A U-shaped protection of altitude against mortality and infection of COVID-19 in Peru: an ecological study.

BACKGROUND: The COVID-19 pandemic has affected the world in multiple ways and has been a challenge for the health systems of each country. From the beginning, risk factors for the severity and mortality of the disease were considered, as the spread of the virus was related to the living conditions of each population. METHODS: In this ecological study we have evaluated the role of geography, precisely the altitude above sea level in the incidence and mortality of COVID-19 in Peru. Incidence and mortality data were taken from the open-access database of the government of Peru until March 2021. COVID-19 cases and COVID-19 mortality were treated as cases/density population and 1000 x cases/inhabitants while altitude was treated as continuous and as a categorical variable divided in 7 categories. The relationship between COVID-19 cases or deaths for COVID-19 and altitude as continuous variable was determined using Spearman correlation test. Meanwhile when altitude was considered as a categorical variable, Poisson regression or negative binomial analyses were applied. RESULTS: A significant inverse correlation was found between COVID-19 cases by population density and altitude (r=-0.37 p < 0.001). By altitude categories, the lowest risk for infection was observed between 3,000 and 3,500 m (IRR 0.08; 95% CI 0.05,0.12). Moreover, we found an inverse correlation between altitude and COVID-19 mortality (r=-0.39 p < 0.001). Also, the lowest risk for mortality was observed between 3,000 and 3,500 m (IRR 0.12; 95%CI 0.08; 0.18). Similar results were found when analyses were adjusted for inhabitants and stratified by sex. CONCLUSION: This study reports an inverse relationship between COVID-19 incidence and mortality with respect to the altitude of residence, particularly, a u-shaped protection is shown, with a highest benefit between 3000 and 3500 m. The possibility of using hypoxia as an alternative treatment requires more complex studies that should allow knowing the physiological and environmental mechanisms of the protective role.

Biomarkers as predictors of mortality in critically ill obese patients with COVID-19 at high altitude.

BACKGROUND: Obesity is a common chronic comorbidity of patients with COVID-19, that has been associated with disease severity and mortality. COVID-19 at high altitude seems to be associated with increased rate of ICU discharge and hospital survival than at sea-level, despite higher immune levels and inflammation. The primary aim of this study was to investigate the survival rate of critically ill obese patients with COVID-19 at altitude in comparison with overweight and normal patients. Secondary aims were to assess the predictive factors for mortality, characteristics of mechanical ventilation setting, extubation rates, and analytical parameters. METHODS: This is a retrospective cohort study in critically ill patients with COVID-19 admitted to a hospital in Quito-Ecuador (2,850 m) from Apr 1, 2020, to Nov 1, 2021. Patients were cathegorized as normal weight, overweight, and obese, according to body mass index [BMI]). RESULTS: In the final analysis 340 patients were included, of whom 154 (45%) were obese, of these 35 (22.7%) were hypertensive and 25 (16.2%) were diabetic. Mortality in obese patients (31%) was lower than in the normal weight (48%) and overweight (40%) groups, but not statistically significant (p = 0.076). At multivariable analysis, in the overall population, older age (> 50 years) was independent risk factor for mortality (B = 0.93, Wald = 14.94, OR = 2.54 95%CI = 1.58-4.07, p < 0.001). Ferritin and the neutrophil/lymphocyte ratio were independent predictors of mortality in obese patients. Overweight and obese patients required more positive and-expiratory pressure compared to normal-weight patients. In obese patients, plateau pressure and mechanical power were significantly higher, whereas extubation failure was lower as compared to overweight and normal weight. CONCLUSIONS: This preliminary study suggests that BMI was not associated with mortality in critically ill patients at high altitude. Age was associated with an increase in mortality independent of the BMI. Biomarkers such as ferritin and neutrophils/lymphocytes ratio were independent predictors of mortality in obese patients with COVID-19 at high altitude.

Disparities in COVID-19 incidence and fatality rates at high-altitude.

