- Email: [email protected]
Pulmonary function tests in children
July 1979
168
TheJournalofPEDIATRICS
Pulmonary function tests in children
T H I S A N D T H E N E X T I S S U E , t w o articles by Hsu e t al present values for selected pulmonary function tests in a large number of "normal" white, black, and MexicanAmerican children and young adults. (Normality is defined by having no history or symptoms of an acute or chronic respiratory ailment, but not by whether or not the subject admitted to smoking.) The papers are heavy on tables, graphs, and equations, which may make some readers of THE JOURNAL wonder about the wisdom of occupying a rather large number of pages with thi s kind of material. After some reflection, that same reader may conclude that the decision to publish the articles must have been based on two assumptions: (1) that pulmonary function testing is an important subject for many, if not most, pediatricians and (2) that the reference standards for such tests are not yet complete Or perfect. Let us examine the validity of these assumptions separately. According to a prevalence report in the U.S. Vital and Health Statistics for 1970, roughly 12 million children, or 18% of the total population below 17 years of age, had one or another chronic respiratory disease; the majority of them were Chronic bronchitis, asthma, or respiratory allergies. The significance of the acute respiratory diseases is underscored by the fact that their mortality accounts for 42% of all deaths under 5 years of age. Both recurrent and chronic lung diseases of children are becoming a steadily increasing public health concern; the belief spreads that they may well be the source of incapacitating respiratory disorders of adults. Every practicing pediatrician will readily admit that a large percentage of the patients seen has respiratory symptoms, but relatively few, approximately 500 to 600 country wide, specialize in pediatric pulmonology. (Those who are not quite at ease with this term may consult the editorial by W.W. Waring 1 for an assortment of synonyms.) According to a 1978 listing of Pediatric Respiratory Disease Training Programs, 32 institutions in the United States and three in Canada offered to train subspecialists for, among many other things, pulmonary function testing in children. -~This JOURNAL announced 33 and 39 fellowship openings in Pulmonary Disease and
IN
Vol. 95, No. 1, pp. 168H70
Physiology for 1977 and 1978, respectively. Institutions offering these training opportunities include 11 pediatric pulmonary centers, supported by Maternal and Child Health Services of HEW, and many of the 125 cystic fibrosis centers and clinics which serve about 13,000 patients suffering from the most severe c h r o n i c lung disease of children and young adults. Widely circulated periodicals, including this JOURNAL, regulary publish scientific articles which present results of pulmonary function testing as part of studies on various lung diseases. Some papers specifically call the attention of pediatricians and pediatric allergists (there are approxi m a t e l y 500 of the latter in the United States) to the practical use of these tests. In Brenneman's Practice of Pediatrics Hudson and Chernick 3 wrote about "Physiolog, ical Assessment and Treatment of Lung Diseases," and stated: "Pulmonary function tests assist primarily in See related article, p 14. quantitation of abnormal f u n c t i o n . . . " and are " . . . useful in differentiating obstructive from restrictive disease . . . . in the evaluation of treatment, or in following the course of chronic lung disease . . . . " T h i s commentator was asked to follow this up with a chapter on "Pulmonary Function Testing in Pediatric Chest Disease, TM in which the basic concepts, technical problems, general objectives, and practical guidelines for the usefulness of such tests in 21 different clinical conditions were discussed. In a recent issue of Pediatric Annals ~, several authors dealt with "Problems in Pediatric Pulmonary Disease." Huang commented: "Tests of pulmonary function have become essential to adequate evaluation of the child with recurrent respiratory tract infections . . . . " Some "instrum e n t s . . , are easily used in private offices." McGeady and Sherman 5 stressed: " . . . the need for measurements of pulmonary function in evaluating the asthmatic child or adolescent. These can be obtained in most hospit a l s . . , if the technician performing the tests relates well to children ..... Pulmonary function testing normally correlates closely with clinical f i n d i n g s . . , is able to detect
0022-3476/79/070168+03500.30/0 9 1979 The C. V. Mosby Co.
