Acute effects of hyperoxia on resting pattern of ventilation and dyspnoea in COPD (original) (raw)
Related papers
Thorax, 2006
Background: Studies examining the physiological interactions of oxygen (O 2) and bronchodilators (BD) during exercise in chronic obstructive pulmonary disease (COPD) should provide new insights into mechanisms of exercise intolerance. We examined the effects of O 2 and BD, alone and in combination, on dyspnoea, ventilation (V E), breathing pattern, operating lung volumes, and exercise endurance. Methods: In a randomised, double blind, crossover study, 16 patients with COPD (mean (SE) FEV 1 43(3)% predicted) performed pulmonary function tests and an incremental exercise test, then completed four visits in which they received either nebulised BD (ipratropium 0.5 mg + salbutamol 2.5 mg) or placebo (PL) with either 50% O 2 or room air (RA). After 90-105 minutes the patients performed pulmonary function tests, then breathed RA or O 2 during symptom limited constant load exercise at 75% peak work rate. Results: With BD the mean (SE) increase in inspiratory capacity (IC) was 0.3 (0.1) l (p,0.05) at rest and during exercise, permitting greater tidal volume (VT) expansion during exercise and a greater peak V E. With O 2 , V E decreased during exercise as a result of decreased breathing frequency (F), with no significant change in IC. During exercise with BD+O 2 , IC and VT increased, F decreased, and V E did not change. Dyspnoea decreased with all interventions at a standardised time during exercise compared with PL+RA (p,0.05). Endurance time was significantly (p,0.05) greater with BD+O 2 (10.4 (1.6) min) than with O 2 (8.5 (1.4) min), BD (7.1 (1.3) min) and PL+RA (5.4 (0.9) min). Conclusion: By combining the benefits of BD (reduced hyperinflation) and O 2 (reduced ventilatory drive), additive effects on exercise endurance were observed in patients with normoxic COPD.
American Journal of Respiratory and Critical Care Medicine, 2000
The detailed mechanisms of oxygen-induced hypercapnia were examined in 22 patients during an acute exacerbation of chronic obstructive pulmonary disease. Ventilation, cardiac output, and the distribution of ventilation-perfusion () ratios were measured using the multiple inert gas elimination technique breathing air and then 100% oxygen through a nose mask. Twelve patients were classified as retainers (R) when Pa CO 2 rose by more than 3 mm Hg (8.3 Ϯ 5.6; mean Ϯ SD) after breathing 100% oxygen for at least 20 min. The other 10 patients showed a change in Pa CO 2 of Ϫ 1.3 Ϯ 2.2 mm Hg breathing oxygen and were classified as nonretainers (NR). Ventilation fell significantly from 9.0 Ϯ 1.5 to 7.2 Ϯ 1.2 L/min in the R group breathing oxygen (p ϭ 0.007), whereas there was no change in ventilation in the NR group (9.8 Ϯ 1.8 to 9.9 Ϯ 1.8 L/min). The dispersion of ratios as measured by log SD of blood flow (log SD) increased significantly in both R (0.96 Ϯ 0.17 to 1.13 Ϯ 0.17) and NR (0.77 Ϯ 0.20 to 1.04 Ϯ 0.23, p Ͻ 0.05) groups breathing oxygen, whereas log SD of ventilation (log SD) increased only in the R group (0.97 Ϯ 0.24 to 1.20 Ϯ 0.46, p Ͻ 0.05). This study suggests that an overall reduction in ventilation characterizes oxygen-induced hypercapnia, as an increased dispersion of blood flow from release of hypoxic vasoconstriction occurred to a significant and similar degree in both groups. The significant increase in wasted ventilation (alveolar dead space) in the R group only may be secondary to the higher carbon dioxide tension, perhaps related to bronchodilatation.
International journal of chronic obstructive pulmonary disease, 2015
The aim of this study was to provide information on heart rate and blood pressure responses during a 3-week intermittent hypoxia breathing program in COPD patients. Sixteen participants with COPD symptoms were randomly assigned to a hypoxia or control group and completed a 3-week intermittent hypoxia breathing program (five sessions per week, each consisting of three to five breathing cycles, each cycle lasting 3-5 minutes with 3-minute breaks between cycles). During the breathing cycles, the hypoxia group received hypoxic air (inspired fraction of oxygen 15%-12%), whereas the control group received normal air (sham hypoxia). During the breaks, all participants breathed normoxic room air. Arterial oxygen saturation, systolic and diastolic blood pressure, and heart rate were measured during the normoxic and hypoxic/sham hypoxic periods. For each breathing cycle, changes from normoxia to hypoxia/sham hypoxia were calculated, and changes were averaged for each of the 15 sessions and fo...