Background: SARS-CoV-2 has affected every demography disproportionately, including even the native highland populations. Hypobaric-hypoxic settings at high-altitude (HA, >2,500 masl) present an extreme environment that impacts the survival of permanent residents, possibly including SARS-CoV-2. Conflicting hypotheses have been presented for COVID-19 incidence and fatality at HA. Objectives: To evaluate protection or risk against COVID-19 incidence and fatality in humans under hypobaric-hypoxic environment of high-altitude (>2,501 masl). Methods: Global COVID-19 data of March 2020-21, employed from official websites of the Indian Government, John Hopkins University, and Worldometer were clustered into 6 altitude categories. Clinical cofactors and comorbidities data were evaluated with COVID-19 incidence and fatality. Extensive comparisons and correlations using several statistical tools estimated the risk and protection. Results: Of relevance, data analyses revealed four distinct responses, namely, partial risk, total risk, partial protection, and total protection from COVID-19 at high-altitude indicating a mixed baggage and complexity of the infection. Surprisingly, it included the countries within the same geographic region. Moreover, body mass index, hypertension, and diabetes correlated significantly with COVID-19 incidence and fatality rate (P ≤ 0.05). Conclusions: Varied patterns of protection and risk against COVID-19 incidence and fatality were observed among the high-altitude populations. It is though premature to generalize COVID-19 effects on any particular demography without further extensive studies.

Mental Disorders and Level of Resilience in Eight High-Altitude Cities of Peru during the Second Pandemic Wave: A Multicenter Population-Based Study.

COVID-19 has led us to take preventive measures, such as social isolation, to reduce the high transmissibility of the disease. This could have affected the mental health of various population groups and the development of resilience as a mitigator. A cross-sectional analytical study was conducted with 700 participants from eight cities. The dependent variables were depression, anxiety, and post-traumatic stress disorder (PTSD). The independent variable was resilience. Generalized logistic regressions were used to identify the associations between the variables. The population consisted mostly of university students (65.0%); the rest of the population was distributed among workers of public or private institutions, housewives, and others (35.0%). High prevalences of anxiety (72.7%), depression (64.1%), and PTSD (15.1%) were found, as well as a median (interquartile range) resilience score of 24 points was determined. Factors associated with a high prevalence of PTSD were having lost employment and having a family member who died from COVID-19. For depression, associated factors were severe food insecurity and hypersomnia. For anxiety, associated factors were were having a deceased family member with COVID-19 and mild food insecurity. Our results show that, during the pandemic, the general population had a higher prevalence of mental disorders. In addition, anxiety was the most prevalent of the dependent variables. Special attention should be paid to the factors influencing the development of mental disorders and mental health prevention and promotion programs should be established.

High Altitude Carotid Body Tumors Growth During active Surveillance.

BACKGROUND: The gold standard for patients with carotid body tumors (CBT) is surgical resection; nevertheless, some patients are unfit for surgery or, for other reasons, could not be operated on. Active surveillance has been known to be a reasonable strategy for these cases. This study aimed to evaluate tumor growth in unoperated patients with CBTs. METHODS: A retrospective review of all unoperated patients with CBT from a single academic hospital diagnosed between 2014 and 2021 was performed. Results of nonparametric testing were presented using the median and ranges for Mann-Whitney-U or Kruskal-Wallis. Significance was defined as a 2-tailed P < .05. RESULTS: The cohort included a total of 31 patients, with a median age of 60 years (range: 37-80 years), of which 27 (87.1%) were females. The patients live at a median altitude of 2800 meters (range: 2756-2980 meters) above sea level. Twenty (64.5%) patients had Shamblin I tumors, eight (25.8%) patients had Shamblin II tumors, and three (9.7%) patients had Shamblin III tumors. Median CBT volume at diagnosis was 14.1 cm3 (range: .9 - 213.3 cm3). Median volume at diagnosis of symptomatic tumors was substantially larger than asymptomatic tumors, 49.2 cm3 vs 7.9 cm3, respectively (P = .03). Median growth of the tumors during a median 15-month follow-up (range: 3-43 months) was 3.3 cm3 (range: 0-199.9 cm3). Overall, 77% (n = 24) of the CBTs grew at least 1 cm3. CONCLUSION: Most patients in the present study had tumor growth by at least 1 cm3, with a median tumor growth of 3.3 cm.3 In the present study tumor growth was shown to be greater than other low altitude CBT active surveillance studies; therefore, surgical resection should be recommended in patients with CBT living at high altitudes.

