American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Jul 1994
Protease-antiprotease imbalance in the lungs of children with cystic fibrosis.
Cystic fibrosis (CF) is characterized in the lung by chronic purulent bronchitis culminating in pulmonary insufficiency. There is evidence to suggest that neutrophil elastase (NE) released by neutrophils on the respiratory epithelial surface plays a major role in the pathogenesis of this lung disease. This study sought to determine the age of onset of the chronic neutrophil-dominated inflammation in CF and the consequences to the NE-anti-NE screen on the respiratory epithelial surface of the CF lung. ⋯ Active NE was found in ELF in 20 of 27 children, including two of four aged 1 yr. Western blot analysis showed the majority of alpha 1AT and SLPI molecules to be complexed and/or degraded. These observations demonstrate that a chronic imbalance of the NE-anti-NE protective screen develops early on the respiratory epithelial surface in persons with CF and is likely well established by 1 yr of age, with resultant potential for lung damage.
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Am. J. Respir. Crit. Care Med. · Jul 1994
Cardiovascular effects of periodic obstructive and central apneas in dogs.
Patients with sleep apnea may experience two types of apnea, central and obstructive. We compared cardiovascular effects of these two types of apnea matched for changes in arterial blood gas tensions and periodicity. In 12 anesthetized, closed chest dogs, obstructive apneas were induced by completely occluding the endotracheal tube at end-expiration for 1 min and allowing 1 min of spontaneous ventilation. ⋯ During obstructive apneas, right atrial pressure increased, as did right heart blood volume. During central apneas, both right atrial pressure and left atrial pressure increased, as did pulmonary blood volume. We conclude that: (1) HR decreases are more severe during central apnea, most likely due to lack of respiratory mechanoreceptor input; (2) CO decreases more with central compared with obstructive apnea due to the heart rate response; (3) HR-induced cardiac dysfunction with central apnea could lead to pulmonary vascular congestion.
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Am. J. Respir. Crit. Care Med. · Jun 1994
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialNebulized versus intravenous albuterol in hypercapnic acute asthma. A multicenter, double-blind, randomized study.
In a multicenter, randomized, double-blind study, we compared the effects of nebulized (5 mg x 2) and intravenous (0.5 mg) albuterol (salbutamol) over 1 h in 47 patients admitted to hospital with severe acute asthma defined as a peak expiratory flow (PEF) below 150 L/min and hypercapnia (Pa(CO2) > or = 40 mm Hg). Additional treatment included nasal oxygen and hydrocortisone succinate. The efficacy was assessed after 1 h. ⋯ The mean increase in PEF was greater in the NEB group than in the i.v. group (+107 +/- 94 L/min versus +42 +/- 66 L/min, p = 0.01) as well as the decrease in Pa(CO2) values (-10 +/- 5 mm Hg versus -2 +/- 12 mm Hg, p < 0.01). Beta agonist-induced hypokalemia was more pronounced in the i.v. group than in the NEB group. We conclude that, in hypercapnic acute asthma, the nebulized route has a greater efficacy and fewer side effects than the intravenous route.
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Am. J. Respir. Crit. Care Med. · Jun 1994
Comparative StudyExtracorporeal carbon dioxide removal technique improves oxygenation without causing overinflation.
Extracorporeal CO2 removal combined with low frequency positive pressure ventilation (ECCO2R-LFPPV) improves gas exchange and decreases peak pressures, respiratory rates, and tidal volumes in animals and in humans. Recent evidence suggests that pulmonary barotrauma results from lung overinflation rather than from high pressures. This study was to test the hypothesis whether ECCO2R-LFPPV could improve gas exchange without causing lung overinflation, despite the use of higher levels of PEEP, when compared with conventional mechanical ventilation. ⋯ By contrast, no evidence of persistent lung overinflation could be detected by either static P-V curves or dynamic measurements in nine of 11 patients who were treated by ECCO2R-LFPPV. The two remaining patients had severe airway obstruction because of bleeding, and they remained ventilated with persistent risk of barotrauma. We conclude that ECCO2R-LFPPV improves gas exchange without causing lung overinflation in a majority of patients with ARDS.
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Am. J. Respir. Crit. Care Med. · Jun 1994
ReviewDeterminants of susceptibility to cigarette smoke. Potential roles for neuroendocrine cells and neuropeptides in airway inflammation, airway wall remodeling, and chronic airflow obstruction.
There is a subgroup of cigarette smokers who are more susceptible than others to the deleterious effects of cigarette smoke and to chronic airflow obstruction. The study of histopathologic and physiologic differences between these "susceptible" smokers and "resistant" smokers, who do not develop clinically significant airflow obstruction, may lead to better understanding of host factors that determine individual susceptibility to cigarette smoke. This report puts forth the hypothesis that individual differences in number or function of pulmonary neuroendocrine cells may play an important role in determining whether cigarette smokers develop chronic airflow obstruction and perhaps other smoking-related disorders. In this context, pulmonary neuroendocrine cells and bombesin-like peptides are discussed, emphasizing those aspects most relevant to the pathobiologic consequences of cigarette smoking.