most sensitive indicator of early disease and is frequently impaired before there are radiographic abnormalities. Con versely, X-ray changes may be evident in the silicotic while the FVC is still normal. FEV^ (Forced Expiratory Volume in One Second) The FEV^ is that volume of air which can be forcibly expelled during the first second of expiration (Fig. 3 ). In those instruments where the chart recorder or kymograph is activated prior to expiration, the zero point for timing the FEV^ must be determined by extrapolating the steepest portion of the volume curve back to the maximal inspiration volume (Fig. 4 ). The FEV has been regarded as the most useful overall spirometric measurement and is abnormal in obstructive disease. In emphysema, resistance to airflow in the bronchial tree can result from airway collapse secondary to intrinsic airways disease and/or loss of elastic support from surrounding lung tissue. In asthma and chronic bronchitis, the bronchial lumen is narrowed by retained mucus and/or spasm of the bronchial musculature. 3 APC 003542 I FEV /FVC% (Forced Expiratory Volume in One Second as a percent of the Total FVC) The FEV^ can be expressed as a percent of the predicted normal value for FEV or as a percent of the total FVC. (Fig. 3 ). By routinely calculating FEV^/FVC* one can avoid a common mistake. This occurs in severe pulmonary restrictive disease where a reduction in FVC alone may falsely suggest airways obstruction. Normally one should be able to expire 70-80% of the FVC in one second, depending upon age and sex. For example, a patient with pulmonary fibrosis may have a significantly reduced FVC of only two liters; but in the absence of airways obstruc tion he should expire 80% of this forced vital capacity in one second. However, this volume would be only 1.6 liters or 50% of his predicted FEV of 3.2 liters. Therefore, one could erroneously assume he has obstructive disease, when in fact only pulmonary restriction is present. The calculated FEV^/FVC% (1.6/2.0) in this case is a normal 80%. If ventilatory obstruction is present, an assessment of reversibili ty may be desirable. The patient is asked to inhale a nebulized bronchodilator such as isoproterenol. After five minutes the FEV is re peated. An increase of 15% or more from the baseline value indicates an element of reversibility. Such information can have both diagnostic and therapeutic implications. Reversibility, particularly if it is complete or nearly so, favors a diagnosis of asthma (a disease more likely to be of occupational origin) rather than chronic bronchitis or emphysema. Reversibility is also indicative of probable improvement with bronchodilators. Conversely, an individual with asthma may have normal 7ulmo function studies on a given day. Inhalation of the cholinergic drug methacholine, can induce mild bronchospasm in asymptomatic asthmatics, allowing the correct diagnosis to be made. A decrease of 15% or more in the FEV as compared to the baseline value is regarded as a positive test. However, to perform this procedure in the face of spirometrically obvious airways obstruction is not only unnecessary, but also poten tially hazardous. Although neither isoproterenol nor methacholine in halation are regarded as routine screening procedures, they can provide further useful information with little additional risk. Under no cir cumstances should either be performed without the supervision of an experienced physician. FEF^g (Forced Expiratory Flow during the middle half of the FVC) The FEF25 75% can be de^ined as the average rate of flow during the middle two quarters of the forced expiratory effort, i.e., from 25-75% of the vital capacity (Fig. 5 ). It was previously known as the MMF or maximal mid-expiratory flow rate. Compared to the FEV^, it is more sensitive in detecting early airways obstruction and tends to reflect changes in airways less than 2 millimeters in diameter. It is in these smaller bronchi and bronchioles that airborne substances are thought to 4 APC 003543 exert their initial deleterious effects; yet because they contribute only 15% to total airway resistance, considerable