Chest, 2001
Study objectives: To assess oxygen desaturation during activities and to evaluate the short-term effects of supplemental O 2 use in patients with severe COPD who do not qualify for long-term O 2 therapy. Design: A double-blind, randomized, placebo-controlled trial. Setting: Outpatients from the pulmonary diseases division of a tertiary-care university hospital. Patients: Twenty patients with stable COPD with FEV 1 /FVC ratios of < 50%, FEV 1 levels < 55% of the predicted normal value, and PaO 2 levels of > 60 mm Hg when resting. Interventions: Patients were initially evaluated with pulmonary function tests, blood gas analysis, and Doppler echocardiography, and they underwent the following three 6-min walking tests (WTs) in a random sequence: basal WT (BWT); WT while breathing compressed air (CAWT); and WT while breathing O 2 (O 2 WT). Measurements and results: The distance walked was recorded in meters. Dyspnea was measured by Borg scale measurement before and after the tests, and arterial oxygen saturation measured by pulse oximetry (SpO 2) was continuously monitored. Results were analyzed by grouping patients in the following manner: desaturators (DSs) (ie, patients with a drop in SpO 2 of at least 5% and < 90% during the WT) vs nondesaturators (NDSs); and O 2 responders (ie, patients with an increase of at least 10% in the distance walked and/or a decrease of at least 3 points in Borg index score) vs nonresponders. During the BWT, 11 of 20 patients (55%) were defined as desaturators. During the O 2 WT, the SpO 2 remained at > 90% in every patient. The distance walked increased by 22% (p < 0.02), and dyspnea decreased 36% (p < 0.01) in DS patients. In NDS patients, O 2 administration reduced dyspnea by 47% (p < 0.001), but the distance walked did not improve. Responses were markedly different from one patient to another. No significant differences were noticed between the results of the BWT and CAWT in any of the groups. Thirteen O 2 responders did not differ from 7 nonresponders either in basal data or in desaturation measure during the BWT, except that all walking responders (five patients) were above the median of basal left ventricle performance. Conclusions: Most of the studied COPD patients desaturated during the BWT. O 2 administration avoided desaturation and could increase the distance walked and reduce dyspnea, but these effects were not related to walking desaturation in individual cases. Improvements were not a placebo effect. The therapeutic role of O 2 during activities in some patients with severe COPD needs to be individually assessed.
The Use of Pulse Oximetry to Determine Hypoxemia in Acute Exacerbations of COPD
COPD: Journal of Chronic Obstructive Pulmonary Disease, 2015
Background: There is little evidence that the guideline-recommended oxygen saturation of 92% is the best cut-off point for detecting hypoxemia in COPD exacerbations. Objective: To detect and validate pulse oximetry oxygen saturation cut-off values likely to detect hypoxemia in patients with aeCOPD, to explore the correlation between oxygen saturation measured by pulse oximetry and hypoxemia or hypercapnic respiratory failure. Methodology: Cross-sectional study nested in the IRYSS-COPD study with 2,181 episodes of aeCOPD recruited between 2008 and 2010 in 16 hospitals belonging to the Spanish Public Health System. Data collected include determination of oxygen saturation by pulse oximetry upon arrival in the emergency department (ED), fi rst arterial blood gasometry values, sociodemographic information, background medical history and clinical variables upon ED arrival. Logistic regression models were performed using as the dependent variables hypoxemia (PaO 2 < 60 mmHg) and hypercapnic respiratory failure (PaO 2 < 60 mmHg and PaCO 2 > 45). Optimal cut-off points were calculated. Results: The correlation coeffi cient between oxygen saturation and pO 2 measured by arterial blood gasometry was 0.89. The area under the curve (AUC) for the hypoxemia model was 0.97 (0.96-0.98) and the optimal cut-off point for hypoxemia was an oxygen saturation of 90%. The AUC for hypercapnic respiratory failure was 0.90 (0.87-0.92) and the optimal cut-off point was an oxygen saturation of 88%. Conclusions: Our results support current recommendations for ordering blood gasometry based on pulse oximetry oxygen saturation cut-offs for hypoxemia. We also provide easy to use formulae to calculate pO 2 from oxygen saturation measured by pulse oximetry. COPD, 00:1-7, 2015
European Respiratory Journal, 2001
Dose-response effect of oxygen on hyperinflation and exercise endurance in nonhypoxaemic COPD patients. A. Somfay, J. Porszasz, S.M. Lee, R. Casaburi. #ERS Journals Ltd 2001. ABSTRACT: Dynamic hyperinflation contributes to exertional breathlessness and reduced exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. This study examined whether oxygen supplementation results in a dose-dependent decrease in hyperinflation associated with functional and symptomatic improvement.