Effect of Altitude on Respiratory Functional Status in COVID-19 Survivors: Results from a Latin American Cohort-FIRCOV.

Laura Gochicoa-Rangel, Santiago C. Arce, Carlos Aguirre-Franco, Wilmer Madrid-Mejía, Mónica Gutiérrez-Clavería, Lorena Noriega-Aguirre, Patricia Schonffeldt-Guerrero, Agustín Acuña-Izcaray, Arturo Cortés-Telles, Luisa Martínez-Valdeavellano, Federico Isaac Hernández-Rocha, Omar Ceballos-Zúñiga, Rodrigo Del Rio Hidalgo, Sonia Sánchez, Erika Meneses-Tamayo, and Iván Chérrez-Ojeda; and on Behalf of the Respiratory Physiology Project in COVID-19 (FIRCOV). Effect of altitude on respiratory functional status in COVID-19 survivors: results from a Latin American Cohort-FIRCOV. High Alt Med Biol 24:37-48, 2023. Persistent symptoms and lung function abnormalities are common in COVID-19 survivors. Objectives: To determine the effect of altitude and other independent variables on respiratory function in COVID-19 survivors. Methods: Analytical, observational, cross-sectional cohort study done at 13 medical centers in Latin America located at different altitudes above sea level. COVID-19 survivors were invited to perform pulmonary function tests at least 3 weeks after diagnosis. Results: 1,368 participants (59% male) had mild (20%), moderate (59%), and severe (21%) disease. Restriction by spirometry was noted in 32%; diffusing capacity of the lung for carbon monoxide (DLCO) was low in 43.7%; and 22.2% walked less meters during the 6-minute walk test (6-MWT). In multiple linear regression models, higher altitude was associated with better spirometry, DLCO and 6-MWT, but lower oxygen saturation at rest and during exercise. Men were 3 times more likely to have restriction and 5.7 times more likely to have a low DLCO. Those who had required mechanical ventilation had lower DLCO and walked less during the 6-MWT. Conclusions: Men were more likely to have lower lung function than women, even after correcting for disease severity and other factors. Patients living at a higher altitude were more likely to have better spirometric patterns and walked farther but had lower DLCO and oxygen saturation.

Changes in Oxygenation Levels During Moderate Altitude Simulation (Hypoxia-Induced): A Pilot Study Investigating the Impact of Skin Pigmentation in Pulse Oximetry.

The current COVID-19 pandemic has shown us that the pulse oximeter is a key medical device for monitoring blood-oxygen levels non-invasively in patients with chronic or acute illness. It has also emphasised limitations in accuracy for individuals with darker skin pigmentation, calling for new methods to provide better measurements. The aim of our study is to identify the impact of skin pigmentation on pulse oximeter measurements. We also explored the benefits of a multi-wavelength approach with an induced change of arterial oxygen saturation. A total of 20 healthy volunteers were recruited. We used time domain diffuse reflectance spectroscopy (TDDRS) from a broad band light source, collecting spectra from the index finger along with three different pulse oximeters used simultaneously for monitoring purposes. Five acute hypoxic events were induced by administering 11% FiO2, produced by a Hypoxico altitude training system, for 120 sec through a face mask with a one-way valve. Our multi-wavelength approach revealed a correlation between the signature of skin pigmentation and the dynamic range of oxygen saturation measurements. Principal component analysis (PCA) showed separation between a range of different pigmented volunteers (PC1 = 56.00%) and oxygen saturation (PC2 = 22.99%). This emphasises the need to take into account skin pigmentation in oximeter measurements. This preliminary study serves to validate the need to better understand the impact of skin pigmentation absorption on optical readings in pulse oximeters. Multi-wavelength approaches have the potential to enable robust and accurate measurements across diverse populations.

In Vitro and In Silico Studies for the Identification of Potent Metabolites of Some High-Altitude Medicinal Plants from Nepal Inhibiting SARS-CoV-2 Spike Protein.

