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(Chest. 2002;121:708-714.)
© 2002 American College of Chest Physicians

Repeatability of Inspiratory Capacity During Incremental Exercise in Patients With Severe COPD*

Thomas E. Dolmage, MSc and Roger S. Goldstein, RS, FCCP

* From the Pulmonary Function Department and Department of Respiratory Medicine, West Park Hospital, Department of Medicine, University of Toronto, Toronto, ON, Canada.

Correspondence to: Roger S. Goldstein, RS, FCCP, West Park Hospital, 82 Buttonwood Ave, Toronto, ON, M6M 2J5; e-mail: roger.goldstein{at}westpark.org


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Study objective: Estimating lung volume using inspiratory capacity (IC) maneuvers is a useful way of tracking dynamic hyperinflation. An understanding of the repeatability of the IC in a clinical setting is important when evaluating an individual’s response to a therapeutic intervention that might influence lung volume. This is the first study to determine the repeatability of serial IC measurements of patients with severe COPD undergoing incremental exercise testing in a clinical setting.

Subjects and methods: Ten patients with severe COPD, inexperienced in exercise testing, cycled with power increased until they reached symptom limitation. Flow was measured at the mouth using a pneumotachograph. IC maneuvers were performed at 1-min to 3-min intervals. Subjects repeated the exercise test 2 days later. Three methods of calculating IC from flow have been described previously. To determine which method provided the best repeatability, we calculated the following: (1) IC calculated by the integration of inspired flow from the start to the end of the IC maneuver (ICINSP); (2) IC calculated from the difference between the drift-corrected peak inspiratory volume (total lung capacity [TLC]) and the drift-corrected end-expiratory lung volume (EELV) of the six breaths that preceded the IC prompt (ICREG); and (3) IC calculated, after correction of the expiratory part of the signal, as the difference between the mean EELV of the six breaths that preceded the IC prompt and the peak inspiratory volume (ICRATIO). Each individual’s IC response was expressed as a function of exercise time and of ventilation.

Results: There was a significant (p < 0.05) decrease in the expired volume of the breath before the IC maneuver (0.11 ± 0.26 L) [mean ± SD]. ICINSP (1.78 ± 0.88 L) was significantly less than the IC calculated using the other two methods (ICREG, 1.88 ± 0.89 L; ICRATIO, 1.86 ± 0.87 L). ICRATIO improved the repeatability of the serial IC measures by as much as 60% over ICINSP and ICREG.

Conclusion: Calculating IC as the difference between EELV and TLC was unaffected by unsatisfactory technique, such as a change in breathing pattern immediately before the maneuver. Adjusting expiratory flow based on premaneuver inspiratory to expiratory volume ratio before estimating EELV improved the repeatability coefficient of the IC.

Key Words: dynamic hyperinflation • end-expiratory lung volume • exercise • inspiratory capacity • lung diseases, obstructive • repeatability • ventilatory limitation


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Standardized laboratory measurements during exercise assess the integrated response of the component systems (neuromuscular, cardiovascular, and pulmonary) used during exercise. Such measurements are also used to estimate functional reserve. Exercise tests can help clinicians identify what limits exercise, establish training routines, and evaluate the effects of therapeutic interventions such as rehabilitation or surgery. In many individuals with COPD, exercise is associated with dynamic hyperinflation.1 2 3 4 5 6 7 As end-expiratory lung volume (EELV) increases, the elastic load to breathing increases, which may contribute to exercise intolerance.5

The inspiratory capacity (IC) is calculated from the difference between the total lung capacity (TLC) and the EELV. An increase in EELV decreases the IC. In order to identify the presence of dynamic hyperinflation, subjects are required to perform serial IC maneuvers during exercise.5 6 8 9 10 11 12 Although several studies have reported measurements of IC among various patient populations, its reproducibility in a clinical setting remains to be determined.13 Clinicians need to know whether a change in a patient’s measured IC exceeds the day-to-day test variability. Repeatability is defined as the closeness of the agreement between the results of successive measurements of the same variable completed under the same conditions on the same individual.14 The repeatability coefficient15 is easily understood and useful to the clinician interpreting a measurement because it is reported in the same units as the measurement itself and provides the probability of error.

