Main Article Content
Idiopathic pulmonary fibrosis, Six-minute walk, Exercise, Desaturation, Desaturation distance ratio
Background and aim: New parameters in the 6-minute walk test (6MWT) are needed for assessing exercise capacity in patients with idiopathic pulmonary fibrosis (IPF). To our knowledge, no previous study has investigated the potential of using the desaturation distance ratio (DDR) to assess exercise capacity specifically in patients with IPF. This study aimed to investigate whether DDR is a potential tool for assessing the exercise capacity of patients with IPF.
Methods: This study conducted with 33 subjects with IPF. Pulmonary function tests and a 6MWT were performed. To calculate the DDR, first, the difference between the patient's SpO2 at each minute and the SpO2 of 100% was summed together to determine the desaturation area (DA). Next, DDR was calculated using dividing DA by the 6-minute walk test distance (6MWD) (i.e., DA/6MWD).
Results: When correlations of 6MWD and DDR with changes (Δ) in the severity of perceived dyspnea were examined, 6MWD did not significantly correlate with ΔBorg. Conversely, there was a significant correlation between the DDR and ΔBorg (r= 0.488, p=0.004). There were significant correlations between 6MWD and FVC % (r=0.370, p=0.034), and FEV1 % (r=0.465, p=0.006). However, DDR was significantly more correlated with FVC % (r= -0.621, p< 0.001), FEV1 % (r= -0.648, p< 0.001). Moreover, there was a significant correlation between DDR and DLCO % (r= -0.342, p=0.052).
Conclusions: The findings of this study suggest that DDR is a promising and more useful parameter for assessing patients with IPF.
2. Butland RJ, Pang J, Gross ER, Woodcock AA, Geddes DM. Two-, six-, and 12-minute walking tests in respiratory disease. Br Med J (Clin Res Ed). 1982;284(6329):1607-8.
3. Guyatt GH, Sullivan MJ, Thompson PJ, et al. The 6-minute walk: a new measure of exercise capacity in patients with chronic heart failure. Can Med Assoc J. 1985;132(8):919-23.
4. Poole-Wilson PA. The 6-minute walk. A simple test with clinical application. Eur Heart J. 2000;21(7):507-8.
5. Solway S, Brooks D, Lacasse Y, Thomas S. A qualitative systematic overview of the measurement properties of functional walk tests used in the cardiorespiratory domain. Chest. 2001;119(1):256-70.
6. Lancaster LH. Utility of the six-minute walk test in patients with idiopathic pulmonary fibrosis. Multidiscip Respir Med. 2018;13:45.
7. 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(1):111-7.
8. Ijiri N, Kanazawa H, Yoshikawa T, Hirata K. Application of a new parameter in the 6-minute walk test for manifold analysis of exercise capacity in patients with COPD. Int J Chron Obstruct Pulmon Dis. 2014;9:1235-40.
9. Pimenta SP, Rocha RB, Baldi BG, Kawassaki Ade M, Kairalla RA, Carvalho CR. Desaturation - distance ratio: a new concept for a functional assessment of interstitial lung diseases. Clinics (Sao Paulo). 2010;65(9):841-6.
10. Lettieri CJ, Nathan SD, Browning RF, Barnett SD, Ahmad S, Shorr AF. The distance-saturation product predicts mortality in idiopathic pulmonary fibrosis. Respir Med. 2006;100(10):1734-41.
11. Lama VN, Flaherty KR, Toews GB, et al. Prognostic value of desaturation during a 6-minute walk test in idiopathic interstitial pneumonia. Am J Respir Crit Care Med. 2003;168(9):1084-90.
12. Chetta A, Aiello M, Foresi A, et al. Relationship between outcome measures of six-minute walk test and baseline lung function in patients with interstitial lung disease. Sarcoidosis Vasc Diffuse Lung Dis. 2001;18(2):170-5.
13. Flaherty KR, Andrei AC, Murray S, et al. Idiopathic pulmonary fibrosis: prognostic value of changes in physiology and six-minute-walk test. Am J Respir Crit Care Med. 2006;174(7):803-9.
14. Bourke SJ. Interstitial lung disease: progress and problems. Postgrad Med J. 2006;82(970):494-9.
15. Macintyre N, Crapo RO, Viegi G, et al. Standardisation of the single-breath determination of carbon monoxide uptake in the lung. Eur Respir J. 2005;26(4):720-35.
16. Miller MR, Hankinson J, Brusasco V, et al. ATS/ERS Task Force. Standardisation of spirometry. Eur Respir J. 2005;26(2):319-38.
17. Field A. Discovering statistics using SPSS. 3rd ed. ed. London: Sage Publications Ltd.; 2009.
18. Eaton T, Young P, Milne D, Wells AU. Six-minute walk, maximal exercise tests: reproducibility in fibrotic interstitial pneumonia. Am J Respir Crit Care Med. 2005;171(10):1150-7.
19. Hallstrand TS, Boitano LJ, Johnson WC, Spada CA, Hayes JG, Raghu G. The timed walk test as a measure of severity and survival in idiopathic pulmonary fibrosis. Eur Respir J. 2005;25(1):96-103.
20. Fujimoto Y, Oki Y, Kaneko M, et al. Usefulness of the desaturation-distance ratio from the six-minute walk test for patients with COPD. Int J Chron Obstruct Pulmon Dis. 2017;12:2669-75.
21. Queiroz DS, da Silva C, Amaral AF, et al. Desaturation-distance ratio during submaximal and maximal exercise tests and its association with lung function parameters in patients with lymphangioleiomyomatosis. Front Med (Lausanne). 2021;8:659416.
22. Mak VH, Bugler JR, Roberts CM, Spiro SG. Effect of arterial oxygen desaturation on six minute walk distance, perceived effort, and perceived breathlessness in patients with airflow limitation. Thorax. 1993;48(1):33-8.