Chest ACCP Member Benefits
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Guest Access | Sign In via User Name/Password
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF) Free
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Article Archive
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via ISI Web of Science (5)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Katier, N.
Right arrow Articles by van der Ent, C. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Katier, N.
Right arrow Articles by van der Ent, C. K.
(Chest. 2005;128:1822-1829.)
© 2005 American College of Chest Physicians

Feasibility and Variability of Neonatal and Infant Lung Function Measurement Using the Single Occlusion Technique*

Nienke Katier, MD; Cuno S. P. M. Uiterwaal, MD, PhD; Brita M. de Jong, MD; Jan L. L. Kimpen, MD, PhD and Cornelis K. van der Ent, MD, PhD

* From the Departments of Pediatric Pulmonology (Drs. Katier, de Jong, and van der Ent), Pediatric Infectious Disease (Dr. Kimpen), and Julius Center for Health Sciences and Primary Care (Dr. Uiterwaal), University Medical Center Utrecht, Utrecht, the Netherlands.

Correspondence to: Cornelis K. van der Ent, MD, PhD, Department of Pediatric Pulmonology, University Medical Center Utrecht, Internal Postal Code: KH 01.419.0, PO Box 85090, 3508 AB Utrecht, the Netherlands; e-mail: k.vanderent{at}wkz.azu.nl


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
 References
 
Introduction: For possible use as a predictor of wheezing illnesses in routine care, we evaluated the feasibility and variability of measurement of passive respiratory mechanics in a large, open population of healthy neonates and infants.

Methods: As part of the ongoing Wheezing Illnesses Study Leidsche Rijn, respiratory compliance (Crs), respiratory resistance (Rrs), and time constant ({tau}rs) were measured during natural sleep in 450 healthy term neonates and infants using the single-occlusion technique (SOT). Interobserver and intraobserver variability of data sampling and the subsequent selection and analysis of occlusions as well as intrameasurement variability were examined.

Results: Technically acceptable lung function measurements could be performed in 328 infants (73%). Low intraobserver and interobserver variability was found for both data sampling (intraclass correlation coefficient [ICC] ≥ 0.87) and for selection and analysis of occlusions (ICC ≥ 0.99). Intrameasurement variability was low, with a mean intrameasurement coefficients of variation for Crs, Rrs, and {tau}rs of 8.5%, 10.4%, and 15.4%, respectively. Averaging three or more occlusions resulted in stable values of Crs, Rrs, and {tau}rs.

Conclusion: Results of this study indicate that feasibility and variability of lung function testing using the SOT is acceptable for use in large populations of healthy neonates and infants in routine care.

Key Words: birth cohort • infant • passive respiratory mechanics • respiratory function test • variability


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 Conclusion
 References
 
Lower respiratory tract illnesses are a major cause of morbidity and mortality in infancy and childhood, with large impact on health care.12 Epidemiologic research concerning the development and prediction of childhood respiratory disease may benefit from lung function measurements in newborn infants. Only a few small prospective cohort studies34567 have investigated premorbid lung function in association with subsequent respiratory disease; these studies used different lung function techniques and showed conflicting results. The major limitation is the lack of simple, reliable, and reproducible lung function tests that are applicable in a large, open population of healthy infants. Although several infant lung function techniques have been developed throughout the last 25 years with considerable methodologic progress and refinement, most require sophisticated equipment and sedation and, therefore, application is limited to specialized research laboratories.

The single occlusion technique (SOT) is a lung function technique for assessment of passive respiratory mechanics.8 First proposed as a simple method for measuring respiratory compliance (Crs) by Olinsky et al9 and later refined by Lesouef et al10 and Mortola et al,11 this technique measures Crs, respiratory resistance (Rrs), and time constant ({tau}rs) of the total respiratory system. It is a noninvasive, easily applicable, and time-saving technique for assessment of lung function in spontaneously breathing infants and young children. Guidelines regarding equipment,12 signal processing, data handling,13 and control and acceptance criteria14 have been published by the European Respiratory Society (ERS)/American Thoracic Society (ATS) Task Force on standards for infant respiratory function testing. Measurement during natural sleep and in awake infants is possible,15 which makes this technique particularly suitable for infant lung function testing. In order to be used as a predictor of wheezing illnesses in routine care, information on the feasibility and variability of the SOT is necessary. However, little is known about the feasibility and variability of the SOT when applied in a large population of healthy neonates and infants in routine care.

