Incidence and risk factors associated with acute mountain sickness in children trekking on Jade Mountain, Taiwan. Reproducibility of Acute Mountain Sickness in Children and Adults: A Prospective Study Effect of dexamethasone on symptoms of acute mountain sickness at Pikes Peak, Colorado (4,300 m). Reliability and utility of a visual analog scale for the assessment of acute mountain sickness. Vascular endothelial growth factor and acute mountain sickness Glucocorticoids as prophylaxis against acute mountain sickness Autonomic cardiovascular regulation in subjects with acute mountain sickness. Pressurization and acute mountain sickness. Acute mountain sickness score and hypoxemia. Acetazolamide and dexamethasone in the prevention of acute mountain sickness. Intravenous iron supplementation may protect against acute mountain sickness: a randomized, double-blinded, placebo-controlled trial. Effects of dexamethasone on the incidence of acute mountain sickness at two intermediate altitudes. Cysteinyl leukotriene blockade does not prevent acute mountain sickness. Dexamethasone for prevention and treatment of acute mountain sickness. Ginkgo biloba Does—and Does Not—Prevent Acute Mountain Sickness Evaluation of the Lake Louise acute mountain sickness scoring system in a hypobaric chamber. Acute mountain sickness, antacids, and ventilation during rapid, active ascent of Mount Rainier.
BACKGROUND Acute mountain sickness ( AMS ) is a pathophysiological symptom complex that occurs in high-altitude areas . The incidence of AMS on Jade Mountain , the highest peak in Taiwan ( 3952 m ) , has been reported to be ∼36 % . There is a lack of data in children trekking at altitude in Taiwan . The purpose of this study was to determine the incidence , risk factors and symptoms of AMS in children trekking on Jade Mountain , Taiwan . METHODS This prospect i ve cohort study included a total of 96 healthy non-acclimatized children aged 11 - 12 years who trekked from an elevation of 2600 - 3952 m in 3 days .  The Lake Louise AMS score  was used to record symptoms associated with AMS . RESULTS AMS were reported in 59 % of children trekking on Jade Mountain over a 3 day period . AMS incidence increased significantly with increasing altitude . The most common AMS symptom was headache , followed by fatigue or weakness , difficulty sleeping , dizziness or lightheadedness and gastrointestinal symptoms . Children who had experienced upper respiratory infection ( URI ) within the 7 days before their trek tended to have a greater risk for development of AMS . AMS incidence did not significantly differ according to gender , recent acute gastroenteritis , menstruation and body mass index . CONCLUSIONS The incidence of AMS in children trekking on Jade Mountain is greater than that observed in adults , and was associated with altitude and recent URI OBJECTIVE : Although a history of previous acute mountain sickness ( AMS ) is commonly used for providing advice and recommending its prophylaxis during subsequent exposure , the intraindividual reproducibility of AMS during repeated high-altitude exposure has never been examined in a prospect i ve controlled study . METHODS : In 27 nonacclimatized children and 29 adults ,  AMS  was assessed during the first 48 hours after rapid ascent to 3450 m on 2 consecutive occasions 9 to 12 months apart . RESULTS : During the first exposure , 18 adults ( 62 % ) and 6 children ( 22 % ) suffered from AMS ; during the second exposure , 14 adults ( 48 % ) and 4 children ( 15 % ) suffered from this problem ( adults versus children , P ≤ .01 ) . Most importantly , the intraindividual reproducibility of AMS  was very different ( P < .001 ) between children and adults . None of the 6 children having suffered from AMS during the first exposure suffered from AMS during the second exposure , but 4 children with no AMS during the first exposure did experience this problem during the second exposure . In contrast , 14 of the 18 adults who suffered from AMS on the first occasion also presented with this problem during the second exposure , and no new case developed in those who had not experienced AMS on the first occasion . CONCLUSIONS : In adults , a history of AMS