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Gastric emptying and the symptoms of vection-induced nausea
Objectives:
To examine the hypothesis that nausea during vection arises directly from an underlying alteration in gastric motility.
Design:
The simultaneous application of vection and assessment of gastric emptying of a liquid, non-nutrient test meal allowed the examination of the interaction between changes in gastric motility and symptoms.
Methods:
Studies were conducted in 14 volunteers. Vection was induced by seating the subject inside a rotating circular drum, which was painted with vertical black and white stripes. In the control study (n = 8) the drum was not rotated. Gastric emptying was measured by gamma scintigraphy of a radiolabelled isosmotic saline test meal.
Results:
Vection induced upper abdominal sensations (epigastric awareness) in 10 subjects, eight of whom subsequently reported nausea; autonomic symptoms of sweating and pallor were experienced by 12 subjects. Two subjects remained completely asymptomatic during vection. None of the subjects experienced any sensations during the control study. Gastric emptying was significantly delayed during vection (P < 0.01). There was a highly significant correlation between gastric emptying and the intensity of nausea. However, examination of the gastric emptying profiles did not support any direct association between altered gastrointestinal motor activity and symptoms. Two subjects with slowing of gastric emptying exhibited no nausea or upper abdominal symptoms, while another two experienced nausea when the underlying rate of gastric emptying was similar to that of the control period.
Conclusions:
The delay in gastric emptying of a liquid test meal induced by vection appears to be a variable epiphenomenon of nausea. A cause and effect relationship between gastric emptying and nausea therefore appears unlikely.