Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài: Pulmonary hemodynamic responses to in utero ventilation in very immature fetal sheep | Allison et al. Respiratory Research 2010 11 111 http content 11 1 111 RESPIRATORY RESEARCH RESEARCH Open Access Pulmonary hemodynamic responses to in utero ventilation in very immature fetal sheep 1 1 1 2 3 4 Beth J Allison Kelly J Crossley Sharon J Flecknoe Colin J Morley Graeme R Polglase Stuart B Hooper Abstract Background The onset of ventilation at birth decreases pulmonary vascular resistance PVR resulting in a large increase in pulmonary blood flow PBF . As the large cross sectional area of the pulmonary vascular bed develops late in gestation we have investigated whether the ventilation-induced increase in PBF is reduced in immature lungs. Methods Surgery was performed in fetal sheep at 105 d GA n 7 term 147 d to insert an endotracheal tube which was connected to a neonatal ventilation circuit and a transonic flow probe was placed around the left pulmonary artery. At 110 d GA fetuses n 7 were ventilated in utero IUV for 12 hrs while continuous measurements of PBF were made fetuses were allowed to develop in utero for a further 7 days following ventilation. Results PBF changes were highly variable between animals increasing from mL min to a maximum of mL min in four fetuses after 10 minutes of ventilation. In the remaining three fetuses little change in PBF was measured in response to IUV. The increases in PBF measured in responding fetuses were not sustained throughout the ventilation period and by 2 hrs of IUV had returned to pre-IUV control values. Discussion and conclusion Ventilation of very immature fetal sheep in utero increased PBF in 57 of fetuses but this increase was not sustained for more than 2 hrs despite continuing ventilation. Immature lungs can increase PBF during ventilation however the present studies show these changes are transient and highly variable. Introduction Very preterm infants 28 weeks gestation are born during the canalicular stage of lung development when the lungs are .