In this study, we determined the repeatability of the IC during incremental exercise. We expressed each individual’s IC response as a function of time and as a function of ventilation. We tested the construct validity of expressing IC as a function of ventilation by measuring it during constant-load exercise in subjects with severe COPD, and measuring it during incremental exercise in subjects in whom FEV1 was > 70% of predicted values. Knowledge of repeatability is important for the IC to be used to track dynamic hyperinflation and to evaluate an individual’s response to a therapeutic intervention that might influence lung volumes.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Subjects
Ten subjects with severe COPD were sequentially recruited from those referred for incremental exercise testing in order to characterize their exercise limitation or to assess preoperative risk. The primary objective (to determine the repeatability coefficient of the measurement of IC), required that 10 subjects each complete two incremental exercise tests. The secondary objective (to test the validity of the measurement of IC during exercise) required that a further 10 subjects with severe COPD complete an incremental exercise test and a constant-power exercise test, and that another group of 10 subjects (FEV1 > 70% of predicted) complete an incremental exercise test. All 30 subjects had recently completed pulmonary function measures and were familiar with the IC maneuver.

Exercise Protocol
Subjects who gave informed consent were requested to adhere to their usual medical regimens but not to eat for 2 h before the test and not to drink caffeinated beverages for 12 h before the test. Exercise tests were carried out in a standard manner16 with an electrically braked cycle ergometer (Collins CPX Bike model 0070; Warren E. Collins; Braintree, MA). The test was discontinued if any cardiovascular instability (hypertension, hypotension, or ECG changes) was observed. The subjects wore nose clips and breathed through the mouthpiece of a calibrated screen pneumotachograph (Collins/Cybermedic model 003500; Warren E. Collins) that was located 5 cm from the mouth. The pneumotachograph calibration procedure conformed to American Thoracic Society standards.17 The accuracy of the pneumotachograph was verified after each exercise test. All subjects breathed room air. The analog flow signal was sampled at 100 Hz and compensated for the sampling of gas at the mouth. Volume was obtained by the integration of the digitized flow signal using data acquisition software (Viewdac; Asyst Software Technologies; Rochester, NY). Ventilation was calculated on a breath-to-breath basis.

After at least 1 min of breathing with the mouthpiece, the subject started unloaded cycling. The load was increased until the subject reached symptom limitation. The rate of increase was designed to induce symptom limitation within approximately 10 min. This usually meant setting the rate of increase between 5 W/min and 25 W/min depending on the level of flow impairment (FEV1, 0.4 to 4.3 L). IC was measured at rest and randomly at 1-min to 3-min intervals thereafter during exercise. The maneuvers were unscheduled during exercise to avoid the possibility of the subjects changing their pattern of breathing in anticipation of the prompt. All measures were made by a single technologist who was experienced in clinical exercise testing.

The IC Maneuver
The technologist demonstrated the IC maneuver before the test. The subjects were instructed that (after the prompt and at the end of the next normal breath out) they were to continue the next breath in until their lungs were full and then try to give an extra effort to fill up even more. They were asked to do this fairly quickly so as not to interrupt breathing for very long. The maneuver ended with a normal, unforced exhalation. During the exercise, the subjects were prompted to perform the IC maneuver, and received verbal encouragement to inspire maximally.2 18

Calculation of IC
All IC maneuvers were included in the analyses. It was assumed that subjects inspired to their TLC. We chose three different approaches to calculate the IC in order to identify which of them provided the best repeatability.

Method 1
In the first method, IC was calculated by the integration of inspired flow from the start to the end of the IC maneuver (ICINSP). This method has often been used in clinical studies.4 It is the only method available in exercise systems that use a single flow device on the inspiratory side of a breathing valve in which expired air is directed to a mixing box or Douglas bag.

Method 2
In the second method, we used the mean EELV from the volume tracing to calculate IC. IC was calculated from the difference between the drift-corrected peak inspiratory volume (TLC) and the drift-corrected EELV of the six breaths that preceded the IC prompt (ICREG). This method accounted for any drift of the integrated flow (volume) that might be attributable to differences (such as temperature, gas density, or humidity) between the measured gas (expired) and the calibration gas (ambient). It has been suggested as an appropriate method for use with systems that use a pneumotachograph for measuring flow during exercise.13 Flow was integrated and a relative EELV was determined from the six breaths that preceded the IC prompt. Linear regression of the EELV as a function of time was then used to calculate the drift (slope). The drift regression equation was subtracted from the entire volume tracing to reset the volume signal, which resulted in a mean EELV of zero.

