Evaluation of Acute Mountain Sickness by Unsedated Transnasal Esophagogastroduodenoscopy at High Altitude

Abstract

BACKGROUND AIMS It is not clear how rapid ascent to high altitude causes the gastrointestinal symptoms of acute mountain sickness (AMS). We assessed the incidence of endoscopic lesions in the upper gastrointestinal tract in healthy mountaineers after rapid ascent to high altitude, their association with symptoms, and their pathogenic mechanisms. METHODS In a prospective study, 25 mountaineers (10 female; mean age, 43.8y±9.5 y) underwent unsedated, transnasal esophago-gastroduodenoscopy in Zurich (490 m) and then on 2 test days (days 2 and 4) at a high altitude laboratory in the Alps (Capanna Regina Margherita, 4559 m). Symptoms were assessed using validated instruments for AMS (the AMS-C and the Lake Louise scoring system) and visual analogue scales (0-100). Levels of mRNAs in duodenal biopsies were measured by qPCR. RESULTS The follow-up endoscopy at high altitude was performed in 19/25 patients on day 2 and in 23/25 patients on day 4. Frequency of endoscopic lesions increased from 12% at baseline to 26.3% on day 2 and 60.9% on day 4 (P<0.001). The incidence of ulcer disease increased from 0 at baseline to 10.5% on day 2 and 21.7% on day 4 (P=.014). Mucosal lesions were associated with lower hunger scores (37.3 vs. 67.4 in patients without lesions; P=.012). Subjects with peptic lesions had higher levels of HIF2A mRNA, which encodes a hypoxia-induced transcription factor, and ICAM1 mRNA, which encodes an adhesion molecule, compared with subjects without lesions (fold changes: 1.38 vs 0.63; P=.001 and 1.37 vs 0.66; P=.011). CONCLUSIONS In a prospective study of 25 mountaineers, fast ascent to high altitude resulted in rapid onset of clinically meaningful mucosal lesions and ulcer disease. Duodenal biopsies from these subjects had increased levels of HIF2A mRNA and ICAM1 mRNA, which might contribute to formation of hypoxia-induced peptic lesions. Further studies are needed of the mechanisms of this process.

Symptom Profiles and Progression in Hospitalized and Nonhospitalized Patients with Coronavirus Disease, Colorado, USA, 2020

“…The timing of anosmia and ageusia in our analysis is similar to previous reports, which found a mean of 3 days from illness onset to anosmia and ageusia in hospitalized and nonhospitalized COVID-19 patients (34,35). The later occurrence of gastrointestinal symptoms and rash among our participants could be related directly to the virus, linked to interventions (e.g., use of antimicrobial drugs or other medications), or, in the case of gastrointestinal symptoms, related to hypoxia (36)(37)(38)(39). We identified an overall progression of reported symptoms that is consistent with, although more detailed than, a recent metaanalysis of symptoms among persons with COVID-19 (20).…”

Hemoglobin concentration of young men at residential altitudes between 200 and 2000m mirrors Switzerland's topography

“…This is important because systemic inflammation has a profound impact on hematopoiesis, gastrointestinal iron absorption, and ferritin plasma levels. 8,9 To assess whether increased ferritin serum levels, a marker for body iron stores, directly depend on a concomitant increase in Hb concentrations, we analyzed the interrelationship among altitude, Hb, ferritin, CRP, and BMI. Analysis of conscripts with normal Hb concentrations (,175 g/L), normal CRP (,5.0 mg/L), and normal BMI (18.5-24.9 kg/m 2 ) revealed that ferritin levels still increased significantly with altitude (Figure 2E).…”

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

“…Other explanations for the above‐described findings can be postulated but seem unlikely: Impaired absorption of lipids can delay absorption of 13 C‐labeled fatty acids in intestinal disorders; however, the observations above require accelerated absorption of nutrition at HA and this is not consistent with reports in animals and humans, discussed above 17 . Moreover, there is no evidence of an increased postprandial blood flow of the mucosa or the intestine at altitude; mucosal blood flow is decreased in hypoxic conditions, which contributes to the high frequency of mucosal erosions documented in endoscopy at HA 17,24 . In the larger vessels like the hepatic portal vein, the postprandial blood flow is not altered by HA exposure 17 .…”