The aim of this study was to examine the feasibility and variability of Crs, Rrs, and {tau}rs measurements using the SOT in a large, population-based birth cohort in a routine care setting. The following questions were addressed: (1) is it feasible to perform SOT measurements in a large group of healthy neonates and infants, (2) what is the interobserver and intraobserver variability of data sampling and subsequent selection and analysis of occlusions, and (3) what is the intrameasurement variability of Crs, Rrs, and {tau}rs values?


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 Conclusion
 References
 
Study Population
All infants were recruited as part of the ongoing Wheezing Illnesses Study Leidsche Rijn (WHISTLER). Briefly, WHISTLER is a single-center, prospective, population-based birth cohort study on determinants for wheezing illnesses (including neonatal lung function). WHISTLER ultimately aims to derive a comprehensive risk score for wheezing illnesses appropriate for use in primary health care as described previously.16 Lung function measurements were performed in healthy neonates and infants < 2 months old before any respiratory illness was present. Exclusion criteria were gestational age < 36 weeks, major congenital abnormalities, and neonatal respiratory disease. Approval of the pediatric medical ethics committee of the University Medical Center Utrecht was given for this study, and written informed parental consent was obtained.

Recording Equipment
Airflow was measured using a heated Lilly-type pneumotachometer (series 8300, linear range, 0 to 10 L/min; Hans Rudolph; Kansas City, MO) attached to a face mask (infant mask, size neonate; Hans Rudolph). The mask was sealed to the infant’s face using therapeutic silicone putty (Magic Putty, medium; Oldelft Benelux BV; Delft, the Netherlands) to prevent air leaks and to minimize dead space. Pressure changes at the airway opening were measured with a pressure transducer (Type 163PC01D75; Honeywell; Morristown, NJ). Volume was obtained by electronic integration of the airflow signal. Flow, volume, and pressure were digitized with a sampling rate of 200 Hz and interfaced to a computer for real-time display, storage, and analysis. Before each measurement, calibration of flow and volume signals was performed using a 100-mL precision syringe (Viasys Health; Höchberg, Germany). The pressure transducer was calibrated over the expected range using a pressure transducer tester (Verical; Utah Medical Products; Midvale, UT). Lung function data were calculated offline using a custom-built software package (Luna 1.6; University Medical Center Utrecht; Utrecht, the Netherlands). Parameters displayed during analysis are as follows: maximal volume and volume at pressure plateau (Vplat), maximum volume – Vplat in percentage, the SD of Vplat and pressure plateau, the regression coefficient (r) of the expiratory part of the flow-volume curve, volume at intercept, and Crs, Rrs, and {tau}rs. Regression length can be varied manually between 40% and 80% of expired volume. Occlusions can be accepted or disregarded based on the displayed values. Final results (all trials or summary statistics) can be exported to standard spreadsheet software.

Measurement Protocol
Measurements of passive respiratory mechanics (Crs, Rrs, and {tau}rs) were performed without the use of any sedation in a routine care setting.811 Lung function measurements were performed after feeding in supine position with a neutral head/neck posture. Data collection was confined to consecutive periods of quiet sleep in which posture was stable and respiration was regular. Once each infant was settled in quiet sleep, the mask was placed gently over the nose and mouth, creating a continuous seal. Brief occlusions were performed manually at maximal inspiration. The occluded airway opening was released when a plateau in mouth pressure was reached. The infant’s breathing was allowed to stabilize between each occlusion for a minimum of five breaths. Occlusions were considered acceptable when they met the criteria of the ERS/ATS Task Force14: (1) smooth expiration within 10% of the previous expiration; (2) expiration without evidence of glottic closure, braking, or active expiratory effort; (3) duration of a pressure plateau ≥ 100 ms; (4) variability of pressure plateau < 0.01 kPa; and (5) linearity of descending part of the passive flow-volume loop over at least 40% of expiration with r2 > 0.99. At least three technically acceptable occlusions (up to 31) were used to calculate mean Crs, Rrs, and {tau}rs.

