Studies of gastric emptying in man
Heading, Robert Campbell
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Measurements of gastric emptying in man have "been made 'by scintigraphic methods "based on a rectilinear scanner or gamma camera. Xn. the initial studies with a scanner. indium-113m DTPA was evaluated as a possible radionuclide marker for a test meal and was found to be satisfactory. Tecluietium~99-1t DTPA was subsequently assessed in similar studies with a gamma camera. It also proved satisfactory, although it differed from the indium compound in being substantially adsorbed to the solid component of a mixed solid and liquid meal. To establish the reproducibility of the gamma camera method, repeated measurements were carried out and in studies with saline test meals, comparison was made with measurements based on aspiration of gastric contents. Recognition of the marked differences between gastric emptying of solids and liquids led to the development and validation of a double isotope method for simultaneous study of solid and liquid components of a test meal. This method was then applied to the study of patients who had undergone gastric surgery in an attempt to learn more about the emptying abnormalities consequent upon gastric surgery. Studies were also undertaken in diabetic patients with suspected gastric stasis due to autonomic neuropathy. The effects of metoclopramide therapy for such patients were examined. Studies of the histamine E^ receptor antagonists, inetiamide and eimetidino were undertaken to determine whether they had any effect on gastric emptying. No clinically significant effect was detected. Gastric emptying was found to be a major regulator of the rate of absorption of orally administered paracetamol. Pharmacological modification of gastric emptying, namely acceleration "by metoclopramide and inhibition by propantheline or by narcotic analgesics was associated with corresponding changes in paracetamol absorption. The absorption of orally administered paracetamol was also delayed by the gel fibres pectin and guar, which delay gastric emptying. Scintigraphic measurements of gastric emptying are not free from experimental error. Measurement of the errors due to count attenuation by tissues demonstrated the superiority of bilateral detection over unilateral detection, especially if relatively low energy gamma emitting radionuclides are being used. The errors associated with unilateral (anterior) detection of indium-113m and technetium-99m were determined in studies with a rectilinear scanner and with a gamma camera.