Poor validity of residual volumes as a marker for risk of aspiration in critically ill patients
Poor validity of residual volumes as a marker for risk of aspiration in critically ill patients
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DOI：
10.1097/01.ccm.0000153413.46627.3a
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发表时间：
2005-02-01
影响因子：
8.8
通讯作者：
Spain, DA
中科院分区：
文献类型：
--
作者：
McClave, SA;Lukan, JK;Spain, DA
背景和目标：残余容量（RV）升高被认为是误吸风险的标志，用于调节肠内管饲的输送。我们设计了这一前瞻性研究，以验证such use.Methods：危重病患者进行机械通气的医疗，冠状动脉，或外科重症监护病房在一所大学为基础的三级保健医院，放置在胃肠道内管喂养通过鼻胃管或经皮内镜胃造口术管，被列入本研究。给患者喂食Probalance（Nestle USA）以提供25 kcal/kg/天（每1，500 mL添加109个黄色显微镜珠和4.5 mL蓝色食用色素）。根据RV的管理，将患者随机分为两组：研究患者中RV> 400 mL或对照组中RV> 200 mL时停止肠内管饲。测定急性生理学和慢性健康状况评估（APACHE）III、肠功能评分和误吸风险评分。每4小时进行一次床边评估，持续3天，以测量RV，检测蓝色食用色素，检查患者位置，并收集气管和口咽的分泌物。通过荧光测定法检测气管/口咽样本中的黄色来定义吸入/返流事件。采用方差分析、斯皮尔曼相关分析、t检验、Tukey检验和Cochran-Armitage检验进行分析。对40例患者（平均年龄44.6岁;范围18 - 88岁; 70%为男性;平均APACHE III评分40.9 [范围12 - 85]）进行了评价（21例接受鼻饲，19例接受经皮内镜下胃造口术喂养）并进入研究。基于1，118份样本（531份经口样本，587份气管样本），每例患者的平均返流频率为31.3%（范围：0%-94%），所有返流事件的平均RV为35.1 mL（范围：0 - 700 mL）。每例患者的平均抽吸频率为22.1%（范围：0%-94%），所有抽吸事件的平均RV为30.6 mL（范围：0 - 700 mL）。返流和抽吸事件的中位RV均为5 mL。在RV的宽范围内，从0 mL增加到> 400 mL，反流和误吸的频率没有明显变化。误吸风险和肠功能评分与误吸或反流的发生率无关。在1,1118个样本中，只有3个（0.27%）检测到蓝色食用色素。RV：84.1%的患者为550 mL，1.4%的患者为> 400 mL。每个指定RV检测抽吸的灵敏度如下：400 mL = 1.5%; 300 mL = 2.3%; 200 mL = 3.0%;和150 mL = 4.5%。低RV不能保证不发生事件，因为当RV> 150 mL时，抽吸频率为23.0%。将停止肠内营养管喂养的指定RV从200 mL提高到400 mL不会增加风险，因为对照组（21.6%）和研究患者（22.6%）之间的误吸频率没有差异。与鼻胃管患者相比，经皮内镜胃造口术管患者的返流频率显著更低（分别为20.3%和40.7%; p = 0.046）。肺炎的发生率与反流或误吸的频率之间无相关性。蓝色食用色素不应用作临床监测。将鼻胃管转换为经皮内镜胃造口术管可能是降低误吸风险的成功策略。由于在广泛的RV范围内灵敏度较差，因此无法推导出用于识别抽吸的适当指定RV水平。研究结果不支持常规使用RV作为吸入风险的标志物。
Background and Aims: Elevated residual volumes (RV), considered a marker for the risk of aspiration, are used to regulate the delivery of enteral tube feeding. We designed this prospective study to validate such use.Methods: Critically ill patients undergoing mechanical ventilation in the medical, coronary, or surgical intensive care units in a university-based tertiary care hospital, placed on intragastric enteral tube feeding through nasogastric or percutaneous endoscopic gastrostomy tubes, were included in this study. Patients were fed Probalance (Nestle USA) to provide 25 kcal/kg per day (to which 109 yellow microscopic beads and 4.5 mL of blue food coloring per 1,500 mL was added). Patients were randomized to one of two groups based on management of RV: cessation of enteral tube feeding for RV > 400 mL in study patients or for RV > 200 mL in controls. Acute Physiology and Chronic Health Evaluation (APACHE) III, bowel function score, and aspiration risk score were determined. Bedside evaluations were done every 4 hrs for 3 days to measure RV, to detect blue food coloring, to check patient position, and to collect secretions from the trachea and oropharynx. Aspiration/regurgitation events were defined by the detection of yellow color in tracheal/oropharyngeal samples by fluorometry. Analysis was done by analysis of variance, Spearman's correlation, Student's t-test, Tukey's method, and Cochran-Armitage test.Results. Forty patients (mean age, 44.6 yrs; range, 18-88 yrs; 70% male; mean APACHE III score, 40.9 [range, 12-85]) were evaluated (21 on nasogastric, 19 on percutaneous endoscopic gastrostomy feeds) and entered into the study. Based on 1,118 samples (531 oral, 587 tracheal), the mean frequency of regurgitation per patient was 31.3% (range, 0% to 94%), with a mean RV for all regurgitation events of 35.1 mL (range, 0-700 mL). The mean frequency of aspiration per patient was 22.1% (range, 0% to 94%), with a mean RV for all aspiration events of 30.6 mL (range, 0-700 mL). The median RV for both regurgitation and aspiration events was 5 mL. Over a wide range of RV, increasing from 0 mL to > 400 mL, the frequency of regurgitation and aspiration did not change appreciably. Aspiration risk and bowel function scores did not correlate with the incidence of aspiration or regurgitation. Blue food coloring was detected on only three of the 1,1118 (0.27%) samples. RV was :550 mL on 84.1% and > 400 mL on 1.4% of bedside evaluations. Sensitivities for detecting aspiration per designated RV were as follows: 400 mL = 1.5%; 300 mL = 2.3%; 200 mL = 3.0%; and 150 mL = 4.5%. Low RV did not assure the absence of events, because the frequency of aspiration was 23.0% when RV was > 150 mL. Raising the designated RV for cessation of enteral tube feeding from 200 mL to 400 mL did not increase the risk, because the frequency of aspiration was no different between controls (21.6%) and study patients (22.6%). The frequency of regurgitation was significantly less for patients with percutaneous endoscopic gastrostomy tubes compared with those with nasogastric tubes (20.3% vs. 40.7%, respectively; p = .046). There was no correlation between the incidence of pneumonia and the frequency of regurgitation or aspiration.Conclusions. Blue food coloring should not be used as a clinical monitor. Converting nasogastric tubes to percutaneous endoscopic gastrostomy tubes may be a successful strategy to reduce the risk of aspiration. No appropriate designated RV level to identify aspiration could be derived as a result of poor sensitivity over a wide range of RV. Study results do not support the conventional use of RV as a marker for the risk of aspiration.