Do changes in gastro-intestinal blood flow explain high-altitude anorexia?

Background  Gastrointestinal symptoms are common on acute exposure to high-altitude (HA). Underlying mechanisms are not understood, but vascular shunting away from the gut could be responsible. Therefore, blood flow in the superior mesenteric artery (SMA) and hepatic portal vein (HPV) was examined at sea level (SL) and after ascent to 4392 m (HA). Materials and methods  Twelve subjects [eight male, mean age 40 (22–72) years] were studied following an overnight fast and a standard meal. Cross-sectional vessel area and blood velocity were measured by ultrasound, systolic and diastolic flow calculated for the SMA (HR × vessel area × velocity, cm3 min−1) and mean flow for the HPV. Results  All subjects experienced reduced appetite at HA. Blood flow in the SMA and HPV increased following food at SL (mean SMA systolic flow 1024 vs. 3316 cm3 min−1, P < 0·001; HPV 505 vs. 1789, P < 0·001) and at HA (2020 vs. 3767, P < 0·001; HPV 708 vs. 1727, P < 0·001). Pre-prandial flow in the SMA and HPV was significantly increased at HA compared with SL. The changes were due to increased vessel diameter and increased flow velocity. There was no difference in post-prandial flow between SL and HA in the HPV, although the increase in post-prandial flow was greater at SL than HA (254% increase vs. 144%). Conclusions  These results show that resting blood flow in the gastrointestinal tract is increased during exposure to high-altitude hypoxia, and that the vascular response of increased blood flow following food ingestion is maintained. Therefore, reduced flow is unlikely to cause gastrointestinal symptoms and reduced appetite at HA

Observational study of organisational responses of 17 US hospitals over the first year of the COVID-19 pandemic

Objectives The COVID-19 pandemic has required significant modifications of hospital care. The objective of this study was to examine the operational approaches taken by US hospitals over time in response to the COVID-19 pandemic.Design, setting and participants This was a prospective observational study of 17 geographically diverse US hospitals from February 2020 to February 2021.Outcomes and analysis We identified 42 potential pandemic-related strategies and obtained week-to-week data about their use. We calculated descriptive statistics for use of each strategy and plotted percent uptake and weeks used. We assessed the relationship between strategy use and hospital type, geographic region and phase of the pandemic using generalised estimating equations (GEEs), adjusting for weekly county case counts.Results We found heterogeneity in strategy uptake over time, some of which was associated with geographic region and phase of pandemic. We identified a body of strategies that were both commonly used and sustained over time, for example, limiting staff in COVID-19 rooms and increasing telehealth capacity, as well as those that were rarely used and/or not sustained, for example, increasing hospital bed capacity.Conclusions Hospital strategies during the COVID-19 pandemic varied in resource intensity, uptake and duration of use. Such information may be valuable to health systems during the ongoing pandemic and future ones