The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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Comparative Study
Nonreversible airflow obstruction in life-long nonsmokers with moderate to severe asthma.
The aim of this longitudinal study was to assess the frequency of nonreversible airflow obstruction (NRAO) among adults with moderate to severe asthma, and to compare the decline of forced expiratory volume in one second (FEV1) in asthmatics with reversible and nonreversible airflow obstruction. Ninety-two (31 males) life-long nonsmokers with asthma participated in a 10-yr follow-up study; mean age 37 yrs (range 18-64) and duration of asthma 16 yrs (range 2-60) at enrolment. Case history, including use of asthma medication, was obtained, and pulmonary function, including diffusion capacity, was measured using standard techniques. ⋯ Increasing degree of bronchodilator reversibility (deltaFEV1% pred) at enrolment (p=0.002) and long-term treatment with oral corticosteroids (p=0.009) were associated with an increased risk for the presence of NRAO at follow-up. The comparison of data for NRAO and RAO patients (at follow-up) revealed no significant differences in mean values for total diffusion capacity (TL,CO), diffusion constant (KCO), or total lung capacity. The findings suggest that a subgroup of asthmatics may experience very steep rates of decline in forced expiratory volume in one second leading to severe nonreversible airflow obstruction, whereas no indication was found that long-standing asthma may lead to the development of emphysema.
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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.
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Manual lung hyperinflation (MH) is one of a number of techniques which are employed by the physiotherapist in the critical care setting. The technique was first described with physiotherapy 30 yrs ago and commonly involves a slow, deep inspiration, inspiratory pause and fast unobstructed expiration. The use of MH varies between and within countries. ⋯ The use of the additional physiotherapy techniques, gravity assisted drainage and chest wall vibrations, may enhance the efficacy of MH in promoting airway clearance, but further research is necessary. Controversy exists regarding the safety and effectiveness of application of manual lung hyperinflation in intubated patients. Clearly, more randomized controlled studies are necessary in order to provide a sound scientific rationale for the application of manual lung hyperinflation in the treatment of critically ill patients.
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Comparative Study
Lung function after bilateral lower lobe lung volume reduction surgery for alpha1-antitrypsin emphysema.
This study explores the mechanism(s) of airflow limitation following lung volume reduction surgery (LVRS) in patients with emphysema due to homozygous alpha1-antitrypsin (AT) deficiency. Bilateral targeted lower lobe stapled LVRS using video thoracoscopy was performed in six patients (five males) aged 61+/-9 yrs (mean+/-SD) with alpha1-AT emphysema. Two patients received only a 6-month follow-up. ⋯ In three patients, static lung elastic recoil at TLC increased from 1.1+/-0.15 to 1.2+/-0.10 kPa. Using flow/pressure curves, the mechanism for expiratory airflow limitation pre-LVRS and the improvement noted post-LVRS could be primarily accounted for by the initial loss and subsequent increase in lung elastic recoil. Bilateral lung volume reduction surgery provides modest physiologic improvement for 2-3 yrs in patients with alpha1-antitrypsin emphysema due to increases in lung elastic recoil.