Articles: animals.
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Biology of the neonate · Jan 1978
Comparative StudyPositive end expiratory pressure: effects on lung mechanics of premature lambs.
Pulmonary mechanics were determined at 0, 3, 6, and 10 cm H2O positive and expiratory pressure (PEEP) in premature lambs at a mean gestational age of 134 days. Functional residual capacity increased (p less than 0.005) by 7% (1.6 ml/kg) per cm H2O PEEP. ⋯ The data suggest that PEEP in excess of 3 cm H2O produces undesirable effects on lung mechanics in premature lambs. These results may be important in predicting contraindications and potential complications of positive pressure breathing in the newborn.
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Caesarean sections were performed on 18 Romney ewes on day 144 of pregnancy. Anaesthesia was induced in 9 ewes with CT 1341 and in 9 ewes with thiopentone and maintained in both groups with halothane administered with oxygen. Surgery was performed with the ewes in lateral recumbency, with respiration unassisted. ⋯ Significant linear relationships were only found in the CT 1341 group between TSR interval and PCO2 and pH. No significant correlations were found between the lD interval and any of the biochemical characteristics. The results of this study suggest that lateral recumbency does not interfere with uteroplacental circulation, that CT 1341 (2.2 mg/kg) is associated with less neonatal depression than thiopentone (10 mg/kg) and that severe neonatal hypercarbia may delay the onset of respiration in lambs with minimal drug depression.
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Cooling is known to prolong survival in newborn animals when used before the onset of asphyxia. It has therefore been advocated as a treatment for birth asphyxia in humans. Since it is not possible to cool a human baby before the onset of birth asphyxia, experiments were designed to test the effect of cooling after asphyxia had already started. ⋯ After deliver they were placed in environmental temperatures of either 37 degrees C, 20 degrees C, or 0 degrees C and observed for spontaneous recovery. The animals who were cooled survived less often than those kept at 37 degrees C. The results of these experiments suggest that hypothermia has little to offer in the treatment of birth asphyxia in humans.