The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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Randomized Controlled Trial Clinical Trial
Dose-response effect of oxygen on hyperinflation and exercise endurance in nonhypoxaemic COPD patients.
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. Ten severe COPD patients without clinically significant oxygen (O2) desaturation during exercise, and seven healthy subjects, performed five exercise tests at 75% of maximally tolerated work rate. ⋯ In healthy subjects, smaller V'E and fR decreases were observed at FI,O2=0.5, accompanied by more modestly increased endurance. Oxygen supplementation during exercise induced dose-dependent improvement in endurance and symptom perception in nonhypoxaemic chronic obstructive pulmonary disease patients, which may be partly related to decreased hyperinflation and slower breathing pattern. This effect is maximized at an inspired oxygen fraction of 0.5.
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Randomized Controlled Trial Clinical Trial
The effects of pressurization rate on breathing pattern, work of breathing, gas exchange and patient comfort in pressure support ventilation.
The aim of this study was to investigate the effects of different pressurization rates during pressure support ventilation on breathing pattern, work of breathing, gas exchange and patient comfort in patients with acute lung injury. The pressurization rate modifies the initial pressure ramp by changing the initial peak flow rate: the increase in pressurization rate is associated with a decrease in the time to reach the level of pressure support ventilation by increasing the peak flow rate. Ten intubated patients (age 64+/-17 yrs, body mass index 24+/-17 Kg x m(-2), arterial oxygen tension/inspired oxygen fraction 214+/-59) were studied in random order varying the pressurization rate at 5 and 15 cmH2O of pressure support ventilation. ⋯ The lowest and the highest pressurization rates caused the worst patient comfort (p<0.05). The gas exchange was stable throughout the study. The presented results suggest: 1) the lowest pressurization rate caused the lowest tidal volume, highest respiratory rate and highest work of breathing; 2) at the other pressurization rates no differences in breathing pattern and work of breathing were observed; and 3) the patient's comfort was worse at the lowest and highest pressurization rates.
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Randomized Controlled Trial Clinical Trial
Prostaglandins mediate bradykinin-induced reduction of exhaled nitric oxide in asthma.
Bradykinin (BK) is a mediator of inflammation in asthma with potent bronchoconstrictor actions. Endogenous release of nitric oxide may inhibit BK-induced bronchoconstriction. This study investigated whether bradykinin inhalation could modulate exhaled NO levels in normal and asthmatic subjects, and whether the bradykinin-induced effects were mediated through the production of cyclo-oxygenase products in patients with asthma, by studying the effect of the cyclo-oxygenase inhibitor, L-acetylsalicylic acid (L-ASA). ⋯ In asthmatic subjects, pretreatment with inhaled L-ASA (90 x mg x mL(-1), 4 mL) did not alter exhaled NO levels, but prevented a BK-induced fall in exhaled NO concentration, as indicated by a significant increase in exhaled NO levels at the provocative concentration of BK causing a 20% fall in FEV1, (5.7 +/- 0.94 ppb after placebo and 12.0 +/- 1.8 ppb after L-ASA; p<0.05). L-ASA significantly reduced bronchial responsiveness to BK 3.9-fold (p<0.01). Inhaled bradykinin induced bronchoconstriction and a reduction in exhaled nitric oxide levels in asthmatic subjects, an effect that is partly mediated by cyclo-oxygenase products.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Snoring and excessive daytime somnolence among Polish middle-aged adults.
There is considerable interest in the association of snoring and health consequences that have been linked to more severe sleep-disordered breathing, including obstructive sleep apnoea syndrome. The goal of this investigation was to assess the independent association of heavy, habitual snoring and daytime sleepiness. For this, a cross-sectional, population based study of snoring, sleepiness and other factors was conducted using the Warsaw sample of the Multinational Monitoring of Trends and Determinants of Cardiovascular Diseases (MONICA) study, a population-based multicentre study of cardiovascular disease. ⋯ Habitual snorers were 5.8 and 3.1 times more likely to report EDS in active and passive situations, respectively, compared to nonsnorers (all p<0.01). It is concluded that habitual snorers, most of whom are probably unlikely to have frank sleep apnoea syndrome, are at substantial risk for daytime sleepiness. These findings add support to the hypothesis that simple snoring is not benign and underscores the need for further research on health outcomes associated with this prevalent condition.
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Randomized Controlled Trial Comparative Study Clinical Trial
Oxygen therapy during exacerbations of chronic obstructive pulmonary disease.
Venturi masks (VMs) and nasal prongs (NPs) are widely used to treat acute respiratory failure (ARF) in chronic obstructive pulmonary disease (COPD). In this study, these devices were compared in terms of their potentiality to worsen respiratory acidosis and their capacity to maintain adequate (> 90%) arterial oxygenation (Sa,O2) through time (approximately 24 h). In a randomized cross-over study, 18 consecutive COPD patients who required hospitalization because of ARF were studied. ⋯ However, despite this adequate initial oxygenation, Sa,O2 was < 90% for 3.7+/-3.8 h using the VM and for 5.4+/-5.9 h using NPs (p<0.05). Regression analysis showed that the degree of arterial hypoxaemia (p<0.05) and arterial hypercapnia (p<0.05) present before starting O2 therapy and, particularly, the initial Sa,O2 achieved after initiation of O2 therapy (p<0.0001) enabled the time (in h) that patients would be poorly oxygenated (Sa,O2 < 90%) on follow-up to be predicted. These findings suggest that, in order to maintain an adequate (> 90%) level of arterial oxygenation in patients with chronic obstructive pulmonary disease and moderate acute respiratory failure: 1) the initial arterial oxygen saturation on oxygen should be maximized whenever possible by increasing the inspiratory oxygen fraction; 2) this strategy seems feasible because neither the VM nor NPs worsen respiratory acidosis significantly; and 3) the Venturi mask (better than nasal prongs) should be recommended.