SummaryStudies were conducted to assess the effect of fetal thyroidectomy early in the third trimester on lung growth and surfactant maturation in the sheep. At 95-99 days of gestation, a fetal thyroidectomy was performed. The preparation was killed 36-45 days postthyroidectomy. The mean weights of the cerebrum, cerebellum, and combined heart and lungs were significantly smaller and the pituitary gland significantly greater in the thyroidectomized fetus. The mean tracheal fluid lecithin to sphingomyelin (L/ S) ratio was significantly lower in the athyrotic fetus; however, there was no significant difference in the mean cortisol concentration or mean whole lung homogenate phosphatidic acid phosphohydrolase (PAPase) specific activity between the two groups. There was a significant direct correlation between the serum cortisol concentration and tracheal fluid L/S ratio and between the whole lung homogenate PAPase specific activity and serum cortisol level in the euthyroid group, which were not present in the thyroidectomized group. The mean lung DNA concentration was significantly increased and mean lung protein/DNA ratio significantly decreased in the thyroidectomized fetus. On histologic examination, the lung from the athyrotic fetus was hypercellular with thickened alveolar septae. The type I1 pneumocyte in the hypothyroid lung was less mature with fewer lamellar bodies or its precursors. These results suggest that in the ovine fetus, thyroid hormone deficiency during the last trimester of intrauterine development impairs lung growth and surfactant maturation. SpeculationThe present results suggest that thyroid hormones are necessary for normal lung growth and surfactant maturation. In the human -u preterm infant, idiopathic respiratory distress syndrome is a major cause of morbidity and mortality. Stimulation of the hypothalamicpituitary-thyroid axis in the fetus at high risk for developing idiopathic respiratory distress syndrome before delivery may accelerate surfactant maturation and decrease the sequelae from this syndrome. onstrate decreased cell size, clumping of chromatin, increased glycogen content and decreased number of osmiophilic inclusion bodies (7,38). In human neonates with idiopathic respiratory distress syndrome, cord thyroid hormone concentrations are lower than in healthy infants of comparable gestational age (12,39). The studies in the present report were conducted to assess the effect of fetal thyroidectomy early in the third trimester on lung growth and surfactant maturation in the sheep. MATERIALS AND METHODS DESCRIPTION OF THE ANIMAL MODELColumbia and Columbia-Suffolk date-bred ewes were obtained from a local source, maintained at the University vivarium and given free access to alfalfa and water. At 95-99 days of gestation, under epidural anesthesia, the uterus was exposed through a lower midabdominal incision in five ewes with singleton pregnancies. After isolation of the fetal head, the uterus was incised and a fetal thyroidectomy performed. No more than 2-3 cotyledons were killed at ...
Artificial and animal lung models initially were used to investigate the removal of foreign bodies from the tracheobronchial tree with the flexible fiberoptic bronchoscope. Different extraction instruments (claw, basket, forceps, and balloon catheter) were passed separately through the channel of the bronchofiberscope, and tested for usefulness prior to human application. The Fogarty balloon catheter served as a valuable aid in dislodging impacted objects so that the operator could then grasp them with the claw, basket or forceps. The wire claw recovered many of the metallic and organic objects, the wire basket was successful in retrieving only the bulky objects and the forceps (ACMI) was effective in capturing all of the metallic foreign bodies. These techniques, developed in our laboratory, are now being used to augment rigid bronchoscopy in the removal of foreign bodies from adults and older children. At the present time fiberoptic foreign body removal is not recommended for pediatric cases because of the small diameter of the trachea and glottis in infants and young children.
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