JPED Journal

1.      Introduction

Achievement of adequate nutrition is paramount to the recovery of critically ill children. Many children admitted to the Pediatric Intensive Care Unit (PICU), however, are not able to eat by mouth and must therefore rely on intravenous feedings or specialized enteral nutrition.Enteral Nutrition (EN) is the preferred routeof nutrient delivery in critically illchildren with a functional gastrointestinal tractbecause of its lower complication rate, lower cost, and beneficial effects on the GI mucosa[1-5]. Additionally, early EN(started within 48 hours of admission to the ICU), can improve protein intake (which is desirable during the acute phase of illness) and may have a survival benefit[6-10].

Because critically ill children often have acute and/or chronic conditions that delay gastric emptying, they are at risk for reflux, feeding aspiration and pneumonia when a feeding tube is placed into the stomach. Risk for theses adverse events is further complicated by stomach-distending therapies such as non-invasive positive pressure[11].Therefore, many clinicians (including those at our institution) favor placing a feeding tube past the pylorus and into the small intestine. While recent guidelines for the provision and assessment ofnutrition support therapy in the pediatric critically ill patient favor the gastric route for EN delivery, they do recognize that the postpyloric or smallintestinal site is advisable for children unable to tolerate gastric feeding or those athigh risk for aspiration [1].This placementmay allow for a greater amount of nutrition to be successfully and safely delivered[11,12].

Placement of Transpyloric (TP) tubes in children, however, can be a challenge. Consequently, bedside placement has been aided by promotility agents, patient positioning and non-invasive devices. Prior to 2014, our PICU routinely used either metoclopramide or erythromycin to aid in correct TP tube positioning.  Recently, our PICU purchasedan Electromagnetic Device (EMD) to aid in TP tube placement and it appears that co-administration of promotility agents has declined substantially.Reports describing the use of EMD in critically ill children have been published,[13-17] but these reports focus on feasibility, safety, efficiency and radiation exposure to determine placement. The use of promotility agents was not considered in these previous reports.  Therefore, the primary aim of this study is to describe thesuccess rate of EMD assistance for TP feeding tube placement in a cohort of critically ill children with a secondary aim focused on the use of promotility agents to augment successful placement. 

2.      Methods

2.1.  Study Design and Setting

This was a retrospective review of patientsadmitted to a32-bed medical/surgical PICU in a large free-standing tertiary care pediatric hospital during a one-year study period (January 1, 2014- January 1, 2015). This study protocol was reviewed and approved by the Colorado Multiple Institutional Review Board with a waiver of informed parent/subject consent.We included all patients who had placement of an 8Fr (or larger) feeding tube with the assistance of the CORTRAK^® EMD (Cardinal Health, Dublin Ohio). Feeding tubes were placed by a core group of PICU nurses, who underwent special training to use the device.Promotility use was defined as the administration of metoclopramide and/or erythromycin, either before placement of thefeeding tube or after placement to propel the tip of the tube into the duodenum.

The following data were collected and reviewed: (i) Patient information: sex, age, weight, Pediatric Risk of Mortality Score (PRISM III), mode of respiratory support and diagnostic category (respiratory failure, trauma/surgical and other). (ii) Feeding tube placement: promotility medication exposure (name of promotility medication, dose, route and timing of administration in relation to tube placement), method used to validate proper tube placement, number of placement deviations and size of feeding tube placed; (iii) Outcomes: success rates of achieving proper feeding tube placement, number of radiographs required and time to initiate EN (from admission to PICU and from placement of TP tube).Successful placement of EN feeding tube was the primary outcome variable and was defined as the tip of the feeding tube in the first part of the duodenum or beyond, per an abdominal radiograph obtained after placement and interpreted by a pediatric radiologist. Secondary outcomes included use of promotility agents and time to initiate enteral feeds.

2.2.  Primary Data Abstraction and Analysis

Outcome measures and patient variables were extracted from the Electronic Medical Record (EMR) by three investigators using a standardized data collection form developed by the investigative group. To improve accuracy and minimize inconsistencies, all records underwent a second data abstraction by a different investigator. Discrepancies in coding were resolved after agreement by all investigators. Demographic and clinical characteristics of the cohort were described and compared between the two groups.  Results are presented as mean ±Standard Deviation (SD) and range, median (IQR)or percentage,as indicated. Two-sample t-tests, Fishers Exact Tests, and Mann-Whitney U testswere used to detect differences between patient groups, for continuous, non-normally distributed continuous and categorical variables. Logistic regression was used to test the association between promotility use and successful feeding tube placement, after adjusting for relevant demographic and clinical characteristics. Statistical analysis was performed using Excel 2016 Softwareand R version 3.4.1. Significance was set at an alpha of 0.05.