Despite ongoing vaccination programs against COVID-19 around the world, cases of infection are still rising with new variants. This infers that an effective antiviral drug against COVID-19 is crucial along with vaccinations to decrease cases. A potential target of such antivirals could be the membrane components of the causative pathogen, SARS-CoV-2, for instance spike (S) protein. In our research, we have deployed in vitro screening of crude extracts of seven ethnomedicinal plants against the spike receptor-binding domain (S1-RBD) of SARS-CoV-2 using an enzyme-linked immunosorbent assay (ELISA). Following encouraging in vitro results for Tinospora cordifolia, in silico studies were conducted for the 14 reported antiviral secondary metabolites isolated from T. cordifolia-a species widely cultivated and used as an antiviral drug in the Himalayan country of Nepal-using Genetic Optimization for Ligand Docking (GOLD), Molecular Operating Environment (MOE), and BIOVIA Discovery Studio. The molecular docking and binding energy study revealed that cordifolioside-A had a higher binding affinity and was the most effective in binding to the competitive site of the spike protein. Molecular dynamics (MD) simulation studies using GROMACS 5.4.1 further assayed the interaction between the potent compound and binding sites of the spike protein. It revealed that cordifolioside-A demonstrated better binding affinity and stability, and resulted in a conformational change in S1-RBD, hence hindering the activities of the protein. In addition, ADMET analysis of the secondary metabolites from T. cordifolia revealed promising pharmacokinetic properties. Our study thus recommends that certain secondary metabolites of T. cordifolia are possible medicinal candidates against SARS-CoV-2.

Severe Respiratory Failure Developing in the Course of High-Altitude Pulmonary Edema in an Alpinist with COVID-19 Pneumonia: A Case Report.

Pigon, Katarzyna, Ryszard Grzanka, Ewa Nowalany-Kozielska, and Andrzej Tomasik. Severe respiratory failure developing in the course of high-altitude pulmonary edema in an alpinist with COVID-19 pneumonia: a case report. High Alt Med Biol. 23:372-376, 2022.-The case of a 38-year-old Polish alpinist, evacuated from base camp (4,200 m) under Lenin's Peak due to severe high-altitude pulmonary edema (HAPE) and symptoms of acute mountain sickness/high-altitude cerebral edema (HACE), is presented. Starting the expedition, the man was asymptomatic and had a negative COVID-19 molecular test. After a few days of trekking, he developed typical HAPE and HACE. After evacuation to the hospital in Bishkek, a diagnosis of acute bronchopneumonia was made by computed tomography (CT) imaging. A COVID-19 test was not performed at that time. After returning to Poland, a complete noninvasive cardiac and pulmonary assessment disclosed no pathology. The initial chest CT reassessment was read as demonstrating the densities typical for COVID-19 pneumonia, and a SARS-CoV-2 antibody test corroborated the diagnosis. Pre-existing lung disease increases the risk of developing HAPE. In the era of the COVID-19 pandemic, people traveling at a high altitude and unaware of the infection are at particular risk.

Health Benefits of Residence at Moderate Altitude Do Not Reduce COVID-19 Mortality.

Moderate altitude (1000−2000 m above sea level) residence is emerging as a protective factor from the mortality of various causes, including of cardiovascular diseases. Conversely, mortality from certain respiratory diseases is higher at these altitudes than in lowlands. These divergent outcomes could indicate either beneficial or detrimental effects of altitude on the mortality of COVID-19 that primarily infects the respiratory tract but results in multi-organ damage. Previous epidemiological data indeed suggest divergent outcomes of moderate to high altitude residence in various countries. Confounding factors, such as variations in the access to clinical facilities or selection biases of investigated populations, may contribute to the equivocation of these observations. We interrogated a dataset of the complete population of an Alpine country in the center of Europe with relatively similar testing and clinical support conditions across altitude-levels of residence (up to around 2000 m) to assess altitude-dependent mortality from COVID-19 throughout 2020. While a reduced all-cause mortality was confirmed for people living higher than 1000 m, no differences in the mortality from COVID-19 between the lowest and the highest altitude regions were observed for the overall population and the population older than 60 years as well. Conversely, COVID-19 mortality seems to have been reduced in the very old (>85 years) women at moderate altitudes.

Long COVID at Different Altitudes: A Countrywide Epidemiological Analysis.

