The sham feeding test is used for confirmation of complete vagotomy.
Patient Preparation:
(1) After a 12 hour fast, collect gastric secretions four 15 minutes intervals over 1 hour in order to establish the basal acid output (BAO).
(2) 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.
(3) 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).
(4) 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:
• 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:
• Swallowing large amounts of food may falsely increase or decrease the acid output after sham feeding.