is highly predictable of the disease on subsequent exposure , whereas in children it has no predictive value . A history of AMS should not prompt practitioners to advise against reexposure to high altitude or to prescribe drugs for its prophylaxis in children In a previous controlled study , dexamethasone ( DEX ) was shown to prevent acute mountain sickness ( AMS ) during exposure to simulated high altitude . To determine the effect of DEX during actual altitude exposure , 16 young men were treated with either DEX ( 4 mg every 6 h ) or placebo for 48 h prior to and 48 h after being rapidly transported from sea level to the summit of Pikes Peak , CO ( 4,300 m ) . Symptoms of AMS were evaluated twice daily at Pikes Peak using the Environmental Symptoms Question naire and a clinical assessment . During treatment the mean symptom scores were higher for subjects taking placebo in 18 out of 20 comparisons . On an individual basis , 60 % of the subjects receiving placebo met the criteria for being " sick " compared to 31 % of subjects receiving DEX . Beginning 24 h after cessation of treatment , DEX subjects experienced a progressive increase in symptom scores which lasted through the end of the altitude sojourn ( day 6 ) . The results indicate that DEX is an effective prophylactic treatment for AMS in an actual mountain environment , but that AMS symptoms can occur if the drug is stopped abruptly Acute mountain sickness ( AMS ) is a common condition that affects people that ascend too rapidly to high altitude . It is typically assessed with the Lake Louise AMS Self-report Score ( LLSelf ) that uses a categorical numeric rating scale to answer five questions addressing AMS-related symptoms , such as headache . A 100-mm visual analog scale ( VAS ) is commonly used to assess subjective phenomena such as pain , but this scale has never been used for the self- assessment of AMS . The purpose of this study was to compare a  VAS score  to the total LLSelf and to evaluate the test-retest and interrater reliability of the VAS when used as an assessment of AMS .  Participants ( N = 356 ) completed both the LLSelf and the VAS on the summit of Mt. Whitney ( 4419 m ) . There was a significant relationship ( r = 0.65 , p < 0.01 ) between the LLSelf ( 2.8 + /- 2.0 , mean + /- SD ) and the VAS ( 14.4 + /- 14.1 mm ) . Fifty-seven participants were r and omly selected for reliability testing of the VAS . Both test-retest reliability ( ICC = 0.996 , 95 % CI = 0.992 to 0.998 ) and interrater reliability ( ICC = 1.000 , 95 % CI = 0.999 to 1.000 ) were high . The mean difference in the VAS score between tests was < 1 mm , as was the difference between raters . These results demonstrate excellent reliability for the VAS as an assessment of AMS Study Objective : Despite causing significant morbidity throughout the mountainous regions of the world , the pathophysiology of acute mountain sickness ( AMS ) remains poorly understood . This study aims to improve the underst and ing of altitude illness by determining if vascular endothelial growth factor ( VEGF ) plays a role in the development of AMS . The purpose of this study was to determine if elevated plasma VEGF correlates with increased symptoms of AMS at high altitude . Patients and Methods : This is a prospect i ve study of a cohort of healthy climbers on Denali ( Mount McKinley ) in Alaska at 14 , 200 feet . Baseline demographics , medications , rates of ascent , and AMS scores were recorded .  Pulse oximetry measurements and venous blood sample s were obtained . Comparisons were made between mountaineers with and without AMS . Results : Seventy-two climbers were approached for participation in the study ; 21 ( 29 % ) refused . Of the 51 climbers participating in the study , 14 subjects ( 27.5 % ) had symptoms of AMS and 37 subjects ( 72.5 % ) were free of symptoms of AMS . Plasma VEGF levels were 79.14 pg/dl ( SD : 121.44 ) and 57.57pg/dl ( SD : 102.71 ) in the AMS and non-AMS groups , respectively . These results were nonsignificant . Similarly , comparison of sex , age , rate of ascent , pulse oximetry values , or history of altitude illness did not reveal significant differences between the AMS and non-AMS groups . Conclusion : This study does not provide evidence in support of the theory that plasma VEGF correlates with symptoms of AMS Objective Acute mountain sickness ( AMS ) characterized by presence of symptoms including headache , nausea , excessive fatigue , loss of appetite , irritability and insomnia is a major impediment to work performance in human subjects who are rapidly inducted to high altitude ( HA ) during the initial phase of induction . The present study aims at to evaluate the efficacy of prophylactic administration of low dose glucocorticoids in prevention of AMS in normal healthy men who are inducted to HA by air The aims of this study were 1 ) to evaluate whether subjects suffering from acute mountain sickness ( AMS ) during exposure to high altitude have signs of autonomic dysfunction and 2 ) to verify whether autonomic variables at low altitude may identify subjects who are prone to develop AMS . Forty-one mountaineers were studied at 4,559-m altitude . AMS was diagnosed using the Lake Louise score , and autonomic cardiovascular function was explored using spectral analysis of R-R interval and blood pressure ( BP ) variability on 10-min resting recordings . Seventeen subjects ( 41 % ) had AMS . Subjects with AMS were older than those without AMS ( P < 0.01 ) . At high altitude , the low-frequency ( LF ) component of systolic BP variability ( LF(SBP ) ) was higher ( P = 0.02 ) and the LF component of R-R variability in normalized units ( LF(RR)NU ) was lower ( P = 0.001 ) in subjects with AMS . After 3 mo , 21 subjects ( 43 % with AMS ) repeated the evaluation at low altitude at rest and in response to a hypoxic gas mixture . LF(RR)NU was similar in the two groups at baseline and during hypoxia at low altitude but increased only in subjects without AMS at high altitude ( P < 0.001 ) and did not change between low and high altitude in subjects with AMS . Conversely , LF(SBP ) increased significantly during short-term hypoxia only in subjects with AMS , who also had higher resting BP ( P < 0.05 ) than those without AMS . Autonomic cardiovascular dysfunction accompanies AMS . Marked LF(SBP ) response to short-term hypoxia identifies AMS-prone subjects , supporting the potential role of an exaggerated individual chemoreflex vasoconstrictive response to hypoxia in the genesis of AMS Numerous cases of acute mountain sickness ( AMS ) during trekking were reported to have been successfully treated with portable pressure chambers . The effect of early pressurization during acute altitude exposure in the Alps had not been previously studied . In order to test the hypothesis that an early pressurization of unacclimatized subjects for 3 h could prevent or delay the appearance of symptoms of AMS , 51 previously healthy subjects climbed from 1,030 to 4,360 m within 12 h. Upon arrival at 4,360 m , AMS scores ( Lake Louise Consensus Question naire ' 91 ) , oxygen saturation ( SaO2 ) , and heart rate ( HR ) were determined at rest . The subjects were then r and omly divided in two groups ; one group was pressurized to 200 mBar for 3 h while the other rested .  AMS score , HR , and SaO2 were similar in both groups before treatment . AMS score had decreased ( from 2.44 + /- 0.41 ( S.E. ) to 0.89 + /- 0.26 , p < 0.05 ) and SaO2 had increased ( from 75.22 + /- 1.32 % to 79.07 + /- 1.27 % , p < 0.05 ) in the treatment group 15 min after leaving the pressure chamber whereas the control group had unchanged AMS score ( 2.50 + /- 0.40 vs. 2.40 + /- 0.40 , N.S. ) and SaO2 ( 77.83 + /- 1.41 vs. 76.67 + /- 1.24 , N.S. ) . The next morning , however , AMS score , HR , and SaO2 were similar for both groups . It is concluded that during acute ascent in the Alps , an early 3-h pressurization of unacclimatized subjects does slightly delay the onset of AMS but does not prevent the illness nor does it attenuate its severity upon appearance BACKGROUND Hypoxemia is the immediate consequence of hyobaric hypoxia , which is the crucial starting mechanism of acute mountain sickness ( AMS ) . The AMS is generally a benign and self-limiting condition which can be prevented by gradual ascent . However , ascent rates recommended for prophylaxis of AMS are far slower than those attempted