Does Lake Louise questionnaire interpret high-altitude headache as acute mountain sickness? Experience in the western Himalayas.

BACKGROUND OBJECTIVES: High-altitude headache (HAH) and headache in acute mountain sickness (AMS) are common among lowlanders ascending to the high altitude and are often confused with one another. A pilot study was undertaken to analyze HAH and AMS cases in Indian lowlanders ascending to Leh city (3500 m) in western Himalayas. METHODS: A total number of 1228 Indian lowlanders, who ascended (fresh and re-inductees) by air and acclimatized, participated in this pilot study. The intensity of headache was assessed by the Visual Analogue Score. The parameters of HAH as per the International Classification of Headache Disorders-3 and 2018 Revised Lake Louise Questionnaire (LLQ) were used to differentiate HAH and AMS. RESULTS: Out of 1228 cases, 78 (6.4%) cases had headache, of which 24 (1.95%) cases were HAH only, 40 (3.25%) cases AMS only and 14 (1.14%) cases were defined as both HAH and AMS. There was a significant difference in heart rate [F (2,51) = (4.756), P =0.01] between these groups. It also showed a difference in the correlation between the parameters within the groups. The Odd's Ratio of AMS in fresh and re-inductees was found to be 4.5 and for HAH it was 4.33. INTERPRETATION CONCLUSIONS: The findings of this study suggest that LLQ has a tendency of overestimating AMS by including HAH cases. Furthermore differential parameters exhibit differences when AMS and HAH are considered separately. Re-inductees showed a lower incidence of HAH and AMS.

Challenges in the management of high-altitude illnesses and emergencies in Bhutan and Nepal.

Many popular tourist attractions and trekking routes in Bhutan and Nepal are situated between 3000 and 6000 m in elevation. High-altitude emergencies are becoming more common and medical providers must be aware of the practical and medical issues in managing these disorders. We reflect on the challenges in providing high-altitude emergency medical services in Bhutan and Nepal.

Predictive model for estimating the risk of high-altitude pulmonary edema: a single-centre retrospective outcome-reporting study.

OBJECTIVE: To develop the first prediction model based on the common clinical symptoms of high-altitude pulmonary edema (HAPE), enabling early identification and an easy-to-execute self-risk prediction tool. METHODS: A total of 614 patients who consulted People's Hospital of Tibet Autonomous Region between January 2014 and April 2022 were enrolled. Out of those, 508 patients (416 males and 92 females) were diagnosed with HAPE and 106 were patients without HAPE (33 females and 72 males). They were randomly distributed into training (n=431) and validation (n=182) groups. Univariate and multivariate analysis were used to screen predictors of HAPE selected from the 36 predictors; nomograms were established based on the results of multivariate analysis. The receiver operating characteristic curve (ROC) was developed to obtain the area under the ROC curve (AUC) of the predictive model, and its predictive power was further evaluated by calibrating the curve, while the Decision Curve Analysis (DCA) was developed to evaluate the clinical applicability of the model, which was visualised by nomogram. RESULTS: All six predictors were significantly associated with the incidence of HAPE, and two models were classified according to whether the value of SpO2 (percentage of oxygen in the blood) was available in the target population. Both could accurately predict the risk of HAPE. In the validation cohort, the AUC of model 1 was 0.934 with 95% CI (0.848 to 1.000), and model 2 had an AUC of 0.889, 95% CI (0.779 to 0.999). Calibration plots showed that the predicted and actual HAPE probabilities fitted well with internal validation, and the clinical decision curve shows intervention in the risk range of 0.01-0.98, resulting in a net benefit of nearly 99%. CONCLUSION: The recommended prediction model (nomogram) could estimate the risk of HAPE with good precision, high discrimination and possible clinical applications for patients with HAPE. More importantly, it is an easy-to-execute scoring tool for individuals without medical professionals' support.

A Randomized Phase 2 Study to Evaluate Efficacy and Safety of AR36 for Prevention of Acute Mountain Sickness.