Method 3
In the third method, the correction was limited to the expiratory part of the signal (Fig 1 ). IC was calculated, after correction of the expiratory part of the signal, as the difference between the mean EELV of the six breaths that preceded the IC prompt and the peak inspiratory volume (ICRATIO). Flow was integrated to provide volume. The inspiratory to expiratory tidal volume ratio was then determined for each of the six uninterrupted tidal breaths that preceded the IC prompt. The average inspired volume of a breath (VI)/expired volume of a breath (VE) [] was calculated. The expiratory flow portion of the flow signal was then multiplied by the . The inspiratory part of the flow signal was unaltered. The conditioned flow signal (inspiratory and expiratory) was then integrated to give volume. The ICRATIO was calculated from the difference between the relative mean EELV of the six breaths that preceded the prompt and the peak inspiratory volume (TLC). This method has also been identified19 as a useful approach but has not been previously evaluated in terms of its repeatability.



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  		Figure 1. A representation of lung volume during an IC maneuver in which the pattern of breathing was unaltered. The upper tracing represents the unaltered volume. The ICINSP is calculated as the VI (from the start to the end of the IC maneuver). During the six breaths, although the EELV does not change, the volume signal drifts upward. To calculate ICRATIO, the mean is calculated from the six breaths that precede the prompt. Expiratory flow is then multiplied by the . The conditioned flow signal (inspiratory and expiratory) is then integrated to give a corrected volume (lower tracing).

 
Determination of Repeatability and Validity
To determine the repeatability coefficient, 10 patients with COPD repeated the exercise test 2 days after the initial test using the identical exercise protocol. To assess the validity of expressing the loss of IC as a function of ventilation, we analyzed the exercise test results of 10 other patients with severe COPD in whom serial IC measures were made during incremental and constant-power exercise tests. The incremental test was as described above. For the constant-power test, subjects pedaled at 70% of the power achieved during the incremental test until they reached symptom intolerance (5 to 15 min). A third group of 10 subjects with FEV1 > 70% of predicted completed an incremental exercise test.

Analysis
To determine if subjects altered their pattern of breathing during the IC maneuver, the variables (inspiratory time of a breath [TI], expiratory time of a breath [TE], VI, and VE) that described the breath immediately before the IC maneuver (B-1) were compared to their respective average (, , , and ) of the six breaths that preceded B-1. Tolerance limits were chosen as three times the SD of the mean (eg, ) to establish the range of typical breathing at that point in the exercise. An IC maneuver outside of this range would have been rejected if the objective criteria of an abnormal breath before the maneuver was included in the analysis of serial IC maneuvers.

To determine whether different methods of calculating IC influenced the measure, we compared the calculated measures using a one-way, repeated-measures analysis of variance. In the absence of a significant difference in the mean values, the limits of agreement between different methods of calculating IC were calculated as twice the SD of the difference of each individual’s measures.15

Repeated incremental exercise measures (such as the slope of ICINSP as a function of time), were first analyzed using a paired t test to determine if the mean difference was significantly greater than zero. We then calculated the coefficient of repeatability as twice the SD of the difference of repeated measures.15

Measurements made during incremental and constant-power exercise tests (such as the slope of ICRATIO as a function of time), were first analyzed by paired t test to determine if the mean difference was significantly greater than zero. We then calculated the limits of agreement as twice the SD of the difference of the two measures.15 We used a t test to determine whether measures made during the incremental exercise tests differed between the 20 subjects with severe COPD and the 10 subjects in whom the FEV1 was > 70% predicted.


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
All values are expressed as mean ± SD unless stated otherwise. The IC maneuver was incorporated into the tests of 30 subjects (18 male and 12 female subjects) referred for exercise testing. Incremental tests were repeated in 10 subjects with moderate-to-severe COPD. Another 10 subjects with moderate-to-severe COPD completed incremental and constant-power exercise tests. A third group of 10 subjects (FEV1 > 70% predicted) completed an incremental exercise test. The subjects’ diagnosis, age, body mass index, and FEV1 are summarized in Table 1 . During the first incremental exercise test, the subjects exercised for 8.0 ± 2.1 min (range, 3.8 to 12.4 min) and completed 5 ± 2 IC maneuvers during exercise.


