Respiratory medicine
-
Respiratory medicine · Mar 1998
Plasma levels of von Willebrand factor antigen in acute bronchitis and in a normal population.
von Willebrand factor (vWF) is a large glycoprotein secreted predominantly by endothelial cells in both the systemic and pulmonary circulations and has a central role in the formation of the platelet plug. It has been put forward as a possible marker of endothelial cell injury, but is not ideal in that it is not specific for either the pulmonary or systemic circulation and may be released as part of the acute phase response from otherwise healthy endothelial cells. We undertook two studies (i) to assess within-subject to assess within-subject variation in plasma von Willebrand factor antigen (vWF:Ag) levels over time and to assess between-subject variation in a healthy patient population, and (ii) as part of a descriptive study of acute bronchitis, to assess whether plasma vWF:Ag levels altered in such a common and minor insult. ⋯ We conclude that there is relatively little variation in an individual's plasma vWF:Ag level but that levels increase significantly with age. The observed elevation occurring with acute bronchitis is a true phenomenon; the absence of an associated acute phase response suggests that endothelial cell injury is the mechanism for the rise. These observations are important in the context of vWF as a marker of endothelial cell damage, as a common and supposedly minor insult such as acute bronchitis may markedly raise plasma levels.
-
Respiratory medicine · Feb 1998
Clinical Trial Controlled Clinical TrialAn evaluation of the use of concentrators for domiciliary oxygen supply for less than 8 h day-1.
Since their introduction in 1985, oxygen concentrators have only been recommended when domiciliary oxygen is used for over 8 h day-1. Subsequent changes in the prices of oxygen merit a reappraisal of the prescribing of concentrators and cylinders when oxygen is used for less than 8 h day-1. Twenty-six patients in two health districts who used oxygen for less than 8 h day-1 completed a crossover study in which each group received oxygen from each source for consecutive 3-month periods. ⋯ They used more oxygen in more rooms of the home during treatment with concentrators, and there were improvements in the quality-of-life measurements. The costing information showed that, both in theory and in practice, oxygen concentrators are cheaper than cylinders when oxygen is used for more than about 1.4 h day-1. These results suggest that the provisions for the supply of domiciliary oxygen should be reviewed and that concentrators should be recommended for patients who use more than around 1.4 h day-1.
-
Respiratory medicine · Feb 1998
Randomized Controlled Trial Comparative Study Clinical TrialBeta 2-agonists administered by a dry powder inhaler can be used in acute asthma.
Patients with acute asthma attending the emergency room were included in a double-blind, double-dummy and parallel group study to investigate whether a dry powder inhaler (Turbuhaler) can be used in acute asthma. If so, the aim was to establish the potency relationship between a beta 2-agonist (salbutamol) administered by the dry powder inhaler and the pressurized metered-dose inhaler (pMDI). Eighty-six patients with a mean age of 38 years and forced expiratory volume in 1 s (FEV1) of 37% of predicted normal value were randomized at Siriraj Hospital in Bangkok to either Turbuhaler (50 micrograms dose -1) or pMDI (100 micrograms dose -1) with spacer (Volumatic). ⋯ A larger decrease in S-potassium was noticed after 75 min in the pMDI group (0.38 mmol l -1) compared with the Turbuhaler group (0.23 mmol l -1) (P = 0.02). In conclusion, the use of a dry powder inhaler, Turbuhaler, was investigated in the emergency room treatment of acute asthma, and was as effective as a pMDI with spacer. Half the dose of salbutamol administered via Turbuhaler was as effective as the full dose given via a pMDI with spacer.
-
Respiratory medicine · Feb 1998
Haemodynamic response during initiation of non-invasive positive pressure ventilation in COPD patients with acute ventilatory failure.
The aim of this study was to check non-invasively the acute haemodynamic effects of non-invasive positive pressure ventilation (NPPV) initiation in patients with chronic obstructive pulmonary disease (COPD) and acute ventilatory failure (AVF). Nineteen consecutive COPD patients with AVF were evaluated clinically and echocardiographically during spontaneous breathing with O2 supplementation and during NPPV plus O2. NPPV was administered with a scheduled inspiratory pressure of 15 cmH2O and an expiratory pressure of 4 cmH2O, via facial mask. ⋯ It was concluded that the initiation of NPPV by facial mask does not alter haemodynamics acutely in most COPD patients with AVF, but individual patients may experience reduction in CO in spite of adequate oxygen saturation levels. This suggests that caution should be used when applying pre-determined and fixed pressures during NPPV. Monitoring haemodynamics by Doppler echocardiography may be useful for early detection of haemodynamic alterations due to NPPV application in patients with AVF.
-
Respiratory medicine · Feb 1998
Epithelial cell damage is induced by neutrophil-derived, not pseudomonas-derived, proteases in cystic fibrosis sputum.
Airway histopathological changes in cystic fibrosis (CF) include damage to the epithelial tissue and accumulation of polymorphonuclear leukocytes (PMN). Airways of CF patients are usually colonized with bacteria such as mucoid Pseudomonas aeruginosa (PA). Bacteria and PMN can both release proteolytic enzymes capable of causing tissue damage. ⋯ PA also induced high levels of EC detachment but Staphylococcus aureus and Haemophilus influenzae, two other bacteria commonly isolated from CF sputa, induced no detachment. Antiprotease inhibition profiles were similar for PMN and sputa-induced EC detachment, but different for PA-induced detachment. These results suggest that PMN proteolytic enzymes, probably elastase and cathepsin G, are more likely to be the inducers of tissue damage in the airways of CF patients than PA proteolytic enzymes.