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University of Virginia Health System

Nutrition Support E-Journal Club

October 2009

 

 

Greetings,

Charlottesville is a glorious in October, with the foliage putting on a show of red and gold displaying their peak colors.   Arriving at work on those cool mornings with brilliant sun requires discipline (and threat of imminent trouble from your teammates) to resist the lure of escaping into Blue Ridge for a hike.  We hosted another great group of trainees, who hailed from Alabama, North Carolina and Korea.          

October Citation: 

Nishiwaki S, Araki H, Shirakami Y, et al.  Inhibition of gastroesophageal reflux by semi-solid nutrients in patients with percutaneous endoscopic gastrostomy.  JPEN J Parenter Enteral Nutr. 2009 Sep-Oct;33(5):513-9.

Summary: 

This was a prospective, randomized, non-blinded before-after study investigating the effect of thickening enteral nutrition formulas with agar on esophageal reflux and gastric emptying.  The study population was a sample of 15 patients with a history of aspiration pneumonia or vomiting after PEG tube placement. 

Subjects received either a 200mL bolus of either liquid tube feeding, or 100mL tube feeding mixed with 100mL water-agar that became pudding consistency (final concentration 0.5% agar).  There was a minimum 2 week wash out period between administration of the liquid and semi-solid feeding, and a random order of which feeding would be administered first. Gastroesophageal reflux and gastric emptying were measured by adding a radiolabel to the nutrient solutions (technetium Tc 99m tin colloid) and scanning with a scintillation camera in the supine position up to 90 minutes after the bolus feeding via the PEG.  Gastroesophageal reflux was defined as the maximal percentage of esophageal counts compared to the total infused radioactivity.  Gastric emptying time was defined as the time for 50% of the initial radioactivity to empty from the stomach.  The enteral formula used was a 1 calorie/mL polymeric formula with 18% protein, 20% fat, and 62% carbohydrates (Racol, Otsuka Pharmaceutical Co., Ltd., Iwate, Japan).

Inclusion and Exclusion Criteria were:

The authors did not list specific inclusion and exclusion criteria, nor did they mention how patients were identified and selected for the study.  The study does state that all patients were "adults with a history of aspiration pneumonia or vomiting after a PEG" and that the study protocols did not begin until at least one month after PEG placement.  Of note, medications that affected gastroesophageal motility and lower esophageal sphincter activity such as metoclopramide, mosapride citrate and nifedipine, were interrupted for at least 3 days before the study.

Major Results reported by authors:

The authors reported that the gastroesophageal index (GERI) of semi-solid nutrients was significantly lower than that of liquid nutrients (0.82 ± 0.32% vs 3.75 ± 1.10%; p < 0.05).  Due to the small number of subjects the investigators were able to present individual patient data and reported that GERI with the semi-solid feeding was decreased in 14 of the 15 patients.

Gastric emptying time was not significantly different between the semi-solid (64.7 +/- 7.8 minutes) and liquid feeding (63.7 +/- 6.6 minutes).

The percentage of feedings that were retained in the stomach (retention ratio) was significantly lower in the semi-solid nutrients at 90 minutes (34.9 ± 2% vs 43.1 ± 2.9 %; p < 0.05).  Additionally, the retention ratio of the semi-solid nutrients in the proximal stomach was significantly decreased after 60 minutes compared with the liquid nutrients.  In the distal stomach the retention rate of the semi-solid nutrients was slightly higher than the liquid nutrients throughout the observation period, although the differences were not statistically significant.  

The investigators described the results of a previous study (1) which reported that patients with > 1.65% of GERI have increased risk of aspiration.  Consequently they postulated that the reduction of GERI from 3.75% with liquid nutrients to 0.82% with semi-solid nutrients could result in a clinically significance decrease in aspiration.

Author's Conclusions:

The authors concluded that gastroesophageal reflux was significantly decreased, and intragastric distribution was improved by semi-solid nutrients. The authors also concluded that "administration of semi-solid nutrients instead of liquid nutrients would be a benefit for long-term management preventing aspiration due to GER after PEG."

Evaluation:

This study presents a novel approach for decreasing the risk of reflux associated with PEG feeding in an attempt to decrease aspiration.  The results do suggest that under the conditions of this study (supine for 90 minutes after a bolus feeding) that agar thickened feeding resulted in less reflux with no decrease in gastric emptying time, compared to liquid feeding.

The most evident limitation of this study for our group was that it is unclear if these results would remain significant or relevant when proper aspiration precautions are in place, especially backrest elevation.  It is also important to remember that reflux is not the same as aspiration, and notwithstanding the investigators previous results, this study used reflux as a surrogate marker, and did not measure a clinically relevant outcome, such as frequency of aspiration pneumonia.

Another limitation to this study is that the semi-solid feeding only contained 100mL of the feeding formula, and the other volume was water-agar to make up the 200mL volume.  Therefore, the semi-solid feeding contained 50% less fat and other nutrients that might influence gastric emptying.  Additionally, there is the practical disadvantage that if each feeding must be diluted with an equal volume of water-agar, then either a larger volume will need to be fed each feeding, or a patient will require twice as many feedings/day to meet nutrition needs.

Additional issues that we discussed were the lack of blinding, the relatively small number of patients in the study, the fact that some of the patients had underlying motility disorders, the potential for clogging of feeding tubes if thickened feedings were used over time, and several of our GI physicians raised the question of the validity of monitoring reflux via scintillation camera.

Our Take Home message:

The results of this study suggest a potential way to decrease reflux with PEG feedings in a high risk population.  However, further randomized and blinded research that measures clinical outcomes would be required before thickened feedings would be considered clinically viable.

Reference:

  • 1) Nishiwaki S, Araki H, Goto N, et al. Clinical analysis of gastroesophageal reflux after PEG. Gastrointest Endosc. 2006 Dec;64(6):890-6.

Other News:

The next Weekend Warrior Mini-Nutrition Support Traineeship is tentatively scheduled for March 13-14, 2010. More details to follow on the website.

Check out the full schedule of webinar programs at:

      http://www.healthsystem.virginia.edudh/webinars.html

  • November 17: Nutrition Support in Renal Failure--Joe Krenitsky, MS, RD
  • December 8: Enteral Nutrition--Carol Parrish, MS, RD
  • January 19:  Evidence Based Medicine-Joe Krenitsky, MS, RD
  • February 23:  The Nutritional Impact of GI Surgery-Carol Parrish, MS, RD
  • March 9:  The Ins and Outs of GI Fistulas-Kate Willcutts, MS, RD, CNSC
  • April 13:  Update on IDPN-Mitch Rosner, MD
  • May 18:  Nutrition Assessment-Joe Krenitsky, MS, RD
  • June 15:  Chyle Leaks-Carol Parrish, MS, RD

See the latest Practical Gastroenterology article:

Available at: http://www.healthsystem.virginia.edu/pub/digestive-health/nutrition/resources.html

  • October 2009:  Curtis CS, Kudsk KA.  Enteral Feedings in Hospitalized Patients: Early versus Delayed Enteral Nutrition.  Practical Gastroenterology 2009;XXXIII(10):22.

 

Joe Krenitsky MS, RD

Carol Rees Parrish MS, RD

PS - Please feel free to forward this on to friends and colleagues.