Metheny Norma A, Pawluszka Ann, Lulic Melanie, Hinyard Leslie J, Meert Kathleen L
Norma A. Metheny is a professor of nursing at Saint Louis University, St Louis, Missouri. Ann Pawluszka is a research coordinator, Melanie Lulic is a research assistant, and Kathleen L. Meert is a professor of pediatrics and chief of critical care medicine at the Children's Hospital of Michigan, Wayne State University, Detroit, Michigan. Leslie J. Hinyard is an associate professor and associate director for academic affairs at the Center for Health Outcomes Research, Saint Louis University.
Am J Crit Care. 2017 Nov;26(6):466-473. doi: 10.4037/ajcc2017378.
Inadvertent positioning of a nasogastric tube in the lung can cause serious complications, so identifying methods to detect improperly inserted tubes is imperative.
To compare the sensitivity, specificity, and negative and positive predictive values of 4 pH cut points (< 4.0, < 4.5, < 5.0, and < 5.5) in differentiating gastric and tracheal aspirates under various treatment conditions and to explore the utility of a pepsin assay for distinguishing between gastric and tracheal aspirates.
Gastric and tracheal aspirates were collected from critically ill infants undergoing mechanical ventilation who had nasogastric or orogastric feeding tubes. Aspirates were tested with colorimetric pH indicators and a rapid pepsin assay. Information about treatment conditions was obtained from medical records.
Two hundred twelve gastric aspirates and 60 tracheal aspirates were collected from 212 patients. Sensitivity was highest and specificity was lowest at the gastric aspirate pH cut point of less than 5.5. Positive predictive values were 100% at all pH cut points less than 5.0. Negative predictive values were higher at the pH cut point of less than 5.0 than at cut points less than 4.5. A higher percentage of pepsin-positive readings was found in gastric aspirates (88.3%) than in tracheal aspirates (5.4%).
For a desired positive predictive value of 100%, a pH cut point of less than 5.0 provides the best negative predictive values, regardless of gastric acid inhibitor administration and feeding status. The pepsin assay is promising as an additional marker to distinguish gastric from tracheal aspirates.
鼻胃管意外插入肺部可导致严重并发症，因此确定检测插管不当的方法势在必行。
比较4个pH切点（<4.0、<4.5、<5.0和<5.5）在不同治疗条件下区分胃液和气管吸出物的敏感性、特异性、阴性和阳性预测值，并探讨胃蛋白酶检测在区分胃液和气管吸出物中的作用。
从接受机械通气且有鼻胃管或口胃管喂养的重症婴儿中收集胃液和气管吸出物。用比色pH指示剂和快速胃蛋白酶检测法对吸出物进行检测。从病历中获取有关治疗条件的信息。
从212例患者中收集了212份胃液吸出物和60份气管吸出物。在胃液吸出物pH切点小于5.5时，敏感性最高，特异性最低。在所有小于5.0的pH切点处，阳性预测值均为100%。小于5.0的pH切点处的阴性预测值高于小于4.5的切点处。胃液吸出物中胃蛋白酶阳性读数的百分比（88.3%）高于气管吸出物（5.4%）。
对于期望的100%阳性预测值，无论是否使用胃酸抑制剂和喂养状态如何，小于5.0的pH切点提供最佳的阴性预测值。胃蛋白酶检测作为区分胃液和气管吸出物的额外标志物很有前景。
