Pediatric research
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We investigated the extent of isoflurane-induced neurodegeneration on the fetuses of pregnant rats exposed in utero. Pregnant rats at gestational d 21 were divided into three experimental groups. Rats in the control group spontaneously breathed 100% oxygen for 1 h. ⋯ The 3% isoflurane treatment group showed significantly higher levels of S100beta levels and significantly increased average densities of total caspase-3-positive cells in the CA1 hippocampus and RS cortex compared with the control and the 1.3% isoflurane groups. There were no differences in S100beta levels or densities of caspase-3-positive cells between the control and 1.3% isoflurane groups. Isoflurane at a concentration of 3% for 1 h increased neurodegeneration in the hippocampal CA1 area and the retrosplenial cortex in the developing brain of fetal rats.
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We investigated return of spontaneous circulation and of cerebral oxygenation after asphyxia-induced cardiac arrest, using ventilation with air, throughout, or with 100% oxygen for a shorter or longer period. Arterial pressure, heart rate, regional cerebral oxygen saturation (CrSO2), and brain tissue oxygen tension (PbtO2) were measured in 1-d-old piglets that were hypoventilated with air and left in apnea until cardiac arrest. They were randomly assigned to be resuscitated with air (n = 13), or with oxygen for 3 (n = 12) or 30 min (n = 13) and then with air. ⋯ They were not significantly different, nor were the arterial pressure responses, times until CrSO2 reached 30%, or times until PbtO2 had increased by 0.1 kPa from its nadir. Peak PbtO2 values during resuscitation were 4.2 (3.3-5.4), 12 (6.4-15), and 25 (15-36) kPa. Thus, pure oxygen did not accelerate the recovery of circulation or of cerebral oxygenation, while even a brief exposure caused cerebral hyperoxia.
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In newborn infants, closed endotracheal tube (ETT) suction may reduce associated adverse effects, but it is not clear whether ventilation is maintained during the procedure. We aimed to determine the effect of ETT size, catheter size, and suction pressure on ventilation parameters measured distal to the ETT. Suction was performed on a test lung, ventilated with conventional (CMV) and high-frequency oscillatory ventilation (HFOV) using ETT sizes 2.5-4.0 mm, catheter sizes 5-8 French gauge (Fr), and suction pressures 80-200 mm Hg. ⋯ Loss of VT, inflation pressure (CMV), and pressure amplitude (HFOV) occurred primarily with insertion of the catheter, and loss of end-expiratory pressure (CMV) and mean tracheal pressure (HFOV) occurred with the application of suction. Circuit pressures were reduced to lesser degree. We conclude that airway pressures and VT are not maintained during closed endotracheal suction with either CMV or HFOV, and choice of equipment and settings will affect the degree of interruption to ventilation.