ENDOTRACHEAL SUCTIONING--OPEN VS. CLOSED SYSTEMS

这项研究的目的是比较开放的交付系统 需要与呼吸机断开连接的补充氧气 使用适配器和音量控制的封闭式系统 通风器。潮气量和150%潮气量时的肺膨胀 卷将在之前、期间和之后进行管理 呼气末压力为0和2的气管内吸气 呼气末正压(PEEP)水平。选定的 将在油酸中监测心肺状况的指标 正常大鼠急性呼吸衰竭的酸损伤模型 肺血管阻力和肺活量增加 血管阻力。杂种狗(22-27公斤)(n=56) 麻醉、插管和机械通气((MA-1)。 右心房、肺动脉、主动脉、胸腔内和呼吸道 将连续测量血压和主动脉血流量。 动脉样本(动脉血气)将在 基线，在三个吸气/充气时期前后， 30秒。间隔1分钟。POST返回维护 通风，1分钟。额外8分钟的间隔。 同时采集动脉和肺动脉样本(适用于动脉 和混合静脉血氧分压和血氧饱和度)和肺 毛细管楔形压力将在基线1分钟时获得。 后返回到维护通风，并在9分钟。从这些 直接测量动脉血氧分压差， 动-静脉氧分压差、心脏分流、氧气 运输，右室充盈压，右室 后负荷，左心室前负荷，总外周阻力， 并计算肺血管阻力。因为一个 最多可以在一只动物身上运行六种变异，这 研究将分四个系列进行，其中三个系列采用2 x 3阶乘 一个是2x2析因设计，另一个是变种 根据拉丁方设计应用，平衡残差 效果。数据将通过方差分析进行重复测量 并将进行适当的事后分析。

The aim of this study is to compare an open system of delivery of supplemental oxygen requiring disconnection from the ventilator to a closed system using an adapter and volume controlled ventilator. Lung inflations at both tidal volume and 150% tidal volume will be administered prior to, during and following endotracheal suctioning at zero end expiratory pressure and two levels of positive end expiratory pressure (PEEP). The selected indices of cardiopulmonary status will be monitored in the oleic acid-injured model of acute respiratory failure with normal pulmonary vascular resistance and with increased pulmonary vascular resistance. Mongrel dogs (22-27 kg) (n=56) will be anesthetized, intubated, and mechanically ventilated ((MA-1). Right atrial, pulmonary arterial, aortic, intrathoracic, and airway pressures and aortic blood flow will be measured continuously. Arterial samples (for arterial blood gases) will be drawn at baseline, before and after each of three suction/inflation periods, at 30 sec. intervals for 1 min. post return to maintenance ventilation, and at 1 min. intervals for 8 additional min. Simultaneous arterial and pulmonary arterial samples (for arterial and mixed venous oxygen tension and saturation) and pulmonary capillary wedge pressure will be obtained at baseline, at 1 min. post return to maintenance ventilation, and at 9 min.. From these direct measures aveolar-arterial oxygen tension differences, arterial-venous oxygen tension differences, cardiac shunt, oxygen transport, right ventricular filling pressure, right ventricular afterload, left ventricular preload, total peripheral resistance, and pulmonary vascular resistance will be calculated. Since a maximum of six variations can be run on a single animal, this study will be conducted in four series, three with 2 x 3 factorial designs and one with a 2 x 2 factorial design, with the variations applied according to a Latin Square design balanced for residual effects. Data will be analyzed by ANOVA for repeated measures and appropriate post hoc analyses will be performed.