ABSTRACT
The gastric emptying times associated with three whey based formulas were significantly shorted than that associated with a casein-based formula in nine gastrostomy-fed patients with spastic quadriplegia (p <0.001). Patients fed whey-based formulas had significantly fewer episodes of emesis than when they were fed casein-based formula (p<0.001). We conclude that whey-based formulas reduce the frequency of emesis by improving the rate of gastric emptying. ( J Pediatr 1992;120:569-72)
INTRODUCTION
Gastro esophageal reflux, a frequent complication in patients with cerebral palsy, may result in under nutrition and aspiration pneumonia.(1). Delayed gastric emptying is an important factor in gastro esophageal reflux in children older than 3 years (2), especially those with cerebral palsy. The rate of gastric emptying associated with a formula is affected by the type of protein the formula contains; for example, gastric emptying occurs more slowly in patients fed a casein-predominant formula than in those fed whey-based formulas.(3)
We undertook this study to determine whether whey-based formulas would improve the rate of gastric emptying and decrease the amount of regurgitation in patients with cerebral palsy, spastic quadriplegia, severe developmental delay, and scoliosis who have been fed casein-predominant formulas.
METHODS
Inclusion Criteria
We studies nine consecutively outpatients with spastic quadriplegia who were attending the clinical nutrition outpatient clinic at the Hospital for Sick Children, Toronto, Ontario, from July 1990 through February 1991. The study was approved by the hospital’s human subjects review committee. All patients included in the study had profound mental retardation, spastic quadriplegia, scoliosis, and developmental delay; all were unable to speak or walk. We chose subjects older than 3 years because gastro esophageal reflux is more closely associated with delayed gastric emptying in children of this age group than in younger children (2)
Only patients already being fed through a gastrostomy tube that had been in place for longer than one month before the study were included; delayed gastric emptying may occur as long as 8 days after the surgical placement of a gastrostomy tube(4). None of our patients underwent fundoplication, which can alter the rate of gastric emptying (5). All had clinical evidence of gstroesophageal reflux; their care givers reported episodes of involuntary regurgitation of food.
Subjects
Nine patients (age range 3 to 18 years) were recruited from the clinical nutrition clinic because of their frequent episodes of vomiting. Patients were being fed a formula containing casein (80% and soy(20%) (Isosource, Sandoz Co., Whitby, Ontario, Canada) through a gastrostomy tube. This was the standard tube formulation in use at our hospital. When the patients were recruited their care givers were instructed to record the number of episodes of regurgitation per day for one month. Within 2 weeks from the start of the study, a gastric emptying scan with radiolabeled liquid technetium Tc 99m sulfur colloid documented delayed gastric emptying in all nine patients. The same casein- predominant formula that patients were routinely fed was used for the scan.
Gastric emptying scans
After delayed gastric emptying was confirmed, each patient participated in a double blind ( caretaker and radiologist both unaware of formula), randomized trial with gastric emptying scans that compared the effects of three different types of whey based formulas: whey predominant (Nan; Nestle S.A., Vevey, Switzerland) , whey hydrolysate (Carnation Good Start; Nestle Inc, Canada) and whey hydrolysate with 70% of the fat as medium chained triglycerides (Peptamen; Clintec, Baxter Healthcare Corp., Mississauga, Ontario, Canada). The composition of these formulas is provided in the table below.
Table. Composition of formulas per 150 ml of test feeding
Casein Whey Whey Whey hydrolysate
Predominant Predominant Hydrolysate (70% MCT)
____________________________________________________________________________
Protein 80% Casein 60% Whey 100% Whey 100% whey
20% Soy 40% Whey hydrolysate hydrolysate
Protein (gm) 5.1 3.4 3.6 6.0
Carbohydrates 20.0 17.2 16.6 19.1
Fat(gm) 6.6 7.7 7.7 5.8
% of fat as MCT 21.0 8.0 9.0 70.0
Osmolality 314.0 470.0 403.0 318.0
Energy (kcal) 159.0 150.0 150.0 150.0
In the morning.when the patients had fasted 8 to 10 hours after their last casein predominant feeding, we used the protocol described by Brophy et al.(6) to study the gastric emptying with radionuclide scan. In each patient, three 2 hour studies with each formula were completed during a 2 week period. Studies were performed at least two days apart. All whey based formulas contained the same volume (150ml) and the same energy per volume ( 1 cal/ml, table)(7,8). Loss of radionuclide was prevented because the volume of the test feeding (150ml) was half of the feeding volume (300ml) that usually resulted in regurgitation. At baseline, 60ml of formula was labeled with 1 ml of mCi of 99mTc-sulfur colloid and given as a bolus by syringe through the gastrostomy tube for one minute. This feeding was immediately followed by the remaining 90 ml of unlabeled formula, to flush any residual radioactivity from the gastrostomy tube. With the patient in a supine position under a gamma camera, we recorded the radioactive counts in the stomach at baseline and the residual gastric radioactivity at 60 and 120 minutes after initial feeding. Patients sat in their chairs between readings. With the 60 and 120 minute readings, corrected for radioactive decay, we determined the percentage of residual gastric radioactivity at 60 and 120 minutes by dividing the amount of radioactivity found in the stomach at 60 minutes and 120 minutes by the total amount of radioactivity measured in the stomach at baseline.