3.      Results

A total of 223 TP tubes were placed during the 1-year study period. Thirty-seven attempts were in infants with feeding tubes that were too small for EMD guidance (16.6%) and 5 attempts were in patients with incomplete EMR data, leaving a total of 182 placements eligible for review. The most common feeding tube size was 8Fr (72%), followed by 10Fr (27%).  The mean age and weight of the cohort was5 yrs and 21.5 kg, respectively. The overall success rate of proper TP feeding tube placement was 85% for the entire cohort. Initial confirmation of tube placement was performed by radiographic examination in 96% of cases and pH paper (with secondary confirmation by radiographic examination) in 4% of cases.

A promotility agent was used in 25 (14%) attempts compared to 157 (86%) initial attempts without. A comparison between patients exposed to a promotility agent and those who were not is illustrated in Table 1 and does not identify major differences. Figure 1 demonstrates the success rates between groups. Initial success rate was 76% (Promotility Group) and 88% (Non-Promotility Group). There was not a significant association between use of a promotility agent and initial success of tube placement after adjusting for age, weight, PRISM III score, use of positive pressure ventilation at time of tube placement and diagnosis; p=0.21.

The choice of promotility agent was weighted heavily towards metoclopramide. Eighteen (of 25) patients (72%) received intravenous metoclopramide (0.1 mg/kg) and five patients (20%) received oral metoclopramide. One patient received oral erythromycin (3 mg/kg) and one patient received both oral erythromycin and intravenous metoclopramide. The median time of promotility administration was 45 minutes prior to TP placement. There was, however, a fair amount of variability, with one patient receiving therapy 150 minutes before TP insertion and six receiving therapy after placement in an effort to propel the mispositioned tube (viewed on EMD computer screen or initial radiograph).

Failed attempts (n=27) were converted to successful placements in 3 of 6 patients in the promotility group (50%) and 9 of 21 in the non-promotility group (43%). Two patients (1 in each group) required tube placement in interventional radiology under fluoroscopy. One patient in the non-promotility group had a mispositioned tube that extended down the left main stem bronchus, perforated the lung and coiled within the pleural space, ultimately requiring a chest tube. The proportion of patients who required 1 radiograph, vs. 2 or 3, was20 (80%) (Promotility Group) and 140 (89%) (Non-Promotility Group); p=0.19.

Time to initiate enteral feeding since admission to the PICU was similar between the promotility and non-promotility groups (median and IQR: 28 (20, 42) vs 24 (16, 41) hours, p= 0.25). In addition, there was no difference in the time to begin enteral feedings following placement of TP tube between groups (median and IQR: 3 (1, 6) vs 2 (1, 4) hours, p= 0.22).

4.      Discussion

This retrospective evaluation of critically ill children described the success rate of proper TP feeding tubeplacement in the era of EMD guidance, both with and without the aid of a promotility agent. Overall success rate was high (at 85%) and although promotility use was uncommon, it did not appear to influence the rates ofaccurate placement. In addition, the number of radiographs and the time to initiate enteral feedings (from admission to the PICU and from placement of the TP tube) were not different between groups of patients.

Swift and accurate placement of a feeding tube is necessary when promoting the strategy of early enteral nutrition. This feeding strategy has been advocated to improve nitrogen balance, reduce inflammation, enhance innate immune function and augment GI tract integrity[7-10]. Although both gastric and small bowel feedings can deliver appropriate caloric and protein intake,small bowel feedingsare often preferred in children at risk for gastroparesis and aspiration. Additional advantages of post pyloric feedings include faster advancement and achievement of goal nutrition (due to fewer interruptions) and improved tolerance in patients requiring positive pressure ventilation[18].Our critical care unit favors TP feedings in children on both non-invasive and invasive positive pressure ventilation, as evidenced by the high percentage of ventilated patients observed in this study.

Many techniques have been developed for proper positioning of post pyloric feeding tubes. Historically, the highest success rates have been documented with radiographic visualization using fluoroscopy[13,14]. This technique, however, has limitations including risk of radiation exposure, requirement of patient transport and high cost. Therefore, bedside techniques have become increasingly popular.“Blind placement” (using external anatomic landmarks formeasurements, air and/or gastric insufflationto propel tube and auscultation for placement confirmation) can be performed by skilled clinicians at the bedside.Although this technique is economical and effective when experienced clinicians and radiographic confirmation are used,there is wide variability in success noted in the literature[15-17,19].In addition, serious complications secondary to malposition have been reported. These complications prompted a patient safety action alert by the Children’s Hospital Association that warned against using the blind technique in children without radiographic confirmation[20].