INTRODUCTION: AR36 is a pharmaceutical-grade plant extract used to support cardiovascular health in traditional Chinese medicine. Studies suggest that AR36 may prevent acute mountain sickness (AMS) during gradual ascent to high altitude. This randomized, placebo-controlled Phase 2 trial aimed to evaluate dosing regimens and assess efficacy and safety of AR36 for AMS prevention during rapid ascent. METHODS: Participants received placebo, low-dose AR36 (225 mg twice daily for 14 d prior and 5 d at altitude), or high-dose AR36 (12 d placebo, 300 mg twice daily for 2 d prior and 5 d at altitude). The primary efficacy outcome was 1993 Lake Louise Scoring System (LLSS) score on the morning after ascent. Safety was assessed through the proportion of treatment-emergent adverse events (TEAEs). RESULTS: One hundred thirty-two participants were randomized. Mean±SD age was 31.4±8.6 (range, 19-54) y. Baseline characteristics did not differ across groups. Lake Louise Scoring System scores on Day 16 in the placebo, low-dose, and high-dose groups were 4.03 (2.88), 4.42 (3.17), and 3.5 (2.31), respectively (placebo versus low-dose, P=0.462; placebo versus high-dose, P=0.574; n=110). The incidence of AMS on Day 16 was 66.7% in the placebo, 61.1% in the low-dose, and 55.3% in the high-dose group (P=0.66). The proportion of TEAEs in the placebo, low-dose, and high-dose groups was 38.4% (81), 28.4% (60), and 33.2% (70), respectively (P=0.205; n=127). There was no statistical difference between groups in LLSS, incidence of AMS, or TEAEs. CONCLUSIONS: AR36 did not improve LLSS or AMS incidence using the current regimens. AR36 was well tolerated.

Acute Mountain Sickness and High Altitude Cerebral Edema in Women: A Scoping Review-UIAA Medical Commission Recommendations.

Derstine, Mia, Dominique Jean, Beth A. Beidleman, Jacqueline Pichler Hefti, David Hillebrandt, Lenka Horakova, Susi Kriemler, Kasté Mateikaité-Pipiriené, Peter Paal, Alison Rosier, Marija Andjelkovic, and Linda E. Keyes. Acute mountain sickness and high altitude cerebral edema in women: A scoping review-UIAA Medical Commission recommendations. High Alt Med Biol. 24:259-267, 2023. Background: Acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) are illnesses associated with rapid ascent to altitudes over 2,500 m in unacclimatized lowlanders. The aim of this scoping review is to summarize the current knowledge on sex differences in the epidemiology, pathophysiology, symptomatology, and treatment of AMS and HACE, especially in women. Methods and Results: The UIAA Medical Commission convened an international author team to review women's health issues at high altitude and to publish updated recommendations. Pertinent literature from PubMed and Cochrane was identified by keyword search combinations (including AMS, HACE, and high altitude), with additional publications found by hand search. The primary search focus was for articles assessing lowland women sojourning at high altitude. Results: The literature search yielded 7,165 articles, 37 of which were ultimately included. The majority of publications included did not find women at increased risk for AMS or HACE. There was extremely limited sex-specific data on risk factors or treatment. Conclusions: There is a limited amount of data on female-specific findings regarding AMS and HACE, with most publications addressing only prevalence or incidence with regard to sex. As such, general prevention and treatment strategies for AMS and HACE should be used regardless of sex.

High-Altitude Pulmonary Edema in Women: A Scoping Review-UIAA Medical Commission Recommendations.

