Mid arm circumference at birth: a screening method for detection of low birth weight.
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Biomedical subjects
Publications and source records attributed to S L Sood.
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Exogenous surfactant therapy is not standard in the acute respiratory distress syndrome (ARDS) because of a lack of proven benefit. Nonuniform surfactant distribution after either bolus or aerosol administration may be an important factor limiting response. In a previous study of acute lung injury, we demonstrated that lavage administration of Exosurf (13.5 mg phospholipid/ml) was both effective and distributed uniformly in the lungs. Since the endogenous surfactant pool is much smaller than the typical dose of exogenous surfactant administered, we hypothesized that dilute surfactant preparations (4-4.5 mg phospholipid/ml) administered by lung lavage would be equally effective in reversing pulmonary dysfunction in a piglet model of acute lung injury. We compared three dilute surfactants: Infasurf (n = 5), KL4-Surfactant (n = 6), and Exosurf (n = 5) with controls (n = 6) and undiluted Exosurf (13. 5 mg phospholipid/ml; n = 6). All dilute surfactant preparations were effective in improving oxygenation and other parameters of pulmonary function. Surfactant administered by lavage resulted in uniform lung distribution. We conclude that dilute surfactants administered by lung lavage are effective in reversing pulmonary dysfunction after acute lung injury. We speculate that doses in the range of 20-40 mg phospholipid/kg may be adequate to improve lung function in ARDS when exogenously administered surfactant is uniformly distributed in the lung.
Abnormalities of pulmonary surfactant function have been described in association with the acute respiratory distress syndrome (ARDS). Because gram-negative sepsis is a common cause of ARDS, we treated neonatal piglets with Escherichia coli endotoxin to create a neonatal ARDS model. We hypothesized that under these conditions administration of exogenous surfactant would improve pulmonary function. Study groups included: control (n-8), Exosurf (5 mL/kg, 13.5 mg phospholipid/mL, n-7), Survanta (4 mL/kg, 25 mg phospholipid/mL, n-6), and saline (5 mL/kg, n = 6). E. coli endotoxin 12 micrograms/kg was infused over 30 min and resulted in significant pulmonary and hemodynamic abnormalities, histopathologic evidence of nonhomogeneous lung injury, and elevated protein levels in bronchoalveolar lavage washings. Neither Exosurf nor Survanta ameliorated the pulmonary effects of endotoxin. Instead, there was a prolonged decrease in arterial oxygen tension (PaO2) and dynamic lung compliance after administration of surfactant and saline. Distribution of a bolus of Exosurf was uneven throughout the lung. We conclude that in this neonatal piglet model of ARDS, bolus surfactant administration had a detrimental effect on oxygenation and pulmonary function.
Evidence for surfactant dysfunction in acute respiratory distress syndrome (ARDS) suggests a role for exogenous surfactant which contains apoprotein for resistance to protein inhibition. We compared the effects of KL-4-Surfactant, an artificial preparation containing a synthetic 21 amino acid peptide with SP-B-like activity, with Exosurf, an artificial protein-free surfactant, and Survanta, a bovine protein-containing surfactant, in a saline lung lavage model of ARDS in neonatal piglets. Two sequential series of lung lavages were performed to lower PaO2 < 100 mm Hg, each followed by administration of surfactant or air and a 90-min observation period. Progressive lung injury was demonstrated by deterioration in pulmonary function, increasing bronchoalveolar lavage protein, and changes in histopathology. All surfactants improved oxygenation, although oxygenation was generally better with Survanta and KL-4-Surfactant. Further, Survanta and KL-4-Surfactant groups showed improvement in ventilation, with decreases in PaCO2 and increases in FRC. Only KL-4-Surfactant demonstrated greater pressure-volume characteristics and lower bronchoalveolar protein than those of Controls. We conclude that the physiologic effects of KL-4-Surfactant are more like Survanta in this model. We speculate that KL-4-Surfactant may improve pulmonary function, reduce alveolar protein leak, and thus be efficacious in the treatment of ARDS.
Despite evidence of surfactant dysfunction in the acute respiratory distress syndrome (ARDS), treatment with exogenous surfactant remains experimental. Uneven pulmonary distribution is one factor that may limit response. We investigated whether exogenous surfactant administered by lavage, consisting of a 35 ml/kg volume instilled by gravity and followed immediately by passive drainage (LAVAGE), would result in better lung distribution and physiologic response than with surfactant administered as a 5 ml/kg bolus (BOLUS). Exosurf, an artificial surfactant, was administered after acute lung injury induced by saline lung lavage in neonatal piglets. In the LAVAGE group (n= 9), 10.1 +/- 0.4 ml/kg of surfactant was retained, corresponding to a phospholipid dose of 136 +/- 5 mg/kg. In the BOLUS group (n = 9), the dose administered was 203 mg/kg phospholipid. Piglets in the LAVAGE group demonstrated greater improvement in pulmonary function, including PaO2, PaCO2, ventilation efficiency index, functional residual capacity (FRC), and pressure-volume curves than piglets in the BOLUS group. Some differences were found in lung distribution of surfactant. We conclude that Exosurf is more effective when administered by lavage in this lung injury model. We speculate that the lavage method of administration holds promise as an alternative method of surfactant administration in patients with ARDS.