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  		Table 1. Subjects Referred for Exercise Testing

 
The effect of the IC maneuver on B-1 was determined using the data from all 30 subjects. There was a significant difference (p < 0.05; t = 6.8; degrees of freedom [df] = 262) between of the six breaths that preceded the prompt (1.05 ± 0.55 L) and the mean VE for B-1 (0.94 ± 0.63 L). There was a significant difference (p < 0.05; t = 8.35; df = 262) between of the six breaths that preceded the prompt (1.75 ± 0.65 s) and the mean TE for B-1 (1.46 ± 0.73 s). Using the tolerance limits (three times the SD), 132 of the 264 IC maneuvers would have been rejected as technically unsatisfactory. Unsatisfactory maneuvers were as likely to occur early in exercise as near the end of exercise.

A one-way analysis of variance analyzing all IC maneuvers from the 30 subjects showed that there was a significant difference among the various methods of calculating IC (p < 0.05: F = 28.0; df = 2, 262). Post hoc analysis showed that the overall mean ICINSP (1.78 ± 0.88 L) was significantly less than the overall mean IC calculated from the two alternative methods (ICREG, 1.88 ± 0.89 L; ICRATIO, 1.86 ± 0.87 L).

Examples of the measured ICINSP and ICRATIO during exercise are shown in Figure 2 . In the upper panel (subject 1 with severe COPD), dynamic hyperinflation was reflected by the progressive decrease (negative slope) in ICRATIO with no inspiratory reserve volume at the end of exercise. In the middle panel (subject 2 with moderate COPD), dynamic hyperinflation was present, but there is disagreement between the slopes derived from ICINSP and ICRATIO. In the lower panel (subject 3 without COPD), there was no dynamic hyperinflation when using ICRATIO to derive the slope. However, the slope was negative when the ICINSP was used, and there was considerable variation of ICINSP about the regression line.



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  		Figure 2. Summarizes the ICINSP (circles) dashed regression line and the ICRATIO (squares) solid regression line, measured during incremental exercise for three subjects. Upper panel, A: a subject with little change in tidal volume (black dot) and good agreement between the two methods. Middle panel, B: the influence of correcting the IC, which would otherwise overestimate dynamic hyperinflation. Lower panel, C: the corrected IC reflects the absence of hyperinflation. The uncorrected measures would have wrongly indicated that hyperinflation was present in this subject.

 
The mean peak power was 37 ± 6 W in the 10 subjects (7 male and 3 female subjects) with COPD who completed a second incremental exercise test. The coefficients of repeatability for the different methods of calculating IC as a function of time and minute ventilation are shown in Table 2 . The coefficients of repeatability for the IC measured closest to the end of exercise are also shown in Table 2 .


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  		Table 2. Repeatability of Exercise Measurements in 10 Subjects With COPD*

 
During constant-power exercise at 24 ± 10 W for 5.8 ± 1.7 min, the slope of ICRATIO expressed as a function of time (- 0.12 ± 0.07 L/min) did not differ from the incremental test (- 0.11 ± 0.05 L/min). The agreement between the two slopes was ± 0.14 L/min. When ICRATIO was expressed as a function of ventilation agreement between the two slopes (constant-power test, - 0.06 ± 0.06 min; incremental test, - 0.07 ± 0.06 min), the agreement was ± 0.03 min.

The 20 subjects with COPD (FEV1, 0.80 ± 0.28 L) differed from the 10 subjects without COPD (FEV1, 3.08 ± 0.98 L) in the slope of ICRATIO as a function of time (COPD, - 0.09 ± 0.04 L/min; no COPD, 0.03 ± 0.05 L/min; p < - 0.05, t = 7.5, df = 28) and ventilation (COPD, - 0.06 ± 0.05 min; no COPD, - 0.01 ± 0.01 min; p < 0.05: t = 4.1, df = 28) using an unpaired t test.


   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
The IC maneuver is a simple noninvasive method for tracking dynamic hyperinflation.2 5 6 8 10 11 12 The operational definition of the construct, dynamic hyperinflation, is a progressive decrease in IC that occurs with an increase in ventilation. This is the first study to examine the repeatability of serial IC measurements of patients with severe COPD undergoing incremental exercise testing in a clinical setting. These individuals demonstrated a linear decrease in IC with increasing ventilation. Compared with other methods of calculating IC, the method of calculating IC that preserved the inspiratory flow and used an average EELV derived from uninterrupted breaths (ICRATIO) improved the repeatability. We tested the validity of this construct in two ways: (1) the progressive decrease of IC during nonsteady-state exercise expressed as a function of ventilation was unaffected by the exercise protocol, and (2) serial IC measures were able to discriminate between subjects with COPD who would be expected to experience dynamic hyperinflation and those who would not.