during military operations and by climbers . OBJECTIVE The current study was carried out to quantify the relationship between AMS and hypoxemia alongwith evaluating the benefits of acetazolamide-dexamethasone chemoprophylaxis during acute ascent . SUBJECTS AND METHODS Twenty-four low l and er male adults ( age mean + /- SE 27.8 + /- 1.24 years ) were selected . They were grouped in a double-blind fashion into four groups and each group ( n = 6 ) received placebo ( multivitamin ) or acetazolamide ( 250 mg ) or dexamethasone ( 4 mg ) or a combined regimen of the two drugs twice daily for 5 days , commencing 24 hours before ascent . The volunteers reached the altitude of 4578 meters within a span of one day . Their AMS symptoms were recorded on modified environmental symptoms question naire ( ESQ ) , after 24 and 72 hours of ascent . Arterial PO2 , SO2 and PCO2 were measured by GEMSTAT blood-gas analyzer ( Mallincrodt-USA ) . RESULTS The ESQ , AMS-C ( cerebral ) and AMS-R ( respiratory ) scores of combined therapy group were significantly lower as compared to the other groups on the symptom rating scale . The significant finding amongst the volunteers taking acetazolamide was mild to moderate diuresis whereas severity of headache was markedly less in dexamethasone group . The commonest feature of combined therapy was that none of the volunteers complained of headache , dysponea , irritability and more than mild disturbance of sleep . The ESQ scores of volunteers were inversely correlated to PaO2 and SaO2 after 24 hours of ascent to 4578 meters . CONCLUSION The study concludes that severity of AMS is closely related to hypoxemia and combination therapy of acetazolamide-dexamethasone may be effective in preventing AMS We r and omly assigned 32 healthy backpackers to receive placebo , acetazolamide ( 250 mg twice a day ) , dexamethasone acetate ( 4 mg four times a day ) , or both drugs in combination to determine the drug efficacy in preventing  acute mountain sickness ( AMS ) at altitudes of 3,650 to 4,050 m ( 12,000 to 13,300 ft ) . The incidence of AMS was high but symptoms were generally mild . Combined drug therapy was superior to both placebo and single drug therapy in risk reduction . Using acetazolamide alone was moderately beneficial in preventing the occurrence of AMS , although minor side effects were frequent . The use of dexamethasone alone did not significantly reduce the AMS incidence , and discontinuing its use result ed in symptoms suggestive of adrenal insufficiency . For recreational backpackers , routine drug prophylaxis is not recommended , in view of the mild nature of this illness and the adverse effects of medications . The efficacy of combined acetazolamide-dexamethasone therapy warrants further investigation at higher altitudes , where AMS is more severe , and the dexamethasone should be withdrawn gradually to avoid a possible adrenal crisis Acute mountain sickness ( AMS ) is a common and disabling condition that occurs in healthy individuals ascending to high altitude . Based on the ability of iron to influence cellular oxygen sensing pathways , we hypothesized that iron supplementation would protect against AMS . To examine this hypothesis , 24 healthy sea-level residents were r and omized to receive either intravenous iron(III)-hydroxide sucrose ( 200 mg ) or saline placebo , before ascending rapidly to Cerro de Pasco , Peru ( 4340 m ) . The Lake Louise scoring system was used to assess incidence and severity of AMS at sea level and on the first full day at altitude . No significant difference in absolute AMS score was detected between the two groups either at baseline or at high altitude . However , the mean increase in AMS score was 65 % smaller in the iron group than in the saline group ( p<0.05 ) , and the change in AMS score correlated negatively with the change in ferritin ( R=-0.43 ; p<0.05 ) . Hematocrit and arterial oxygen saturation were unaffected by iron . In conclusion , this preliminary r and omized , double-blinded , placebo-controlled trial suggests that intravenous iron supplementation may protect against the symptoms of AMS in healthy volunteers To test the value of dexamethasone acetate for ameliorating