The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
-
The rise in adenosine deaminase (ADA) activity in the pleural fluid of tuberculous pleurisy patients, though used for diagnosis, is of unknown origin. In this work, we determined ADA activity and the activities of 2'-deoxyadenosine deaminase and ADA-2 in 350 patients. We also considered whether the results throw light on the origin of high pleural fluid ADA in tuberculous pleurisy and estimated the diagnostic efficiency of 2'-deoxyadenosine deaminase, ADA-2 and total ADA activities with and without the inclusion of the 2'-deoxyadenosine deaminase/ADA activity ratio in a combined criterion. ⋯ L-1, ADA-2 > 40 U. L-1 and a 2'-deoxyadenosine deaminase/ADA activity ratio < 0.49 was satisfied by all the tuberculous effusions but only eight others (all neoplastic) (sensitivity 100%, specificity 97%, efficiency 98%). We conclude that: 1) high total ADA activity in tuberculous pleural effusions is due mainly to an increase in ADA-2, and, therefore, originated from the only known source monocytes and macrophages; 2) ADA-2 was a more efficient diagnostic marker of tuberculous pleurisy than total ADA activity, although the difference was not statistically significant; and 3) among effusions with high total ADA the 2'-deoxyadenosine deaminase/ADA activity ratio differentiates tuberculous effusions from empyemas and parapneumonic effusions, but fails to discriminate well between tuberculous and neoplastic effusions.
-
We have previously observed large phasic variations of respiratory mechanical impedance in chronic obstructive pulmonary disease (COPD) patients mechanically-ventilated for acute respiratory failure, and postulated that they were due to expiratory flow limitation (EFL). The aim of this study was to test that assumption experimentally and to assess the value of impedance for automatic and noninvasive detection of EFL during mechanical ventilation. The study was performed: 1) in a mechanical analogue, including a flow-limiting element; and 2) in eight anaesthetized and paralysed rabbits, before and during histamine infusion. ⋯ A threshold of -50% provided a sensitivity of 96% and a specificity of 100% for detecting EFL. The observed phasic variations may be explained by airway wall shunt properties. The study suggests that a large decrease of the imaginary part of impedance during the expiratory phase is a sensitive and specific index of expiratory flow limitation during artificial ventilation.
-
When supplementary oxygen is necessary with nasal intermittent positive pressure ventilation (NIPPV), the optimal route by which it should be added to the ventilator circuit is unknown. We investigated the oxygen concentration received when oxygen was supplied at flow rates between 0 and 6 L.min-1 into the proximal ventilator tubing or the nasal mask whilst patients were ventilated with air. Eleven patients with stable chronic hypercapnic respiratory failure were studied. ⋯ However, there was no significant difference between the two routes in the inspired oxygen concentration achieved at all flow rates: 1 L.min-1 supplied approximately 31% oxygen; 2 L.min-1 37%; 3 L.min-1 40%; and 4 L.min-1 44%. Flow rates above 4 L.min-1 had little additional effect. In conclusion, oxygen supplementation during nasal intermittent positive pressure ventilation can be provided into the ventilator tubing or the nasal mask with equal efficiency.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Effect of salmeterol compared with beclomethasone on allergen-induced asthmatic and inflammatory responses.
Salmeterol is a selective long-acting beta 2-agonist bronchodilator considered to have added anti-inflammatory effects, but this is controversial. We investigated the effects of a single dose of salmeterol, 100 micrograms, on the physiological and inflammatory responses to inhaled allergen and compared these with the effects of a single dose of beclomethasone, 500 micrograms, and of placebo. Eight atopic adults with mild stable asthma, treated only with inhaled short-acting beta 2-agonist when needed, attended the laboratory sequentially for screening tests, two single-blind control inhalation tests preceded 30 min by placebo or salmeterol and three allergen inhalation tests preceded by placebo, salmeterol or beclomethasone double-blind in random order. ⋯ In conclusion, whilst salmeterol had no demonstrable anti-inflammatory action in sputum after allergen challenge in asthma, neither did a single dose of the positive anti-inflammatory control, beclomethasone. The latter result excludes a more positive judgement on the possible anti-inflammatory action of salmeterol. However, the results do indicate that potent functional effects of a single dose of salmeterol can mask the airway inflammatory cell influx caused by inhaled allergen.
-
Noninvasive positive pressure ventilation (NPPV) has been proposed in COPD patients with acute on chronic respiratory failure (ACRF) in order to avoid endotracheal intubation and to improve immediate outcome, but long-term outcome of this therapeutic approach is still undefined. We evaluated short- and long-term (1 year) outcome of early administration of NPPV in 24 patients with ACRF due to exacerbated COPD (Group A) in comparison with 24 matched historical-control patients treated conventionally (Group B). Patients of Group A were initially treated with NPPV via nasal mask in the presence of pH < or = 7.32, and/or Pa,O2 < 7.98 kPa, and/or Pa,CO2 > 7.18 kPa, plus signs of respiratory distress. ⋯ The number and length of further hospitalizations for pulmonary exacerbations were significantly higher in Group B compared with Group A. The survival rate at 12 months was significantly lower in Group B than in Group A (50% vs 71%). In conclusion, NPPV administration in patients with ACRF due to exacerbated COPD improves not only immediate but also long-term outcome.