Dynamic hyperinflation can be reflected by changes in serial IC measures during exercise.2 5 This study confirms previous observations that serial IC measures expressed as a linear function of ventilation will adequately describe dynamic hyperinflation in patients with severe COPD.5 The slope of the line summarizes the entire response. Calculating IC in a way that was unaffected by unsatisfactory technique improved the repeatability coefficient by as much as 60%. Using the ICRATIO, a patient with COPD would have to change the slope of volume loss (dynamic hyperinflation) by > 0.02 min for a clinician to be 95% confident that this change did not reflect the inherent error of the measurement. This translates to a volume change of 0.28 L in our COPD patients who increased ventilation from 13 to 27 L/min from rest to end-exercise. Serial IC measures (using the ICINSP method) have been reported as reliable2 when assessing COPD patients exercising to symptom limitation. From the reported coefficient of variation, the repeatability coefficient for the IC was 0.62 L at end-exercise, which was similar to the repeatability coefficient at end-exercise (using the same ICINSP method) in our subjects. However using the ICRATIO method, the repeatability coefficient improved to 0.22 L. Thus, a clinically important change of 0.30 to 0.40 L in dynamic hyperinflation2 would be detectable using the ICRATIO method.

Using the rate of change of IC during nonsteady-state exercise has the advantage of not requiring subjects to reach the same absolute exercise power output or ventilation for the clinician to assess the influence of an intervention on the IC. When expressed as a function of ventilation, the repeatability improved and the measurement was independent of the exercise protocol. The relationship between ventilation and IC was consistent irrespective of whether constant-power or incremental exercise was used.

A patient’s ventilatory response to exercise can provide valuable information20 regarding the extent of expiratory flow limitation. The correct placement of the flow-volume loop (from the measurement of IC) relative to the absolute lung volume (TLC) is very important.13 A poor quality measure could result in an erroneous conclusion regarding the amount of expiratory flow limitation that occurs. Although at rest the measurement can be repeated until an acceptable technique is achieved, data that are sampled every 2 to 3 min during a 10-minute incremental exercise test cannot be remeasured if technically unsatisfactory. At high breathing frequencies, an unsatisfactory technique in which IC was affected by breathing pattern may be difficult to detect. This might well have contributed to the high variability of the IC measured during exercise.2 Using objective criteria (tolerance limits from the six breaths before), we identified almost 50% of the measurements as unacceptable. Therefore, establishing the relative EELV before the IC prompt is important when serial IC measurements are used.

Using serial measures of IC to monitor EELV assumes that the TLC does not change with exercise and that the diaphragm is maximally activated. Previous reports have shown that the TLC did not change during exercise in patients with COPD3 21 22 and that the inspiratory muscles were maximally activated in dyspneic patients.2 18 23 As with all effort-dependent tests, encouragement is necessary to ensure that the effort is maximal. Just as consistent measures are used to confirm maximal effort during spirometry, the same approach can be applied to the IC maneuver during exercise.24 Serial IC measurements were noted to be more consistent when they were unaffected by changes in lung volume during the maneuver.

We calculated IC in three different ways to establish which method would provide the best repeatability. Exercise testing systems that measure flow on the inspiratory side of a one-way valve are limited to the ICINSP method. Both the ICRATIO and ICREG methods establish a relative EELV baseline, and changes in response to the maneuver prompt are not included in the calculation. Subjects do not need either practice or elaborate instructions to perform repeated IC maneuvers during exercise. In the ICRATIO method, only the expired volume is corrected. Inspiratory volume (derived from flow) remained consistent with the calibration under the identical circumstances of humidity, temperature, and composition. However, given that expired gas is warmer, more humid, and is composed differently (more carbon dioxide, less oxygen) than the calibration room air, the volume signal can drift in the absence of an actual change in lung volume. In a technically correct IC maneuver (constant EELV), the ICINSP and the ICRATIO would be the same. However, the ICREG method could still differ from the other methods, as it alters inspired as well as expired volume without a valid rationale for adjusting the inspired volume. The ICREG does not improve the repeatability of the IC measure, because error is introduced by the variability of the drift. For example, a deviant breath within the six control breaths could have a disproportionately strong influence on the regression. The observed drift in the volume signal might be attributable to the respiratory exchange ratio. However, such a change (maximum of 3 to 6 mL per breath) would not have a significant effect on the measured IC by any method. Even if it did, corrections to account for the respiratory exchange ratio need only be applied to the expiratory volume signal.