acute mountain sickness ( AMS ) , we conducted a double-blind , r and omized study that compared the effects of 4 mg of dexamethasone acetate or a placebo ( given every six hours for six doses beginning at the time of exposure ) at 2700 and 2050 m. Study subjects , who were recruited from health professionals who attended continuing medical education programs at ski resorts in the Rocky Mountains , were classified as having AMS when they reported three or more of the five usual symptoms ( headache , insomnia , dyspnea , anorexia , and /or fatigue ) on a single day . All symptoms with an intensity of at least grade 2 ( moderate ) out of 5 were analyzed . At 2700 m , there was a 50 % decrease in the mean AMS symptom score in the dexamethasone group ( 0.94 + /- 1.11 vs 1.84 + /- 1.44 [ mean + /- SD ] ) and the incidence of AMS was 20 % of that in the control group ( 3/38 vs 14/35 ) . At 2050 m , there was no difference between dexamethasone and a placebo in the mean AMS symptom score ( 1.52 + /- 1.50 vs 1.24 + /- 1.33 ) and the incidence of AMS ( 5/25 vs 4/25 ) . Dexamethasone ameliorates the usual symptoms of AMS at 2700 m but not at 2050 BACKGROUND Acute Mountain Sickness ( AMS ) is a multi-system disorder that is characterized by headache , anorexia , nausea , vomiting , insomnia , lassitude , and malaise . The syndrome is common in unacclimatized low altitude residents who rapidly ascend to terrestrial elevations exceeding 2,500 m. AMS may be a manifestation of hypoxia-induced cerebral edema result ing , in part , from increased capillary permeability . HYPOTHESIS We hypothesized that cysteinyl leukotrienes ( CysLTs ) may be involved in the pathogenesis of AMS , as these compounds are known to increase endothelial permeability . METHODS To test this hypothesis , we orally administered a CysLTs type-1 receptor antagonist ( montelukast ) to 11 subjects prior to and during exposure to high altitude ( 4,300 m ) in a hypobaric chamber in a r and omized , placebo-controlled , crossover design . We measured the result ing prevalence and /or severity of AMS , plasma CysLTs levels and urinary CysLTE4 , and associated physiological responses . RESULTS At 12 h exposure , AMS prevalence and symptom severity was lower ( p = 0.002 ) during montelukast administration compared with placebo , but not different at 22 h exposure . Plasma CysLTs and urinary LTE4 levels were not significantly elevated at 22 h exposure , nor did these CysLTs levels correlate with AMS severity . Compared with placebo , montelukast administration was not associated with any significant differences in physiologic measures at sea level or high altitude . CONCLUSIONS These results do not support a role for the CysLTs mediating the early development of AMS through the CysLT-1 receptor We wished to determine in a field study the effectiveness of dexamethasone for prevention and treatment of  acute mountain sickness ( AMS ) .  Prevention Trial : We transported 15 subjects from sea level to 4,400 m ( PB = 400 mm Hg ) on Denali ( Mt. McKinley ) by means of a 1-h helicopter flight . In a r and omized , double-blind fashion we gave eight subjects a placebo and seven subjects 2 mg dexamethasone orally every 6 h , starting 1 h before take-off . The entire placebo group and five of the dexamethasone group developed AMS within 5 h , and became progressively more ill until 12 h when the trial was terminated . We concluded that 2 mg of dexamethasone every 6 h did not prevent AMS in active soldiers rapidly transported to high altitude . Treatment Trial : We treated 11 of those with moderate to severe AMS ( symptom score 4.5 + /- 0.7 , range 3 to 11 ) with 4 mg of dexamethasone every 6 h orally or intramuscularly for 24 h. All were markedly improved at 12 h ( symptom score 1.0 + /- 0.3 , p less than 0.001 , range 0 to 3 ) , but symptoms increased after the drug was discontinued at 24 h ( symptom score = 2.4 + /- 0.5 ) . We conclude that dexamethasone in a dosage of 4 mg PO or IM every 6 h is an effective treatment for AMS , but that illness may recur with abrupt discontinuation of the drug Abstract Objective .