DETECTING ASPIRATION ASSOCIATED WITH TUBE FEEDINGS

本研究的最终目的是提高机械通气管饲患者的安全性。由于这些患者有胃内容物反流的高风险，他们很容易发生危及生命的院内肺炎。在实践环境中努力及早发现这些事件，以便能够采取干预措施，防止发病和死亡。然而，护士往往不确定如何做到这一点，因为检测方案没有很好地定义；此外，目前使用的方法的敏感性和特异性也存在问题。所提出的工作的总体主要目的是确定这些目前使用的方法的准确性（观察气管分泌物中添加到管饲配方中的染料，检测气管分泌物中的葡萄糖以确定是否存在富含葡萄糖的配方）和一种潜在的新测试，包括检测气管分泌物中的胃蛋白酶。这项研究将需要240只实验兔插管和机械通气，然后将人胃液和染色肠内配方的混合物缓慢地注入它们的气管。五个自变量是：两种浓度的染料（0.8 ml/L和1.5 ml/L），三种浓度的葡萄糖在肠内配方（低、中、高），两种体积的液体（0.2 ml/kg/hr和0.33 ml/kg/hr），既往是否存在轻度肺损伤，以及观察时间（2,4和6小时）。在6小时的时间内，每2小时观察一次吸入气管分泌物，因变量包括：染料可见度、葡萄糖浓度和分泌物中胃蛋白酶浓度。20只对照动物气管内灌注生理盐水。该研究的第二个目的是确定在肺健康的家兔中是否有三个其他因变量（气道峰值压力，混合）来确定在肺健康的家兔中是否有三个其他因变量(气道峰值压力，混合静脉混合物读数，死后肺灌洗液中的中性粒细胞计数受到另一个独立变量的影响（240名急性病人使用或不使用胃酸抑制剂，这些人将为兔子提供气管灌注胃液）。研究完成后，这些动物将被安乐死，并洗肺检测中性粒细胞计数。数据将主要通过协方差重复测量分析（ANCOVAs）和主效应F检验进行分析。虽然不可能将动物的结果直接外推到人类，但本研究的结果将提供信息，帮助护士制定临床使用的方案，以更有效地监测机械通气管饲患者的吸入情况。

The ultimate goal of the proposed study is to increase the safety of mechanically ventilated tube-fed patients. Because these patients are at high risk for frequent micro-aspirations of regurgitated gastric contents, they are prone to potentially life-threatening nosocomial pneumonia. Efforts are made in practice settings to detect these events early so that interventions can be initiated to prevent morbidity and mortality. However, nurses are often unsure about how to accomplish this because protocols for detection are not well defined; further, there are questions about the sensitivity and specificity for currently used methods. The overall major aim of the proposed work is to determine the accuracy of these currently used methods (observing tracheal secretions for dye added to the tube-feeding formula, and testing for glucose in tracheal secretions to determine if glucose-rich formula is present) and a potential new test which consists of assaying for pepsin in tracheal secretions. The study will require 240 experimental rabbits who will intubated and mechanically ventilated prior to have a mixture of human gastric juice and dye-stained enteral formula slowly instilled into their tracheas. The five independent variables are: two concentrations of dye (0.8 ml/L and 1.5 ml/L), three concentrations of glucose in the enteral formulas (low, moderate, and high), two volumes of the fluid instilled (0.2 ml/kg/hr and 0.33 ml/kg/hr), presence or absence of prior mild lung injury, and time of observation (2, 4 and 6 hours). Observations will be made on suctioned tracheal secretions every 2 hours over a 6-hour period and dependent variables will consist of: visibility of dye, concentration of glucose, and concentration of pepsin in the secretions. Twenty control animals with have normal saline intratracheally instilled. A secondary aim of the study is to determine in rabbits with healthy lungs whether three other dependent variables (peak airway pressures, mixed to determine in rabbits with healthy lungs whether three other dependent variables (peak airway pressures, mixed venous admixture readings, and neutrophil counts in post mortem pulmonary lavage fluid) are affected by an additional independent variable (use or non-use of gastric acid inhibiting agents by the 240 acutely ill humans who will provide the gastric juice for tracheal instillation in the rabbits). Following completion of the study, the animals will be euthanized and their lungs lavaged for neutrophil counts. Data will primarily be analyzed by repeated measures analyses of covariance (ANCOVAs) and main-effect F tests. While direct extrapolation of results from animals to humans is not possible, results from this study will provide information that will help nurses develop protocols for use in clinical settings to more effectively monitor for aspiration in mechanically ventilated tube-fed patients.