TheRelationship ofthe6-Min WalkTest toMaximalOxygen Consumption in Transplant Candidates WithEnd-Stage Lung Disease*
01 Jan 2017-
TL;DR: The distance ambulated during a 6'WT can predict VO2 max in patients with end-stage lung disease and the addition of several patient characteristics can increase the ability to predictVO2 max and account for more of the variability.
Abstract: STUDY OBJECTIVE
To assess the relationship of distance ambulated during the 6-min walk test (6'WT) to maximal oxygen consumption (VO2 max).
DESIGN
Multivariate analysis of patient characteristics to VO2 max.
SETTING
Pre-lung transplant evaluation.
PATIENTS
60 patients (22 men, 38 women; mean age, 44 years) with end-stage lung disease (mean FEV1 and forced vital capacity of 0.97 and 1.93, respectively).
MEASUREMENTS AND RESULTS
The 6'WT was performed on a level hallway surface, and VO2 max was obtained during maximal cycle ergometry exercise testing with respiratory gas analysis. Multivariate analysis of patient characteristics (age, sex, weight, FEV1, FVC, diffusing capacity for carbon monoxide (DCO), 6'WT distance ambulated, number of rests per 6'WT, and the maximal heart rate, blood pressure, rate-pressure product, respiratory rate, oxygen saturation, rating of perceived exertion, and amount of supplemental oxygen used during the 6'WT) was performed on two groups of 30 patients each (group A or B) who were randomly assigned to either group by a process of random selection using a computer-generated random numbers program. Distance ambulated was the strongest independent predictor of VO2 max (r = 0.73; p < 0.0001) in both groups, and adding age, weight, and pulmonary function test results (FVC, FEV1, and DCO) to the regression equation increased the correlation coefficient to 0.83. Because of the significant correlation of distance ambulated during the 6'WT to VO2 max, the prediction equation obtained from the multivariate analysis of group A, VO2 max = 0.006 x distance (feet) +3.38, was used to estimate the VO2 max of the group B patients. No significant difference was observed between the estimated (x +/- SD = 8.9 +/- 2.4 mL/kg/min) and observed (x +/- SD = 9.4 +/- 3.8 mL/kg/min) VO2 max (mean difference, 0.5 mL/kg/min; SD of the difference = 2.88).
CONCLUSIONS
The distance ambulated during a 6'WT can predict VO2 max in patients with end-stage lung disease. The addition of several patient characteristics can increase the ability to predict VO2 max and account for more of the variability. Such information is valuable when assessing patient response to therapeutic intervention if respiratory gas analysis is unavailable or impractical.
Citations
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TL;DR: Preliminary descriptive data suggest that physical therapists should use age-related data when interpreting patient data obtained for the 6MW, BBS, TUG, CGS and FGS measurements, which showed high test-retest reliability.
Abstract: Background and Purpose. The interpretation of patient scores on clinical tests of physical mobility is limited by a lack of data describing the range of performance among people without disabilities. The purpose of this study was to provide data for 4 common clinical tests in a sample of community-dwelling older adults. Subjects. Ninety-six community-dwelling elderly people (61–89 years of age) with independent functioning performed 4 clinical tests. Methods. Data were collected on the Six-Minute Walk Test (6MW), Berg Balance Scale (BBS), and Timed Up & Go Test (TUG) and during comfortable- and fast-speed walking (CGS and FGS). Intraclass correlation coefficients (ICCs) were used to determine the test-retest reliability for the 6MW, TUG, CGS, and FGS measurements. Data were analyzed by gender and age (60–69, 70–79, and 80–89 years) cohorts, similar to previous studies. Means, standard deviations, and 95% confidence intervals for each measurement were calculated for each cohort. Results. The 6MW, TUG, CGS, and FGS measurements showed high test-retest reliability (ICC [2,1]=.95–.97). Mean test scores showed a trend of age-related declines for the 6MW, BBS, TUG, CGS, and FGS for both male and female subjects. Discussion and Conclusion. Preliminary descriptive data suggest that physical therapists should use age-related data when interpreting patient data obtained for the 6MW, BBS, TUG, CGS and FGS. Further data on these clinical tests with larger sample sizes are needed to serve as a reference for patient comparisons.
1,956 citations
TL;DR: In four important domains of quality of life (QoL) (Chronic Respiratory Questionnaire (CRQ) scores for dyspnoea, fatigue, emotional function and mastery), the effect was larger than the minimal clinically important difference (MCID) of 0.4%.
Abstract: Background The widespread application pulmonary rehabilitation in chronic obstructive pulmonary disease (COPD) should be preceded by demonstrable improvements in function attributable to the programs. This review updates that reported by Lacasse et al Lancet 1996; 748:1115-1119. Objectives To determine the impact of rehabilitation on health-related quality of life (QoL) and exercise capacity in patients with COPD. Search strategy The 14 randomized controlled trials (RCTs) included in the original meta-analysis were included. Additional RCTs were identified from the Cochrane Airways Group's registry of COPD RCTs using the strategy: [exp, lung diseases, obstructive] and [exp, rehabilitation or exp, exercise therapy] and [research design or longitudinal studies or evaluation study or randomized controlled trial]. Abstracts presented at American Thoracic Society 1980-2000, American College of Chest Physicians 1980-2000 and European Respiratory Society 1987-2000 were also searched. Selection criteria RCTs of rehabilitation in patients with COPD in which quality of life (QoL) and/or functional (FEC) or maximal (MEC) exercise capacity were measured. Rehabilitation was defined as exercise training for at least 4 weeks with or without education and/or psychological support. Control groups received conventional community care without rehabilitation. Data collection and analysis Weighted mean differences (WMD) were calculated using a random-effects model. Missing data from the primary study reports were requested from the authors. Main results 23 RCTs met the inclusion criteria. Statistically significant improvements were found for all the outcomes. In three important domains of QoL (Chronic Respiratory Questionnaire scores for Dyspnea, Fatigue and Mastery), the effect was larger than the minimal clinically important difference of 0.5 units using this instrument. For example Dyspnoea score: WMD 0.98 units, 95% Confidence Interval (95% CI) 0.74 - 1.22 units; n=9 trials. For FEC and MEC, the effect was small and a little below the threshold of clinical significance for the 6- minute walking distance: WMD 49 m, 95% CI: 26 - 72 m; n=10 trials. Reviewer's conclusions Rehabilitation relieves dyspnea and fatigue and enhances patients' sense of control over their condition. These improvements are moderately large and clinically significant. The average improvement in exercise capacity was modest. Rehabilitation forms an important component of the management of COPD.