BACKGROUND: Several reports from around the world have reported that some patients who have recovered from COVID-19 have experienced a range of persistent or new clinical symptoms after a SARS-CoV-2 infection. These symptoms can last from weeks to months, impacting everyday functioning to a significant number of patients. METHODS: A cross-sectional analysis based on an online, self-reporting questionnaire was conducted in Ecuador from April to July 2022. Participants were invited by social media, radio, and TV to voluntarily participate in our study. A total of 2103 surveys were included in this study. We compared socio-demographic variables and long-term persisting symptoms at low (<2500 m) and high altitude (>2500 m). RESULTS: Overall, 1100 (52.3%) responders claimed to have Long-COVID symptoms after SARS-CoV-2 infection. Most of these were reported by women (64.0%); the most affected group was young adults between 21 to 40 years (68.5%), and most long-haulers were mestizos (91.6%). We found that high altitude residents were more likely to report persisting symptoms (71.7%) versus those living at lower altitudes (29.3%). The most common symptoms were fatigue or tiredness (8.4%), hair loss (5.1%) and difficulty concentrating (5.0%). The highest proportion of symptoms was observed in the group that received less than 2 doses. CONCLUSIONS: This is the first study describing post-COVID symptoms' persistence in low and high-altitude residents. Our findings demonstrate that women, especially those aging between 21-40, are more likely to describe Long-COVID. We also found that living at a high altitude was associated with higher reports of mood changes, tachycardia, decreased libido, insomnia, and palpitations compared to lowlanders. Finally, we found a greater risk to report Long-COVID symptoms among women, those with previous comorbidities and those who had a severer acute SARS-CoV-2 infection.

Prevalence and factors associated with food insecurity in eight high-altitude cities in Peru during the second wave of the COVID-19 pandemic: a retrospective, cross-sectional study.

BACKGROUND: Food insecurity has increased during the COVID-19 pandemic, affecting an estimated 260 million people. However, little evidence is available on how pandemic-related characteristics influence food security in a high-altitude population. The objective of this study was to assess factors associated with food insecurity in high-altitude Peruvian cities during the second epidemic wave of COVID-19. METHODS: A retrospective, cross-sectional study was conducted in eight Peruvian cities over 1,500 m above sea level. An online survey measuring food security, presence of anxiety & depressive symptoms, sleep quality, post-traumatic stress disorder (PTSD), resilience, and sociodemographic characteristics was disseminated through social networks between December 2020 and February 2021. Generalized linear models were used to identify an association between the study variables. RESULTS: Of 700 participants, the median age was 23 years, and more than half were female (56.7%). The prevalence of food insecurity was 37.1%. Anxiety symptoms, depressive symptoms, and PTSD were present in 72.7%, 64.1%, and 15% of respondents, respectively. The prevalence of food insecurity was higher in people with fair (PR: 1.60, 95% CI: 1.23-2.07) and very bad perception of their health (PR: 4.06, 95% CI: 2.63-6.26), individuals seeking mental health support (PR: 1.42, 95% CI: 1.25-1.62), and in those who lost their job due to the pandemic (PR: 1.82, 95% CI: 1.62-2.04). Having moderate (PR: 1.52, 95% CI: 1.26-1.83) and moderate to severe depressive symptoms (PR: 1.58, 95% CI: 1.11-2.27) also increased the prevalence of food insecurity. CONCLUSION: During the pandemic, the prevalence of food insecurity has increased in the Peruvian high-altitude population, revealing the need for preventive strategies. Identification of pandemic-related characteristics that influence food insecurity can guide interventions in at-risk individuals and reduce the long-term impact of this problem on overall health and quality of life.

Revisiting the COVID-19 fatality rate and altitude association through a comprehensive analysis.

The emergence of COVID-19 virus has led to a pandemic with staggering morbidity and mortality. There is evidence showing that pre-existing conditions and environmental factors are associated with worse COVID-19 outcomes. Among these conditions, altitude is of particular interest. Altitude has been shown to influence the morbidity and mortality of multiple chronic pathologies such as cardiovascular disease, chronic obstructive pulmonary disease and lung cancer. COVID-19 fatality rate has been associated with as altitude as well, but findings are disputed. Therefore, we revisit this assessment with a comprehensive analysis of the relationship between COVID-19 fatality rates and altitude for the Mountain region of the United States while considering the effect of additional comorbidities and sociodemographic factors. A Generalized Additive Model (GAM) approach using one year of county data adjusted by population density was performed to evaluate associations within states and for the whole region. Our analysis revealed a consistent effect where COVID-19 case-fatality rate is decreased with higher altitude, even when controlling for pre-existing conditions and certain demographic variables. In summary, the work presented provides evidence that suggests that the protective effects of high altitude are likely to be influenced by physiologic factors but demographic trends that are associated with life at high altitude must also be considered.