Several levels of the process of data sampling and the subsequent selection and analysis of the occlusions can cause variability in the ultimate values of Crs, Rrs, and {tau}rs. First, differences in infant and device handling might result in differences in the infant’s respiration between different observers (interobserver variability of data sampling). Second, repeated data sampling by the same observer in the same child might result in differences due to small changes, for example, in the child’s position of the face mask (intraobserver variability of data sampling). Thirdly, after sampling and electronic storage of measurement tracings, differences in selection and analysis of occlusions from the recorded tracings might result in different values of Crs, Rrs, and {tau}rs between observers (interobserver variability of selection and analysis of occlusions). Fourthly, this process of selecting and analyzing occlusions might also cause differences in results within one observer (intraobserver variability of selection and analysis of occlusions). Ultimately, the number of occlusion used for the calculation of Crs, Rrs, and {tau}rs within one measurement and analyzed by one observer might influence the ultimate values of Crs, Rrs, and {tau}rs (intrameasurement variability). Figure 1 gives an overview of the study components to address these issues. For the interobserver variability study of data sampling, 40 infants underwent repetitive measurements within a short time interval by two different observers. For the intraobserver variability study of data sampling, another 40 infants underwent repetitive measurements performed by one of the observers. For the evaluation of interobserver variability of selection and analysis of occlusions, two different observers interpreted 259 single lung function measurements. Observers independently selected and analyzed occlusions based on the criteria of the ERS/ATS Task Force. To evaluate intraobserver variability of selection and analysis of occlusions, one observer interpreted 40 lung function measurements twice blinded to the results earlier obtained. Thirty measurements were randomly selected in order to analyze the intrameasurement variability of Crs, Rrs, and {tau}rs values based on 2 to 10 sequential occlusions.



View larger version (19K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 1.. Study overview.

 
Statistical Analysis
Data are reported as mean ± SD, unless specified otherwise. For comparison of data, Student (paired) t test was used. An intraclass correlation coefficient (ICC) was used to evaluate intraobserver and interobserver agreement, and to evaluate the intrameasurement variability of average Crs, Rrs, and {tau}rs values based on 2 to 10 sequential occlusions. To obtain a graphic representation of the difference between and within observers, differences were plotted against the mean and the mean difference, the limits of the agreement, and the 95% confidence intervals (CI)s for the limits were calculated, as described by Bland and Altman.17 Intrameasurement variability was also expressed as coefficient of variation (CV); ie, the ratio of the SD to the mean. Differences were considered statistically significant if the p value was ≤ 0.05. Statistical analysis was performed using the statistical software (SPSS version 11.0; SPSS; Chicago, IL).


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 Conclusion
 References
 
Feasibility
Subject characteristics and the results of the pulmonary function tests are shown in Table 1 . Of the 450 infants recruited for this study, technically acceptable lung function measurements could be performed in 311 infants (69%) on the first occasion. Twenty-three parents were willing to return for a second visit, resulting in additional successful measurements in 17 infants (4%). Failure of technically acceptable measurements was mainly due to failure to fall asleep naturally within 1.5 h of study onset (16%), consistent failure to relax during occlusions (5%), marked expiratory airflow braking (4%), and persistent leak around the face mask (2%). The median number of successful occlusions per measurement was 5 (range, 3 to 31). Eighty-two percent of these infants were white. A history of active maternal smoking was positive in 8.9% of infants, and postnatal environmental smoking by parents or caregivers was present in 4.5%. The characteristics of infants with unsuccessful lung function measurements were not different from infants with successful measurements, except for a significantly younger age (Table 1). This is also shown in Figure 2 , top, A, as failure rates decline with increasing age at measurement (range of age at measurement, 1.4 to 9.1 weeks). Failure rates were also dependent on the experience of the observers (Fig 2, bottom, B). We divided the 450 measurements in three parts of 150 measurements numbered in sequence of time. The failure rate during the first 150 measurements was 27%, during the last 150 measurements it decreased to 15%. Age was not a confounding variable; ie, the last 150 measurements were not made in older children.