Volume 95 Number 1
unsuspected airway obstruction or a i r t r a p p i n g . . . " and " . . . Will also indicate the degree of reversibility of the airway disease." Souhrada and Buckley,6 discussing pulmonary function testing in asthmatic children, suggested that we extend the interpretation and use of these into the pediatrician's office and emphasized that the asthmatic child deserves a careful clinical evaluation, which includes all available pulmonary functiOn testing. Kendig's Disorders o f the Respiratory Tract m Children 7 includes a 10-page chapter on pulmonary function testing in the office and clinic, in which it is admitted "it is more difficult to obtain meaningful results in children than in adults" and "perhaps this explains the general lack of enthusiasm for testing children". However, it is also stated: "a capable office or clinic nurse can be easily trained to perform these-tests..." and "most children learn the maneuvers reliably after 4 to 5 minutes of practice." A useful table with recommendations for specific tests and equipment is also provided The text by Williams and Phelan 8 suggests: "Clinicians caring for children With chest diseases should understand the physiological principles underlying the commonly used tests..." which " . . . allow objective documentation of abnormalities, therapeutic responses, and progress of chronic disease." To these indicators of the importance and the increasing acceptance of pulmonary function testing in pediatrics could be added a not-so-modest reference by this commentator concerning his book with V. PromadhatY which was the first one entirely devoted to this stlbject. Mentioning this book should also be taken as a reminder of the second assumption initially made. i.e., that reference standards or "normal values" for pulmonary function tests in childhood are not yet complete and perfect. The cumbersome attempt to collect all the then-available and reliable "normal" data. and to produce some kind of synthesis for practical usage in laboratories and offices. was justified by the following statement in the preface: "The idea of this b o o k . . , had been developed by our everyday experience with the frustrating lack of a body of well-organized normal data with which to compare values measured in the pulmonary function laboratory for children." Using self-determined criteria for acceptability, data of a total of 25 papers were selected from a much larger number. Values for the more routine tests were based on measurements of approximately 7,000 children. The relatively simple technique used for developing summarized growth curves, tables, and corresponding equations was rightfully criticized by some, yet these are still much quoted and reprinted. The precision of the
Editor's column
16 9
summary curves, even for the basic tests, was a priori compromised because techniques and instruments were not truly standardized; because for the then-newer tests the number of children examined was too small; and because for many measurements the distribution of tested children over the whole age or body height range, between the sexes and among racial or ethnic groups was uneven, not stated, or purposely disregarded. In 1977, the American Thoracic Society, with the support of the National Heart, Lung and Blood Institute, held a conference, in order to produce "minimum standards" for spirometry in adults. 1~ Such standards were established for the specification of instruments and for the performance and evaluation of seven different tests. Afterward, 17 commercial spirometers were tested, eight of which did meet the standards, seven did not, and two Were judged questionable. All this happened more than 50 years after spirometry was introduced as a clinical tool for adults. In March of 1978. the Cystic Fibrosis Foundation, for one of its periodic GAP (Guidance-Action-Progress) Conferences. selected the topic "Cystic Fibrosis Patient EvalUation and Scoring Systems." There it was recommended that a separate conference be arranged for the standardization of pulmonary function testing in children. This second conference took place in the fall of 1978. Besides considering standardization of pediatrically oriented methodology, it was decided to specify areas in which collection of new data for reference standards is desirable: to determine uniformly applicable statistical and mathematical expressions of these standards; and to develop practical guidelines for how to use them. An international committee is presently at work on these recommendations. It was found that during the last eight years, since the completion of the book by Polgar and Promadhat. as many worthwhile articles, with data on thousands of children, had been published as during the 48 years before. Several of these new publications, including those by Hsu et al in this JOURNAL, did much more than repeat earlier investigators' work. They used better standardized techniques: they refined, extended, and diversified the studies, and provided valuable material for filling gaps and establishing more reliable reference standards. If we intend to use pulmonary function testing in individual pediatric patients for all the worthwhile clinical causes listed in the first part of these comments, we must use reliable growth charts for all variables, just as we have to do for properly diagnosing somatic growth failure, or deviation from normal development related to the functions of any organ system. The two papers by Hsu et al are very helpful contributions toward this goal.