disease may be present in them without being reflected in the FEV . A diminished FEF i frequently the only abnormality noted in tth*e; asymptomatic asthmatZc%or young cigarette smoker. has been regarded as less dependent on voluntary more susceptible to instrumental artifacts and its coefficient of varia tion (variability in the same individual) may be as great as 25% com pared to 2-6% for the FEV1 and FVC. Due in part to this variability, the FEF^ ^ % has not been design ated by OSHA or the Navy as a required screening^test. Although it can be easily calculated from the forced expiratory tracing, it must be interpreted only by a physician qualified to evaluate chest disease. No individual should be denied employment, transferred or referred for an exhaustive pulmonary evaluation solely on the basis of a decreased FEF25-75%- The "normal" values for FEF25 are a<?e dependent. For indivi duals under 50 years of age, less than 75% of the predicted value may be abnormal. In those over 50, the "lower limit of normal" is 70% of pre dicted. In follow-up studies, where the individual functions as his own control, comparison must be made to the previously recorded highest value for that individual. A decline in FEF25 75% of 20% or more may he significant. Several additional tests should be mentioned primarily to discourage their use. The FEF2oo-1200 '*'s the flow between 200 and 1200cc of the vital capacity. Formerly known as MEFR or the maximal e .piratory flow rate, it reflects changes in the large airways, but has little further to add to that information obtained from the FEV . Peak expiratory flow rates are significantly influenced by patient effort, are quite variable and provide less information than the FEV^ or FVC. The MW (maximum voluntary ventilation) is unpleasant, exhausting and very effort depen dent. In addition, it cannot be performed adequately on some spiro meters. Although sometimes required by law in the evaluation of pulmon ary disability, it is not a useful screening test. Correction to BTPS (body temperature, ambient pressure, saturated with water vapor) is an important step in'the calculation of spirometric tests. This is necessary because the patient exhales the gas at body temperature (37C) while the volume recorded by the spirometer is at a somewhat lower ambient temperature. This volume of gas recorded by the spirometer must then be multiplied by a factor to convert it to what it should be at normal body temperature (Table I ). This usually increases the gas volume recorded by the spirometer by approximately 8%, but it may vary from 4-10% depending upon ambient temperature. This correction is particularly important in-field studies, where ambient temperature may 5 APC 003544 vary considerably. Some manufacturers build in an automatic correction factor, either into the apparatus itself (electronic spirometer) or in the recording paper. The latter is acceptable, but less desirable than direct calculation of the conversion to BTPS. IV. INTERPRETATION OF BASELINE AND FOLLOW-UP SPIROGRAMS After the population at risk has been identified, baseline studies should be obtained, ideally prior to any work-related exposure. The decision as to whether baseline studies are "normal" is usually made by comparison with a set of published predicted normal values. Many phy sicians still use data derived by Kory and his associates from the 1960 VA - Army Cooperative Study of Pulmonary Function. This group contained a large proportion of smokers and its values generally run lower than those of Morris and co-workers published in 1971 by the American Review of Respiratory Disease. These were derived from a population of healthy, non-smoking men and women with relatively little exposure to air pol lution. They are regarded by many as the preferred set of predicted normals (Figs. 6 and 7). Abnormal functions are present when the: 1. FEV^ or FVC is less than 80% of predicted; or 2. FEV^/FVC% is less than 70%. If a qualified physician is available for assessment of the FEF25 75%' its interpretation should be done according to the guidelines on page 4. It must be