View this table:
[in this window]
[in a new window]

  		Table 1.. Patient Characteristics and Results From Respiratory Function Measurements in 450 Healthy Infants*

 


View larger version (32K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 2.. Failure rates in function of age at the time of measurement (top, A) and experience of the observer (bottom, B).

 
Variability of Data Sampling
For the intraobserver variability study of data sampling, the ICCs were calculated for Crs, Rrs, and {tau}rs, and were found to be 0.96, 0.98, and 0.95, respectively. Between two different observers, the ICCs for Crs, Rrs, and {tau}rs were 0.97, 0.91, and 0.87, respectively. The mean differences of Crs, Rrs, and {tau}rs between two consecutive measurements performed by the same observer and two different observers, the limits of agreement, and the 95% CIs of the limits, as described by Bland and Altman,17 are shown in Table 2 .


View this table:
[in this window]
[in a new window]

  		Table 2.. Differences, Limits of Agreement, and 95% CIs Among Observers

 
Variability of Selection and Analysis of Occlusions
For the intraobserver variability study of selection and analysis of occlusions, ICCs were calculated for Crs, Rrs, and {tau}rs, and were found to be 0.99, 0.99, and 0.99, respectively. Between two different observers, the ICCs for Crs, Rrs, and {tau}rs were again 0.99, 0.99, and 0.99, respectively. The mean differences of Crs, Rrs, and {tau}rs between and within interpreters of lung function measurements, the limits of agreement and the 95% CIs of the limits are shown in Table 2.

Intrameasurement Variability of Crs, Rrs, and {tau}rs Values
For 30 randomly selected measurements, the mean Crs, Rrs, and {tau}rs and their SDs of 2 to 10 occlusions within one measurement were calculated. Intrameasurement CVs ranged from 5.1 to 12.0% with a mean of 8.5% for Crs; from 4.5 to 14.8% with a mean of 10.4% for Rrs; and from 10.2 to 20.3% with a mean of 15.4% for {tau}rs. The CVs of Crs, Rrs, and {tau}rs within one measurement correlated with the mean Crs (r = 0.57, p = 0.001), Rrs (r = 0.80, p < 0.001), and {tau}rs (r = 0.85, p < 0.001) within one subject; ie, the SD was proportional to the mean.

Another way to investigate intrameasurement variability is to evaluate the intrameasurement stability of average Crs, Rrs, and {tau}rs values. ICCs were calculated for 2 to 10 occlusions within one measurement, as shown in Figure 3 . The nearer the ICC is to 1, the more stable the average ratio. The use of two occlusions would result in a value of Crs with an ICC of 0.95, a value of Rrs with an ICC of 0.91, and a value of {tau}rs with an ICC of 0.84. An increase in the number of occlusions increases the ICC of the subsequently measured values of Crs, Rrs, and {tau}rs. Averaging three or more occlusions resulted in stable values (ICC ≥ 0.90) for all three parameters; averaging more than six curves did not improve the stability of the mean values.



View larger version (13K):
[in this window]
[in a new window]
[Download PPT slide]
  		Figure 3.. ICCs of (top, A) Crs calculated as an average of the number of sequential occlusions; (center, B) Rrs calculated as an average of the number of sequential occlusions; and (bottom, C) {tau}rs calculated as an average of the number of sequential occlusions.

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
Conclusion
 References
 
Using a large and unique data set of neonatal lung function measurements, this study was able to assess the feasibility and variability of the SOT in a large, open population of healthy neonates and infants. In the majority of infants, technically acceptable lung function measurements could be performed, with intrameasurement CVs ranging from 8 to 15%. Low interobserver and intraobserver variability was found for data sampling and for the subsequent selection and analysis of occlusions. Results of this study indicate that feasibility and variability of lung function testing using the SOT is acceptable for use in open populations of healthy neonates and infants and may be used a possible predictor of wheezing illnesses in routine care.