Pichler Hefti, Jacqueline, Dominique Jean, Alison Rosier, Mia Derstine, David Hillebrandt, Lenka Horakova, Linda E. Keyes, Kaste Mateikaite-Pipiriene, Peter Paal, Marija Andjelkovic, Beth Beidlemann, and Susi Kriemler. High-altitude pulmonary edema in women: a scoping review-UIAA Medical Commission Recommendations. High Alt Med Biol. 24:268-273, 2023. Background: High-altitude pulmonary edema (HAPE) can occur >2,500-3,000 m asl and is a life-threatening medical condition. This scoping review aims to summarize the current data on sex differences in HAPE. Methods: The International Climbing and Mountaineering Federation (UIAA) Medical Commission convened an international author team to review women's health issues at high altitude. Pertinent literature from PubMed and Cochrane was identified by keyword search combinations (including HAPE), with additional publications found by hand search. The primary search focus was for original articles that included minimum one woman and at least a rudimentary subgroup analysis. Results: The literature search yielded 7,165 articles, 416 of which were relevant for HAPE, and 7 of which were ultimately included here. Six were case series, consistently reporting a lower HAPE prevalence in women. The one retrospective case-control study reported male HAPE prevalence at 10/100,000 and female at 0.74/100,000. No studies were identified that directly compared sex differences in the prevalence of HAPE. No published data was found for topics other than epidemiology. Conclusions: Few studies and associated methodological limitations allow few conclusions to be drawn. Incidence of HAPE may be lower in women than in men. We speculate that besides physiological aspects, behavioral differences may contribute to this potential sex difference.

Potential plasma biomarkers at low altitude for prediction of acute mountain sickness.

Background: Ascending to high altitude can induce a range of physiological and molecular alterations, rendering a proportion of lowlanders unacclimatized. The prediction of acute mountain sickness (AMS) prior to ascent to high altitude remains elusive. Methods: A total of 40 participants were enrolled for our study in the discovery cohort, and plasma samples were collected from all individuals. The subjects were divided into severe AMS-susceptible (sAMS) group, moderate AMS-susceptible (mAMS) group and non-AMS group based on the Lake Louise Score (LLS) at both 5000m and 3700m. Proteomic analysis was conducted on a cohort of 40 individuals to elucidate differentially expressed proteins (DEPs) and associated pathways between AMS-susceptible group and AMS-resistant group at low altitude (1400m) and middle high-altitude (3700m). Subsequently, a validation cohort consisting of 118 individuals was enrolled. The plasma concentration of selected DEPs were quantified using ELISA. Comparative analyses of DEPs among different groups in validation cohort were performed, followed by Receiver Operating Characteristic (ROC) analysis to evaluate the predictive efficiency of DEPs for the occurrence of AMS. Results: The occurrence of the AMS symptoms and LLS differed significantly among the three groups in the discovery cohort (p<0.05), as well as in the validation cohort. Comparison of plasma protein profiles using GO analysis revealed that DEPs were primarily enriched in granulocyte activation, neutrophil mediated immunity, and humoral immune response. The comparison of potential biomarkers between the sAMS group and non-AMS group at low altitude revealed statistically higher levels of AAT, SAP and LTF in sAMS group (p=0.01), with a combined area under the curve(AUC) of 0.965. Compared to the mAMS group at low altitude, both SAP and LTF were found to be significantly elevated in the sAMS group, with a combined AUC of 0.887. HSP90-α and SAP exhibited statistically higher levels in the mAMS group compared to the non-AMS group at low altitude, with a combined AUC of 0.874. Conclusion: Inflammatory and immune related biological processes were significantly different between AMS-susceptible and AMS-resistant groups at low altitude and middle high-altitude. SAP, AAT, LTF and HSP90-α were considered as potential biomarkers at low altitude for the prediction of AMS.

Prevalence and knowledge about acute mountain sickness in the Western Alps.