Promotility agents (Metoclopramide and Erythromycin) have been studied in children with mixed results. Prior to the introduction of an EMD into our practice, we routinely administered a promotility agent 30-45 minutes before TP tube placement. Successful bedside TP feeding tube placement with the aid of metoclopramide has been reported[10]. Ninety children (age: 1week-15 yrs) with non-weighted silicone rubber 6Fr or 8Fr tubeswere able to achieve 93% success with metoclopramide, air insufflation and positioning[10]. However, since there was no comparison group, the influence of metoclopramide alone could not be determined. In another report, 74 children were randomly assigned to receive erythromycin or placebo 60 minutes prior to TP placement[21]. This study failed to demonstrate any advantage of promotilityuse on proper TP positioning or enhancement of duodenal tubes further into the small bowel. A third trial, performed in 75 critically ill children, found no influence of placement technique on the success rates of TP positionusing standard positioning technique, standard technique plus gastric insufflation or standard technique with preinsertingerythromycin[22].These mixed results are also described within the adult literature, with two 2 meta-analyses failing to demonstrate benefit from metoclopramide[23-31].

Reports ofEMD assistance in children have also been published[32-36].These devices can track and display the position of a feeding tubeon a computer screen and allow the user to see the path of the feeding tube as it proceeds down the esophagus, through the stomach and into the small intestine. The previous work published in children is very promising, yet either uniformly used promotility agents[33]did not separate results based on the co-administration of promotility agents[32,36] or did not mention the use of promotility agents[34,35].October et al evaluated 50 children using EMD assistance and reported an overall success rate of 82%. Twenty percent of children (n=10), however, received a prokinetic agent and results were not categorized based on this exposure. ¹⁸ Kline reported the use ofEMD guidance (n= 22) compared to standard blind technique (n=27) for placement of TP feeding tubes in children[33]. Successfulplacements with EMD was 100% versus 92% in the blind technique group (p=0.49) – yet all patients received pre-placement metoclopramide. Finally, a recent report comparing the success rates and extent of radiation exposure between two groups of children requiring a TP feeding tube with (n=43) and without (n=30) the aid of EMD was published[32]. Children in the EMD group experienced higher rates of successful transpyloric tube placement (p=0.009) with significantly lower radiation exposure (p= 0.006). The use of promotility agents was low in the EMD group (at 7%) but was not further analyzed. The current evaluation is the largest study to date that describes postpyloric tube placement in children using EMD (both with and without promotility agents) and attempts to discern the prevalence of promotility use and the influence of promotility exposure on success. Since the establishment of EMD into our unit, the overall use of promotility agents has declined and is now quite low.

Although adverse events related to tube malposition are less likely when using an EMD guidance system, they are still reports of misdirected tubes and subsequent patient harm[37-38]. The current report had one mispositioned tube in the lung that resulted in the requirement of a chest tube. According to the Food and Drug Administration’s Manufacture and User Facility Device Experience (MAUDE) database, the lung is the most common location of misplaced feeding tubes reported with CORTRAK EMD guidance system[37]. Some of these misdirected tubes resulted in pneumothorax, bleeding, and even death. This underscores the importance of a skilled user for tube placement and confirmation of anatomic position by a radiograph.

There are limitations to this work that must be acknowledged.  First, the study design did not allow for control of factors that may have impacted outcomes. In particular, the decision to use a promotility agent was completely at the discretion of the prescribing provider and the resulting study groups were unequal. It is possible that circumstances not readily obvious with a retrospective study design could have influenced the decision to use a promotility agent. We attempted to control for this limitation by performing a multiple logistic regression but were limited to inclusion of variables previously measured.In addition, this study reflects the experience of a singlecenter with a group of trained PICU nurses for TP placement.

In conclusion, this report describes thehigh success rates achieved for proper TP feeding tube placement using EMD guidance in a cohort of critically ill children. This report further highlights the decline in concomitant promotility use as a method to augment proper placement and suggests that promotility administration does not appear to influence the rate of successful positioning, number of radiographs required nor time to initiation of enteral feeding. It seems plausible that the high success rates achieved with EMD guidance and expert bedside nursing placement may eliminate the need for routine promotility agents. However, a definitive answer to the utility of promotility agents in the placement of TP tubes cannot be fully understood without a prospective, randomized trial.

Funding Source: This work was not funded by any grant or other resources

Financial Disclosure: The authors have no financial relationships relevant to this article to disclose.

Conflict of Interest: The authors have no conflicts of interest to disclose.

Contributor Statements:

All authors were responsible for conceptualizing and designing the study; creating the data collection form and reviewing data collection

Pamela Reiter was responsible for drafting the initial article, requesting and retrieving the data and initial analysis

Claire Palmer was responsible for final data analysis validation and interpretation

All authors were responsible for reviewing, revising and approving the final article and take responsibility for the paper as a whole

Figure 1: Description of Initial Transpyloric (TP) feeding tube placements using electromagnetic device guidance in 182 patients with (n=25) or without (n=157) the assistance of a promotility agent.

Table 1: Characteristics of 182 children requiring placement of a transpyloric feeding tube, with and without exposure to a promotility agent.

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