The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology
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Airflow limitation has two well-defined components, increased resistance, which is found predominantly in the small airways, and loss of elastic recoil. Small airways contribute to the increased resistance to flow by the narrowing of the airway lumen. Morphometric studies have shown that smokers have increased epithelial abnormalities, cellular inflammatory infiltrates in the airway wall, increased muscle and fibrosis, when compared with nonsmokers. ⋯ Furthermore, in PLE, airflow limitation is correlated with loss of recoil but not with abnormalities in the small airways. We believe that the mechanisms involved in the pathogenesis of the two types of emphysema in smokers are different; an airborne mechanism for CLE, possibly related to airway hyperresponsiveness, and a bloodborne mechanism for PLE, which may be related to dysfunction of alpha 1-antiproteases. We conclude that the separation of smokers based on their emphysema type is essential if we are to understand the pathogenesis of chronic obstructive pulmonary disease (COPD) in these subjects.
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Case Reports
Tracheocele: a rare cause of difficult endotracheal intubation and subsequent pneumomediastinum.
A case is described in which accidental perforation of a tracheocele caused by endotracheal intubation resulted in a postoperative pneumomediastinum. The tracheocele, an extremely rare finding in clinical anaesthesia, was confirmed radiologically and for the first time demonstrated by computed tomography.
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We report the case of a 33 year old man with herpetic bronchitis and bilateral pneumonitis. He presented without mucocutaneous lesions, and his cellular and humoral immunity were not compromised. Diagnosis was established on histological and cytological findings and confirmed by serology. Acyclovir treatment led to a favourable outcome.
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In order to quantify the extent of centrilobular (CLE) and panacinar (PLE) emphysema and the degree of the possible overlap between the two forms in smokers, the lungs of 25 smokers undergoing lung resection for peripheral lung tumours were studied. The extent of CLE and PLE was assessed by point counting, and the lungs were classified as having pure CLE (C, n = 5), predominant CLE with areas of PLE (CP, n = 7), predominant PLE with features of CLE (PC, n = 7), and pure PLE (P, n = 6) according to the percentage of lung involved by either form. Preoperative pulmonary function tests and the score of inflammation and the diameters of the small airways were also measured. ⋯ Small airway pathology was a predominant feature in lungs with CLE, and was significantly decreased in a stepwise fashion as the amount of PLE increased. This was especially so for the amount of muscle in the airway wall and the diameters of the airways. By contrast, lung compliance was higher in panacinar than in centrilobular emphysema.(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
The effect of positive end-expiratory pressure on respiratory resistive properties in anaesthetized paralysed humans.
The respiratory resistive properties of the normal human respiratory system are volume-dependent. The overall flow resistance (Rmax,rs) can be partitioned into airway resistance (Raw) and the additional resistance (delta Rrs) which may result from the viscoelastic properties of the respiratory system, from inequality of time constants (pendelluft), or from both. Because positive end-expiratory pressure (PEEP) increases end-expiratory lung volume and may equalize ventilation within the lungs, the effect of PEEP on Raw, delta Rrs, and their sum (Rmax,rs) was assessed in anaesthetized surgical patients without evidence of lung disease. ⋯ We conclude that the overall flow resistance was not affected by PEEP. In contrast, PEEP clearly modified the contribution of its two components. The decrease in Raw with PEEP could have resulted, at least in part, from modification in the basal vagal tone.