pointed out the FVC and FEV^ of non-Caucasian is ap proximately 15% lower than in whites of the same age and height; dif ferences in the FEV^/FVC% are not significant, however. Allowances for these ethnic differences must be made during pre-employment evaluations to avoid serious errors in interpretation. In non-Caucasians (blacks, Orientals), the predicted FEV^ and FVC for any given individual should be multiplied by 0.85 to adjust for this 15% difference. No such cor rection is necessary for the FEV^/FVC%. Before labelling any baseline or pre-employment studies as abnormal, they should be repeated in two weeks. More sensitive than comparing the spirometric values of a particular worker with a set of predicted normals, is the longitudinal or repeat testing of the same worker over a period of time. Here he serves as his own control and follow-up values can be compared to changes in pulmonary function which might normally be expected with aging. In males, a 30 milliliter annual decline in FEV and 25 milliliters in FVC can be attributed to normal aging. In females, it is 25 milliliters for both the FEV1 and FVC. In addition to the effects of age and disease, other sources of 6 variability exist. The coefficient of variation, the change in any given subject repeatedly tested over a period of time, may be 2 - 6% for the FEV^ and FVC. This variation includes both biological (fluctuating patient effort) and instrumentation (changes in calibration) factors. Comparing follow-up values obtained on different spirometers can be an additional source of error. This is a particularly serious problem in any large organization like the Navy where different spirometers are in use and where the work force is relatively mobile. There seems to be no solution to this problem at present; the ideal situation, the use of a single type of spirometer, is simply not feasible. An alternate ap proach would be utilization of appropriate "conversion factors". This would allow pulmonary function values obtained on different instruments to be expressed as if they had been done on one standard type of spiro meter, e.g., a water-sealed Stead-Wells. Whether a compilation of such conversion factors will ever be published is presently a matter of conjecture. One of the references at the end of this manual, "Assess ment of Ventilatory Capacity", describes the procedure for determining conversion factors. The predictable pattern of daily and seasonal variation must also be considered. Measurements of pulmonary function are highest in the afternoon, and decline slightly during the evening hours. Values are also higher during the summer than the winter. If annual follow-up studies are contemplated, ideally they should be scheduled during the same shift and month. In addition to accelerating the normal effects of aging, cigarette smoking may transiently alter certain pulmonary function tests, particu lar!. the forced expiratory flow rates. This effect may be particularly pronounced for an hour after smoking and one should wait this long prior to the performance of spirometry. Fixed airways obstruction eventually occurs in many smokers and hence one can generally expect to find lower values for FEV^ and FEV^/FVC% as well. Given these variables and technical considerations what criteria should be used to decide if a given change is due to disease? For follow-up studies, comparison should be made with the previously re corded highest value for each test. This highest value may not neces sarily have occurred during baseline or pre-employment testing. If the following changes are not clearly attributable to the effects non disease related variables, they should be considered abnormal: 1. decline in the FEV1 or FVC greater than 8%; 2. decrease in the FEV1/FVC% greater than 6%; or, 3. FEV^/FVC% less than 70% at any time. Any abnormalities of either baseline or follow-up pulmonary functions should be verified by repeating spirometry in two weeks. If abnormali- 7 APC 003546 ties persist, clinical assessment by a physician qualified to evaluate chest disease is essential. It should be re-emphasized that pulmonary