Meher Prakash1, Ron Fried1, Oliver Götze2, Francisca May3, Petra Frings-Meuthen3, Edwin Mulder3, Judit Valentini4, Mark Fox1,5, Michael Fried1,5, Werner Schwizer1,5, Benjamin Misselwitz6. 1. Division of Gastroenterology and Hepatology, University Hospital Zurich and Zurich University, Rämistr. 100, 8091, Zurich, Switzerland. 2. Division of Hepatology, Department of Medicine II, University Hospital Würzburg, Würzburg, Germany. 3. Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany. 4. Swiss Center of Excellence for Agricultural Research (Agroscope), Bern, Switzerland. 5. Zurich Integrative Human Physiology Group, University of Zurich, Zurich, Switzerland. 6. Division of Gastroenterology and Hepatology, University Hospital Zurich and Zurich University, Rämistr. 100, 8091, Zurich, Switzerland. benjamin.misselwitz@usz.ch.
Abstract
BACKGROUND: Space motion sickness (SMS) is the most relevant medical problem during the first days in microgravity. Studies addressing pathophysiology in space face severe technical challenges and microgravity is frequently simulated using the 6° head-down tilt bed rest test (HDT). AIM: We were aiming to test whether SMS could be simulated by HDT, identify related changes in gastrointestinal physiology and test for beneficial effects of exercise interventions. METHODS:HDT was performed in ten healthy individuals. Each individual was tested in three study campaigns varying by a 30-min daily exercise intervention of either standing, an upright exercise regimen, or no intervention. Gastrointestinal symptoms, stool characteristics, gastric emptying time, and small intestinal transit were assessed using standardized questionnaires, (13)C octanoate breath test, and H2 lactulose breath test, respectively, before and at day 2 and 5 of HDT. RESULTS: Individuals described no or minimal gastrointestinal symptoms during HDT. Gastric emptying remained unchanged relative to baseline data collection (BDC). At day 2 of HDT the H₂ peak of the lactulose test appeared earlier (mean ± standard error for BDC-1, HDT2, HDT5: 198 ± 7, 139 ± 18, 183 ± 10 min; p: 0.040), indicating accelerated small intestinal transit. Furthermore, during HDT, stool was softer and stool mass increased (BDC: 47± 6, HDT: 91 ± 12, recovery: 53 ± 8 g/day; p: 0.014), indicating accelerated colonic transit. Exercise interventions had no effect. CONCLUSION:HDT did not induce symptoms of SMS. During HDT, gastric emptying remained unchanged, but small and large intestinal transit was accelerated.
RCT Entities:
BACKGROUND: Space motion sickness (SMS) is the most relevant medical problem during the first days in microgravity. Studies addressing pathophysiology in space face severe technical challenges and microgravity is frequently simulated using the 6° head-down tilt bed rest test (HDT). AIM: We were aiming to test whether SMS could be simulated by HDT, identify related changes in gastrointestinal physiology and test for beneficial effects of exercise interventions. METHODS: HDT was performed in ten healthy individuals. Each individual was tested in three study campaigns varying by a 30-min daily exercise intervention of either standing, an upright exercise regimen, or no intervention. Gastrointestinal symptoms, stool characteristics, gastric emptying time, and small intestinal transit were assessed using standardized questionnaires, (13)C octanoate breath test, and H2 lactulose breath test, respectively, before and at day 2 and 5 of HDT. RESULTS: Individuals described no or minimal gastrointestinal symptoms during HDT. Gastric emptying remained unchanged relative to baseline data collection (BDC). At day 2 of HDT the H₂ peak of the lactulose test appeared earlier (mean ± standard error for BDC-1, HDT2, HDT5: 198 ± 7, 139 ± 18, 183 ± 10 min; p: 0.040), indicating accelerated small intestinal transit. Furthermore, during HDT, stool was softer and stool mass increased (BDC: 47 ± 6, HDT: 91 ± 12, recovery: 53 ± 8 g/day; p: 0.014), indicating accelerated colonic transit. Exercise interventions had no effect. CONCLUSION: HDT did not induce symptoms of SMS. During HDT, gastric emptying remained unchanged, but small and large intestinal transit was accelerated.
Authors: Richard J Saad; Satish S C Rao; Kenneth L Koch; Braden Kuo; Henry P Parkman; Richard W McCallum; Michael D Sitrin; Gregory E Wilding; Jack R Semler; William D Chey Journal: Am J Gastroenterol Date: 2009-11-03 Impact factor: 10.864
Authors: Henriette Heinrich; Oliver Goetze; Dieter Menne; Peter X Iten; Heiko Fruehauf; Stephan R Vavricka; Werner Schwizer; Michael Fried; Mark Fox Journal: BMJ Date: 2010-12-14