Your vaccine attitude determines your altitude. What are the determinants of attitudes toward vaccination?

Attitudes toward vaccination are doubtless an important determinant of public health, and this became evident after the first year of the last COVID-19 pandemic. The issue, long-debated within European societies, especially with respect to occasional surges of diseases in given years, has become a crucial determinant of the wellbeing of a country since 2021. In this study, using microdata from a 2019 Eurobarometer survey, we frame and deepen our knowledge about the main determinants of vaccination attitudes as observed by the related literature. We argue that a positive attitude toward vaccination may be due to individualistic or altruistic reasons, or various incentives; our analysis aims to improve our knowledge about the determinants of such a complex decision. Our findings, obtained by means of a quantitative analysis that employs Ordered Probit, Ordered Logit and Generalized Ordered Logit estimations, provide complete support for some of the theories that have been debated in the literature, limited support for others because of mixed evidence, and no support for some.

A comparative analysis of SARS-CoV-2 viral load across different altitudes.

SARS-CoV-2 has spread throughout the world, including areas located at high or very high altitudes. There is a debate about the role of high altitude hypoxia on viral transmission, incidence, and COVID-19 related mortality. This is the first comparison of SARS-CoV-2 viral load across elevations ranging from 0 to 4300 m. To describe the SARS-CoV-2 viral load across samples coming from 62 cities located at low, moderate, high, and very high altitudes in Ecuador. An observational analysis of viral loads among nasopharyngeal swap samples coming from a cohort of 4929 patients with a RT-qPCR test positive for SARS-CoV-2. The relationship between high and low altitude only considering our sample of 4929 persons is equal in both cases and not significative (p-value 0.19). In the case of low altitude, adding the sex variable to the analysis, it was possible to find a significative difference between men and women (p-value < 0.05). Considering initially sex and then altitude, it was possible to find a significative difference between high and low altitude for men (p-value 0.05). There is not enough evidence to state that viral load is affected directly by altitude range but adding a new variable as sex in the analysis shows that the presence of new variables influences the relationship of altitude range and viral load. There is no evidence that viral loads (Ct and copies/ml) differ at low or high altitude. Using sex as a co-factor, we found that men have higher viral loads than women at low and moderate altitude locations, while living at high altitude, no differences were found. When Ct values were aggregated by low, moderate, and high viral load, we found no significant differences when sex was excluded from the analysis. We conclude that viral load is not directly affected by altitude, but COVID-19 incidence and mortality are rather affected by socio-demographic and idiosyncratic dynamics.

Treatment of Focal and Segmental Glomerulosclerosis Secondary to High Altitude Polycythemia with Acetazolamide.

Vizcarra-Vizcarra, Cristhian A., Eduardo Chávez-Velázquez, Carmen Asato-Higa, and Abdías Hurtado-Aréstegui. Treatment of focal and segmental glomerulosclerosis secondary to high altitude polycythemia with acetazolamide. High Alt Med Biol. 23:286-290, 2022.-Focal segmental glomerulosclerosis (FSGS) is a morphological pattern, caused by glomerular injury and is the leading cause of nephrotic syndrome in adults. We present the case of a 59-year-old female patient, resident of a high-altitude city (3,824 m), who had polycythemia and nephrotic syndrome. A renal biopsy was performed, and the findings were compatible with FSGS. The patient received phlebotomy 500 ml three times, which reduced, partially, the hemoglobin concentration. However, she had refractory proteinuria, despite the use of enalapril and spironolactone. We observed that proteinuria worsened with the increase in hemoglobin levels. So, she was treated with acetazolamide 250 mg bid for 4 months, which reduced proteinuria and hemoglobin. During the coronavirus disease 2019 (COVID-19) pandemic, the patient did not take acetazolamide and again, she had an increase in hemoglobin and proteinuria levels. We conclude that acetazolamide may be an effective treatment in FSGS due to high altitude polycythemia.

