Criteria abstracted from The Users' Guide to Medical Literature, from the Health Information Research Unit and Clinical Epidemiology and Biostatistics, McMaster University

Highlighted lines and questions below provide links to the pertinent description of criteria in The EBM User's Guide, now available at the Canadian Centres for Health Evidence

Article Reviewed:

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Gastric vs Small-Bowel Feeding in Critically Ill Children Receiving Mechanical Ventilation: A Randomized Controlled Trial.

Meert KL, Daphtary KM, Metheny NA.

Chest 2004;126 872-878. [abstract]

Reviewed by Sami Rishmawi MD, Advocate Hope Children's Hospital, Oak Lawn, IL

Review posted March 8, 2005

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I. What is being studied?:

The study objective:

To determine the risks and benefits of feeding tube position (small-bowel vs. gastric) in critically ill pediatric patients receiving mechanical ventilation.

The study design:

A single center, non-blinded, randomized control trial

The patients included:

Patients < 18 years of age on mechanical ventilation and receiving enteral feedings (n=62).

The patients excluded:

1. Overt gastrointestinal (GI) tract bleeding
2. Anatomic obstruction of the GI tract
3. Recent esophageal or GI surgery, and
4. Presence of a percutaneous feeding tube.

The interventions compared:

Gastric and small-bowel feeding tube placement

The outcomes evaluated:

There are two outcomes in this study. The primary one is the percentage of daily caloric goals achieved during tube feeding, and the secondary outcome is the incidence of aspiration (by detection of pepsin in tracheal aspirates) and other complications, e.g., vomiting, diarrhea, and abdominal distention.

II. Are the results of the study valid?

Primary questions:

1. Was the assignment of patients to treatments randomized?

Yes. The assignments of patients to treatments were randomized. Randomization was performed in blocks of 12 with a ratio of five gastric to seven small-bowel patient assignments (based upon anticipated 70% success rate of bedside transpyloric tube placement). If an nj-assigned patient could not have their tube placed, they exited the study, i.e., they did not cross over to the ng group. Patients were also stratified by the presence or absence of known gastroesophageal reflux.

2. Were all patients who entered the trial properly accounted for and attributed at its conclusion?

Was followup complete?

Yes. The patients were followed to the point when enteral feedings were not required ( or a maximum of 14 days) and no follow up beyond that was mentioned. PICU and hospital length of stay were recorded. 74 patients were randomized; 12 exited for inability to place a tube. The remaining 62 patients (32 in the ng group, 30 in the nj group) were studied.

Were patients analyzed in the groups to which they were randomized?

Yes, it seems that patients were analyzed with an intention-to-treat analysis. While there was cross over between the groups where tubes became dislodged from small-bowel group and could not be replaced, the patient remained in the small-bowel group for the purpose of data analysis. This occurred in 5 of the patients assigned to small bowel feeding. Of the 245 tube feeding days in the small bowel group, 219 days involved feeds delivered via a transpyloric tube.

Secondary questions:

3. Were patients, health workers, and study personnel "blind" to treatment?

No. Clinicians were not blinded to feeding tube placement. It appears no one was blinded - the study personnel placed the tubes therefore they also knew which patient was being fed by which means. In addition, because of the daily chest radiographs were obtained on all patient for the duration of mechanical ventilation and for several days after extubation, the upper abdomen could be usually be sufficiently visualized on most chest radiographs and determine the location of the feeding tube placement.

4. Were the groups similar at the start of the trial?

Yes. Both groups at the start of the trial were similar in regard of baseline characteristics. At baseline, the groups had similar age, gender, incidence of gastroesophageal reflux, cuffed endotracheal tube use, abnormalities on chest radiograph, PRISM score at PICU admission, weight, % ideal body weight, prealbumin levels, intensive care days at randomization and days fasted prior to feeding.

5. Aside from the experimental intervention, were the groups treated equally?

The feeding regimen was applied similarly in both groups, including reasons for holding feeding. However, feedings were advanced at the bedside nurses' discretion. Reasoning that the likelihood of gastric distention and/or aspiration of feedings would be low in the small bowel feeding tube patients, nurses could have advanced feedings more aggressively in this group. This could bias the study results in favor of this group being more likely to achieve feeding goals. We don't know if they were treated equally - the authors offered no mention or comparisons, or were the two groups provided the same bowel regimens, protein supplements, feed advancement, sedation, etc?

III. What were the results?

1. How large was the treatment effect?

This study concluded that small-bowel feeds enabled more calories to be delivered to critically ill children receiving mechanical ventilation than did gastric feeds. However it is not known whether the difference found between two groups in the percentage of the caloric goals achieved is clinically important.

In the gastric feeding group, daily caloric goals were achieved 30 ± 23% of the time compared to 47 ± 22 % in the small-bowel group (p = 0.01). The incidence of aspiration was not different between the gastric and small-bowel groups (19 gastric versus 20 small-bowel patients, p = 0.8).

A daily caloric goal was determined for each patient based on their age, body weight and RDA (Recommended dietary allowances, reference 24). The amount of calories that the patient actually received each day was calculated from the volume of formula received and the caloric density of the formula. The calories actually received in a 24 hour period divided by the 24 hour goal = the percent of daily caloric goal achieved. This variable was determined daily for each patient.

2. How precise was the estimate of the treatment effect?

Although the small bowel feeding group had a statistically higher proportion of patients in whom the feeding goal was reached, the 95% confidence intervals for these estimates (30 vs 47%) were not provided, but from data provided we can calculate 95% confidence interval for the difference of 17% between the two groups. With 95% confidence, we can state that the difference lies between 5.8% and 28.2%.

IV. Will the results help me in caring for my patients?

1. Can the results be applied to my patient care?

Yes, the patients in this study were representative of the kind of patients I care for in our PICU.

2. Were all clinically important outcomes considered?

The outcomes in this study relate to the primary hypothesis whether small-bowel vs. gastric feeds provided better nutrient delivery and reduced feeding complications, but there was no mention of other complications related to tube insertion, duration of tube position, etc.

3. Are the likely treatment benefits worth the potential harms and costs?

This is a good study and this is the first study in the pediatric population dealing with small-bowel vs. gastric tube placement. The benefit was better nutrient delivery, but whether that really affects the patient's outcome is uncertain. The harms seem minimal - although they also failed to show that the harm of potential aspiration with NG feedings was less - and the costs would also likely be minimal, as these tubes are not that much more expensive than regular ng feeding tubes. On balance, the use of nj tubes appears to have a favorable harm/cost to benefit ratio. However, the same caloric goals could potentially be met with different or more flexible feeding regimens, without the "need" to use the nj route.

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