Although feasibility and variability of the SOT are described in a routine care setting, it has to be considered that measurements are still performed within a research design with dedicated and through time highly experienced researchers. Application of the SOT by different observers in routine care may in practice turn out to be less accurate.

Feasibility
In the present study, measurements were performed without use of sedation in a routine care setting by trained personnel and, as strictly as possible, according to the criteria of the ERS/ATS Task Force.14 Relatively few studies have reported failure rates when describing occlusion techniques.1819 Failure rates in a setting as described in the present study are to our knowledge not available. Therefore, it is difficult to ascertain whether the failure rates in the present studies are attributable to the strict criteria applied or to the type of setting and study population. Successful lung function testing was feasible in 73% of the infants. The main reason for measurement failure was not falling asleep naturally within 1.5 h of study onset (16%). The use of sedation would diminish these failure rates; however, this would limit the technique to specialized research laboratories and would be more time consuming and invasive. Five percent of infants consistently failed to relax during occlusions generally recognized as a rising pressure at airway opening when the infants made an expiratory effort against the occlusion. Stocks et al20 reported a percentage of 9.5% in sedated and anesthetized infants during the first 2 years of life. Marked expiratory braking was the reason for 4% of failures. Potential errors in assessing passive respiratory mechanics due to expiratory airflow modulation could be detected in the present study by a linearity of the flow-volume curve (r2 < 0.99). Problems in the use of the SOT due to expiratory braking have been reported previously in approximately 10 to 30% of infants.1921 One explanation that could account for the differences in failure rates between the present study and others is the infant’s age at measurement. The few previous studies reporting failure rates measured infants that were either older2021 or preterm.19 Another explanation could be the experience of observers performing the measurements. Previous studies1819 reporting failure rates measured only small groups of infants. In this study, a large group of infants was measured, with failure rates declining with increasing experience of the observers. Failure rates during the first 150 measurements were, however, lower than during the second 150 measurements. This may be due to the fact that during the first measurements, an experienced supervisor was always present to take over the measurement when necessary. During the second and last 150 measurements, observers started measuring without supervision; as experience increased, failure rates declined.

The values of Rrs are in close agreement with Hanrahan et al22 but are higher than those reported by Masters et al,23 Lodrup Carlsen et al,24 and Reiterer and Muller.25 Crs levels in the current study are somewhat lower than reported in previous studies, but comparable to values reported by Stocks et al26 and Migdal et al.27 One explanation that could account for the differences is that the postnatal age in the population assessed in the present study was higher, except for the study of Masters et al.23 However, in this study only seven healthy infants were assessed. Differences may also be due to use of different recording equipment in different studies. The published recommendations and guidelines regarding equipment12 and signal processing and data handling13 may improve comparison of passive respiratory mechanics measurements of different studies and avoid misinterpretation of results.

Variability of Crs, Rrs, and {tau}rs Measurements
Limited data are available on the variability of the SOT. Data on interobserver and intraobserver variability of the SOT data sampling are to our knowledge not available. Passive respiratory mechanics are frequency dependent and may be influenced by upper airway resistance (laryngeal obstruction) to flow. Dynamic increase in functional residual capacity often occurs in neonates and might also cause difference in results of repeated measurements within and between different observers. However, we found high agreement within and between observers on repetitive measurements of neonatal lung function within a short time span. Obviously, these disturbing factors do not importantly limit the use of the SOT in the open population setting.

The variability of the method is also highly dependent on selection and analysis of occlusions that are used for calculating Crs, Rrs, and {tau}rs. An excellent level of agreement was found between two observers with acceptably narrow limits of agreement. The intraobserver agreement was equally high. The low interobserver and intraobserver variability of data selection and analysis may be due to the strict use of the criteria of the ERS/ATS task force. The use of international criteria for selection and analysis of occlusions may greatly decrease the variability of the method.

