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Overview :
The
sham feeding test is used for confirmation of complete vagotomy.
Patient
Preparation:
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After a 12 hour fast, collect gastric secretions four 15 minutes intervals over
1 hour in order to establish the basal acid output (BAO).
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The patient is served a test meal of sirloin steak, french fries and water. The
food is chewed but not swallowed; the chewed food is spit out into a discard
container. This constitutes the "sham" meal.
•
For two 15 minute collections (30 minutes) during the sham meal and for two 15
minute collections (30 minutes) after the sham meal collect gastric secretions
and measure acid output (SAO).
•
The patient is administered pentagastric SC (6 µg/kg). The 2 highest consecutive
15 minute outputs after pentagastrin stimulation are used to determine peak acid
output (PAO); their sum is expressed in mmol/hr (after multiplying by 2).
Interpretation:
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reference population will have a SAO-to-PAO ratio > 0.10
•
patients after complete vagotomy will have a ration <= 0.10. After an
adequate vagotomy the sham feeding does not stimulate acid secretion.
•
in patients with PAO close to 0, the SAO-to-PAO ratio should be interpreted
carefully
Limitations:
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Swallowing large amounts of food may falsely increase or decrease the acid
output after sham feeding.
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