function tests are non specific; one can seldom make a diagnosis based on spirometric findings alone. The total clinical presentation must be considered including the medical history, physical examination, chest X-ray and appropriate laboratory studies. Similarly, medical management in the occupational setting must be tempered by clinical judgment. It is seldom justifiable to deny an individual employment or transfer him to another job solely on the basis of minimally abnormal spirometry (Table II ). Most abnor malities on these screening tests are not due to work-related disorders. Smoking, non-occupational lung disease, and variation in technique are more common causes of alterations in pulmonary function. The necessity of maintaining complete medical records should also be underscored. Both pre-employment (baseline) and follow-up values must be inscribed on a flow sheet (Fig. 8 ). It is also advisable to incor porate the spirographic tracing itself into the worker's record. V. INSTRUMENT SPECIFICATIONS Various types of spirometers are available; many are technically satisfactory, but a significant minority are not. The following general guidelines on what constitutes an acceptable spirometer have been de rived from currently available sources, including the NIOSH-ALOSH (Ap palachian Laboratory for Occupational Safety and Health) Pulmonary Function Standards submitted to OSHA in 1977. Volume - The volume capacity of the instrument should be 7 liters at BTPS. This is the chief inadequacy of the Air Shields Vitalor, an in strument designed primarily for monitoring hospitalized patients. It is not recommended for screening healthy young males. In addition, spiro meters should be capable of accumulating volume for at least 8 seconds. Accuracy-linearity - For measuring FEV^ and FVC, the instrument should be accurate within 50 milliliters or within 3% of reading, whichever is greater. Inertia + resistance - The instrument should have low inertia and offer low resistance to air flow. The combined effect of inertia and resis tance may be assessed by measuring the back pressure in the tubing during the performance of the test. In a subject with a FEV^ of at least 3.5 liters, back pressure at the mouthpiece should not exceed 10 cm of H^O for longer than 0.5 seconds and 2 centimeters of water during the remainder of the maneuver. Timing - The timing units of instruments so equipped should be accurate to within 3%, be capable of calibration in the field, and be actuated by exhalation of 50 milliliters or after an expiratory flow of 200 milli- APC 003547 liters per second has been achieved. If a chart recorder or kymograph is used in the determination of ^ must be activated at least one second prior to the forced ex piration to ensure operation at the proper speed. Conversion to BTPS - The instrument or user of the instrument must have a means of correcting volumes to BTPS under conditions of varying am bient temperature. Provision of ci written tracing - The instrument should provide a tracing or display of either flow versus volume or volume versus time during the entire forced expiration. This is necessary to determine whether a patient has performed the test properly. The tracing should be of suf ficient size such that hand calculations can be made (7.5 millimeters of chart per liter of volume and 20 millimeters of chart per second of time). Calibration - The instrument should be capable of calibration in the field with respect to FEV1 and FVC. Periodic recalibration of the in strument should be performed using a syringe or other known volume source of at least 2 liters. The frequency of such calibration will vary with the use of the spirometer. Instruments that provide elec trical outputs proportional to volume and/or flow (electronic spiro meters) should be calibrated at least daily according to the manufac turer's instructions. VI. SPECIFIC TYPES OF SPIROMETERS The water-seal spirometers, such as the Stead-Wells and Collins, are time-tested instruments and are frequently used as a standard to which other devices are compared (Fig. 9 ). Although they provide a high de gree