The American review of respiratory disease
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Am. Rev. Respir. Dis. · Apr 1988
Oxygen consumption during spontaneous ventilation with acute lung injury in anesthetized pigs.
Acute lung injury causes a restrictive pulmonary defect, decreases lung compliance, and increases the work of breathing. We wished to determine the oxygen cost of the increased elastic work of breathing associated with acute lung injury. Extracorporeal venous circulation with a membrane lung was used to extract CO2 and to induce apnea in 14 anesthetized pigs. ⋯ Acute lung injury decreased lung compliance from 101 +/- 79 (mean +/- SD) to 52 +/- 25 ml/cm H2O (p less than 0.04), and increased the elastic work of breathing from 700 +/- 590 to 1,060 +/- 630 ml.cm H2O (p = 0.01). During spontaneous ventilation, the increases in total O2 consumption and the O2 cost of breathing caused by acute lung injury were sufficiently small as to be undetectable, and, therefore, less than 3 to 4% of basal O2 consumption despite markedly increased elastic work and ventilatory power requirements. The increase in O2 consumption imposed by acute lung injury was small enough (less than 3 to 4% of total O2 consumption) that it appears to be clinically insignificant.
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Am. Rev. Respir. Dis. · Mar 1988
Increased procollagen III aminoterminal peptide-related antigens and fibroblast growth signals in the lungs of patients with idiopathic pulmonary fibrosis.
Idiopathic pulmonary fibrosis (IPF) is a chronic lung disorder characterized by an increased density of inflammatory cells, fibroblasts, and collagen within the lung parenchyma. To gain insights into the mechanisms leading to the increased density of fibroblasts and altered collagen metabolism in the IPF lung, bronchoalveolar lavage fluid from normal subjects and patients with IPF or sarcoidosis was analyzed for (1) the presence of antigenic material related to the aminoterminal propeptide domain of type III procollagen, and (2) fibroblast growth-promoting activity in the extracellular milieu of the lower respiratory tract. ⋯ Furthermore, BALF from patients with IPF markedly stimulated human lung fibroblast proliferation in vitro (199% increase, p less than 0.01), whereas lavage fluid from patients with sarcoidosis and from control subjects did not. The enhanced fibroblast proliferation induced by IPF BALF occurred in the absence of serum and exogenous growth factors, suggesting that both competence- and progression-type growth factors were present in the lavage fluid.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. Rev. Respir. Dis. · Dec 1987
Comparative StudyHigh frequency chest wall oscillation in patients with chronic air-flow obstruction.
In order to assess high frequency chest wall oscillation (HFCWO) as a way to assist spontaneous breathing in obstructive lung disease, we studied 12 patients with severe and stable COPD. HFCWO at 5 Hz were applied by means of an inflatable vest. In order to avoid any discomfort, oscillations were applied only during the expiratory phase of the spontaneous breathing cycle. ⋯ In addition, duty cycle (Ti/Ttot) decreased (p less than 0.001) from 0.37 +/- 0.03 s during control to 0.29 +/- 0.05 s during HFCWO. Such a decrease in duty cycle suggest that inspiratory muscle work was facilitated under HFCWO. In 8 patients, we obtained the tension-time index (TTdi), or the product of duty cycle and Pdi/Pdimax, and found that this index significantly decreased (p less than 0.05) from 0.06 +/- 0.03 during control to 0.04 +/- 0.02 during HFCWO.(ABSTRACT TRUNCATED AT 250 WORDS)
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Since the early 1970s, the health effects of indoor air pollution have been investigated with increasing intensity. Consequently, a large body of literature is now available on diverse aspects of indoor air pollution: sources, concentrations, health effects, engineering, and policy. ⋯ Subsequently, exposure to indoor air pollutants and health effects are considered, with an emphasis on those indoor air quality problems of greatest concern at present: passive exposure to tobacco smoke, nitrogen dioxide from gas-fueled cooking stoves, formaldehyde exposure, radon daughter exposure, and the diverse health problems encountered by workers in newer sealed office buildings. The review concludes by briefly addressing assessment of indoor air quality, control technology, research needs, and clinical implications.
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Am. Rev. Respir. Dis. · Nov 1987
Pulmonary vascular tone improves pulmonary gas exchange in the adult respiratory distress syndrome.
Hemodynamics, blood gases, lung mechanics, and the distributions of ventilation-perfusion ratios (VA/Q) were studied before and after iv diltiazem, 0.5 mg/kg over 30 min, in 6 patients with pulmonary hypertension secondary to the adult respiratory distress syndrome (ARDS) ventilated with 7 to 20 cm H2O positive end-expiratory pressure (PEEP). Diltiazem decreased systemic and pulmonary arterial pressures without changes in cardiac output and in filling pressures of the heart, and with a slowing of heart rate. Pulmonary vascular resistances decreased from 401 +/- 59 to 329 +/- 58 dyne.s.cm-5.m2 (mean +/- SEM), p less than 0.01. ⋯ Lung compliance and airway resistances did not change. Diltiazem increased true shunt from 23 +/- 5 to 30 +/- 7% of total blood flow (p less than 0.02) without other modification in the pattern of VA/Q distribution as measured by the multiple inert gas elimination technique. These results suggest that pulmonary vascular tone contributes to the maintenance of VA/Q matching in patients with ARDS.