No normal values for healthy pediatric patients older than 3 years and younger than 18 years have been published. We adopted as normal values for the mean residual percentage of radiolabeled liquid meals those established by Notivol et al (9) for normal, healthy patients aged 18 to 31 years: 47% +or – 5% and 22% +or- 5% at 60 and 120 minutes, respectively. Delayed gastric emptying was defined as more than 62% and 37% residual gastric radioactivity at 60 and 120 minutes, respectively; these values are more than 3 Standard Deviations from the mean value.
Episodes of Vomiting
Once the three gastric emptying studies were completed, each patient was fed a randomly assigned whey based formula through the gastrostomy tube for one month. The feeding schedule was identical to that previously used for the casein based standard formula. In this open trial the same care givers who had recorded the preliminary observations for the casein predominant formula again recorded the number of emesis that occurred per day for one month. The number of episodes of emesis that occurred with the casein predominant formula was then compared with the number that occurred with the whey based formulas.
Statistical Analysis
An analysis of variance was used to compare the gastric emptying rate associated with the casein predominant formula with those associated with the three different whey based formulas. Results are expressed as a mean value + or – standard deviation. A one tailed paired Student t test was used to compare the number of emesis episodes that occurred when patients were fed the casein predominant formula with the number that occurred when they were fed whey based formulas.
RESULTS
The results of the gastric emptying scans at 60 and 120 minutes are expressed as the mean +/- the standard deviation percentage of residual gastric radioactivity for all nine patients for each formula. With the casein predominant formula, the mean percentage of residual gastric radioactivity at 60 minutes was 85 +/- 11%. There was a significantly lower mean percentage of residual gastric radioactivity associated with each whey based formula at 60 minutes (whey predominant 48% +/- 19%, whey hydrolysate 56% +/- 23% and whey hydrolysate with 70% medium chain triglycerides 59% +/- 19%) than with casein predominant formula ( p<0.001).
At 120 minutes the mean percentage of residual gastric radioactivity for the casein predominant formula was 69% +/- 14%. At 120 minutes there was also a significantly lower mean percentage of residual gastric activity for each whey based formula minutes (whey predominant 28% +/- 18%, whey hydrolysate 31% +/- 26% and whey hydrolysate with 70% medium chain triglycerides 27% +/- 13%) than with casein predominant formula ( p<0.001). The difference in the mean percentage of residual gastric radioactivity among the three whey based formulas at 60 and 120 minutes was not statistically significant. (p>0.1)
There was an accompanying reduction in episodes of vomiting in all patients fed whey based formulas ( 2 +/- 2 episodes, range up to 7 episodes) from the number associated with casein predominant formula ( mean 12 +/- episodes, range 4 to 35 episodes: p<0.05)
DISCUSSION
All patients fulfilling our selection criteria had delayed gastric emptying when fed casein predominant formula. This placed them at higher risk for such complications of gastro esophageal reflux as aspiration pneumonia. Our data showed that whey based formulas are associated with improved rates of gastric emptying and fewer episodes of vomiting in all patients.
One of the major determinants of the rate of gastric emptying is the energy density of the formula used. Isocaloric formulas emptied at the same rate despite differences in the amount of protein, carbohydrate and fat. (7,8). The whey based and casein predominant formulas used in this study were isocaloric, but the casein predominant formulas still emptied more slowly than the whey based formulas, presumably because differences in the type of protein(3)- a second major determinant in the rate of gastric emptying. All three isocaloric whey based formulas emptied at similar rates despite differences in osmolarity(10), amount of protein, and amount of medium chained triglycerides.(11).
We conclude that whey based formulas reduce the number of episodes of vomiting by inproving the rate of gastric emptying in patients 3 years and older with profound mental retardation, spastic quadriplegia, developmental delay and scoliosis. Improved gastric emptying and fewer episodes of regurgitation should benefit these patient by improving their nutritional status and by decreasing the risk of aspiration pneumonia.
REFERENCES
- Sondheimer JM Gastroesophageal reflux among severely retarded children. J Pediatr 1979;94:710-4.
- Di Lorenzo C et al. Gastric emptying with gastroesophageal reflux. Arch Dis Child 1987;62:449-53
- Billeaud C et al. Gastric emptying in infants with or without gastroesophageal reflux according to the type of milk. Eur J Clin Nutr 1990;44:577-83
- Woods SDS, MitchellGJ. Delayed return of gastric emptying after gastroenterostomy. Br J Surg 1989;76:145-8
- Maddern GJ, Jamieson GG. Fundoplication enhances gastric emptying. Ann Surg 1985; 201:296-9.
- Brophy CM et al. Variability of gastric emptying measurements in man employing standard radiolabeled meals. DigDis Sci 1986;31:799-806.
- Hunt JN, et al. effect of meal volume and energy density on the gastric emptying of carbohydrates. Gastroenterology 1985;89:1326-30
- Hunt JN, Stubs DF. The volume and energy content of meals as determinants of gastric emptying. J Physiol 1975; 245:209-25
- Notivol R et al. Gastric emptying of solid and liquid meals in healthy young subjects. Scand J Gastroent 1984;19:1107-13.
- Meeroff JC et al. Control of gastric emptying by osmolality of duodenal contents in man. Gastroenterology 1975;68:1144-51.
- Siegel M, Krantz B, Lebenthal E. Effect of fat and carbohydrate composition on the gastric emptying of isocaloric feedings in premature infants. Gastroenterology 1985;89:785-90.
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