Everesting: cycling the elevation of the tallest mountain on Earth.

PURPOSE: With few cycling races on the calendar in 2020 due to COVID-19, Everesting became a popular challenge: you select one hill and cycle up and down it until you reach the accumulated elevation of Mt. Everest (8,848 m or 29,029ft). With an almost infinite number of different hills across the world, the question arises what the optimal hill for Everesting would be. Here, we address the biomechanics and energetics of up- and downhill cycling to determine the characteristics of this optimal hill. METHODS: During uphill cycling, the mechanical power output equals the power necessary to overcome air resistance, rolling resistance, and work against gravity, and for a fast Everesting time, one should maximize this latter term. To determine the optimal section length (i.e., number of repetitions), we applied the critical power concept and assumed that the U-turn associated with an additional repetition comes with a 6 s time penalty. RESULTS: To use most mechanical power to overcoming gravity, slopes of at least 12% are most suitable, especially since gross efficiency seems only minimally diminished on steeper slopes. Next, we found 24 repetitions to be optimal, yet this number slightly depends on the assumptions made. Finally, we discuss other factors (fueling, altitude, fatigue) not incorporated in the model but also affecting Everesting performances. CONCLUSION: For a fast Everesting time, our model suggests to select a hill climb which preferably starts at (or close to) sea level, with a slope of 12-20% and length of 2-3 km.

High-altitude is associated with better short-term survival in critically ill COVID-19 patients admitted to the ICU.

BACKGROUND: Multiple studies have attempted to elucidate the relationship between chronic hypoxia and SARS-CoV-2 infection. It seems that high-altitude is associated with lower COVID-19 related mortality and incidence rates; nevertheless, all the data came from observational studies, being this the first one looking into prospectively collected clinical data from severely ill patients residing at two significantly different altitudes. METHODS: A prospective cohort, a two-center study among COVID-19 confirmed adult patients admitted to a low (sea level) and high-altitude (2,850 m) ICU unit in Ecuador was conducted. Two hundred and thirty confirmed patients were enrolled from March 15th to July 15th, 2020. RESULTS: From 230 patients, 149 were men (64.8%) and 81 women (35.2%). The median age of all the patients was 60 years, and at least 105 (45.7%) of patients had at least one underlying comorbidity, including hypertension (33.5%), diabetes (16.5%), and chronic kidney failure (5.7%). The APACHE II scale (Score that estimates ICU mortality) at 72 hours was especially higher in the low altitude group with a median of 18 points (IQR: 9.5-24.0), compared to 9 points (IQR: 5.0-22.0) obtained in the high-altitude group. There is evidence of a difference in survival in favor of the high-altitude group (p = 0.006), the median survival being 39 days, compared to 21 days in the low altitude group. CONCLUSION: There has been a substantial improvement in survival amongst people admitted to the high-altitude ICU. Residing at high-altitudes was associated with improved survival, especially among patients with no comorbidities. COVID-19 patients admitted to the high-altitude ICU unit have improved severity-of-disease classification system scores at 72 hours.

SARS-CoV-2 Viral Load Analysis at Low and High Altitude: A Case Study from Ecuador.

SARS-CoV-2 has spread throughout the world, including remote areas such as those located at high altitudes. There is a debate about the role of hypobaric hypoxia on viral transmission and COVID-19 incidence. A descriptive cross-sectional analysis of SARS-CoV-2 infection and viral load among patients living at low (230 m) and high altitude (3800 m) in Ecuador was completed. Within these two communities, the total number of infected people at the time of the study was 108 cases (40.3%). The COVID-19 incidence proportion at low altitude was 64% while at high altitude was 30.3%. The mean viral load from those patients who tested positive was 3,499,184 copies/mL (SD = 23,931,479 copies/mL). At low altitude (Limoncocha), the average viral load was 140,223.8 copies/mL (SD = 990,840.9 copies/mL), while for the high altitude group (Oyacachi), the mean viral load was 6,394,789 copies/mL (SD = 32,493,469 copies/mL). We found no statistically significant differences when both results were compared (p = 0.056). We found no significant differences across people living at low or high altitude; however, men and younger populations had higher viral load than women older populations, respectively.