of accuracy and reproducibility, they require more technician so phistication, and are larger and more expensive than the commonly used bellows instruments. This latter group of spirometers replaces the water-sealed drum with a bellows apparatus. They include among others, the Vitalograph* by Vitalograph Ltd. (Fig. 10 ) and the Jones Pulmonar (Fig. 11 ). In most respects they compare reasonably well with the water-sealed instruments. Their advantages include portability, sim plicity of operation and reasonable cost. Recent years have witnessed the proliferation of several types of electronic spirometers (Fig. 12 ). These are of two basic designs. One type employs a turbinometer, the rotational speed of its blades being proportional to the flow of expired air. The other uses a thermistor, a hot wire which is kept at a constant temperature by an electric cur rent. Expired air cools the wire and the current required to re-estab- The use of manufacturer's names does not constitute endorsement of a specific instrument by either the author or the Department of Defense. 9 APC 003548 lish the original temperature is proportional to the flow rate. These electronic spirometers offer many conveniences including ease and rapidy of operation, digital readout of results and automatic conversion of values to BTPS. Inadequacies in certain models have been documented, however, and include alinearity, variability, lack of a written record, necessity of frequent calibration and relatively high cost. These weaknesses should not be taken as a general condemnation of electronic spirometers, however, and each instrument should be evaluated on its own merits. Another innovation in the field was the introduction of the dry, rolling seal spirometer manufactured by Ohio Medical Products and Warren E. Collins, among others. A U-shaped silastic device is the method of sealing between the piston and the cylinder (Fig. 13 ). This plastic seal rolls freely upon itself during function testing and is responsible for the low resistance of these spirometers (Fig. 14 ). The wide variety of available spirometers poses problems in deciding which one is right for your particular facility and purposes. Financial considerations are oftentimes of paramount importance, although a sub standard spirometer at any price is no bargain. Acceptable instruments can be purchased for approximately $1,000. Prior to ordering any spiro meter, one should review currently recommended standards for equipment specifications. VII. CONCLUSION The foregoing recommendations represent the essentials of a valid, practical pulmonary function screening program. Along with industrial hygiene practices, biological monitoring such as spirometry, comprise the core of any effective occupational health endeavor. Properly im plemented, they will help fulfill the intent of the Occupational Safety and Health Act, "to assure safe and healthful working conditions for working men and women". 10 ARC 003549  1 Selected References 1. The assessment of ventilatory capacity. Statement of the Committees on Environmental Health and Respiratory Physiology, American College of Chest Physician, Chest, 67: 95-97, 1975. 2. Bates, D., Macklem, P., Christie, R.: Respiratory Function in Dis ease^ Philadelphia, W. B. Saunders, 1971. 3. Baum, G.: Textbook of Pulmonary Diseases. Boston, Little, Brown, 1974. 4. Cotes, J. R.: Tests of lung function in current use: proposals for their standarization. Respiratory Function Tests in Pneumoconiosis Occupational Safety and Health Series, Geneva, ILO, (6) 93-140, 1966. 5. Morgan, W. K., Seaton, A.: Occupational Lung Diseases. Philadel phia, W. B. Saunders, 1975. 6. Morris, J. F., Koski, A., Johnson, L. C.: Spirometric Standards for healthy non-smoking adults. Am. Rev. Resp. Pis., 103: 57-67, 1971. 7. Parker, C. D., et. al.: Methacholine aerosol as test for bronchial asthma. Arch. Int. Med. 115:452-458, 1965. 8. Parkes, W. R.: Occupational Lung Disorders. London, Butterworths, 1974. 9. Ruppel, G.: Pulmonary Function Testing. C. V. Mosby, St. Louis, 1975. 10. Weill, H.: Pulmonary Function Testing in industry. J. Occup. Med., 15:693-699, 1973. 