OBJECTIVE: To assess the prevalence of acute mountain sickness (AMS) in 1370 mountaineers at four different altitudes in the Western Alps. We also examined the influence of potential risk factors and the knowledge about AMS on its prevalence. METHODS: In this observational cross-sectional study AMS was assessed on the day of ascent by the Lake Louise score (LLS, cut-off ≥3, version 2018) and the AMS-Cerebral (AMS-C) score of the environmental symptom questionnaire (cut-off ≥0,70). The latter was also obtained in the next morning. Knowledge regarding AMS and high-altitude cerebral edema (HACE) and the potential risk factors for AMS were evaluated by questionnaires. RESULTS: On the day of ascent, the prevalence of AMS assessed by the LLS and AMS-C score was 5.8 and 3.9% at 2850 m, 2.1 and 3.1% at 3050 m, 14.8 and 10.1% at 3650 m, and 21.9 and 15% at 4559 m, respectively. The AMS prevalence increased overnight from 10.1 to 14.5% and from 15 to 25.2% at 3650 m and 4559 m, respectively, and was unchanged at 2850 m and 3050 m. A history of AMS, higher altitude, lower degree of pre-acclimatization, and younger age were identified as risk factors for developing AMS. Slow ascent was weakly associated with AMS prevalence, and sex and knowledge about AMS and HACE were indistinct. CONCLUSION: AMS is common at altitudes ≥ 3650 m and better knowledge about AMS and HACE was not associated with less AMS in mountaineers with on average little knowledge.

Active ascent accelerates the time course but not the overall incidence and severity of acute mountain sickness at 3,600 m.

Acute mountain sickness (AMS) typically peaks following the first night at high altitude (HA) and resolves over the next 2-3 days, but the impact of active ascent on AMS is debated. To determine the impact of ascent conditions on AMS, 78 healthy Soldiers (means ± SD; age = 26 ± 5 yr) were tested at baseline residence, transported to Taos, NM (2,845 m), hiked (n = 39) or were driven (n = 39) to HA (3,600 m), and stayed for 4 days. AMS-cerebral (AMS-C) factor score was assessed at HA twice on day 1 (HA1), five times on days 2 and 3 (HA2 and HA3), and once on day 4 (HA4). If AMS-C was ≥0.7 at any assessment, individuals were AMS susceptible (AMS+; n = 33); others were nonsusceptible (AMS-; n = 45). Daily peak AMS-C scores were analyzed. Ascent conditions (active vs. passive) did not impact the overall incidence and severity of AMS at HA1-HA4. The AMS+ group, however, demonstrated a higher (P < 0.05) AMS incidence in the active vs. passive ascent cohort on HA1 (93% vs. 56%), similar incidence on HA2 (60% vs. 78%), lower incidence (P < 0.05) on HA3 (33% vs. 67%), and similar incidence on HA4 (13% vs. 28%). The AMS+ group also demonstrated a higher (P < 0.05) AMS severity in the active vs. passive ascent cohort on HA1 (1.35 ± 0.97 vs. 0.90 ± 0.70), similar score on HA2 (1.00 ± 0.97 vs. 1.34 ± 0.70), and lower (P < 0.05) score on HA3 (0.56 ± 0.55 vs. 1.02 ± 0.75) and HA4 (0.32 ± 0.41 vs. 0.60 ± 0.72). Active compared with passive ascent accelerated the time course of AMS with more individuals sick on HA1 and less individuals sick on HA3 and HA4.NEW & NOTEWORTHY This research demonstrated that active ascent accelerated the time course but not overall incidence and severity of acute mountain sickness (AMS) following rapid ascent to 3,600 m in unacclimatized lowlanders. Active ascenders became sicker faster and recovered quicker than passive ascenders, which may be due to differences in body fluid regulation. Findings from this well-controlled large sample-size study suggest that previously reported discrepancies in the literature regarding the impact of exercise on AMS may be related to differences in the timing of AMS measurements between studies.

Association between high cardiac output at altitude and acute mountain sickness: preliminary study on Mt. Fuji.