170
Editor's column
The Journal of Pediatrics July 1979
All the above should be regarded as justifications rather than as excuses for having these articles published. Those who do pulmonary function testings regularly will be able to use the results right away; those who are concerned witll producing g e n e r a l standards for functional lung development will have these data as one of the latest sources of well-organized information. To all the other readers I would suggest what I have often heard from a respected scientist and teacher in physiology: "I am perfectly satisfied if I can remember one significant sentence Of an article pertaining to the broader discipline but not to the special focus of my interest." That one sentence could be taken from the first of the two articles by Hsu et al: "This project was designed to study the ventilatory functions of normal boys and girls o f . . . three ethnic groups; . . . significant differences of lung volume and flow rate exist among the t h r e e . . , and between male and female subjects."
George Polgar, M.D. Wayne State University School of Medicine Department of Pediatrics Children's Hospital of Michigan 3901 Beaubien Blvd. Detroit, M I 48201
REFERENCES
1. Waring WW: A lung is a lung is a lung, Am Rev Resp Dis 113:1, 1976. 2. Am Rev Resp Dis 118:161, 1978. 3. Hodson WA, and Chernick V: Brenneman's practice of pediatrics, vol 4, part Two, chapter 63. Hagerstown, Md., 1976, Harper & Row, Publ. Inc., 4. Polgar G: Brenneman's Practice of Pediatrics, vol 4, Part ' Two, Chapter 63A, Hagerstown, Md., 1976, Harper & Row, Publishers, Inc. 5. Pediatric Annals 6:No. 8; 1977. 6. Souhrada JF, and Buckley JM: Pulmonary function testing in asthmatic children, Pediatr Clin North Am 23:249, 1976. 7. Kendig EL Jr, editor: Disorders of the respiratory tract in children, ed 3, Philadelphia, 1977, WB Saunders Company. 8. Williams HE, and Phelan PD: Respiratory Illness in Children~ Oxford, 1975, Blackwell Scientific Publications. 9. Polgar G, and Promadhat: Pulmonary function testing in children: Techniques and standards, Philadelphia, 1971, WB Saunders Company. 10. Report of Snowbird Workshop on Standardization of Spirometry, Jan. 18-19, 1977, ATS News, 3:20, 1977.
168
TheJournalofPEDIATRICS
Pulmonary function tests in children
T H I S A N D T H E N E X T I S S U E , t w o articles by Hsu e t al present values for selected pulmonary function tests in a large number of "normal" white, black, and MexicanAmerican children and young adults. (Normality is defined by having no history or symptoms of an acute or chronic respiratory ailment, but not by whether or not the subject admitted to smoking.) The papers are heavy on tables, graphs, and equations, which may make some readers of THE JOURNAL wonder about the wisdom of occupying a rather large number of pages with thi s kind of material. After some reflection, that same reader may conclude that the decision to publish the articles must have been based on two assumptions: (1) that pulmonary function testing is an important subject for many, if not most, pediatricians and (2) that the reference standards for such tests are not yet complete Or perfect. Let us examine the validity of these assumptions separately. According to a prevalence report in the U.S. Vital and Health Statistics for 1970, roughly 12 million children, or 18% of the total population below 17 years of age, had one or another chronic respiratory disease; the majority of them were Chronic bronchitis, asthma, or respiratory allergies. The significance of the acute respiratory diseases is underscored by the fact that their mortality accounts for 42% of all deaths under 5 years of age. Both recurrent and chronic lung diseases of children are becoming a steadily increasing public health concern; the belief spreads that they may well be the source of incapacitating respiratory disorders of adults. Every practicing pediatrician will readily admit that a large percentage of the patients seen has respiratory symptoms, but relatively few, approximately 500 to 600 country wide, specialize in pediatric pulmonology. (Those who are not quite at ease with this term may consult the editorial by W.W. Waring 1 for an assortment of synonyms.) According to a 1978 listing of Pediatric Respiratory Disease Training Programs, 32 institutions in the United States and three in Canada offered to train subspecialists for, among many other things, pulmonary function testing in children. -~This JOURNAL announced 33 and 39 fellowship openings in Pulmonary Disease and
IN
Vol. 95, No. 1, pp. 168H70
