American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Oct 1997
Comparative StudyEffect of prone and supine positions on functional residual capacity, oxygenation, and respiratory mechanics in ventilated infants and children.
Although numerous reports have described the improvement in PAO2 in patients in the prone position, the underlying mechanism has yet to be determined. Some authors have suggested this phenomenon may be related to an increase in functional residual capacity (FRC); however, no previous studies have described positional changes in FRC in children with severe lung disease or in those under neuromuscular blockade. We measured arterial blood gases, FRC, Rrs, and Crs in supine and prone positions in 30 patients under neuromuscular blockade with lung disorders including moderately severe restrictive (n = 10) and obstructive (n = 10) disease and control subjects without significant lung disease (n = 10). ⋯ No significant changes in Crs were seen in the prone position. We conclude that prone positioning has no effect on FRC and in this series of 30 patients significantly improved oxygenation only in patients with obstructive airway disease. A significant decrease in Rrs in patients with obstructive lung disease was also observed.
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Am. J. Respir. Crit. Care Med. · Oct 1997
Ventilation-perfusion mismatch in patients with pleural effusion: effects of thoracentesis.
Pleural effusion (PE) often causes abnormal pulmonary gas exchange. Thoracentesis is commonly used to relieve dyspnea in patients with PE, but its effect upon arterial oxygenation is varied and poorly understood. This investigation sought to: (1) characterize the distribution of ventilation-perfusion (VA/Q) ratios in patients with PE and (2) assess the effects of PE drainage by thoracentesis upon pulmonary gas exchange. ⋯ While thoracentesis drained 693+/-424 ml of fluid and caused a significant fall in mean pleural pressure (by -10.7 +/- 7.1 mm Hg; p < 0.01), PaO2, AaPO2, and shunt remained unchanged; only the amount of blood flow perfusing low VA/Q ratios increased slightly (2.4+/-2.6%; p < 0.05). This study shows that: (1) intrapulmonary shunt is the main mechanism underlying arterial hypoxemia in patients with PE and (2) effective thoracentesis has minor short-term effects upon pulmonary gas exchange. These findings are in accord with delayed (> 30 min) pulmonary volume re-expansion after thoracentesis with or without the coexistence of mild ex vacuo pulmonary edema.
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Am. J. Respir. Crit. Care Med. · Oct 1997
Comparative StudyExogenous surfactant and partial liquid ventilation: physiologic and pathologic effects.
We compared the effects of surfactant and partial liquid ventilation (PLV), and the impact of administration order, on oxygenation, respiratory system compliance (Crs), hemodynamics, and lung pathology in an animal lung injury model. We studied four groups: surfactant alone (S; n = 8); partial liquid ventilation alone (PLV-only; n = 8); surfactant followed by partial liquid ventilation (S-PLV; n = 8); and partial liquid ventilation-followed by surfactant (PLV-S; n = 8). Following treatments, all animals had improved oxygenation index (OI) and Crs. ⋯ Pathologic analysis demonstrated decreased lung injury in dependent lobes of all PLV-treated animals, and in all lobes of S-PLV animals, when compared with the lobes of the S animals (p < 0.05). We conclude that surfactant therapy in combination with PLV improved oxygenation, respiratory system mechanics, and lung pathology to a greater degree than surfactant therapy alone. Administration order affected initial physiologic response and ultimate pathology: surfactant given before PLV produced the greatest improvements in pathologic outcomes.
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This cost of illness analysis examines national cost and resource utilization by persons with asthma using a single, comprehensive data source, the 1987 National Medical Expenditure Survey. Direct medical expenditures included payments for ambulatory care visits, hospital outpatient services, hospital inpatient stays, emergency department visits, physician and facility payments, and prescribed medicines. Indirect medical costs included costs resulting from missed work or school and days with restricted activity at work. ⋯ More than 80% of resources were used by 20% of the population (defined as 'high-cost patients'). The estimated annual per patient cost for those high-cost patients was $2,584, in contrast with $140 for the rest of the sample. Findings from this study indicate that future asthma research and intervention efforts directed at hospitalizations and high-cost patients could help to decrease health care resource use and provide cost savings.