A common problem when using a small sample to establish general exercise values for any population is that the recruited subjects may not represent the target population. We calculated repeatability coefficients for other measures made during the incremental exercise tests and present them in Table 2 . The results are similar to the only two studies25 26 from which the repeatability coefficients can be calculated for COPD patients repeating incremental exercise tests. For example, repeatability coefficients calculated from the data of Covey et al25 were 9 W, 7.02 L/min, 12 beats/min, and 0.204 L/min for peak power, minute ventilation, heart rate, and oxygen uptake, respectively. Thus, the subjects used in this study to establish the response of IC showed a similar variability in their exercise response as other patients with severe COPD completing incremental exercise tests on a cycle ergometer.

In summary, subjects undergoing incremental exercise altered their pattern of breathing immediately before making the IC maneuver. Therefore, it is necessary to establish a premaneuver baseline volume from which to calculate the IC. The absolute difference between the two methods of calculation that established a premaneuver baseline (ICREG vs ICRATIO) appears trivial, but the difference between the clinically important repeatability coefficient was considerable. Using the ICRATIO method to calculate the IC improved the repeatability of the measure of IC. This was the case when IC was expressed as an absolute value at end-exercise, or when it was expressed as a time-dependant or a ventilation-dependent process. Furthermore, ICRATIO had face validity because the calibrated inspired flow was unaltered. Incorporating such approaches into the analysis of IC during exercise will assist in tracking dynamic hyperinflation in patients with COPD.


   Footnotes
 
Abbreviations: B-1 = breath immediately before the inspiratory capacity maneuver; df = degrees of freedom; EELV = end-expiratory lung volume; IC = inspiratory capacity; ICINSP = inspiratory capacity calculated by the integration of inspired flow from the start to the end of the inspiratory capacity maneuver; ICRATIO = inspiratory capacity calculated, after correction of the expiratory part of the signal, as the difference between the mean end-expiratory lung volume of the six breaths that preceded the inspiratory capacity prompt and the peak inspiratory volume; ICREG = inspiratory capacity calculated from the difference between the drift-corrected peak inspiratory volume (total lung capacity) and the drift-corrected end-expiratory lung volume of the six breaths that preceded the inspiratory capacity prompt; TE = expiratory time of a breath; TI = inspiratory time of a breath; VE = expired volume of a breath; VI = inspired volume of a breath; = average inspired volume of a breath/expired volume of a breath for the six uninterrupted breaths that preceded the inspiratory capacity prompt

