American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Jul 1994
Comparative StudyEffects of dobutamine on oxygen consumption in septic patients. Direct versus indirect determinations.
Dobutamine has been proposed as a means of disclosing a pathologic oxygen supply (DO2) dependency in critically ill patients. Like other catecholamines, however, dobutamine might increase cellular metabolism, so that oxygen consumption (VO2) would increase regardless of the presence or absence of a supply dependency. This study investigated the effects of graded doses of dobutamine on VO2 in stable, septic patients. ⋯ All of the measured parameters were similar at baseline and after discontinuation of the dobutamine infusion. Dobutamine induced a dose-related increase in the cardiac index (from 3.84 +/- 0.97 to 6.19 +/- 1.56 L/min/m2, p < 0.01) and DO2 (from 501 +/- 123 to 801 +/- 219 ml/min/m2, p < 0.01). Both VO2DIR and VO2INDIR increased, from 161 +/- 37 to 183 +/- 40 ml/min/m2 and from 140 +/- 29 to 168 +/- 42 ml/min/m2, respectively (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. J. Respir. Crit. Care Med. · Jul 1994
Evolution of bronchoalveolar cell populations in the adult respiratory distress syndrome.
To characterize the evolution of inflammation in the adult respiratory distress syndrome (ARDS) and test the hypothesis that sustained alveolar inflammation is associated with a poor outcome in patients with ARDS, we performed fiberoptic bronchoscopy and bronchoalveolar lavage (BAL) in 125 patients and compared BAL cells and protein concentrations in survivors and nonsurvivors. ARDS followed sepsis syndrome in 35 patients, major trauma in 41, and other causes in 49. When possible, BAL was performed on Days 3, 7, and 14 after the onset of ARDS. ⋯ In patients with ARDS following trauma and other risks, however, BAL PMN measures did not distinguish survivors from patients who died. Analysis of serial data from the patients with more than one BAL showed that alveolar macrophages (AM) increased in survivors of ARDS, both in absolute numbers and as a percentage of total cells; this pattern was most pronounced in the sepsis patients. The cross-sectional data analysis suggests that sustained alveolar inflammation occurs frequently in patients with ARDS following sepsis and is associated with a high mortality.
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Am. J. Respir. Crit. Care Med. · Jul 1994
Ventilation-perfusion distributions during mechanical ventilation with superimposed spontaneous breathing in canine lung injury.
Biphasic positive airway pressure (BIPAP) allows unrestricted spontaneous breathing throughout mechanical ventilation. Effects of spontaneous breathing during BIPAP on pulmonary gas exchange were studied on a randomized basis in 12 dogs with oleic acid-induced lung injury using the multiple inert gas elimination technique. ⋯ Improved pulmonary gas exchange caused by better ventilation/perfusion (VA/Q) matching was indicated by a 17 +/- 3% decrease (p < 0.01) in blood flow to shunt units (VA/Q < 0.005), a 15 +/- 3% increase (p < 0.05) in perfusion of normal VA/Q units (0.1 < VA/Q < 10), and a 6 +/- 3% reduction in ventilation of dead space (VA/Q > 100) areas (p < 0.05). Spontaneous breaths superimposed on mechanical ventilation may convert shunt VA/Q units to normal by increased ventilation of poorly or nonventilated units and/or increase blood flow to previously minimal or nonperfused areas.
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Am. J. Respir. Crit. Care Med. · Jul 1994
Mechanism by which the prone position improves oxygenation in acute lung injury.
The mechanism by which oxygenation improves when patients with ARDS are turned from supine to prone position is not known. From results of our previous studies we reasoned that (1) when supine, in the setting of lung injury, transpulmonary pressure will be less than airway opening pressure and (2) atelectasis will develop preferentially in dorsal lung areas, and (3) both ventilation and ventilation/perfusion ratios would improve in these regions on turning prone. ⋯ After oleic acid, the prone position improved (1) oxygenation (mean +/- SD PaO2 = 140 +/- 112 versus 453 +/- 54 mm Hg), (2) median ventilation/perfusion ratios (0.77 versus 0.95), (3) ventilation/perfusion heterogeneity (coefficient of variation 86 +/- 15 versus 61 +/- 6), and (4) the gravitational ventilation/perfusion gradient (dependent to non-dependent slopes of 0.22 versus -0.02, all p < 0.05). The prone position generates a transpulmonary pressure sufficient to exceed airway opening pressure in dorsal lung regions, i.e., in regions where atelectasis, shunt, and ventilation/perfusion heterogeneity are most severe, without adversely affecting ventral lung regions.
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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.