Physiology for 1977 and 1978, respectively. Institutions offering these training opportunities include 11 pediatric pulmonary centers, supported by Maternal and Child Health Services of HEW, and many of the 125 cystic fibrosis centers and clinics which serve about 13,000 patients suffering from the most severe c h r o n i c lung disease of children and young adults. Widely circulated periodicals, including this JOURNAL, regulary publish scientific articles which present results of pulmonary function testing as part of studies on various lung diseases. Some papers specifically call the attention of pediatricians and pediatric allergists (there are approxi m a t e l y 500 of the latter in the United States) to the practical use of these tests. In Brenneman's Practice of Pediatrics Hudson and Chernick 3 wrote about "Physiolog, ical Assessment and Treatment of Lung Diseases," and stated: "Pulmonary function tests assist primarily in See related article, p 14. quantitation of abnormal f u n c t i o n . . . " and are " . . . useful in differentiating obstructive from restrictive disease . . . . in the evaluation of treatment, or in following the course of chronic lung disease . . . . " T h i s commentator was asked to follow this up with a chapter on "Pulmonary Function Testing in Pediatric Chest Disease, TM in which the basic concepts, technical problems, general objectives, and practical guidelines for the usefulness of such tests in 21 different clinical conditions were discussed. In a recent issue of Pediatric Annals ~, several authors dealt with "Problems in Pediatric Pulmonary Disease." Huang commented: "Tests of pulmonary function have become essential to adequate evaluation of the child with recurrent respiratory tract infections . . . . " Some "instrum e n t s . . , are easily used in private offices." McGeady and Sherman 5 stressed: " . . . the need for measurements of pulmonary function in evaluating the asthmatic child or adolescent. These can be obtained in most hospit a l s . . , if the technician performing the tests relates well to children ..... Pulmonary function testing normally correlates closely with clinical f i n d i n g s . . , is able to detect
0022-3476/79/070168+03500.30/0 9 1979 The C. V. Mosby Co.
Volume 95 Number 1
unsuspected airway obstruction or a i r t r a p p i n g . . . " and " . . . Will also indicate the degree of reversibility of the airway disease." Souhrada and Buckley,6 discussing pulmonary function testing in asthmatic children, suggested that we extend the interpretation and use of these into the pediatrician's office and emphasized that the asthmatic child deserves a careful clinical evaluation, which includes all available pulmonary functiOn testing. Kendig's Disorders o f the Respiratory Tract m Children 7 includes a 10-page chapter on pulmonary function testing in the office and clinic, in which it is admitted "it is more difficult to obtain meaningful results in children than in adults" and "perhaps this explains the general lack of enthusiasm for testing children". However, it is also stated: "a capable office or clinic nurse can be easily trained to perform these-tests..." and "most children learn the maneuvers reliably after 4 to 5 minutes of practice." A useful table with recommendations for specific tests and equipment is also provided The text by Williams and Phelan 8 suggests: "Clinicians caring for children With chest diseases should understand the physiological principles underlying the commonly used tests..." which " . . . allow objective documentation of abnormalities, therapeutic responses, and progress of chronic disease." To these indicators of the importance and the increasing acceptance of pulmonary function testing in pediatrics could be added a not-so-modest reference by this commentator concerning his book with V. PromadhatY which was the first one entirely devoted to this stlbject. Mentioning this book should also be taken as a reminder of the second assumption initially made. i.e., that reference standards or "normal values" for pulmonary function tests in childhood are not yet complete and perfect. The cumbersome attempt to collect all the then-available and reliable "normal" data. and to produce some kind of synthesis for practical usage in laboratories and offices. was justified by the following statement in the preface: "The idea of this b o o k . . , had been developed by our everyday experience with the frustrating lack of a body of well-organized normal data with which to compare values measured in the pulmonary function laboratory for children." Using self-determined criteria for acceptability, data of a total of 25 papers were selected from a much larger number. Values for the more routine tests were based on measurements of approximately 7,000 children. The relatively simple technique used for developing summarized growth curves, tables, and corresponding equations was rightfully criticized by some, yet these are still much quoted and reprinted. The precision of the
Editor's column
16 9
