ENDOTRACHEAL SUCTIONING--OPEN VS. CLOSED SYSTEMS

本研究的目的是比较一个开放的系统， 需要与呼吸机断开连接的补充氧气 使用适配器和体积控制的封闭系统 通风机 潮气量和150%潮气量时的肺充气 在给药前、给药期间和给药后， 呼气末压力为零时气管内吸痰， 呼气末正压（PEEP）。 所选 将在油酸中监测心肺状态指数 正常人急性呼吸衰竭酸损伤模型 肺血管阻力增加， 血管阻力 杂种犬（22-27 kg）（n=56）将 麻醉、插管和机械通气（MA-1）。 右心房、肺动脉、主动脉、胸内和气道 将连续测量压力和主动脉血流量。 动脉样本（动脉血气）将在 基线，在三个抽吸/充气期之前和之后， 在30秒时。恢复维护后间隔1分钟 通气，并以1分钟间隔再持续8分钟。 同时进行动脉和肺动脉采样（对于动脉 和混合静脉氧张力和饱和度）和肺动脉 将在基线处、1分钟时获得毛细楔压。 恢复维护通风后，9分钟。 从这些 直接测量肺泡-动脉氧分压差， 动静脉氧分压差，心脏分流，氧 转运，右心室充盈压，右心室 后负荷，左心室前负荷，总外周阻力， 并计算肺血管阻力。 由于 最多可以在单个动物上运行六个变化， 研究将在四个系列中进行，三个系列具有2 x 3的析因 设计和一个2 x 2析因设计， 根据平衡残差的拉丁方设计应用 方面的影响. 将通过ANOVA分析重复测量的数据 并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.