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Exercise tolerance in children with cystic fibrosis undergoing lung transplantation assessment
P Aurora1, S A Prasad, I M Balfour-Lynn
1Cardiorespiratory and Critical Care Directorate, Great Ormond Street Hospital for Children, London, UK.
Insights
The 3-minute step test shows greater changes in heart rate and oxygen saturation than the 6-minute walk test for children with cystic fibrosis (CF) lung disease. This exercise test may help assess transplant suitability.
Area of Science:
- Pediatric Pulmonology
- Cardiopulmonary Exercise Testing
- Cystic Fibrosis Research
Background:
- Exercise intolerance is a key concern in pediatric cystic fibrosis (CF) patients with moderate to severe lung disease.
- Accurate assessment of exercise tolerance is crucial for managing CF and evaluating lung transplantation candidacy.
- The 6-minute walk test (6MWT) is a standard measure, but newer tests like the 3-minute step test (3MST) are emerging.
Purpose of the Study:
- To compare the efficacy of the 3-minute step test (3MST) against the 6-minute walk test (6MWT) in assessing exercise tolerance.
- To evaluate exercise responses, specifically heart rate (HR) and arterial oxygen saturation (Sa,O2), during both tests in children with CF.
- To determine the utility of the 3MST in the context of lung transplantation assessment for pediatric CF patients.
Main Methods:
- Twenty-eight children (mean age 13.7 years) with moderate to severe CF lung disease underwent both the 6MWT and 3MST.
- Measurements included maximum rise in heart rate (HR) and maximum fall in arterial oxygen saturation (Sa,O2) during each test.
- Bland-Altman analysis was used to assess agreement between the two tests.
Main Results:
- Both tests induced significant increases in HR and decreases in Sa,O2.
- The 3MST resulted in a significantly greater percentage rise in HR (30% vs. 18%) and a greater percentage fall in Sa,O2 (4% vs. 2%) compared to the 6MWT.
- While both tests were well-tolerated, Bland-Altman analysis indicated wide limits of agreement between the tests for HR and Sa,O2 changes.
Conclusions:
- The 3-minute step test elicits a more pronounced physiological response in terms of heart rate and oxygen saturation compared to the 6-minute walk test in children with advanced CF lung disease.
- The 3MST demonstrates potential as a valuable tool for assessing exercise capacity and suitability for lung transplantation in this population.
- Further research may explore the prognostic value of the 3MST in pediatric CF patients awaiting or undergoing transplantation.
Abstract:
The aim of this study was to compare the 6-min walk test against the recently developed 3-min step test, as measures of exercise tolerance in children with moderate to severe cystic fibrosis (CF) lung disease referred for lung transplantation assessment. Twenty-eight children with CF (16 girls, 12 boys), with a mean age of 13.7 yrs (range 7.2-17.8 yrs) and mean forced expiratory volume in one second of 34% predicted (range 17%-67%) were recruited. All subjects performed both the 6-min walk and 3-min step-tests. Outcome measures were maximum rise in heart rate (HR), and maximum fall in arterial oxygen saturation (Sa,O2). There was no significant difference in resting HR or Sa,O2 prior to starting the two tests. Both step and walk tests produced significant rises in median HR (from 114-149 min(-1), p<0.0005, and 119-138 min(-1), p<0.0005, respectively) and significant falls in Sa,O2 (both from 94-92%, p<0.0005). The step test produced a significantly greater percentage rise in HR (30% versus 18%, p<0.0005) and a significantly greater percentage fall in Sa,O2 (4% versus 2%, p=0.002). Bland-Altman analysis gave wide 95% limits of agreement (10.7-29.3% for rise in HR, -2.14.6% for fall in Sa,O2). The step test was well tolerated. The 3-min step test produced a greater fall in Sa,O2 and a greater rise in HR than the 6-min walk test in children with moderate to severe CF lung disease. It may be of value when assessing a child's suitability for lung transplantation.