The American review of respiratory disease
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Am. Rev. Respir. Dis. · Jul 1982
Case ReportsOccult positive end-expiratory pressure in mechanically ventilated patients with airflow obstruction: the auto-PEEP effect.
Alveolar pressure can remain positive throughout the ventilatory cycle of mechanically-ventilated patients with airflow obstruction, even when positive end-expiratory pressure (PEEP) is not applied intentionally. The increase of intrathoracic pressure associated with this "auto-PEEP" phenomenon can severely depress cardiac output as well as elevate the end-expiratory pulmonary artery wedge pressure. ⋯ Failure to recognize the hemodynamic consequences of auto-PEEP may lead to inappropriate fluid restriction or unnecessary vasopressor therapy. Although not apparent during normal ventilator operation, the auto-PEEP effect can be detected and quantified by a simple bedside maneuver: expiratory port occlusion at the end of the set exhalation period.
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Am. Rev. Respir. Dis. · Jul 1982
A simple procedure for the isolation of pulmonary parenchyma free of major blood vessels and airways for biochemical studies.
A new method of preparation of lung parenchyma free from small and medium sized airways and blood vessels is described. The lung is frozen in the inflated state and cut into thin slices to facilitate visualization and separation of large blood vessels and airways. ⋯ The fall-through portion consists almost entirely of alveoli. Amino acid analysis of elastin separated from the sieved fragments is similar to lung parenchymal elastin isolated and dissected from fresh lung tissue.
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Am. Rev. Respir. Dis. · Jun 1982
Case ReportsFailure of trimethoprim-sulfamethoxazole in the therapy of recurrent Pneumocystis carinii pneumonia.
The use of trimethoprim-sulfamethoxazole in the treatment and prophylaxis of Pneumocystis cariniii is well established. Treatment failure with this regimen has been ascribed to inadequate antibiotic serum concentrations. ⋯ Subsequently, a response to pentamidine isethionate was obtained. The reason for failure and therapeutic implications in patients with Pneumocystis carini pneumonia who have received trimethoprim-sulfamethoxazole are discussed.
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Am. Rev. Respir. Dis. · May 1982
Refractory period after exercise-induced asthma unexplained by respiratory heat loss.
Fifteen asthmatic children and young adults each exercised for 6 min by cycling on a cycle ergometer while breathing either cold (4.1 degrees C +/- 0.5 SEM) and dry (2.05 mg/L +/- 0.05) air or warm (37.2 degrees C +/- 0.3) fully saturated air. Each subject performed 4 tests arranged in pairs. Test pair A consisted of cold dry exercise followed by another cold dry exercise and test pair B consisted of a warm humid exercise followed by a cold dry exercise. ⋯ The 12 remaining subjects exhibited a refractory period similar to that shown in test pair A. They did not develop EIA after the warm humid test (delta FEV1 = 1 +/- 2), but after the subsequent cold dry exercise the per cent decrease in FEV1 was 19 +/- 3, similar to that in the second of the 2 cold dry exercise tests. These experiments suggest that in the majority of subjects exercise per se appears to be the cause for refractoriness and not airway cooling or bronchoconstriction.