The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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Randomized Controlled Trial Clinical Trial
The effect of dipyridamole and theophylline on hypercapnic ventilatory responses: the role of adenosine.
The purine nucleoside, adenosine, has been implicated as a neuromodulator in central respiratory depression during prolonged exposure to hypoxia. It may also be a mediator of hypoxic hyperpnoea, acting on the carotid bodies. As there may be adenosine-sensitive mechanisms of hypoxic respiratory control, we sought to determine whether adenosine might be involved as a respiratory modulator in another central but non-oxygen-related control mechanism, the ventilatory response to hyperoxic hypercapnia. ⋯ However, neither the slope nor the PET, CO2 intercept of the relationship between ventilation or respiratory drive and PET, CO2 were altered by the study drugs under hyperoxic conditions. We conclude that endogenous adenosine-related mechanisms are unlikely to be involved in determining either the sensitivity or the threshold of the ventilatory response to carbon dioxide under hyperoxic conditions. However, in normoxia, a centrally-acting, tonic, adenosine-mediated, respiratory modulation is not ruled out.
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Randomized Controlled Trial Comparative Study Clinical Trial
The effect of nitrous oxide on the measurement of single-breath transfer factor.
One hour after a bone marrow biopsy and inhalation of Entonox gas (50% nitrous oxide (N2O) and 50% oxygen), a patient had a markedly reduced transfer factor of the lung for carbon monoxide (TL,CO). Three hours after Entonox, the patient had a normal TL,CO. Since carbon monoxide (CO) and N2O have similar spectral wavelengths, it was proposed that residual N2O in the lungs was interfering with the infra-red analysers used to detect CO concentrations. ⋯ In a group of healthy nonsmoking subjects, N2O markedly affected the measurement of the transfer factor of the lungs for carbon monoxide using infra-red analysers. The time course over which the measurement was reduced was at least 2 h for a 10 min inhalation period. The effect was entirely due to a measurement error associated with infra-red technology.
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Randomized Controlled Trial Clinical Trial
Influence of moderate alcohol consumption on obstructive sleep apnoea with and without AutoSet nasal CPAP therapy.
Snoring worsens with high alcohol consumption. It is unclear whether moderate alcohol intake worsens sleep and breathing in subjects with obstructive sleep apnoea syndrome (OSAS), and whether alcohol increases the pressure requirement for nasal continuous positive airway pressure (CPAP). Fourteen adult males with untreated OSAS but without heart or lung disease were studied (age 53+/-9 yrs, body mass index (BMI) 33+/-5 kg x m(-2) (mean+/-SD). ⋯ There was no change in the pressure requirement for CPAP (full night: control 11.9+/-0.9 vs alcohol 12.5+/-0.9 cm H2O; first 2 h: 10.9+/-0.6 vs 11.1+/-0.8 cm H2O). Moderate alcohol intake (in the form of vodka) has little effect on breathing or saturation during sleep in subjects with mild-to-severe obstructive sleep apnoea, and no effect on the pressure required for continuous positive airway pressure in order to prevent apnoea, snoring, and flow limitation. These results cannot be extrapolated to other doses or forms of alcohol, or to subjects with concurrent heart or lung disease.
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Randomized Controlled Trial Multicenter Study Clinical Trial
Comparison of inhaled salmeterol and individually dose-titrated slow-release theophylline in patients with reversible airway obstruction. European Study Group.
The aim of this study was to compare the clinical efficacy of salmeterol versus theophylline in the treatment of moderate-to-severe asthma. One hundred and eighty nine asthmatic patients (forced expiratory volume in one second (FEV1) or peak expiratory flow (PEF) >50% of predicted) were randomized to receive either salmeterol dry powder, 50 microg b.i.d. via a Diskhaler (n=92) or dose-titrated slow-release theophylline capsules ("Theo-Dur") b.i.d. (n=97), in a double-blind, double-dummy, parallel group study for 4 weeks. Patients had previously been titrated with theophylline to a serum theophylline level of 10-20 microg x mL-1. ⋯ No significant difference between the two treatments was observed for PEF, symptoms or additional salbutamol medication during the day. The incidence of gastrointestinal symptoms (gastric irritation, nausea and vomiting) was greater among patients receiving theophylline (11%) than with salmeterol (3%). These findings suggest that inhaled salmeterol is more effective in relieving symptoms of asthma, and better tolerated than theophylline in patients with moderate-to-severe asthma.
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Randomized Controlled Trial Clinical Trial
Noninvasive ventilatory support does not facilitate recovery from acute respiratory failure in chronic obstructive pulmonary disease.
This investigation evaluates, in a prospective, randomized and controlled manner, whether noninvasive ventilatory support (NIVS) with bilevel positive airway pressure (BiPAP) facilitates recovery from acute respiratory failure (ARF) in patients with chronic obstructive pulmonary disease (COPD). Twenty four patients (mean age (+/-SEM) 68 +/- 2 yrs) with COPD (forced expiratory volume in one second (FEV1) at discharge 33 +/- 2% predicted), who attended the emergency room because of ARF (pH 7.33 +/- 0.01; arterial oxygen tension (Pa,O2) 6.0 +/- 0.2 kPa; arterial carbon dioxide tension (Pa,CO2) 7.9 +/- 0.3 kPa), were initially randomized. Four out of the 14 patients (29%) allocated to received NIVS did not tolerate it. ⋯ We conclude that noninvasive ventilatory support with bilevel positive airway pressure does not facilitate recovery from acute respiratory failure in patients with chronic obstructive pulmonary disease. Furthermore, a substantial proportion of patients (29%) do not tolerate noninvasive ventilatory support under these circumstances. From these results, we cannot recommend the use of noninvasive ventilatory support with bilevel positive airway pressure in the routine management of chronic obstructive pulmonary disease patients recovering from acute respiratory failure.