American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Aug 1995
Comparative StudyAlterations of lung and chest wall mechanics in patients with acute lung injury: effects of positive end-expiratory pressure.
In 16 mechanically ventilated patients with acute lung injury (ALI) (eight patients with moderate ALI [moderate group], eight patients with severe ALI [adult respiratory distress syndrome, ARDS group]) and in eight normal anesthetized-paralyzed subjects (control group), we partitioned the total respiratory system mechanics into the lung (L) and chest wall (w) mechanics using the esophageal balloon technique together with the airway occlusion technique during constant flow inflation. We measured lung elastance (Est,L), chest wall elastance (Est,w), and total lung (Rmax, L) and chest wall (Rmax,w) resistance. Rmax,L includes airway (Rmin,L) and "additional" lung resistance (DR,L). ⋯ The end-expiratory lung volume (EELV) was measured at each level of PEEP. Specific total lung (sRmax,L), airway (sRmin,L), and "additional" lung (sDR,L) resistances were obtained as Rmax,L x EELV, Rmin,L x EELV, and DR,L x EELV, respectively. At PEEP 0 cm H2O, we found that both Est,L (23.7 +/- 5.5 and 13.8 +/- 3.3 versus 9.3 +/- 1.7 cm H2O/L; p < 0.01) and Est,w (13.2 +/- 5.4 and 9.9 +/- 2.1 versus 5.6 +/- 2.3 cm H2O/L; p < 0.01) were markedly increased in patients with ARDS and moderate ALI compared with control subjects, with a significant (p < 0.01) effect of the severity of the disease on Est,L (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. J. Respir. Crit. Care Med. · Aug 1995
Randomized Controlled Trial Comparative Study Clinical TrialA randomized, double-blind comparison of methoxamine and epinephrine in human cardiopulmonary arrest.
The beneficial effect of epinephrine has been attributed to its alpha-adrenergic properties. The present study was designed to compare the effects of epinephrine and methoxamine in witnessed cardiac arrests. Consecutive, witnessed cardiac-arrest victims presenting to the emergency room or from the inpatient population of our institution were enrolled in this study. ⋯ Of the 145 patients remaining, 77 received methoxamine (M) and 68 epinephrine (E). There was no difference in rate of successful resuscitation (42% versus 53%, M versus E, respectively), or in neurologic outcome as measured by the Glasgow-Pittsburgh Coma Score (GPCS). This study failed to demonstrate any difference in the rate of initial resuscitation, survival to discharge from the hospital, or neurologic status with methoxamine as opposed to epinephrine in the setting of cardiac arrest.
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Am. J. Respir. Crit. Care Med. · Aug 1995
Comparative StudyShould mechanical ventilation be optimized to blood gases, lung mechanics, or thoracic CT scan?
This study was aimed at providing data for optimization of mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). The effects of ventilation with positive end-expiratory pressure (PEEP) titrated to blood gases were studied by thoracic computed tomographic (CT) scans and lung mechanics measurements in eight patients. CT density histograms at end-expiration were used to investigate the effects of PEEP on three differently aerated zones. ⋯ With regard to plateau pressures, only one patient was ventilated above the deflection point. However, monitoring of volumes showed that these four patients had an end-inspiratory volume above this point. We conclude that mechanical ventilation may be initially adjusted on the basis of blood gas values and then optimized on the basis of lung mechanics to limit the risk of baro-volotrauma.
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Am. J. Respir. Crit. Care Med. · Aug 1995
Efficacy of expiratory tracheal gas insufflation in a canine model of lung injury.
Tracheal gas insufflation (TGI) improves the efficiency of CO2 elimination by reducing the CO2-laden dead space of the airways. The effect of TGI on PaCO2 diminishes in the setting of acute lung injury (ALI) because an increased alveolar component dominates the total physiologic dead space. Nevertheless, adopting a strategy of permissive hypercapnia should partially offset the decreased efficacy of TGI by increasing CO2 concentration in the proximal airways. ⋯ The corresponding decrements in PaCO2 produced by TGI at a flow rate of 10 L/min were 16 +/- 3, 24 +/- 10, and 10 +/- 2 mm Hg, respectively. TGI decreased total physiologic dead space per breath (VD) by 56, 31, and 28 ml during the pre-OAI, post-OAI, and post-OA/VT stages, respectively. Despite a smaller reduction in VD during the post-OAI stage, the effect of TGI on PaCO2 was preserved because of the relatively high PaCO2 prior to its initiation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. J. Respir. Crit. Care Med. · Aug 1995
Racial differences in the association between maternal smoking during pregnancy and lung function in children.
We recently reported that suburban white schoolchildren whose mothers smoked during pregnancy have significantly reduced lung function. Because inner-city and minority children may be at greater risk for respiratory morbidity, we evaluated the relationship between maternal smoking during pregnancy and lung function in 493 white and 383 black schoolchildren 9 to 11 yr of age in three areas of Philadelphia. The child's passive smoking history was determined from reports by the mother. ⋯ After adjusting for height, weight, age, sex, area of city, race, socioeconomic status, and current exposure to environmental tobacco smoke at home, maternal smoking during pregnancy was associated with significant deficits in FEF25-75 (-8.1%) and FEV1/FVC (-2.0%). The observed deficits were larger for black children than for white children, and they were larger for boys than for girls. These results provide additional evidence of an association between maternal smoking during pregnancy and reduced pulmonary function in children, and they suggest that the association may be modified by race and/or sex.