Tuberc Respir Dis.  2008 Jun;64(6):433-438.

Predicting Oxygen Uptake for Men with Moderate to Severe Chronic Obstructive Pulmonary Disease

• Kim C
• Park YB
• Mo EK
• Choi EH
• Nam HS
• Lee SS
• Yoo YW
• Yang YJ
• Moon JW
• Kim DS
• Lee HY
• Jin YS
• Lee HY
• Chun EM

Abstract

BACKGROUND
Measurement of the maximum oxygen uptake in patients with chronic obstructive pulmonary disease (COPD) has been used to determine the intensity of exercise and to estimate the patient's response to treatment during pulmonary rehabilitation. However, cardiopulmonary exercise testing is not widely available in Korea. The 6-minute walk test (6MWT) is a simple method of measuring the exercise capacity of a patient. It also provides high reliability data and it reflects the fluctuation in one's exercise capacity relatively well with using the standardized protocol. The prime objective of the present study is to develop a regression equation for estimating the peak oxygen uptake (VO2) for men with moderate to very severe COPD from the results of a 6MWT.
METHODS
A total of 33 male patients with moderate to very severe COPD agreed to participate in this study. Pulmonary function testing, cardiopulmonary exercise testing and a 6MWT were performed on their first visits. The index of work (6Mwork, 6-minute walk distance [6MWD]xbody weight) was calculated for each patient. Those variables that were closely related to the peak VO2 were identified through correlation analysis. With including such variables, the equation to predict the peak VO2 was generated by the multiple linear regression method.
RESULTS
The peak VO2 averaged 1,015+/-392 ml/min, and the mean 6MWD was 516+/-195 meters. The 6Mwork (r=.597) was better correlated to the peak VO2 than the 6MWD (r=.415). The other variables highly correlated with the peak VO2 were the FEV1 (r=.742), DLco (r=.734) and FVC (r=.679). The derived prediction equation was VO2 (ml/min)=(274.306xFEV1)+(36.242xDLco)+(0.007x6Mwork)-84.867.
CONCLUSION
Under the circumstances when measurement of the peak VO2 is not possible, we consider the 6MWT to be a simple alternative to measuring the peak VO2. Of course, it is necessary to perform a trial on much larger scale to validate our prediction equation.

Keyword

COPD; Peak oxygen uptake; 6-minute walk test

MeSH Terms

Exercise Test
Humans
Korea
Linear Models
Male
Oxygen
Pulmonary Disease, Chronic Obstructive
Respiratory Function Tests
Oxygen

Figure

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  Figure 1 Index of work (6Mwork) was better correlated to peak oxygen uptake (VO2) than 6-minute work distance (6MWD). Scatterplot of peak VO2 to 6MWD (r=0.415, p=0.016) (A). Scatterplot of peak VO2 to 6Mwork (r=0.597, p<0.001) (B).

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  Figure 2 FEV1 and DLco were highly correlated, but age was not correlated with peak oxygen uptake (VO2). Scatterplot of peak VO2 to FEV1 (r=0.742, p<0.001) (A). Scatterplot of peak VO2 to DLco (r=0.734, p<0.001) (B). Scatterplot of peak VO2 to age (r=-0.334, p>0.05) (C).

Reference

1. Pauwels RA, Buist AS, Calverley PM, Jenkins CR, Hurd SS. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO Global Initiative for Chronic Obstructive Lung Disease (GOLD) Workshop summary. Am J Respir Crit Care Med. 2001. 163:1256–1276.

2. Chronic obstructive pulmonary disease. National clinical guideline on management of chronic obstructive pulmonary disease in adults in primary and secondary care. Thorax. 2004. 59 Suppl 1:1–232.

3. Bruce RA. Methods of exercise testing. Step test, bicycle, treadmill, isometrics. Am J Cardiol. 1974. 33:715–720.

4. Hlatky M, Boineau RE, Higginbotham MB, Lee KL, Mark DB, Califf RM, et al. A brief self-administered questionnaire to determine functional capacity (the Duke Activity Status Index). Am J Cardiol. 1989. 64:651–654.

5. Noseda A, Carpiaux JP, Prigogine T, Schmerber J. Lung function, maximum and submaximum exercise testing in COPD patients: reproducibility over a long interval. Lung. 1989. 167:247–257.

6. Cox NJ, Hendriks JC, Binkhorst RA, Folgering HT, van Herwaarden CL. Reproducibility of incremental maximal cycle ergometer tests in patients with mild to moderate obstructive lung disease. Lung. 1989. 167:129–133.

7. Wasserman K, Whipp BJ. Exercise physiology in health and disease. Am Rev Respir Dis. 1975. 112:219–249.

8. Hamilton DM, Haennel RG. Validity and reliability of the 6-minute walk test in a cardiac rehabilitation population. J Cardiopulm Rehabil. 2000. 20:156–164.

9. Harada ND, Chiu V, Stewart AL. Morbility-related function in older adults: assessment with a 6-minute walk test. Arch Phys Med Rehabil. 1999. 80:837–841.

10. ATS Committee on Proficiency Standards for Clinical Pulmonary Function Laboratories. ATS statement: guidelines for the six-minute walk test. Am J Respir Crit Care Med. 2002. 166:111–117.

11. Chuang ML, Lin IF, Wasserman K. The body weight-walking distance product as related to lung function, anaerobic threshold and peak Vo2 in COPD patients. Respir Med. 2001. 95:618–626.

12. Carter R, Holiday DB, Stocks J, Grothues C, Tiep B. Predicting oxygen uptake for men and women with moderate to severe chronic obstructive pulmonary disease. Arch Phys Med Rehabil. 2003. 84:1158–1164.

13. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease (Revised 2006) [Internet]. Global initiative for chronic obstructive lung disease (GOLD). Available from: http;//goldcopd.com.

14. American Thoracic Society. Pulmonary rehabilitation-1999. Am J Respir Crit Care Med. 1999. 159:1666–1682.

15. British Thoracic Society Standards of Care Subcommittee on Pulmonary Rehabilitation.Pulmonary rehabilitation. Thorax. 2001. 56:827–834.

16. Troosters T, Casaburi R, Gosselink R, Decramer M. Pulmonary rehabilitation in chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2005. 172:19–38.

17. Cooper KH. A means of assessing maximal oxygen uptake. Correlation between field and treadmill testing. JAMA. 1968. 203:201–204.

18. Carlson DJ, Ries AL, Kaplan RM. Prediction of maximum exercise tolerance in patients with COPD. Chest. 1991. 100:307–311.

19. Cahalin L, Pappagianopoulos P, Prevost S, Wain J, Ginns L. The relationship of the 6-min walk test to maximal oxygen consumption in transplant candidates with end-stage lung disease. Chest. 1995. 108:452–459.

20. Chuang ML, Lin IF, Vintch JR. Comparison of estimated and measured maximal oxygen uptake during exercise testing in patients with chronic obstructive pulmonary disease. Intern Med J. 2004. 34:469–474.

21. Chuang ML, Ting H, Otsuka T, Sun XG, Chiu FY, Beaver WL, et al. Aerobically generated CO(2) stored during early exercise. J Appl Physiol. 1999. 87:1048–1058.

22. Bernstein ML, Despars JA, Singh NP, Avalos K, Stansbury DW, Light RW. Reanalysis of the 12-minute walk in patients with chronic obstructive pulmonary disease. Chest. 1994. 105:163–167.