99 99 li ARC 003550 APPENDIX A PROCEDURE AND INTERPRETATION - A SUMMARY 1. Screening spirometry should not be performed if the subject: a. is acutely ill from any cause; b. has smoked or used an aerosolized bronchodilator within the past hour; c. has ingested a heavy meal within the previous two hours; d. has experienced an upper or lower respiratory tract infection during the past three weeks. (For example: influenza, severe "cold", "bronchitis", or pneumonia). 2. The procedure should be adequately explained to the subject. 3. The subject should be instructed to remove any tight clothing or dentures and to sit or stand comfortably in front of the spirometer. The chin should be slightly elevated with the neck slightly extended. The use of a nose clip is recommended. 4. The subject should be told to take the deepest possible inspiration, close his mouth firmly around the mouthpiece and without further hesita tion, blow into the apparatus as hard, fast and completely as possible. Active coaching throughout the entire duration of the forced expiration is desirable to elicit maximum subject effort. Positioning of the lips around the mouthpiece should be checked. 5. After two practice attempts, three further tracings should be re corded. If the technician believes that the subject has not made a full inspiration prior to the forced expiration, not put forth a maximal effort or not continued expiration sufficiently long, that particular tracing should be repeated. Attempts marred by coughing should also be repeated. The variation between the largest and smallest FVC of three satisfactory tracings should not exceed 10%. 6. From the three satisfactory tracings, the FVC, FEV^, and FEV1/FVC% should be determined. The largest FVC and FEV^ should be used in the calculations regardless of the curvets) on which they occur. Transcribe results on the "Pulmonary Function Record" sheet under "observed" (Obs.). The tracing itself should also be maintained as part of the medical re cord. 7. If the tests are baseline studies, determine the predicted values from Morris et. al. and calculate the subject's percent of the predicted normal, and transcribe results on the record sheet. In non-Caucasians, the predicted FEV and FVC should be multiplied by 0.85 to adjust for 12 APC 003551 ethnic differences. No correction factor is necessary for the FEV / FVC%. Abnormal functions are present when: FEV^ or FVC is less than 80% of predicted: or, FEV1/FVC% is less than 70%. 8. If the tests are follow-up studies, comparison should be made with the previously recorded highest value for each test. This highest value may not necessarily have occurred during baseline testings. If the fol lowing changes cannot clearly be attributed to the effects non-disease related variables or to the effects of aging*, they should be considered abnormal: a. decline in the FEV^ or FVC greater than 8%; b. decrease in the FEV^/FVC% greater than 6%. 9. Any abnormalities in either baseline or follow-up pulmonary func tions, should be verified by repeating spirometry in two weeks. If abnormalities persist, clinical assessment by a physician qualified to 'evaluate chest disease is essential. 10. In those circumstances where screening spirometry is performed and interpreted without direct physician supervision or review, referral of the subject is mandatory when: a. the caseline or follow-up values are abnormal as defined in 7. or 8. above and remain so after repeat studies in two weeks; or, b. respiratory symptoms are present, regardless of pulmonary func tion values. * In males, a 30 millimeters annual decline in FEV^ and 25 millimeters FVC can be attributed to normal aging. In females, it is 25 milli meters in both the FEV^ and FVC. 13 APC 003552 9 r I 9I * i* FIGURE 1 14 N"\ CSI APC 003553 F ig u re 1. Three unaco :b le tra c in g s . A. E x p ira tio n too b r ie f. B. Cough. C. Inadequate e ffo r t. r FIGURE 2 15 F ig u re 2. Three a c c e p ta b le tra c in g s . The v a r ia tio n between the la r g e s t and s m a lle s t FVC Is le s s th a n 10%. ri APC 003554 r rt r* r FIGURE 3 *16 K* U > uW>, -3c3 o a>- wa>* .CeJ o oc CM r3 C uB0) a0J m cj 3bO o I 1 i| i Maximal Ins piratory LevEL \| r ___ ML(--ExtRAPOLATED L INE *o Point i i \ " ---- : 1 __ j ^1 ;t -- FEVj TieIAL VOLJUME l \Y\\ \ \ N* P/C 11i1 11 _J____ \ \ TIf- 3 1' 1 L 1 l Sv r !! 