A few reports on intrameasurement variability of lung function measurements using the SOT exist. The intrameasurement variability of lung function measurements consisting of 2 to 10 occlusions in the present study was low compared to earlier reports of Lodrup-Carlsen et al24 and Hanrahan et al.22 This difference may be due to the large sample size of the present study, with increasing experience of the observers and the fact that measurements were confined to periods of quiet sleep. ICCs for statistical evaluation of the stability of Crs, Rrs, and {tau}rs after 2 to 10 occlusions within one measurement showed that after three occlusions reliable values can be found, indicating that a minimum of three occlusions, as recommended, is acceptable.14 The ICCs after six occlusions rose to 0.97, 0.98, and 0.97 for Crs, Rrs, and {tau}rs, respectively, with no improvement of stability when averaging more occlusions.


   Conclusion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
References
 
This study has demonstrated that it is feasible to measure lung function using the SOT in unsedated healthy neonates and infants in routine care with low interobserver and intraobserver variability of data sampling and the subsequent selection and analysis of occlusions. The results indicate that the SOT is a simple, accurate, and reliable technique to assess lung function in large open populations of healthy neonates and infants. Further investigations are needed to explore the physiologic determinants of passive respiratory mechanics in healthy neonates, prenatal and early life events that influence lung function in infancy, and the uses and limitations in epidemiologic research, eg, in the evaluation of the possible predictive value of neonatal lung function for later respiratory disease.


   Acknowledgements
 
The authors thank Claire Nollen and Cora de Kiviet for assistance during lung function measurements and Myriam Olling-de Kok for secretarial work.


   Footnotes
 
Abbreviations: ATS = American Thoracic Society; CI = confidence interval; Crs = respiratory compliance; CV = coefficient of variation; ERS = European Respiratory Society; ICC = intraclass correlation coefficient; Rrs = respiratory resistance; SOT = single occlusion technique; {tau}rs = time constant; Vplat = volume at pressure plateau; WHISTLER = Wheezing Illnesses Study Leidsche Rijn

This study was funded by the Health Research and Development Council of the Netherlands grant No. 2001–1-1322, and by an unrestricted grant from Glaxo Smith Kline Netherlands.

Received for publication December 2, 2004. Accepted for publication February 8, 2005.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
 References
 