Breathing pattern and carbon dioxide retention in severe chronic obstructive pulmonary disease
Thorax, 1996
Background -The factors leading to chronic hypercapnia and rapid shallow breathing in patients with severe chronic obstructive pulmonary disease (COPD) are not completely understood. In this study the interrelations between chronic carbon dioxide retention, breathing pattern, dyspnoea, and the pressure required for breathing relative to inspiratory muscle strength in stable COPD patients with severe airflow obstruction were studied.
Respiratory Research, 2011
Background: Dyspnea while performing the activities of daily living has been suggested to be a better measurement than peak dyspnea during exercise. Furthermore, the inspiratory capacity (IC) has been shown to be more closely related to exercise tolerance and dyspnea than the FEV 1 , because dynamic hyperinflation is the main cause of shortness of breath in patients with COPD. However, breathlessness during exercise is measured in most studies to evaluate this relationship. Purpose: To evaluate the correlation between breathlessness during daily activities and airflow limitation or static hyperinflation in COPD. Methods: We examined 167 consecutive outpatients with stable COPD. The Baseline Dyspnea Index (BDI) was used to evaluate dyspnea with activities of daily living. The relationship between the BDI score and the clinical measurements of pulmonary function was then investigated. Results: The Spearman rank correlation coefficients (Rs) between the BDI score and the FEV 1 (L), FEV 1 (%pred) and FEV 1 /FVC were 0.60, 0.56 and 0.56, respectively. On the other hand, the BDI score also correlated with the IC, IC/ predicted total lung capacity (TLC) and IC/TLC (Rs = 0.45, 0.46 and 0.47, respectively). Although all of the relationships studied were strongly correlated, the correlation coefficients were better between dyspnea and airflow limitation than between dyspnea and static hyperinflation. In stepwise multiple regression analyses, the BDI score was most significantly explained by the FEV 1 (R 2 = 26.2%) and the diffusion capacity for carbon monoxide (R 2 = 14.4%) (Cumulative R 2 = 40.6%). Static hyperinflation was not a significant factor for clinical dyspnea on the stepwise multiple regression analysis. Conclusion: Both static hyperinflation and airflow limitation contributed greatly to dyspnea in COPD patients.
Chest, 2011
Background: There is considerable evidence that oxidative stress is increased in patients with COPD, although little information is available about its relationship with the structural and functional alterations produced by COPD. In this study, we evaluated the relationship between 8-isoprostane in exhaled breath condensate (EBC) of stable patients with COPD and the main parameters of the disease (such as dyspnea), stages of severity, lung parenchyma densities, lung function impairment, and exercise tolerance in order to identify the predictors of airway oxidative stress. Methods: In a cross-sectional study, we included 76 men with moderate to very severe COPD. 8-Isoprostane levels in EBC were measured by enzyme immunoassay. Regional lung densities were measured by lung densitometry with high-resolution CT scanning. Arterial blood gas levels, lung volumes, and diffusing capacity were determined. Patients performed a 6-min walk test and an incremental exercise test with measurement of breathing pattern and operating lung volumes. Results: Signifi cant severity-related differences in 8-isoprostane were identifi ed according to the BMI, obstruction, dyspnea, and exercise (BODE) index. 8-Isoprostane levels were related to smoking intensity, lung densities in expiration, static lung volumes, Pa O 2 , diffusion capacity, distance walked in 6 min, peak oxygen uptake, and anaerobic threshold. Concentration of 8-isoprostane was higher in the 60 patients (79%) who developed dynamic hyperinfl ation than in the remaining 16 (21%) who did not. In a multivariate linear regression analysis using 8-isoprostane as a dependent variable, end-expiratory lung volume change and Pa O 2 were retained in the prediction model (r 2 5 0.734, P , .001). Conclusions: In stable patients with COPD, oxygen level and dynamic hyperinfl ation are related to airway oxidative stress.