3_ Figur e 4. Detent inatic n of t he zer o poin t for timing the F EVi- Extra polate a lir e froo the s teepes t potJ on of the vo lume c urve back to the maxis al ins pirate ry le? el. T he in tersect ion of -- these lines is th e zerc point FIGURE 4 17'' ri c ri r` > r ;, ... 00 C 4-1 --cH 3u X o 01 4-1 c 0 c c o u c o cn u co 01 ij a. --c 01 Cfl Cfl u tcH 3 *c-4 c u 01 u ^4 O 01 1--4 a. 43J tC 3 3 ^B4 u c4 <9 u CJ Q u c u01 0 a. o w3 C 01 01 3 o 01 Cfl 01 nJ a u X > HinU. 0) <9i 3 T3 0 cfl IM u 01 <cJ 4c-f>l m1 X *-* u 01 01 X *104 CM U* U-l <0 u H *3 u u- O 40-11 Cfl 0) Hin c U eo *^4 X r- 2 4J 4J "O uo T3 U 01 IM 0 a cfl u C cfl > 3 3 c H *4 - 01 0 (J 0 m *3 < *j 01 T< CM i_> C01 ~ CO 9) c3c *H 6u V 00 4-1 ^e4 X 01 4J C -3 0) tfl Cfl 4-1 ^c4 -D cfl 0 a 0u1 V) u 3 u 4 pH 4J 0) c0n1 cfl 01 vj o m 01 u u co a01 u c u H u u X rafl. c CO 0c0 1-1 oa. to 01 3 c 01 -c3 CM 3 CO to o 030 u cfl w01 o u o u 9) H U- u u Xu 01 CO a> X 91 u FIGURE 5 is APC 003557 Table I FACTORS FOR CONVERTING GAS VOLUMES FROM ROOM TEMPERATURE TO BTPS ersion factor 1.114 1.111 1.102 1.096 1.091 1.085 1.080 1.075 1.068 1.063 1.057 1.051 1.045 1.039 1.032 1.026 1 20 1.014 1.007 1.000 Gas temperature (centigrade) 13 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 Splrometric Standards for Normal MALES (BTPS) TO USE NOMOGRAM: Lay a stra.ghi edge bthn th patent's height a* read cr in* HEIGHT seal*, and hg eg* at a ipoin on th AGE seal*. FVC.L nr 5 0 HEIGHT, In. cm. 5t 39 60 I 50 tl 155 62-1 C3 tto 64-T CS-f-liS .' sr-l-iro .r (9 173 T0-3 71 190 n-:: 73J - lS '78 - 7S-; r 190 7.J: 77-1:'" FEF200-i20o >L/**e FEF23-73%|L/*8C fevLOil T S'3 10.0-r 43.0 9.3-7 9.0-7 AGE, 3.3-r 13 : yr* 3.04 ZOl45si- 80 4 +-8.3 +-8.0 JT40-f- 75 4 404 F 4- 3 5 5o435t 7.0 6043.04- e.jFi 430 70i"4 6.0-I sol 4204 90J 3.3-F- 423 I St 304 l.0-=- : +-2jO 43-r 4.0-E- 4.1.5 -1.0 -f-55 -4-3-0 -e-8.3 8.0 -4 3 3 79-=:200 10^ R SEE FEFjoo-ijoo * 0109 M| ' 0-047 A 2.010 [0.44 1.66] FEF23-73% * 0047 H,,-0.043 A 2.513 [0.53 1.12] 3.0 FEVi.0..c 1 0-092 Hu - 0.032 A - 1.260 [0.73 0.33] F VC * 0.148 H,,- 0.023 A - 4.241 [0.63 0.74] IJ Morris, J.F., et. al.: Aaer.Rev.Reap.D1s . , 103:57, 1971 Note: The predicted FEVj end FVC In non-Caucasians ust be ultlplled by 0.85. Figure 6. 20 Spirometric Standards for Normal FEMALES (BIPS) TO USE NOMOGRAM: Liy a itn.ght toga b.tw.an tha oaluni, he-ghi at r-ad s- :na HEIGHT tcala. and h i aga it a aooaa-1 on tha AGE tcalt. ccc ,, f t '200-1200 I L/tC FVC,L TS.O HEIGHT, in cm. 5 6-a. 57-*_iS 58-1 39- 150 60 - 61- 153 6263- 160 64 65-J-I65 66-;: 67-i- 170 es-j: 69-f-173 7071 180 72 fev,.0(l 4.0-1- 70 - i- 4.5 F^p25-75%i'-/'sec 63 45-r 35 --40 - -6.0 AGE, 40+ yri 201 30- 33-P 3.0-- -3.5 ,L 33 4050- 3.0-- - - - 5.0 2.5 -- ; 602 5- 70- -8-5-1-30 80- 2 0 -- - 2.0- 90- -40 15- -r 2.5 1.3 -- --J.3 I.0-1- --30 1.0 -i- 2.0 u - 23 R SEE i-i.s ^^^200-1200 : 0.145 Hin- 0.036 A - 2.532 [0.53 1.19] FEF25.75% = 0.060 HiB- 0.030 A + 0.551 [0.56 0.80] FEV| 0lle - 0.089 Hin- 0.025 A - 1.932 [0.73 0.47] F VC : 0.1 15 Hin- 0.024 A - 2.852 [0.7 I 0.52] Morris, J.F., et. al.: Amer.Rev.Resp.Dis., 103:57, 1971 Note: The predicted FEV^ and FVC in non-Caucasians must be multiplied by 0.85. Figure 7. .21 APC 003560 >t ^^ Table II SPIROMETRIC GUIDELINES FOR THE ASSESSMENT OF RESPIRATORY IMPAIRMENT Normal Mild Moderate Severe Obstructive Disease FEV]/FVC% >0.70 0.61 - 0.69 0.45 - 0.60 <0.45 o 00 ?. Restrictive Disease FVC FVC Pred. % 0.66 - 0.79 0.51 - 0.65 <0. 50 } r-^rr -- i t * ' ~ ' 22 ,y APC 003561 tI f k ft lT! CO o .2 'O r -i3 eI u -Q u tn ri UD rfl Ui i ci 0 c 1- FIGURE 9 Collins water-seal spirometer. 24 APC 003563 p r FIGURE 11 Jones Pulmonar. 26 ppc 003565 APC 003566 FIGURE 13 Dry rolling seal spirometer. Cutaway view demonstrating the U-shaped silastic seal between the piston and cylinder. FIGURE 14 Plastic seal' rolling freely upon itself during performance of spirometry.