DETECTING ASPIRATION ASSOCIATED WITH TUBE FEEDINGS

这项研究的最终目的是提高机械通气管饲患者的安全性。由于这些患者经常微量吸入消化道胃内容物的风险很高，他们很容易发生潜在的危及生命的医院获得性肺炎。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，预防发病和死亡。然而，护士往往不确定如何实现这一点，因为检测协议没有很好地定义;此外，目前使用的方法的灵敏度和特异性也存在问题。拟议工作的总体主要目标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，并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）和潜在的新检测，包括测定气管分泌物中的胃蛋白酶。该研究将需要240只实验兔，在将人胃液和染色肠内配方的混合物缓慢滴入其气管之前，对这些兔进行插管和机械通气。五个独立变量为：两种染料浓度（0.8 ml/L和1.5 ml/L）、肠内配方中的三种葡萄糖浓度（低、中和高）、两种液体滴注量（0.2 ml/kg/hr和0.33 ml/kg/hr）、是否存在既往轻度肺损伤以及观察时间（2、4和6小时）。在6小时内，每2小时对吸入的气管分泌物进行一次观察，因变量包括：分泌物中染料的可见度、葡萄糖浓度和胃蛋白酶浓度。对20只对照动物进行气管内滴注生理盐水。研究的第二个目的是确定在肺健康的兔子中，（峰值气道压力，混合以确定在具有健康肺的兔子中是否存在三个其它因变量（峰值气道压力，混合静脉混合物读数，和死后肺灌洗液中的中性粒细胞计数）受另外的自变量影响（由240名急性病患者使用或不使用胃酸抑制剂，这些患者将提供胃液用于家兔的气管滴注）。研究完成后，将对动物实施安乐死，并对其肺部进行灌洗，以测定中性粒细胞计数。主要通过重复测量协方差分析（ANCOVA）和主效应F检验分析数据。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，帮助护士制定用于临床环境的方案，以更有效地监测机械通气管饲患者的误吸。

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.