summary curves, even for the basic tests, was a priori compromised because techniques and instruments were not truly standardized; because for the then-newer tests the number of children examined was too small; and because for many measurements the distribution of tested children over the whole age or body height range, between the sexes and among racial or ethnic groups was uneven, not stated, or purposely disregarded. In 1977, the American Thoracic Society, with the support of the National Heart, Lung and Blood Institute, held a conference, in order to produce "minimum standards" for spirometry in adults. 1~ Such standards were established for the specification of instruments and for the performance and evaluation of seven different tests. Afterward, 17 commercial spirometers were tested, eight of which did meet the standards, seven did not, and two Were judged questionable. All this happened more than 50 years after spirometry was introduced as a clinical tool for adults. In March of 1978. the Cystic Fibrosis Foundation, for one of its periodic GAP (Guidance-Action-Progress) Conferences. selected the topic "Cystic Fibrosis Patient EvalUation and Scoring Systems." There it was recommended that a separate conference be arranged for the standardization of pulmonary function testing in children. This second conference took place in the fall of 1978. Besides considering standardization of pediatrically oriented methodology, it was decided to specify areas in which collection of new data for reference standards is desirable: to determine uniformly applicable statistical and mathematical expressions of these standards; and to develop practical guidelines for how to use them. An international committee is presently at work on these recommendations. It was found that during the last eight years, since the completion of the book by Polgar and Promadhat. as many worthwhile articles, with data on thousands of children, had been published as during the 48 years before. Several of these new publications, including those by Hsu et al in this JOURNAL, did much more than repeat earlier investigators' work. They used better standardized techniques: they refined, extended, and diversified the studies, and provided valuable material for filling gaps and establishing more reliable reference standards. If we intend to use pulmonary function testing in individual pediatric patients for all the worthwhile clinical causes listed in the first part of these comments, we must use reliable growth charts for all variables, just as we have to do for properly diagnosing somatic growth failure, or deviation from normal development related to the functions of any organ system. The two papers by Hsu et al are very helpful contributions toward this goal.
170
Editor's column
The Journal of Pediatrics July 1979
All the above should be regarded as justifications rather than as excuses for having these articles published. Those who do pulmonary function testings regularly will be able to use the results right away; those who are concerned witll producing g e n e r a l standards for functional lung development will have these data as one of the latest sources of well-organized information. To all the other readers I would suggest what I have often heard from a respected scientist and teacher in physiology: "I am perfectly satisfied if I can remember one significant sentence Of an article pertaining to the broader discipline but not to the special focus of my interest." That one sentence could be taken from the first of the two articles by Hsu et al: "This project was designed to study the ventilatory functions of normal boys and girls o f . . . three ethnic groups; . . . significant differences of lung volume and flow rate exist among the t h r e e . . , and between male and female subjects."
George Polgar, M.D. Wayne State University School of Medicine Department of Pediatrics Children's Hospital of Michigan 3901 Beaubien Blvd. Detroit, M I 48201
REFERENCES
1. Waring WW: A lung is a lung is a lung, Am Rev Resp Dis 113:1, 1976. 2. Am Rev Resp Dis 118:161, 1978. 3. Hodson WA, and Chernick V: Brenneman's practice of pediatrics, vol 4, part Two, chapter 63. Hagerstown, Md., 1976, Harper & Row, Publ. Inc., 4. Polgar G: Brenneman's Practice of Pediatrics, vol 4, Part ' Two, Chapter 63A, Hagerstown, Md., 1976, Harper & Row, Publishers, Inc. 5. Pediatric Annals 6:No. 8; 1977. 6. Souhrada JF, and Buckley JM: Pulmonary function testing in asthmatic children, Pediatr Clin North Am 23:249, 1976. 7. Kendig EL Jr, editor: Disorders of the respiratory tract in children, ed 3, Philadelphia, 1977, WB Saunders Company. 8. Williams HE, and Phelan PD: Respiratory Illness in Children~ Oxford, 1975, Blackwell Scientific Publications. 9. Polgar G, and Promadhat: Pulmonary function testing in children: Techniques and standards, Philadelphia, 1971, WB Saunders Company. 10. Report of Snowbird Workshop on Standardization of Spirometry, Jan. 18-19, 1977, ATS News, 3:20, 1977.