选择 pH 值截断值以安全验证鼻胃管放置位置：决策分析建模方法。
Selecting pH cut-offs for the safe verification of nasogastric feeding tube placement: a decision analytical modelling approach.
机构信息
Department of Surgery and Cancer, St Mary's Hospital, Imperial College London, London, UK.
Specialist Surgery, Royal Devon and Exeter Hospital NHS Foundation Trust, Exeter, UK.
出版信息
BMJ Open. 2017 Nov 4;7(11):e018128. doi: 10.1136/bmjopen-2017-018128.
OBJECTIVES
The existing British National Patient Safety Agency (NPSA) safety guideline recommends testing the pH of nasogastric (NG) tube aspirates. Feeding is considered safe if a pH of 5.5 or lower has been observed; otherwise chest X-rays are recommended. Our previous research found that at 5.5, the pH test lacks sensitivity towards oesophageal placements, a major risk identified by feeding experts. The aim of this research is to use a decision analytic modelling approach to systematically assess the safety of the pH test under cut-offs 1-9.
MATERIALS AND METHODS
We mapped out the care pathway according to the existing safety guideline where the pH test is used as a first-line test, followed by chest x-rays. Decision outcomes were scored on a 0-100 scale in terms of safety. Sensitivities and specificities of the pH test at each cut-off were extracted from our previous research. Aggregating outcome scores and probabilities resulted in weighted scores which enabled an analysis of the relative safety of the checking procedure under various pH cut-offs.
RESULTS
The pH test was the safest under cut-off 5 when there was ≥30% of NG tube misplacements. Under cut-off 5, respiratory feeding was excluded; oesophageal feeding was kept to a minimum to balance the need of chest X-rays for patients with a pH higher than 5. Routine chest X-rays were less safe than the pH test while to feed all without safety checks was the most risky.
DISCUSSION
The safety of the current checking procedure is sensitive to the choice of pH cut-offs, the impact of feeding delays, the accuracy of the pH in the oesophagus, as well as the extent of tube misplacements.
CONCLUSIONS
The pH test with 5 as the cut-off was the safest overall. It is important to understand the local clinical environment so that appropriate choice of pH cut-offs can be made to maximise safety and to minimise the use of chest X-rays.
TRIAL REGISTRATION NUMBER
ISRCTN11170249; Pre-results.
目的
现有的英国国家患者安全管理局（NPSA）安全指南建议测试鼻胃（NG）管抽吸物的 pH 值。如果观察到 pH 值为 5.5 或更低，则认为喂养是安全的；否则建议进行胸部 X 光检查。我们之前的研究发现，在 5.5 时，pH 值测试对食管放置的敏感性不足，这是喂养专家确定的一个主要风险。本研究旨在使用决策分析建模方法系统评估 pH 值测试在 1-9 截止值下的安全性。
材料和方法
我们根据现有的安全指南规划了护理途径，其中 pH 值测试作为一线测试，随后进行胸部 X 光检查。决策结果根据安全性在 0-100 分制上进行评分。我们从之前的研究中提取了每个截止值下 pH 值测试的灵敏度和特异性。汇总结果评分和概率得出加权评分，使我们能够分析在各种 pH 值截止值下检查程序的相对安全性。
结果
当 NG 管错位率≥30%时，pH 值测试在截止值 5 时最安全。在截止值 5 下，排除了呼吸喂养；为了平衡 pH 值高于 5 的患者对胸部 X 光检查的需求，食管喂养保持在最低限度。常规胸部 X 光检查不如 pH 值测试安全，而不进行任何安全检查而进行喂养则是最危险的。
讨论
当前检查程序的安全性对 pH 值截止值的选择、喂养延迟的影响、食管中 pH 值的准确性以及管错位的程度敏感。
结论
总体而言，以 5 为截止值的 pH 值测试最安全。了解当地的临床环境很重要，以便能够做出适当的 pH 值截止值选择，以最大限度地提高安全性并尽量减少胸部 X 光检查的使用。
试验注册号
ISRCTN86632101；预结果。
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