Effect of high altitude on human postprandial ¹³C‐octanoate metabolism, intermediary metabolites, gastrointestinal peptides, and visceral perception

Abstract

Objective: At high altitude (HA), acute mountain sickness (AMS) is accompanied by neurologic and upper gastrointestinal symptoms (UGS). The primary aim of this study was to test the hypothesis that delayed gastric emptying (GE), assessed by 13 C-octanoate breath testing (OBT), causes UGS in AMS. The secondary aim was to assess post-gastric mechanisms of OBT, which could confound results under these conditions, by determination of intermediary metabolites, gastrointestinal peptides, and basal metabolic rate.Methods: A prospective trial was performed in 25 healthy participants (15 male) at 4559 m (HA) and at 490 m (Zurich). GE was assessed by OBT (428 kcal solid meal) and UGS by visual analogue scales (VAS). Blood sampling of metabolites (glucose, free fatty acids (FFA), triglycerides (TG), beta-hydroxyl butyrate (BHB), L-lactate) and gastrointestinal peptides (insulin, amylin, PYY, etc.) was performed as well as blood gas analysis and spirometry. Statistical analysis: variance analyses, bivariate correlation, and multilinear regression analysis. Results:After 24 h under hypoxic conditions at HA, participants developed AMS (p < 0.001). 13 CO 2 exhalation kinetics increased (p < 0.05) resulting in reduced estimates of gastric half-emptying times (p < 0.01). However, median resting respiratory quotients and plasma profiles of TG indicated that augmented beta-oxidation was the main predictor of accelerated 13 CO 2 -generation under these conditions. Conclusion:Quantification of 13 C-octanoate oxidation by a breath test is sensitive to variation in metabolic (liver) function under hypoxic conditions. 13 C-breath testing using short-chain fatty acids is not reliable for measurement of gastric function at HA and should be considered critically in other severe hypoxic conditions, like sepsis or chronic lung disease.

Endoscopic findings of acid peptic disease at low and high altitude: Kathmandu versus Rasuwa districts of Nepal

“…16 Neurologic and upper gastrointestinal symptoms like delayed gastric emptying are seen in AMS at high altitudes. 17 There is suppressed gastric motility and emptying due to changes in vagal activity which further results in gastric distension and sensation of satiety at high altitude; thus, an enthusiastic feeding may further aggravate nausea and vomiting which is commonly seen in AMS. In the present study, there were more cases of severe acid peptic activities in patients from the high altitude of Rasuwa compared to Kathmandu valley, with a comparatively higher percentage of ulcers, duodenal (7.7% vs. 7%), gastric (8.5% vs 5.6%) and esophageal (4.1% vs.…”