1,863 citations
TL;DR: Measurement properties of the 6MWT have been the most extensively researched and established and is currently the test of choice when using a functional walk test for clinical or research purposes.
1,034 citations
Journal Article•
TL;DR: Clinical practice guidelines were generated and finalised in a functional algorithm for risk stratification of the lung resection candidates, emphasising cardiological evaluation, forced expiratory volume in 1 s, systematic carbon monoxide lung diffusion capacity and exercise testing.
613 citations
TL;DR: It is demonstrated that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease and responsive to interventions that included exercise training.
Abstract: This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease. Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013. The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r50.59-0.93) and physical activity (r50.40-0.85) than with respiratory function (r50.10-0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training. The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.
580 citations
References
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TL;DR: From incremental exercise tests on 10 subjects, the point of excess CO2 output (AT) predicted closely the lactate and HCO-3 thresholds and could be more reliably determined by the V-slope method.
Abstract: Excess CO2 is generated when lactate is increased during exercise because its [H+] is buffered primarily by HCO-3 (22 ml for each meq of lactic acid). We developed a method to detect the anaerobic threshold (AT), using computerized regression analysis of the slopes of the CO2 uptake (VCO2) vs. O2 uptake (VO2) plot, which detects the beginning of the excess CO2 output generated from the buffering of [H+], termed the V-slope method. From incremental exercise tests on 10 subjects, the point of excess CO2 output (AT) predicted closely the lactate and HCO-3 thresholds. The mean gas exchange AT was found to correspond to a small increment of lactate above the mathematically defined lactate threshold [0.50 +/- 0.34 (SD) meq/l] and not to differ significantly from the estimated HCO-3 threshold. The mean VO2 at AT computed by the V-slope analysis did not differ significantly from the mean value determined by a panel of six experienced reviewers using traditional visual methods, but the AT could be more reliably determined by the V-slope method. The respiratory compensation point, detected separately by examining the minute ventilation vs. VCO2 plot, was consistently higher than the AT (2.51 +/- 0.42 vs. 1.83 +/- 0.30 l/min of VO2). This method for determining the AT has significant advantages over others that depend on regular breathing pattern and respiratory chemosensitivity.
3,805 citations
2,653 citations
Book•
01 Feb 1994
TL;DR: In this paper, the principles of exercise testing and interpretation are presented for exercise testing in the Libros de Medicina (Patologia) 5/e - Patologia - 139,00
Abstract: Principles of Exercise Testing and Interpretation, 5/e - Libros de Medicina - Patologia - 139,00
2,331 citations
TL;DR: These data suggest that cardiac transplantation can be safely deferred in ambulatory patients with severe left ventricular dysfunction and peak exercise Vo2 of more than 14 ml/min/kg.
Abstract: BACKGROUNDOptimal timing of cardiac transplantation in ambulatory patients with severe left ventricular dysfunction is often difficult. To determine whether measurement of peak oxygen consumption (VO2) during maximal exercise testing can be used to identify patients in whom transplantation can be safely deferred, we prospectively performed exercise testing on all ambulatory patients referred for transplant between October 1986 and December 1989.METHODS AND RESULTSPatients were assigned into one of three groups on the basis of exercise data: Group 1 (n = 35) comprised patients accepted for transplant (VO2 less than or equal to 14 ml/kg/min); group 2 (n = 52) comprised patients considered too well for transplant (VO2 greater than 14 ml/kg/min); and group 3 (n = 27) comprised patients with low VO2 rejected for transplant due to noncardiac problems. All three groups were comparable in New York Heart Association functional class, ejection fraction, and cardiac index (p = NS). Pulmonary capillary wedge pressure...
1,695 citations
TL;DR: This study produced predicted values for forced vital capacity and forced expiratory volume in one second that were almost identical to those predicted by Morris and associates when the data from their study were modified to be compatible with the back extrapolation technique recommended by the ATS.
Abstract: Forced expiratory volumes and flows were measured in 251 healthy nonsmoking men and women using techniques and equipment that meet American Thoracic Society (ATS) recommendations. Linear regression equations using height and age alone predict spirometric parameters as well as more complex equations using additional variables. Single values for 95% confidence intervals are acceptable and should replace the commonly used method of subtracting 20% to determine the lower limit of normal for a predicted value. Our study produced predicted values for forced vital capacity and forced expiratory volume in one second that were almost identical to those predicted by Morris and associates (1) when the data from their study were modified to be compatible with the back extrapolation technique recommended by the ATS. The study of Morris and colleagues was performed at sea level in rural subjects, whereas ours was performed at an altitude of 1,400 m in urban subjects. Either the present study or the study of Morris and co-workers, modified to back extrapolation, could be recommended for predicting normal values.
1,528 citations