Received for publication March 20, 2001. Accepted for publication August 29, 2001.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. O’Donnell, DE, Bertley, JC, Chau, LK, et al (1997) Qualitative aspects of exertional breathlessness in chronic airflow limitation: pathophysiologic mechanisms. Am J Respir Crit Care Med 155,109-115[Abstract]
  2. O’Donnell, DE, Lam, M, Webb, KA (1998) Measurement of symptoms, lung hyperinflation, and endurance during exercise in chronic obstructive pulmonary disease. Am J Respir Crit Care Med 158,1557-1565[Abstract/Free Full Text]
  3. Stubbing, DG, Pengelly, LD, Morse, JL, et al (1980) Pulmonary mechanics during exercise in subjects with chronic airflow obstruction. J Appl Physiol 49,511-515[Abstract/Free Full Text]
  4. O’Donnell, DE, Webb, KA (1993) Exertional breathlessness in patients with chronic airflow limitation: the role of lung hyperinflation. Am Rev Respir Dis 148,1351-1357[ISI][Medline]
  5. Bauerle, O, Chrusch, CA, Younes, M (1998) Mechanisms by which COPD affects exercise tolerance. Am J Respir Crit Care Med 157,57-68[Free Full Text]
  6. Belman, MJ, Botnick, WC, Shin, JW (1996) Inhaled bronchodilators reduce dynamic hyperinflation during exercise in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 153,967-975[Abstract]
  7. Sliwinski, P (1998) Partitioning of the elastic work of inspiration in patients with COPD during exercise. Eur Respir J 11,416-421[Abstract]
  8. Koulouris, NG, Dimopoulou, I, Valta, P, et al (1997) Detection of expiratory flow limitation during exercise in COPD patients. J Appl Physiol 82,723-731[Abstract/Free Full Text]
  9. O’Donnell, DE, Chau, LKL, Webb, KA (1998) Qualitative aspects of exertional dyspnea in patients with interstitial lung disease. J Appl Physiol 84,2000-2009[Abstract/Free Full Text]
  10. Martinez, FJ, de Oca, MM, Whyte, RI, et al (1997) Lung-volume reduction improves dyspnea, dynamic hyperinflation, and respiratory muscle function. Am J Respir Crit Care Med 155,1984-1990[Abstract]
  11. Babb, TG, Rodarte, JR (1992) Exercise capacity and breathing mechanics in patients with airflow limitation. Med Sci Sports Exerc 24,967-974[ISI][Medline]
  12. Babb, TG, Rodarte, JR (1993) Estimation of ventilatory capacity during submaximal exercise. J Appl Physiol 74,2016-2022[Abstract/Free Full Text]
  13. Johnson, BD, Weisman, IM, Zaballos, RJ, et al (1999) Emerging concepts in the evaluation of ventilatory limitation during exercise: the exercise tidal flow-volume loop. Chest 116,488-503[Abstract/Free Full Text]
  14. ISO 5725–1994 accuracy (trueness and precision) of measurement methods and results. Geneva, Switzerland: International Organization for Standardization, 1994
  15. Bland, JM, Altman, DG (1986) Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1,307-310[CrossRef][ISI][Medline]
  16. Jones, NL (1988) Clinical exercise testing 3rd ed. W.B. Saunders Philadelphia, PA.
  17. . American Thoracic Society (1995) Standardization of spirometry, 1994 update. Am J Respir Crit Care Med 152,1107-1136[ISI][Medline]
  18. Yan, S, Kaminski, D, Sliwinski, P (1997) Reliability of inspiratory capacity for estimating end-expiratory lung volume changes during exercise in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 156,55-59[Abstract/Free Full Text]
  19. Dolmage, TE, Goldstein, RS (1999) Monitoring dynamic hyperinflation using repeated inspiratory capacity maneuvers during cardiopulmonary exercise testing [abstract]. Chest 116(suppl 2),334S
  20. Levine, S (1999) Tidal flow-volume analysis of ventilation during exercise: a useful approach for diagnosing the mechanism of ventilatory limitation to exercise during cardiopulmonary exercise testing. Chest 116,277-278[Free Full Text]
  21. Younes, M, Kivinen, G (1984) Respiratory mechanics and breathing pattern during and following maximal exercise. J Appl Physiol 57,1773-1782[Abstract/Free Full Text]
  22. Babb, TG, Viggiano, R, Hurley, B, et al (1991) Effect of mild-to-moderate airflow limitation on exercise capacity. J Appl Physiol 70,223-230[Abstract/Free Full Text]
  23. Newell, SZ, McKenzie, DK, Gandevia, SC (1989) Inspiratory and skeletal muscle strength and endurance and diaphragmatic activation in patients with chronic airflow limitation. Thorax 44,903-912[Abstract]
  24. Younes, M (1984) Interpretation of clinical exercise testing in respiratory disease. Clin Chest Med 5,189-206[Medline]
  25. Covey, MK, Larson, JL, Alex, CG, et al (1999) Test-retest reliability of symptom-limited cycle ergometer tests in patients with chronic obstructive pulmonary disease. Nurs Res 48,9-19[CrossRef][ISI][Medline]
  26. Brown, S, Fischer, C, Stansbury, D, et al (1985) Reproducibility of VO2max in patients with chronic air-flow obstruction. Am Rev Respir Dis 131,435-438[ISI][Medline]



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T. E. Dolmage and R. S. Goldstein
Effects of One-Legged Exercise Training of Patients With COPD
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T. E. Dolmage and R. S. Goldstein
Response to One-Legged Cycling in Patients With COPD.
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T.E. Dolmage, T.K. Waddell, F. Maltais, G.H. Guyatt, T.R.J. Todd, S. Keshavjee, S. van Rooy, B. Krip, P. LeBlanc, and R.S. Goldstein
The influence of lung volume reduction surgery on exercise in patients with COPD
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