Abstract | RATIONALE:
Hyperoxia and normoxic helium independently reduce dynamic hyperinflation and improve the exercise tolerance of patients with chronic obstructive pulmonary disease ( COPD). Combining these gases could have an additive effect on dynamic hyperinflation and a greater impact on respiratory mechanics and exercise tolerance. OBJECTIVE: To investigate whether helium- hyperoxia improves the exercise tolerance and respiratory mechanics of patients with COPD. METHODS: Ten males with COPD (FEV(1) = 47 +/- 17% pred [mean +/- SD]) performed randomized constant-load cycling at 60% of maximal work rate breathing air, hyperoxia (40% O(2), 60% N(2)), normoxic helium (21% O(2), 79% He), or helium- hyperoxia (40% O(2), 60% He). MEASUREMENTS: Exercise time, inspiratory capacity (IC), work of breathing, and exertional symptoms were measured with each gas. RESULTS: Compared with air (9.4 +/- 5.2 min), exercise time was increased with hyperoxia (17.8 +/- 5.8 min) and normoxic helium (16.7 +/- 9.1 min) but the improvement with helium- hyperoxia (26.3 +/- 10.6 min) was greater than both these gases (p = 0.019 and p = 0.007, respectively). At an isotime during exercise, all three gases reduced dyspnea and both helium mixtures increased IC and tidal volume. Only helium- hyperoxia significantly reduced the resistive work of breathing (15.8 +/- 4.2 vs. 10.1 +/- 4.1 L . cm H(2)O(-1)) and the work to overcome intrinsic positive end-expiratory pressure (7.7 +/- 1.9 vs. 3.6 +/- 2.1 L . cm H(2)O(-1)). At symptom limitation, tidal volume remained augmented with both helium mixtures, but IC and the work of breathing were unchanged compared with air. CONCLUSION: Combining helium and hyperoxia delays dynamic hyperinflation and improves respiratory mechanics, which translates into added improvements in exercise tolerance for patients with COPD.
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Authors | Neil D Eves, Stewart R Petersen, Mark J Haykowsky, Eric Y Wong, Richard L Jones |
Journal | American journal of respiratory and critical care medicine
(Am J Respir Crit Care Med)
Vol. 174
Issue 7
Pg. 763-71
(Oct 01 2006)
ISSN: 1073-449X [Print] United States |
PMID | 16840742
(Publication Type: Journal Article, Randomized Controlled Trial)
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Chemical References |
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Topics |
- Aged
- Analysis of Variance
- Cross-Over Studies
- Exercise
(physiology)
- Exercise Tolerance
(drug effects)
- Helium
(administration & dosage)
- Humans
- Lung Volume Measurements
- Male
- Middle Aged
- Oxygen
(administration & dosage)
- Pulmonary Disease, Chronic Obstructive
(physiopathology)
- Respiratory Mechanics
(drug effects)
- Tidal Volume
(drug effects)
- Work of Breathing
(drug effects)
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