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Board Questions

1. What is the main benefit of postpyloric vs. gastric feeds? 

a) Less interruption in feeds overall
b) Less risk of aspiration
c) Ability to bolus feeds as needed
d) All of the above

2. In which situation is the respiratory quotient (R) >1? 

a) Carbohydrate metabolism
b) Fatty acid oxidation
c) Protein breakdown
d) Lipogenesis

3. How can one estimate basal caloric requirements in a pediatric patient? 

a) Ask the dietician
b) Perform a REE
c) Use the 4-2-1 Rule
d) All of the above


ANSWERS & EXPLANATIONS

1. A- While intuitively, it would seem that postpyloric feeds would reduce the risk of aspiration vs. gastric feed, studies in which feeds have been dyed with methylene blue and then tracheal aspirates examined to determine aspiration into the lungs have not revealed a significant difference in aspiration risk (Kamat et al, PCCM 2008). Postpyloric feeds typically enter the duodenum, and thus should NOT be bolused like gastric feeds. Hence, A is the correct answer as it does appear feeds are interrupted less when they are postpyloric vs. gastric.

2. D- The respiratory quotient is a dimensionless number and is the ratio of CO2 eliminated to O2 consumed. It is used in the alveolar gas equation. Normally, we use a value of 0.8 for R to represent a typical diet consisting of carbohydrates, fats, and protein. A pure fat diet would have a R of 0.7, a pure carbohydrate diet of 1.0 and a pure protein diet of around 0.8. During breakdown of carbohydrates for lipogenesis, the R value >1. The respiratory quotient can be important in a patient with difficulty ventilating as consideration of their nutritional intake and composition can affect the amount of CO2 they produce. 

3. D- All of the above methods are acceptable for estimating basal energy requirements in our patients. A rough measure can be used utilizing the 4-2-1 rule devised by Holliday and Segar as while our common practice is to utilize 4-2-1 for maintenance fluid requirements, the actual calculations were done for caloric requirements, with the math working out so that 1 kcal= 1 cc maintenance fluid. While there are valid criticisms of Holliday and Segar's work from the 1950's, using the 4-2-1 is still a reasonable approach to estimate basal metabolic requirements in an otherwise healthy child. Asking the dietician and performing an REE can also give you estimates of resting energy expenditure or basal metabolic requirement. 



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