PurposeTo investigate whether there is a differential response at rest and following exercise to conditions of genuine high altitude (GHA), normobaric hypoxia (NH), hypobaric hypoxia (HH), and normobaric normoxia (NN).MethodMarkers of sympathoadrenal and adrenocortical function [plasma normetanephrine (PNORMET), metanephrine (PMET), cortisol], myocardial injury [highly sensitive cardiac troponin T (hscTnT)], and function [N-terminal brain natriuretic peptide (NT-proBNP)] were evaluated at rest and with exercise under NN, at 3375 m in the Alps (GHA) and at equivalent simulated altitude under NH and HH. Participants cycled for 2 h [15-min warm-up, 105 min at 55% Wmax (maximal workload)] with venous blood samples taken prior (T0), immediately following (T120) and 2-h post-exercise (T240).ResultsExercise in the three hypoxic environments produced a similar pattern of response with the only difference between environments being in relation to PNORMET. Exercise in NN only induced a rise in PNORMET and PMET.ConclusionBiochemical markers that reflect sympathoadrenal, adrenocortical, and myocardial responses to physiological stress demonstrate significant differences in the response to exercise under conditions of normoxia versus hypoxia, while NH and HH appear to induce broadly similar responses to GHA and may, therefore, be reasonable surrogates.

This represents the first informative dataset for Mount Kenya ascents and altitude. The incidence of AMS during AT on Mount Kenya using this ascent profile is high. Adapting the current ascent profile, planning the ascent after time in country and reducing perceived exertion during the trek may reduce the incidence of AMS.

Background Control of the arterial partial pressure of carbon dioxide (PaCO2) is important in the ventilated patient. End-tidal carbon dioxide (ETCO2) levels are often used as a proxy, but are clinically limited. The difference between the PaCO2 and ETCO2 has been suggested to be 0.5–1.0 kPa. However, this has not been consistently reflected in the physiologically unstable pre-hospital patient. This study aims to elucidate the PaCO2-ETCO2 gradient for pre-hospital intubated patients. Methods This was a retrospective, cohort study using data identified from the HEMSbase 2 database (Feb 2015–Nov 2018). Patients were included if they had documented ETCO2 and arterial PaCO2 measurements. Arterial PaCO2 data that could not be linked to within 5 minutes of ETCO2 were excluded. Bland-Altman plots were calculated to describe agreement. Results A total of 73 patients were identified. Aetiology was arranged into three categories: 13 (17.8%) medical, 22 (30.1%) traumatic and 38 (52.1%) out-of-hospital cardiac arrest (OHCA). The median PaCO2-ETCO2 gradient was 2.0 [1.3–3.1] kPa. A PaCO2-ETCO2 gradient of 0–1 kPa was seen for only 11 (15.1%) of total patients. The Bland-Altman agreement for all aetiologies was more than the accepted gradient of 0-1 kPa with the largest bias and widest limits of agreement seen for OHCA (–3.2 [0.3 – –6.8]). Conclusion The magnitude of the differences between the ETCO2 and PaCO2, levels of variation and inability to predict this suggest that ETCO2 is not a suitable surrogate upon which to base ventilatory settings in conditions where pH or PaCO2 require precise control.

IntroductionThere is significant interest in the mental health impact of the COVID-19 pandemic. Helicopter Emergency Medical Services (HEMS) attend the most seriously unwell and injured patients in the community; their data therefore present an early opportunity to examine self-harm trends. The primary aim was to compare the incidence of deliberate self-harm incident (DSH-I) encounters by HEMS before and during the first wave of COVID-19.MethodsData were obtained from all three East of England HEMS: total number of activations and stand-downs, number of DSH-I activations and stand-downs, self-harm mechanism and number of ‘severe’ DSH-I patient encounters, in two 61-day periods: 1 March to 30 April in 2019 (control) and 2020 (COVID-19). Severe DSH-I was defined as cardiac arrest and/or died prehospital. Proportions were compared with a Fisher’s exact test.ResultsThere were a total of 1725 HEMS activations: n=981 (control) and n=744 (COVID-19), a decrease of 24.2% during COVID-19. DSH-I patient encounters increased by 65.4%: n=26 (control) and n=43 (COVID-19). The proportion of encounters that were DSH-I and severe DSH-I both significantly increased during COVID-19: p=0.002 and p=0.001, respectively. The absolute number of hangings and falls from height both approximately tripled during COVID-19, whereas the number of other mechanisms remained almost constant.ConclusionDespite a reduction in overall HEMS patient encounters, there were significant increases in both the proportion of DSH-Is and their severity attended by HEMS during the first wave of the COVID-19 pandemic in the East of England.