The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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Comparative Study
A five year follow-up of lung function among chemical workers using flow-volume and impedance measurements.
Impedance of the respiratory system, measured using the forced oscillation technique (FOT), has repeatedly been proposed as a tool for occupational health screening. The aim of this study was to compare the outcome of impedance measurements and flow-volume curves, and to study relationships between lung function decline and specific exposures and smoking. Both measurements were applied in 136 chemical workers from seven main production/personnel groups during a 5 year follow-up (1990-1995). ⋯ Smoking had a significant effect on most flow-volume parameters but only for frequency dependence among the impedance outcomes. It is concluded that alterations in impedance parameters do reflect changes in flow-volume curves induced by age. smoking and occupational exposure. Therefore, these data are a valuable extension to current cross-sectional data.
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Comparative Study
Glucocorticoid resistant asthma: T-lymphocyte steroid metabolism and sensitivity to glucocorticoids and immunosuppressive agents.
We have previously shown that T-lymphocytes from clinically glucocorticoid (GC) resistant asthmatics are more refractory to dexamethasone suppression in vitro than those of GC sensitive asthmatics. We wished to extend these observations to compare three GCs used topically for asthma therapy (budesonide, beclomethasone dipropionate and fluticasone 17 alpha-propionate) and three immunosuppressive drugs (cyclosporin A, FK506 (tacrolimus) and mycophenolate mofetil) with dexamethasone for their antiproliferative effects on T-lymphocytes from GC sensitive and resistant asthmatics, and also to compare the rates of steroid metabolism by T-lymphocytes from these patients. Antiproliferative activity of the drugs was measured on peripheral blood T-lymphocytes activated with phytohaemagglutinin (PHA) and anti-CD3 antibody in vitro. ⋯ The rates of total metabolism and 20 alpha-hydroxylation of steroid by homogenates of T-lymphocytes from GC sensitive and resistant asthmatics were equivalent. Thus, relative GC resistance in T-lymphocytes from GC resistant as compared with sensitive asthmatics is: 1) manifest with GC molecules of variable molecular structure; 2) not accompanied by elevated intracellular metabolism of steroids; and 3) overcome by immunosuppressive drugs which inhibit T-lymphocytes by non-GC-mediated mechanisms. We conclude that current anti-asthma glucocorticoids at therapeutic concentrations are unlikely to be of benefit for the therapy of glucocorticoid resistant asthma, and that other immunosuppressive drugs may have potential as therapeutic agents in these patients.
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Case Reports
Fatal ball-valve airway obstruction by an extensive blood clot during mechanical ventilation.
A ball-valve airway obstruction by a blood clot cast of almost the whole bronchial tree occurred in a small-cell lung cancer patient, who had been on mechanical ventilation for 9 days. Chest radiographs revealed overinflated lungs. ⋯ A postmortem extraction of the clot was performed with a rigid tube. This case is rare because of absence of severe haemoptysis and lung volume reduction.
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In a prospective study, we investigated the effect of single-lung transplantation (SLT) on pulmonary haemodynamics and the relationship between pulmonary hypertension (PH) and the fraction of perfusion to the transplant in patients with end-stage pulmonary parenchymal disease. Twenty four SLT recipients were included in the study, 19 with chronic obstructive pulmonary disease (COPD), two with sarcoidosis and three with fibrosing alveolitis. Spirometry, determination of arterial blood gas values, perfusion scintigraphy and right heart catheterization were performed before and 1, 6, 12 and 24 months after transplantation. ⋯ In conclusion, patients with pulmonary hypertension obtain pulmonary haemodynamics within the normal range after single-lung transplantation. Presence or absence of pulmonary hypertension before transplantation does not influence perfusion to the graft. These findings persist up to 2 yrs, despite the coexistence of an "end-stage" native lung and a lung transplant.
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Weaning from mechanical ventilation is a period of transition from total ventilatory support to spontaneous breathing. It represents a relevant clinical problem because as many as 25% of intubated and mechanically-ventilated critically ill patients will need a progressive withdrawal from artificial ventilatory support. From a clinical standpoint, it is very important to recognize as soon as possible when a patient is ready to be weaned. ⋯ Different ventilatory techniques can be used to wean these patients from mechanical ventilation. Up to now, the most efficient techniques seem to be pressure support ventilation and once daily trials of T-piece interspersed with conventional volume assist-control ventilation. Finally, knowledge-based system applied to modern microprocessor mechanical ventilators can help in the process of weaning by automatically reducing the ventilatory assistance and indicating the optimal time to perform extubation.