BACKGROUND: Acute mountain sickness (AMS) affects around 30% of people climbing Mt. Fuji, but its pathogenesis is incompletely understood. The influence of a rapid ascent to high altitude by climbing and summiting Mt. Fuji on cardiac function in the general population is unknown, and its association with altitude sickness has not been clarified. METHODS: Subjects climbing Mt. Fuji were included. Heart rate, oxygen saturation, systolic blood pressure, cardiac index (CI) and stroke volume index were measured multiple times at 120 m as baseline values and at Mt. Fuji Research Station (MFRS) at 3,775 m. Each value and its difference from the baseline value (Δ) of subjects with AMS (defined as Lake Louise Score [LLS] ≥ 3 with headache after sleeping at 3,775 m) were compared with those of non-AMS subjects. RESULTS: Eleven volunteers who climbed from 2,380 m to MFRS within 8 h and stayed overnight at MFRS were included. Four suffered AMS. Compared with the non-AMS subjects, CI in the AMS subjects was significantly higher than that before sleeping (median [interquartile range]: 4.9 [4.5, 5.0] vs. 3.8 [3.4, 3.9] mL/min/m2; p = 0.04), and their ΔCI was significantly higher before sleeping (1.6 [1.4, 2.1] vs. 0.2 [0.0, 0.7] mL/min/m2; p < 0.01) and after sleeping (0.7 [0.3, 1.7] vs. -0.2 [-0.5, 0.0] mL/min/m2; p < 0.01). ΔCI in the AMS subjects dropped significantly after sleeping versus before sleeping (3.8 [3.6, 4.5] vs. 4.9 [4.5, 5.0] mL/min/m2; p = 0.04). CONCLUSIONS: Higher values of CI and ΔCI were observed at high altitude in the AMS subjects. A high cardiac output might be associated with the development of AMS.

Remote ischemic preconditioning improves spatial memory and sleep of young males during acute high-altitude exposure.

OBJECTIVE: The high-altitude hypoxia environment will cause poor acclimatization in a portion of the population. Remote ischemic preconditioning（RIPC）has been demonstrated to prevent cardiovascular and cerebrovascular diseases under ischemic or hypoxic conditions. However, its role in improving acclimatization and preventing acute mountain sickness (AMS) at high altitude has been undetermined. This study aims to estimate the effect of RIPC on acclimatization of individuals exposed to high altitude. METHODS: The project was designed as a randomized controlled trial with 82 healthy young males, who received RIPC training once a day for 7 consecutive days. Then they were transported by aircraft to a high altitude (3680 m) and examined for 6 days. Lake Louise Score(LLS) of AMS, physiological index, self-reported sleep pattern, and Pittsburgh Sleep Quality Index（PSQI）score were applied to assess the acclimatization to the high altitude. Five neurobehavioral tests were conducted to assess cognitive function. RESULTS: The result showed that the RIPC group had a significantly lower AMSscore than the control group (2.43 ± 1.58 vs 3.29 ± 2.03, respectively; adjusted mean difference-0.84, 95% confidence interval-1.61 to -0.06, P = 0.036). and there was no significant difference in AMS incidence between the two groups (25.0% vs 28.57%, P = 0.555). The RIPC group performed better than the control group in spatial memory span score (11[9-12] vs 10[7.5-11], P=0.025) and the passing digit (7[6-7.5] vs 6[5-7], P= 0.001). Spatial memory was significantly higher in the high-altitude RIPC group than in the low-altitude RIPC group (P＜0.01). And the RIPC group obtained significantly lower self-reported sleep quality score (P = 0.024) and PSQI score (P = 0.031). CONCLUSIONS: The RIPC treatment improved spatial memory and sleep quality in subjects exposed to acute hypoxic exposure and this may lead to improved performance at high altitude.

High Altitude Illness among Rapidly Ascending Pilgrims to Kailash Mansarovar.

BACKGROUND: High altitude pilgrims typically ascend rapidly, are not well prepared for the austere environment and tend to have multiple co-morbidities. Here, we list the trend of altitude and other illnesses who visited Humla district hospital (2,950 meters) following very rapid ascent to Kailash Mansarovar (4,500 meters). METHODS: A prospective study was conducted among 55 patients at the Humla District Hospital from September 2019 - August 2022. Patients who fell ill during pilgrimage and brought to the hospital were included. The patients were assessed with medical history and clinical examination. Lake Louise Score Acute Mountain Sickness Score (2018) was used for the diagnosis of Acute Mountain Sickness. RESULTS: A total of 56 evacuees visited the hospital which included 55 patients and 1 brought dead. The mean age was 50.63 ± 10.91 years. Sixteen patients (29.1%) developed symptoms within 24 hours and 15 patients (27.3%) within 48 hours of ascent. Headache 42 (76.4%) was the most common complain. Mild acute mountain sickness (30.9%; 17 patients) was the most common altitude related illness while 14 patients (25.4%) were diagnosed with non-altitude related illnesses. Twelve patients (21.8%) had co-morbidities like hypertension and diabetes mellitus. CONCLUSIONS: In the rapidly ascending pilgrims, majority of travelers requiring medical attention are suffering from some form of altitude illnesses. Hence, proper planning and public awareness about slow and gradual ascent profile is necessary to make the travel safer.

