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Positive intrapulmonary oncotic pressure enhances short-term lung growth acceleration after fetal tracheal occlusion
Alexander Dzakovic1, Amir Kaviani, Russell W Jennings
1Department of Surgery, Children's Hospital and Harvard Medical School, and Harvard Center for Minimally Invasive Surgery, Boston, MA 02115, USA.
Purpose:
This study was aimed at determining whether positive oncotic pressure induced in the fetal lung liquid could safely maximize accelerated lung growth after tracheal occlusion.
Methods:
Fetal lambs (n = 21) were divided into 4 groups: group I (n = 5) consisted of sham-operated controls; group II (n = 5) underwent simple tracheal occlusion (TO); group III (n = 5) received TO and 60 mL of saline injected into the trachea; and group IV (n = 6) underwent TO and intratracheal infusion of 60 mL of iso-osmotic, 6% Dextran 70. All fetuses were delivered near term, at a mean of 15.9 +/- 1 days postoperatively. Their lungs were studied by standard morphometric techniques, and the basic chemical profile of the lung liquid was analyzed. Statistical comparisons were by 1-way analysis of variance (ANOVA) and post-hoc analyses by the Bonferroni correction for multiple comparisons, with P values less than.05 considered significant.
Results:
The lung volume-to-body-weight ratio (LV:BW) was significantly different among groups. Pairwise comparisons of LV:BW showed that it was higher in group IV than in all other groups, but there was no difference between groups II and III. Airspace fraction was not significantly different among groups, and histologic appearance was normal in all lung samples. There were no differences in lung liquid osmolarity, pH level, and electrolyte concentrations.
Conclusion:
Positive intrapulmonary oncotic pressure by an isosmotic agent boosts short-term lung growth acceleration after fetal tracheal occlusion with no evidence of cell damage.