The Lake Louise Score: A Critical Assessment of Its Specificity

Oxygen comfort evaluation method based on symptom index for short-term internal migrants to Tibet

In Tibet, the hypobaric-hypoxic environment found at high altitudes leads to dysfunction in short-term internal migrants and has noticeable effects on physiology, psychological health, and comfort level. Therefore, it is essential to accurately determine the degree of hypoxia and improve the hypoxic environment of plateaus. Despite advances in the medical diagnosis and treatment of pathological hypoxic injuries, there are some limitations in the oxygenic evaluation of internal migrants with mild hypoxia. An oxygen comfort evaluation method (OCEM) based on typical anoxic symptomatology and physiological indices is proposed in this study. Experiments with different oxygen concentrations were conducted to measure anoxic symptomatology and physiological indices. Using item and exploratory factor analyses, 19 symptom indices were screened to predict oxygen sensation in humans. Finally, the OCEM was established using an artificial neural network and fuzzy mathematics method and its accuracy was verified through a field survey. The results showed that the artificial neural network model using symptomatologic indices could predict human oxygen sensation, with an area under the receiver operating characteristic curve of 0.630-0.913 and prediction accuracy of 93 %. Oxygen comfort can be predicted from the oxygen sensation and typical physiological indices using the fuzzy mathematics method; the weighted kappa coefficient was 0.825, indicating a strong correlation between the predicted and actual values. The proposed OCEM can help determine the oxygen comfort conditions of high-altitude internal migrants and provide a basis for indoor oxygen environment regulation in high-altitude buildings.

AZU1 (HBP/CAP37) and PRKCG (PKC-gamma) may be candidate genes affecting the severity of acute mountain sickness

BACKGROUND

Acute Mountain Sickness (AMS) is one of the diseases that predispose to sudden ascent to high altitudes above 2500 m. Among the many studies on the occurrence and development of AMS, there are few studies on the severity of AMS. Some unidentified phenotypes or genes that determine the severity of AMS may be vital to elucidating the mechanisms of AMS. This study aims to explore the underlying genes or phenotypes associated with AMS severity and to provide evidence for a better understanding of the mechanisms of AMS.

METHODS

GSE103927 dataset was downloaded from the Gene Expression Omnibus database, and a total of 19 subjects were enrolled in the study. Subjects were divided into a moderate to severe AMS (MS-AMS, 9 subjects) group and a no or mild AMS (NM-AMS, 10 subjects) group based on the Lake Louise score (LLS). Various bioinformatics analyses were used to compare the differences between the two groups. Another dataset, Real-time quantitative PCR (RT-qPCR), and another grouping method were used to validate the analysis results.

RESULT

No statistically significant differences in phenotypic and clinical data existed between the MS-AMS and NM-AMS groups. Eight differential expression genes are associated with LLS, and their biological functions are related regulating of the apoptotic process and programmed cell death. The ROC curves showed that AZU1 and PRKCG had a better predictive performance for MS-AMS. AZU1 and PRKCG were significantly associated with the severity of AMS. The expression of AZU1 and PRKCG were significantly higher in the MS-AMS group compared to the NM-AMS group. The hypoxic environment promotes the expression of AZU1 and PRKCG. The results of these analyses were validated by an alternative grouping method and RT-qPCR results. AZU1 and PRKCG were enriched in the Neutrophil extracellular trap formation pathway, suggesting the importance of this pathway in influencing the severity of AMS.

CONCLUSION

AZU1 and PRKCG may be key genes influencing the severity of acute mountain sickness, and can be used as good diagnostic or predictive indicators of the severity of AMS. Our study provides a new perspective to explore the molecular mechanism of AMS.

Companion Rescue and Risk Management of Trekkers on the Everest Trek, Solo Khumbu Region, Nepal

BACKGROUND

Trekking to high-altitude locations presents inherent health-related hazards, many of which can managed with specific first aid (FA) training. This study evaluates the trip preparation, FA knowledge, and FA self-assessment of trekkers (organized by tour operators vs. individually planned tours). Data obtained shall be used for specific FA trip preparation and management of emergencies en route for this population.

METHODS

A total of 366 trekkers on the Everest Base Camp Trek, Nepal, were interviewed using a questionnaire specifically designed to evaluate their FA knowledge and management of emergencies. Data evaluation was performed using descriptive statistics.

RESULTS

A total of 40.5% of trekkers experienced at least one medical incident during their trip, of which almost 50% were due to acute mountain sickness (AMS). There was more AMS in commercially organized groups than in individually planned ones (55% vs. 40%). For more than 50%, no medical care was available during their trip. A total of 80% could answer only 3/21 FA questions completely correctly. Only 1% showed adequate knowledge concerning FA strategies. A total of 70% were willing to enroll in an FA class specialized towards the needs of trekkers.

CONCLUSIONS

The importance of high-altitude FA knowledge and trip preparation is widely underestimated. There is an unmet demand amongst trekkers for specific wilderness FA classes.

Incidence and predictors of severe altitude illness symptoms in Mt. Kilimanjaro hikers: a prospective cohort study

BACKGROUND

Each year several Mt. Kilimanjaro hikers die due to altitude illness (AI) although urgent descent is technically easily possible. The objectives of this study were to determine the incidence and predictors of severe altitude illness (SAI) symptoms and of summit success in Mt. Kilimanjaro hikers, and the measures taken when AI symptoms develop.

METHODS

A prospective observational cohort study in Mt. Kilimanjaro hikers was conducted from December 2019 until March 2020. Participants were asked to complete a questionnaire at the entrance gate and one at the descend gate. A multivariate logistic regression was performed to study the relations between the variables.

RESULTS

A total of 1237 recreational hikers and 266 porters or guides were included. The incidence of severe symptoms was 8.6% in recreational hikers and 1.5% in porters and guides. One percent (1.1%) of hikers was hospitalized due to SAI. A history of SAI, young age, summit failure and lack of clear advice predicted the development of severe symptoms. Uhuru peak was reached by 87.9% of the hikers. Absence of severe symptoms, acetazolamide prophylaxis, climbing higher in daytime, young age and climbing in more days predicted summit success. The majority climbed further despite the presence of mild or severe symptoms. The only measure taken in case of mild symptoms that was associated with a lower incidence of severe symptoms was not climbing further.

CONCLUSION

The incidence of SAI symptoms in Mt. Kilimanjaro hikers was observed to be high. However, how hikers reacted during symptoms was not appropriate. Therefore, travel health counsellors should emphasize even more that hikers do not ascend higher until mild symptoms have resolved and that it is vital to descend immediately when severe symptoms develop. In addition, they can be informed on the measures, which improved summit success.

Assessment of Acute Mountain Sickness Using 1993 and 2018 Versions of the Lake Louise Score in a Large Chinese Cohort

Chen, Renzheng, Yong Wang, Chen Zhang, Xiaolin Luo, Jie Yang, Chuan Liu, and Lan Huang. Assessment of acute mountain sickness using 1993 and 2018 versions of the Lake Louise Score in a large Chinese cohort. High Alt Med Biol. 22:362-368, 2021. Background: This study uses Lake Louise Score (LLS) in its original (LLS1993) and new (LLS2018) versions to assess acute mountain sickness (AMS) and aims to provide more clinical information about the AMS scoring system. Methods: We enrolled 1,026 male Chinese soldiers who traveled from an altitude of 500 to 3,700 m by airplane in 2.5 hours. We observed each subject's symptoms after arrival at 3,700 m in 24 and 48 hours. Each item was dropped from LLS1993 to evaluate its sensitivity and effect on AMS diagnosis. The relationship between each symptom and AMS was assessed by correlation analysis. Exploratory and confirmatory factor analyses evaluated the factor structure of LLS, while the ordinal alpha coefficient was calculated to determine its internal consistency. Results: Four hundred fifty-nine subjects were not followed up on day 2. We defined two observed cohorts (cohort 1, n = 1,026 and cohort 2, n = 567). Headache was the most common symptom in 24 hours, while sleep disturbance was the fourth-most common symptom at 24 hours and the most common symptom at 48 hours. When we dropped gastrointestinal symptoms, the drop rate was lowest in each situation (1.0% in cohort 1, 1.3% in cohort 2 at 24 hours, and 5.7% in cohort 2 at 48 hours, respectively). The incidence of AMS decreased from 18.4% at 24 hours to 36.4% at 48 hours when lost sleep disturbance in cohort 2. Moreover, the statistical method of Mantel/Haenszel square test was used for correlation analysis and the results showed a correlation between sleep disturbance and AMS. Besides, both LLS1993 and LLS2018 had acceptable internal consistencies, and all items had good loading coefficients in LLS1993. Conclusions: We have demonstrated that there could be an association between sleep disturbance and AMS diagnosis. Both LLS1993 and LLS2018 applied to young Chinese men.

Evaluation of the Lake Louise Score for Acute Mountain Sickness and Its 2018 Version in a Cohort of 484 Trekkers at High Altitude

Richalet, Jean-Paul, Chantal Julia, and François J. Lhuissier. Evaluation of the Lake Louise Score for acute mountain sickness and its 2018 version in a cohort of 484 trekkers at high altitude. High Alt Med Biol. 22:353-361, 2021. Background: The Lake Louise Score (LLS) is widely used in field studies and chamber studies for the diagnosis of Acute Mountain Sickness (AMS). This score aggregates symptoms that are nonspecific: headache, gastrointestinal symptoms, fatigue, dizziness and sleep disturbance can be due to a variety of causes unrelated to altitude hypoxia. The objectives of this study were to (1) reevaluate the need for a headache score >0 for the diagnosis of AMS, (2) evaluate the role of sleep disturbances, in relation with other symptoms, (3) evaluate the significance of dizziness. Materials and Methods: We analyzed LLS from 484 trekkers at high altitude. Among them, 212 suffered from moderate AMS (mAMS: 3 ≤ LLS < 6) and 115 from severe AMS (sAMS: LLS ≥ 6). Results: Cluster analysis of AMS revealed three main groups presenting the following symptoms: Group 1 includes 254 subjects who had less than 2 symptoms; Group 2 includes 137 subjects who had fatigue, sleep disturbance, and headache, corresponding to mAMS; Group 3 includes 93 subjects who had headache, fatigue, dizziness and sleep disturbance, corresponding to sAMS. A headache score of zero was found in 25% of mAMS and 5% of sAMS subjects. Only the absence of headache associated with the absence of fatigue was specific of absence of sAMS. In subjects with a dizziness score > 1, end-tidal partial pressure of carbon dioxide during a hypoxic exercise test was lower than that in subjects with a dizziness score < 2. Subjects with high ventilatory response to hypoxia may develop dizziness with high altitude exposure. Conclusion: (1) An isolated headache score > 0 should not be mandatory to define AMS, (2) sleep disruption contributes to the diagnosis of AMS, (3) gastrointestinal symptoms and dizziness are weaker contributors to the LLS, (4) dizziness might be linked to a hyperresponsiveness to hypoxia and not to AMS itself.