—To determine the efficacy of 2 different sources of Ginkgo biloba extract ( GBE ) in reducing the incidence and severity of acute mountain sickness ( AMS ) following rapid ascent to high altitude . Methods .—Two r and omized , double-blind , placebo-controlled cohort studies were conducted in which participants were treated with GBE ( 240 mg·d−1 ) or placebo prior to and including the day of ascent from 1600 m to 4300 m ( ascent in 2 hours by car ) . Acute mountain sickness was diagnosed if the Environmental Symptom Question naire III acute mountain sickness – cerebral ( AMS-C ) score was ≥0.7 and the Lake Louise Symptom ( LLS ) score was ≥3 and the participant reported a headache . Symptom severity was also determined by these scores . Results .— Results were conflicting : Ginkgo biloba  reduced the incidence and severity of AMS compared to placebo in the first but not the second study . In the first study , GBE reduced AMS incidence ( 7/21 ) vs placebo ( 13/19 ) ( P = .027 , number needed to treat = 3 ) , and it also reduced severity ( AMS-C = 0.77 ± 0.26 vs 1.59 ± 0.27 , P = .029 ) . In the second study , GBE did not reduce incidence or severity of AMS ( GBE 4/15 vs placebo 10/22 , P = .247 ; AMS-C = 0.48 ± 0.13 vs 0.58 ± 0.11 , P = .272 ) . The primary difference between the 2 studies was the source of GBE . Conclusions .—The source and composition of GBE products may determine the effectiveness of GBE for prophylaxis of AMS This study evaluated the relevance of the Lake Louise acute mountain sickness ( AMS ) scoring system in comparison with other AMS scoring systems . To achieve this objective nine subjects were su bmi tted to a 9-hr exposure to hypoxia in a hypobaric chamber ( altitude 4500 - 5500 m ) that led to the development of AMS . AMS was scored at the end of this exposure period both by question naires ( Hackett AMS question naire , Lake Louise AMS self-report question naire , Environmental Symptoms Question naire ESQ II and ESQ IV ) and by a clinical investigation following the Lake Louise AMS clinical and functional AMS assessment . The AMS scores were between 0 and 9 for the Hackett AMS score , 0 and 38 for the ESQ II AMS score , 0 and 13.7 for the ESQ IV AMS score , 0 and 10 for the Lake Louise AMS self-report , 0 and 2 for the Lake Louise AMS clinical assessment score , and between 0 and 2 for the Lake Louise functional score . All the AMS question naire scores were related to the clinical AMS assessment score ( p < 0.05 ) without significant differences between them . The Lake Louise AMS self-report score appeared highly correlated to other AMS scoring systems ( Hackett , ESQ II and ESQ IV ) ( p < 0.05 ) . Suggestions were proposed to improve the sensitivity and the specificity of the Lake Louise AMS scoring question naire but also the Lake Louise AMS clinical assessment . In conclusion , this study suggests the relevance of the Lake Louise AMS self-report question naire to assess and score AMS with simplicity and rapidity A double-blind r and omized study of 45 climbers on Mt. Rainier was conducted to test the effectiveness of antacids in preventing  acute mountain sickness .  All 45 climbed to 3353 m , and 31 continued to the summit . Ten climbers listed  acute mountain sickness as the reason for not attaining the summit . Of symptoms monitored throughout the climb , neither headache , nausea , dizziness , pounding heart , nor shortness of breath differed in severity between antacid-treated and placebo-treated groups . In both groups vital capacity decreased significantly with ascent ( p less than 0.05 ) , while peak flow ( p less than 0.005 ) and minute ventilation ( p less than 0.001 ) increased significantly . The 7 climbers with the most severe AMS symptom scores above 4000 m had significantly lower peak flow at sea level prior to ascent compared with the other 25 climbers who completed sea level tests ( p less than 0.005 ) . The results of this study fail to document efficacy for antacid use for the prevention of acute mountain sickness
Ensuring that the characteristics of the history and future ascents are similar may improve the clinical utility of AMS history
PURPOSE The goal of this meta- analysis was to determine the clinical utility of  acute mountain sickness ( AMS ) history to predict future incidents of AMS .