Flying to high-altitude destinations: Is the risk of acute mountain sickness greater?

BACKGROUND: Altitude sojourns increasingly attract individuals of all ages and different health statuses due to the appeal of high-altitude destinations worldwide and easy access to air travel. The risk of acute mountain sickness (AMS) when flying to high-altitude destinations remains underemphasized. Thus, this review aims to evaluate the altitude-dependent AMS incidence depending on the mode of ascending, e.g. by air vs terrestrial travel. METHODS: A literature search was performed to identify the observational studies assessing AMS incidence after acute ascent of primarily healthy adults to real high altitude. In addition, placebo arms of interventional trials evaluating the prophylactic efficacy of various drugs have been separately analysed to confirm or refute the findings from the observational studies. Linear regression analyses were used to evaluate the altitude-dependent AMS incidence. RESULTS: Findings of 12 observational studies, in which the AMS incidence in 11 021 individuals ascending to 19 different altitudes (2200-4559 m) was evaluated, revealed an impressive 4.5-fold steeper increase in the AMS incidence for air travel as compared with slower ascent modes, i.e. hiking or combined car and/or air travel and hiking. The higher AMS incidence following transportation by flight vs slower means was also confirmed in placebo-treated participants in 10 studies of drug prophylaxis against AMS. CONCLUSIONS: Due to the short time span in going from low to high altitude, reduced acclimatization likely is the main reason for a higher AMS risk when travelling to high-altitude destinations by flight. To avoid frustrating travel experiences and health risks, appropriate and timely medical advice on how to prepare for air travel to high altitude is of vital importance. Effective preparation options include the use of modern pre-acclimatization strategies and pharmacological prophylaxis by acetazolamide or dexamethasone, or even considering alternate itineraries with more gradual ascent.

Application of SARIMA model in forecasting and analyzing inpatient cases of acute mountain sickness.

BACKGROUND: Acute Mountain Sickness (AMS) is typically triggered by hypoxia under high altitude conditions. Currently, rule of time among AMS inpatients was not clear. Thus, this study aimed to analyze the time distribution of AMS inpatients in the past ten years and construct a prediction model of AMS hospitalized cases. METHODS: We retrospectively collected medical records of AMS inpatients admitted to the military hospitals from January 2009 to December 2018 and analyzed the time series characteristics. Seasonal Auto-Regressive Integrated Moving Average (SARIMA) was established through training data to finally forecast in the test data set. RESULTS: A total of 22 663 inpatients were included in this study and recorded monthly, with predominant peak annually, early spring (March) and mid-to-late summer (July to August), respectively. Using the training data from January 2009 to December 2017, the model SARIMA (1, 1, 1) (1, 0, 1) 12 was employed to predict the test data from January 2018 to December 2018. In 2018, the total predicted value after adjustment was 9.24%, less than the actual value. CONCLUSION: AMS inpatients have obvious periodicity and seasonality. The SARIMA model has good fitting ability and high short-term prediction accuracy. It can help explore the characteristics of AMS disease and provide decision-making basis for allocation of relevant medical resources for AMS inpatients.

[Incidence and risk factors of acute mountain sickness in grid construction personnel working at plateau].

Objective: To analyze the incidence and risk factors of acute mountain sickness (AMS) in grid construction personnel working at plateau. Methods: A total of 10 956 plateau construction personnel of Ali Network Project from January 1, 2019 to December 31, 2020 were included. Baseline information (including age, sex, body mass index, developmental and nutritional status, relevant clinical indicators, etc.) and follow-up data of AMS were obtained from the medical record of Ali Internet engineering staff medical station. The altitude of the residence place in early life and the working environment were obtained from the website (https://zh-cn.topographic-map.com/legal/). The incidences of overall AMS and its subgroups were calculated, and the Cox proportional hazards model was used to explore the risk factors for AMS. Results: The age of the participants was (36.1±10.5) years old at baseline, and 95.27% (10 438) of them were males. The follow-up time was (17.46±4.23) months. The altitude of the residence place in early-life and working environment were (1 959±937) m and (4 533±233) m, respectively. During the follow-up period, the incidence of AMS was 15.58% (1 707 cases), and the incidence for acute mountain sickness and high altitude pulmonary edema were 15.53% (1 702 cases) and 0.05% (5 cases), respectively. No high altitude cerebral edema patients were found. Cox proportional hazards model showed that the risk of AMS increased by 45% for every 100 m elevation in the altitude of working environment [HR (95%CI): 1.45 (1.41-1.51)]. The higher the altitude for the residence place in early-life, the lower the risk of AMS [HR (95%CI): 0.84 (0.80-0.88)]. Compared with the group with oxygen saturation during 90%-94%, the participants with oxygen saturation<75% [HR (95%CI): 1.67 (1.24-2.23)] at baseline was also associated with increased risk of AMS. Conclusions: The incidence of AMS is relatively low in grid construction workers working on plateau. The risk factors of AMS included higher working altitude, lower altitude of the residence place in early-life and oxygen saturation<75%.

High Altitude Pulmonary Edema, High Altitude Cerebral Edema, and Acute Mountain Sickness: an enhanced opinion from the High Andes - La Paz, Bolivia 3,500 m.

Traveling to high altitudes for entertainment or work is sometimes associated with acute high altitude pathologies. In the past, scientific literature from the lowlander point of view was primarily based on mountain climbing. Sea level scientists developed all guidelines, but they need modifications for medical care in high altitude cities. Acute Mountain Sickness, High Altitude Pulmonary Edema, and High Altitude Cerebral Edema are medical conditions that some travelers can face. We present how to diagnose and treat acute high altitude pathologies, based on 51 years of high altitude physiology research and medical practice in hypobaric hypoxic diseases in La Paz, Bolivia (3,600 m; 11,811 ft), at the High Altitude Pulmonary and Pathology Institute (HAPPI - IPPA). These can occasionally present after flights to high altitude cities, both in lowlanders or high-altitude residents during re-entry. Acute high altitude ascent diseases can be adequately diagnosed and treated in high altitude cities following the presented guidelines. Treating these high-altitude illnesses, we had no loss of life. Traveling to a high altitude with sound medical advice should not be feared as it has many benefits. Nowadays, altitude descent and evacuation are not mandatory in populated highland cities, with adequate medical resources.

High altitude pulmonary edema in children: A systematic review.

INTRODUCTION: High altitude pulmonary edema (HAPE) is a form of acute noncardiogenic pulmonary edema caused by altitude-related hypoxia seen in children as well as in adults. In this systematic review we focus in HAPE occurring in children and adolescents. METHODS: A systematic review was conducted including publications in children 0-18 years of age from three databases up to June 2022. RESULTS: Thirty-five studies representing 210 cases were found. The mean age was 9.8 ± 3.6 years with a male/female ratio of 2.6. The peak age incidence was seen in children between 6 and 10 years old. Only two children (0.9%) were ≤2 years old. The mean altitude in 166 cases was 2861 masl. Only 17 cases (8.1%) occurred at altitudes below 2500 masl. Regarding the different HAPE subtypes there was a predominance of re-entry HAPE (R-HAPE) with 58%, followed by classic HAPE (C-HAPE) with 37.6%. The mean time between arrival and onset of symptoms was 16.5 h. The mortality rate was 1.4%. In 10/28 (36%) of C-HAPE cases there was a structural cardiac/pulmonary anomaly compared to 1/19 (5%) in R-HAPE (p < 0.01). HAPE recurrence was found in 46 cases (21.9%). The involvement in the chest X-rays was seen predominantly in the apices and in the right lung. CONCLUSIONS: R-HAPE was the most common HAPE subtype; HAPE peak age was found between 6 and 10 years of age; HAPE was more frequent in males and was rare in children under 2 years old; associated HAPE structural abnormalities were more common in C-HAPE than in R-HAPE.

Mean corpuscular haemoglobin concentration (MCHC): a new biomarker for high-altitude pulmonary edema in the Ecuadorian Andes.

Ascent to high altitude (> 3000 m height above sea level or m.a.s.l) exposes people to hypobaric atmospheric pressure and hypoxemia, which provokes mountain sickness and whose symptoms vary from the mild acute mountain sickness to the life-threatening, high-altitude pulmonary edema (HAPE). This study analysed the risk factors underlying HAPE in dwellers and travellers of the Ecuadorian Andes after sojourning over 3000 m height. A group of HAPE patients (N = 58) was compared to a NO HAPE group (N = 713), through demographic (ethnicity, sex, and age), red blood cell parameters (erythrocytes counts, hematocrit, median corpuscular volume, median corpuscular haemoglobin, and median corpuscular haemoglobin concentration (MCHC)), altitude (threshold: 3000 m.a.s.l.), and health status (vital signs) variables. Analysis of Deviance for Generalised Linear Model Fits (logit regression) revealed patterns of significant associations. High-altitude dwellers, particularly children and elder people, were HAPE-prone, while women were more tolerant of HAPE than men. Interestingly, HAPE prevalence was strongly related to an increment of MCH. The residence at middle altitude was inversely related to the odds of suffering HAPE. Ethnicity did not have a significant influence in HAPE susceptibility. Elevated MCHC emerges like a blood adaptation of Andean highlanders to high altitude and biomarker of HAPE risk.

Cardiovascular Risk Profiles and Pre-Existing Health Conditions of Trekkers in the Solu-Khumbu Region, Nepal.

BACKGROUND: High-altitude tourist trekking continues to grow in popularity on the Everest Trek in Nepal. We examined which pre-existing cardiovascular and health conditions these global trekkers had and what health issues they encountered during the trek, be it exacerbations of pre-existing conditions, or new acute ones. METHOD: Trekkers (n = 350) were recruited from guesthouses along the Everest Trek, mostly at Tengboche (3860 m). After completing a questionnaire on their health and travel preparation, they underwent a basic physical examination with an interview. RESULTS: Almost half (45%) had pre-existing conditions, mostly orthopaedic and cardiovascular diseases. The average age was 42.7 years (range 18-76). The average BMI was 23.4 kg/m2, but 21% were overweight. A third were smokers (30%), and 86% had at least one major cardiovascular risk factor. A quarter (25%) were suffering from manifest acute mountain sickness (AMS), and 72% had at least one symptom of AMS. Adequate pre-travel examination, consultation, and sufficient personal preparation were rarely found. In some cases, a distinct cardiovascular risk profile was assessed. Hypertensive patients showed moderately elevated blood pressure, and cholesterol levels were favourable in most cases. No cardiovascular emergencies were found, which was fortunate as timely, sufficient care was not available during the trek. CONCLUSION: The results of earlier studies in the Annapurna region should be revalidated. Every trekker to the Himalayas should consult a physician prior to departure, ideally a travel medicine specialist. Preventative measures and education on AMS warrant special attention. Travellers with heart disease or with a pronounced cardiovascular risk profile should be presented to an internal medicine professional. Travel plans must be adjusted individually, especially with respect to adequate acclimatisation time and no physical overloading. With these and other precautions, trekking at high altitudes is generally safe and possible, even with significant pre-existing health conditions. Trekking can lead to invaluable personal experiences. Since organized groups are limited in their flexibility to change their itinerary, individual trekking or guided tours in small groups should be preferred.