Chest
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Tracheobronchial constriction in asthmatics induced by isocapnic hyperventilation with dry cold air.
Although it is well known that isocapnic hyperventilation (IHV) with dry cold air produces airway constriction in asthmatic subjects, the site of airway narrowing is nuclear. To address this issue, we have quantified the tracheal and bronchial response to IHV with dry cold air in 15 patients with mild asthma and 7 healthy control subjects. We employed the acoustic reflection technique to evaluate changes in airway cross-sectional areas caused by IHV with dry cold air. ⋯ In asthmatics, at 5 to 10 min after challenge, we found that FEV1 decreased by 22 +/- 5% (mean +/- SEM) (p < 0.0001), V30p by 33 +/- 8% (p < 0.003), intrathoracic tracheal area by 10.7% +/- 2% (p < 0.03), and main bronchial area by 14 +/- 3% (p < 0.003). At 30 min, tracheal and main bronchial areas were returned to baseline levels; however, FEV1 and V30p were still significantly decreased, by 13 +/- 3% and 16 +/- 4%, respectively. We conclude that in asthmatics, IHV with dry cold air causes both tracheal and bronchial constriction, and that recovery seems to occur first in the central airways.
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To determine whether sectional development in pulmonary and critical care medicine influences medical house officers' (HO) interests and knowledge about respiratory medicine, we reviewed HO performance on the American Board of Internal Medicine (ABIM) certifying examination during 4 years before and 5 years after reorganization of our section. After major changes in the program and introduction of new educational opportunities, HOs more often selected pulmonary consultation electives (68.6% vs 47.8%; p = 0.009) and entered pulmonary fellowships after completion of residency training (12% vs 3%; p = 0.047). Total ABIM examination score did not change, but performance on its respiratory disease component improved from a median national percentile score of 48.5% (1986 to 1989) to 80.0% (1990 to 1994) (p = 0.0365). ⋯ Academic development in pulmonary/critical care faculty has an important influence on medical HO interests in and knowledge of that discipline. Plans for the future structure of academic pulmonary/critical care sections must take into account this impact on the training of generalists. Although institutional priorities, resources, and shifting external forces will define how, where, and by whom respiratory medicine will be taught, an appropriate number of faculty members and sufficient commitment of their time to HO education must be preserved.
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It is occasionally desirable for patients with a tracheostomy tube to breathe through their native airway. We hypothesized that capped tracheostomy tubes with cuffs deflated would create substantial additional resistance to airflow without fenestration but would provide minimal resistance to airflow when the tube had a fenestration. ⋯ The effort required to move gas across the native airway in the absence of a fenestration may be substantial. If a patient is to breathe through a native airway, a fenestrated tube should be used unless the tracheostomy tube is a No. 4.