  1. Koopman, LP, Brunekreef, B, de Jongste, JC, et al (2001) Definition of respiratory symptoms and disease in early childhood in large prospective birth cohort studies that predict the development of asthma. Pediatr Allergy Immunol 12,118-124[CrossRef][ISI][Medline]
  2. Stevens, CA, Turner, D, Kuehni, CE, et al The economic impact of preschool asthma and wheeze. Eur Respir J 2003;21,1000-1006[Abstract/Free Full Text]
  3. Young, S, Arnott, J, O’Keeffe, PT, et al The association between early life lung function and wheezing during the first 2 yrs of life. Eur Respir J 2000;15,151-157[Abstract]
  4. Martinez, FD, Morgan, WJ, Wright, AL, et al Diminished lung function as a predisposing factor for wheezing respiratory illness in infants. N Engl J Med 1988;319,1112-1117[Abstract]
  5. Dezateux, C, Stocks, J, Wade, AM, et al Airway function at one year: association with premorbid airway function, wheezing, and maternal smoking. Thorax 2001;56,680-686[Abstract/Free Full Text]
  6. Clarke, JR, Salmon, B, Silverman, M Bronchial responsiveness in the neonatal period as a risk factor for wheezing in infancy. Am J Respir Crit Care Med 1995;151,1434-1440[Abstract]
  7. Adler, A, Tager, IB, Brown, RW, et al Relationship between an index of tidal flow and lower respiratory illness in the first year of life. Pediatr Pulmonol 1995;20,137-144[Medline]
  8. Fletcher, ME, Baraldi, B, Steinbrugger, B Passive respiratory mechanics. Stock, J Sly, PD Tepper, RSet al eds. Infant respiratory function testing 1996,283-327 Wiley-Liss. New York, NY:
  9. Olinsky, A, Bryan, AC, Bryan, MH A simple method of measuring total respiratory system compliance in newborn infants. S Afr Med J 1976;50,128-130[Medline]
  10. Lesouef, PN, England, SJ, Bryan, AC Passive respiratory mechanics in newborns and children. Am Rev Respir Dis 1984;129,552-556[ISI][Medline]
  11. Mortola, JP, Fisher, JT, Smith, B, et al Dynamics of breathing in infants. J Appl Physiol 1982;52,1209-1215[Abstract/Free Full Text]
  12. Frey, U, Stocks, J, Coates, A, et al Specifications for equipment used for infant pulmonary function testing. ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. European Respiratory Society/American Thoracic Society Eur Respir J 2000;16,731-740[Abstract]
  13. Frey, U, Stocks, J, Sly, P, et al Specification for signal processing and data handling used for infant pulmonary function testing. ERS/ATS Task Force on Standards for Infant Respiratory Function Testing. European Respiratory Society/American Thoracic Society. Eur Respir J 2000;16,1016-1022[Abstract]
  14. Gappa, M, Colin, AA, Goetz, I, et al Passive respiratory mechanics: the occlusion techniques. Eur Respir J 2001;17,141-148[Abstract/Free Full Text]
  15. Lodrup, KC, Mowinckel, P, Carlsen, KH Lung-function measurements in awake compared to sleeping newborn-infants. Pediatr Pulmonol 1992;12,99-104[ISI][Medline]
  16. Katier, N, Uiterwaal, CSPM, de Jong, BM, et al The Wheezing Illnesses Study Leidsche Rijn (WHISTLER): rationale and design. Eur J Epidemiol 2004;19,895-903[CrossRef][Medline]
  17. Bland, JM, Altman, DG Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1,307-310[CrossRef][ISI][Medline]
  18. Fletcher, ME, Dezateux, CA, Stocks, J Respiratory compliance in infants: a preliminary evaluation of the multiple interrupter technique. Pediatr Pulmonol 1992;14,118-125[Medline]
  19. Gappa, M, Rabbette, PS, Costeloe, KL, et al Assessment of passive respiratory compliance in healthy preterm infants: a critical evaluation. Pediatr Pulmonol 1993;15,304-311[Medline]
  20. Stocks, J, Nothen, U, Sutherland, P, et al Improved accuracy of the occlusion technique for assessing total respiratory compliance in infants. Pediatr Pulmonol 1987;3,71-77[Medline]
  21. Goetz, I, Hoo, AF, Lum, S, et al Assessment of passive respiratory mechanics in infants: double versus single occlusion? Eur Respir J 2001;17,449-455[Abstract/Free Full Text]
  22. Hanrahan, JP, Brown, RW, Carey, VJ, et al Passive respiratory mechanics in healthy infants: effects of growth, gender, and smoking. Am J Respir Crit Care Med 1996;154,670-680[Abstract]
  23. Masters, IB, Seidenberg, J, Hudson, I, et al Longitudinal study of lung mechanics in normal infants. Pediatr Pulmonol 1987;3,3-7[Medline]
  24. Lodrup Carlsen, KC, Magnus, P, Carlsen, KH Lung function by tidal breathing in awake healthy newborn infants. Eur Respir J 1994;7,1660-1668[Abstract]
  25. Reiterer, F, Muller, W Assessment of the single-occlusion technique for measurements of respiratory mechanics and respiratory drive in healthy term neonates using a commercially available computerized pulmonary function testing system. Biol Neonate 2003;83,117-122[Medline]
  26. Stocks, J, Gappa, M, Rabbette, PS, et al A comparison of respiratory function in Afro-Caribbean and Caucasian infants. Eur Respir J 1994;7,11-16[Abstract]
  27. Migdal, M, Dreizzen, E, Praud, JP, et al Compliance of the total respiratory system in healthy preterm and full-term newborns. Pediatr Pulmonol 1987;3,214-218[Medline]




This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF) Free
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Article Archive
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via ISI Web of Science (5)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Katier, N.
Right arrow Articles by van der Ent, C. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Katier, N.
Right arrow Articles by van der Ent, C. K.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS