Acute Mountain Sickness Patients Research Articles

Cardiovascular Indicators of Systemic Circulation and Acute Mountain Sickness: An Observational Cohort Study.

Background: Acute high-altitude (HA) exposure results in blood pressure (BP) and cardiac function variations in most subjects, some of whom suffer from acute mountain sickness (AMS). Several previous studies have found that cardiovascular function indicators are potentially correlated with AMS.Objectives: This study aims to examine HA-induced cardiovascular adaptations in AMS patients and compare them with healthy subjects. It also aims to investigate the relationship between cardiovascular function indicators and AMS, as well as to provide some insightful information about the prevention and treatment of AMS.Methods: Seventy-two subjects were enrolled in this cohort study. All the subjects ascended Litang (4,100 m above sea level). They were monitored by a 24-h ambulatory blood pressure (ABP) device and underwent echocardiography examination within 24 h of altitude exposure. The 2018 Lake Louise questionnaire was used to evaluate AMS.Results: Acute mountain sickness group consisted of more women (17 [60.7%] vs. 10 [22.7%], p = 0.001) and fewer smokers (5 [17.9%] vs. 23 [52.3%], p = 0.003). Compared with subjects without AMS, subjects with AMS had lower pulse pressure (PP) (daytime PP, 45.23 ± 7.88 vs. 52.14 ± 4.75, p < 0.001; nighttime PP, 42.81 ± 5.92 vs. 49.39 ± 7.67, p < 0.001) and lower effective arterial elastance (Ea) (1.53 ± 0.24 vs. 1.73 ± 0.39, p = 0.023). Multivariate regression indicated that female sex (OR = 0.23, p = 0.024), lower daytime PP (OR = 0.86, p = 0.004), and lower Ea (OR = 0.03, p = 0.015) at low altitude (LA) were independent risk factors for AMS. Combined daytime PP and Ea at LA had a high predictive value for AMS (AUC = 0.873; 95% CI: 0.789–0.956). Correlation analysis showed that AMS-induced headache correlated with daytime PP (R = −0.401, p < 0.001) and nighttime PP at LA (R = −0.401, p < 0.001).Conclusion: Our study demonstrated that AMS patients had a lower PP and Ea at LA. These baseline indicators of vasodilation at LA were closely associated with AMS, which may explain the higher headache severity in subjects with higher PP at LA.

Low Stroke Volume Index in Healthy Young Men Is Associated with the Incidence of Acute Mountain Sickness after an Ascent by Airplane: A Case-Control Study.

Background The aims of this study were to explore the characteristics of left ventricular (LV) functional changes in subjects with or without acute mountain sickness (AMS) and their associations with AMS incidence. Methods A total of 589 healthy men were enrolled and took a trip from Chengdu (500 m, above sea level (asl)) to Lhasa (3700 m, asl) by airplane. Basic characteristics, physiological data, and echocardiographic parameters were collected both at Chengdu and Lhasa, respectively. AMS was identified by the Lake Louise Questionnaire Score. Results The oxygen saturation (SpO2), end-systolic volume index, end-diastolic volume index (EDVi), stroke volume index (SVi), E-wave velocity, and E/A ratio were decreased, whereas the heart rate (HR), ejection fraction, cardiac index (CI), and A-wave velocity were increased at the third day after arrival, as evaluated by an oximeter and echocardiography. However, AMS patients showed higher HR and lower EDVi, SVi, CI, E-wave velocity, and E/A ratio than AMS-free subjects. Among them, SVi, which is mainly correlated with the changes of EDVi and altered LV filling pattern, was the most valuable factor associated with AMS incidence following receiver-operator characteristic curves and linear and Poisson regression. Compared with subjects in the highest SVi tertile, subjects in the middle SVi tertile showed higher multivariable Incidence Rate Ratios (IRR) for AMS with higher incidences of mild headache and gastrointestinal symptoms, whereas subjects in the lowest SVi tertile showed even higher multivariable IRR with higher incidences of all the symptoms. Conclusions This relatively large-scale case-control study revealed that the reduction of SVi correlated with the altered LV filling pattern was associated with the incidence and clinical severity of AMS.

EPAS1 and VEGFA gene variants are related to the symptoms of acute mountain sickness in Chinese Han population: a cross-sectional study

BackgroundMore people ascend to high altitude (HA) for various activities, and some individuals are susceptible to HA illness after rapidly ascending from plains. Acute mountain sickness (AMS) is a general complaint that affects activities of daily living at HA. Although genomic association analyses suggest that single nucleotide polymorphisms (SNPs) are involved in the genesis of AMS, no major gene variants associated with AMS-related symptoms have been identified.MethodsIn this cross-sectional study, 604 young, healthy Chinese Han men were recruited in June and July of 2012 in Chengdu, and rapidly taken to above 3700 m by plane. Basic demographic parameters were collected at sea level, and heart rate, pulse oxygen saturation (SpO2), systolic and diastolic blood pressure and AMS-related symptoms were determined within 18–24 h after arriving in Lhasa. AMS patients were identified according to the latest Lake Louise scoring system (LLSS). Potential associations between variant genotypes and AMS/AMS-related symptoms were identified by logistic regression after adjusting for potential confounders (age, body mass index and smoking status).ResultsIn total, 320 subjects (53.0%) were diagnosed with AMS, with no cases of high-altitude pulmonary edema or high-altitude cerebral edema. SpO2 was significantly lower in the AMS group than that in the non-AMS group (P = 0.003). Four SNPs in hypoxia-inducible factor-related genes were found to be associated with AMS before multiple hypothesis testing correction. The rs6756667 (EPAS1) was associated with mild gastrointestinal symptoms (P = 0.013), while rs3025039 (VEGFA) was related to mild headache (P = 0.0007). The combination of rs6756667 GG and rs3025039 CT/TT further increased the risk of developing AMS (OR = 2.70, P < 0.001).ConclusionsUnder the latest LLSS, we find that EPAS1 and VEGFA gene variants are related to AMS susceptibility through different AMS-related symptoms in the Chinese Han population; this tool might be useful for screening susceptible populations and predicting clinical symptoms leading to AMS before an individual reaches HA.Trial registrationChinese Clinical Trial Registration, ChiCTR-RCS-12002232. Registered 31 May 2012.

P4370Doppler echocardiography, RV Strain and 3D RV Imaging in diagnosis of Acute mountain sickness

Abstract Introduction Right Ventricular (RV) strain and 3D RV ejection fraction sensitivity and specificity has made it a practical and reliable test to detect Acute mountain sickness. All previous studies have been done mainly using M Mode and 2D Echo. Hence it was conceived that 3D Echocardiography would be a better option. Regardless of the type of Acute Mountain Sickness (AMS), the echocardiographic evidence is always the same: Severe Pulmonary hypertension. The visual analysis of these abnormalities requires a trained operator. This operator-dependence has promoted the search for a semiautomatic method to reduce limitations of Echocardiography and improve test accuracy Purpose The purpose was to study AMS by 3D Echocardiography Methods and results Two dimensional echocardiography with RV strain analysis by speckle tracking echocardiography along with 3D RV ejection fraction was done in nine patients with AMS who were tourists on unplanned, unacclimatized assent to Pangong lake, situated near Leh-Ladakh in the Himalayas, approximately at the height of 4350 meters above sea level and six highlanders, living in Leh-Ladakh. Figure 1A shows the map of the Pangong Lake, B. Shows features of Acute Pulmonary Edema in the Chest X-ray from a patient with AMS, C. Shows the TAPSE (Tricuspid Annular Plane Systolic Excursion) D. Shows the Speckle tracking derived RV Free Wall strain (From a software made for LV) and E: Methodology to derive 3D RV Ejection Fraction. 3D Echocardiographic Equipment with LV strain (which was modified to derive RV Free wall strain) and 3D RV Ejection Fraction software was used for acquisition of images and offline analysis was done. TAPSE, FAC, RV Free wall strain and 3D RV EF were consistently lower in patients with AMS than in persons living in high altitude (High landers). TR peak gradient, RV EDV index, RV ESV index were elevated in AMS patients compared to High landers. Table 1. Table 1 Age Sex M/F 3D RV EF% TAPSE (mm) FAC TRP E/e' RVFW Strain RV EDVI (ml/m2) RV ESVI (ml/m2) AMS (9) 40.2±2.3 5/4 36±3.2 16±1.7 38.2±2.7 49.2±7.6 5.4±1.2 14±1.9 55±3.7 35±2.4 High Landers (6) 53.6±3.7 5/1 45±2.3 20±2.7 46.9±4.7 26.52±6.7 7±1.7 28±2.2 52±4.1 29±2.8 RV: Right Ventricle; EF: Ejection Fraction; TAPSE: Tricuspid Annular Plane Systolic Excursion; FAC: Fractional Area Change; TRP: Tricuspid Regurgitation Peak gradient; E: Mitral E Velocity; e' Medial mitral Tissue doppler e velocity; FW: Free Wall; EDVI: End Diastolic Volume Index; ESV: End systolic volume index. Figure 1 Conclusion Strain or myocardial deformation analysis based on two-dimensional (2D) speckle tracking and 3D RV ejection fraction is feasible even in the remote altitudes apart from standard M Mode and Doppler measurements and allow accurate quantification in analysis of acute mountain sickness.

IL-10 Dysregulation in Acute Mountain Sickness Revealed by Transcriptome Analysis.

Acute mountain sickness (AMS), which may progress to life-threatening high-altitude cerebral edema, is a major threat to millions of people who live in or travel to high altitude. Although studies have revealed the risk factors and pathophysiology theories of AMS, the molecular mechanisms of it do not comprehensively illustrate. Here, we used a system-level methodology, RNA sequencing, to explore the molecular mechanisms of AMS at genome-wide level in 10 individuals. After exposure to high altitude, a total of 1,164 and 1,322 differentially expressed transcripts were identified in AMS and non-AMS groups, respectively. Among them, only 328 common transcripts presented between the two groups. Immune and inflammatory responses were overrepresented in participants with AMS, but not in non-AMS individuals. Anti-inflammatory cytokine IL10 and inflammation cytokines IF17F and CCL8 exhibited significantly different genetic connectivity in AMS compared to that of non-AMS individuals based on network analysis. IL10 was downregulated and both IF17F and CCL8 were upregulated in AMS individuals. Moreover, the serum concentration of IL10 significantly decreased in AMS patients after exposure to high altitude (p = 0.001) in another population (n = 22). There was a large negative correlation between the changes in IL10 concentration, r(22) = −0.52, p = 0.013, and Lake Louise Score. Taken together, our analysis provides unprecedented characterization of AMS transcriptome and identifies that genes involved in immune and inflammatory responses were disturbed in AMS individuals by high-altitude exposure. The reduction of IL10 after exposure to high altitude was associated with AMS.

A study of autonomic cardiovascular regulation in subjects with acute mountain sickness

Background: Increased sympathetic activity is a part of the integrated physiological response to a hypoxic stimulus but it is not clear if it plays a role in the genesis of acute mountain sickness (AMS). Aims and Objectives: This study was conducted to evaluate the role of the autonomic nervous system in AMS during the initial phase of acute high-altitude exposure. Materials and Methods: The study was conducted on 42 lowlanders ascended at an altitude of 3500 m by airplane. Autonomic function tests of 20 subjects who suffered from AMS were studied, and the results were compared with 22 healthy individuals. AMS was diagnosed using the Lake Louise score, and autonomic cardiovascular functions were evaluated using non-invasive cardiovascular reflex tests. Results: At high-altitude, the diastolic blood pressure (DBP) rise in response to sustained handgrip was higher in AMS subjects than the control group. The rise in DBP in cold pressor test was higher in AMS subjects than controls. The valsalva ratio was also significantly higher in AMS patients than controls. Conclusion: Sympathetic hyperactivity on induction to high altitude is positively associated with the development of AMS.

A higher baseline somatization score at sea level as an independent predictor of acute mountain sickness

ObjectiveThe current study aimed to identify the predictive values of psychological factors that are evaluated by the Symptoms Checklist-90 (SCL-90) for acute mountain sickness (AMS). MethodsThe subjects (n=285, non-acclimatized young Chinese men), who were recruited in July 2013, completed a case report questionnaire. In addition, their vital signs (heart rate [HR], blood pressure and pulse oxygen saturation) were measured, and their psychological factors were examined using the SCL-90 at sea level. AMS was diagnosed using the Lake Louise self-assessment scoring system in the morning of the second day after their arrival at 3450m. ResultsOf the nine factors of the SCL-90, the AMS patients (AMS score≥3) were characterized by significantly higher scores for baseline somatization [14.0 (5.0) vs. 13.0 (3.0), p<0.001], obsession–compulsion, depression, anxiety and hostility compared with the non-AMS group (all p values<0.05). Spearman's correlation analyses revealed associations between AMS scores and somatization (r=0.316, p<0.001), depression, anxiety, obsession–compulsion, interpersonal sensitivity, hostility, phobic anxiety, paranoid ideation and psychoticism scores (all p values<0.001). Although all nine factors were associated with AMS in a univariate regression (all p<0.05), a further adjusted logistic regression analysis indicated that only baseline somatization score (odds ratio=1.129, p=0.001) was an independent predictor of AMS. Furthermore, some non-AMS often-occurred symptoms (paresthesia, shortness of breath, reduced activity and tinnitus) were also found to be associated with the baseline SCL-90 scores. ConclusionAMS is correlated with the baseline somatization score at sea level, which was measured using the SCL-90. A higher baseline somatization score is also an independent predictor of AMS.

Principal Component Analysis and Risk Factors for Acute Mountain Sickness upon Acute Exposure at 3700 m.

ObjectiveWe aimed to describe the heterogeneity in the clinical presentation of acute mountain sickness (AMS) and to identify its primary risk factors.MethodsThe participants (n = 163) received case report form questionnaires, and their heart rate (HR), oxygen saturation (SpO2), echocardiographic and transcranial Doppler variables, ability to perform mental and physical work, mood and psychological factors were assessed within 18 to 22 hours after arriving at 3700 m from sea level (500 m) by plane. First, we examined the differences in all variables between the AMS-positive and the AMS-negative groups. Second, an adjusted regression analysis was performed after correlation and principal component analyses.ResultsThe AMS patients had a higher diastolic vertebral artery velocity (Vd; p = 0.018), a higher HR (p = 0.006) and a lower SpO2. The AMS subjects also experienced poorer sleep quality, as quantified using the Athens Insomnia Scale (AIS). Moreover, the AMS population exhibited more negative mood states, including anxiety, depression, hostility, fatigue and confusion. Five principal components focused on diverse aspects were also found to be significant. Additionally, more advanced age (p = 0.007), a higher HR (p = 0.034), a higher Vd (p = 0.014), a higher AIS score (p = 0.030), a decreased pursuit aiming capacity (p = 0.035) and decreased vigor (p = 0.015) were risk factors for AMS.ConclusionsMood states play critical roles in the development of AMS. Furthermore, an elevated HR and Vd, advanced age, elevated AIS sores, insufficient vigor and decreased mental work capacity are independent risk factors for AMS.

Pro: pulse oximetry is useful in predicting acute mountain sickness.

Pro: pulse oximetry is useful in predicting acute mountain sickness.

Association of arterial oxygen saturation and acute mountain sickness susceptibility: a meta-analysis.

Acute mountain sickness (AMS) is the most common high altitude illnesses experienced during rapid ascent to a higher altitude without prior acclimation. It is mainly characterized by a headache which may be accompanied with nausea, vomiting, anorexia, dizziness, lethargy, fatigue, and sleep disturbance. If not diagnosed and treated in a timely manner, AMS can develop into deadly high altitude pulmonary edema or high altitude cerebral edema. In the previous studies of individual variation in susceptibility to AMS, arterial oxygen saturation (SO2) was identified as being associated with AMS. However, other studies have reported no association between AMS and arterial oxygen saturation. In this study, the association between SO2 and AMS was assessed through a meta-analysis of published data. The literature databases PubMed, Web of Science, LWW, Science Direct, and Embase were queried for papers published before 15 April 2014. A fixed-effects model and a random-effects model were applied (Revman 5.0) on the basis of heterogeneity, and the study quality was assessed in duplicate. Twelve studies with 614 AMS patients and 1,025 control subjects were analyzed. There was a significant association with differences in SO2 and the risk of developing AMS. SO2 values are associated with AMS incidence.

EPAS1 and EGLN1 associations with high altitude sickness in Han and Tibetan Chinese at the Qinghai–Tibetan Plateau

High altitude sickness (HAS) occurs among humans visiting or inhabiting high altitude environments. Genetic differences in the EPAS1 and EGLN1 genes have been found between lowland (Han) and highland (Tibetan) Chinese. Three SNPs within EPAS1 and EGLN1 were evaluated in Han and Tibetan patients with acute mountain sickness (AMS) and chronic mountain sickness (CMS). We compared 85 patients with AMS to 79 Han unaffected with mountain sickness (MS) as well as 45 CMS patients to 34 unaffected Tibetan subjects. The three SNPs studied were EPAS1 [ch2: 46441523 (hg18], EGLN1 (rs480902) and (rs516651). Direct sequencing was used to identify individual genotypes for the three SNPs. Age was found to be significantly associated with the EPAS1 SNP in the CMS patients while heart rate (HR) and oxygen saturation level of hemoglobin (SaO(2)) were found to be significantly associated with the EGLN1 (rs480902) SNP in the Han patients with AMS. The individuals with CMS were found to diverge significantly for the EPAS1 SNP compared to their Tibetan control group as measured by genetic distance (0.123) indicating positive selection of the EPAS-G allele with age and illness. The EGLN1 (rs480902) SNP had a significant correlation with hematocrit (HCT), HR and SaO(2) in AMS patients. AMS and CMS were found to be significantly associated with the EPAS1 and EGLN1 SNPs compared to their Han and Tibetan control groups, respectively, indicating these nucleotide alterations have a physiological effect for the development of high altitude sickness.

Medical and Commercial Ethics in Altitude Trekking

Medical and Commercial Ethics in Altitude Trekking

Microhemorrhages in Nonfatal High-Altitude Cerebral Edema

Vasogenic edema in the corpus callosum is a characteristic finding in high-altitude cerebral edema (HACE). Furthermore, microhemorrhages have been found at autopsies in brains of HACE victims. The objective of this study was to determine if microhemorrhages also occur in nonlethal HACE. Consequently, magnetic resonance imaging (MRI) was performed in patients who had suffered from HACE and in patients who had suffered from severe acute mountain sickness (AMS) by applying imaging techniques highly susceptible to blood or blood remnants. Two experienced neuroradiologists independently evaluated the exams blinded to clinical data. The MRI was performed 2 to 31 months after the event. The MRI of the HACE patients revealed multiple hemosiderin depositions in the brain--predominantly found in the corpus callosum--indicative of microhemorrhages. These changes were not present in the three AMS patients. In summary, hemosiderin deposits detectable by MRI predominantly in the corpus callosum indicate that microhemorrhages occur in nonlethal HACE, which may serve as a novel diagnostic MRI sign for HACE even many months after the event.

Protocols for the use of a portable hyperbaric chamber for the treatment of high altitude disorders

Descent remains the definitive treatment for high altitude illness. However, in alpine settings of over 8000 ft, immediate evacuation is often impossible. A portable, lightweight (7 kg) hyperbaric bag has been devised capable of withstanding a pressure of 2 psi. The author investigated the optimal period of treatment in the bag to achieve resolution of symptoms and to prevent recurrence. Observations were recorded in Pheriche, Nepal at 13 920 ft. At this altitude, inflation of the bag to 2 psi effects a descent to 8400 ft. Dramatic improvements were seen in victims with symptoms of acute mountain sickness (AMS), high altitude pulmonary edema (HAPE) and cerebral edema (HACE). AMS, HAPE and HACE patients required time frames of 2, 4, and 6 h respectively to provide resolution of symptoms without complications or deterioration. The author advocates the hyperbaric bag as an effective adjunct and temporizing measure in the treatment of HAPE and HACE.