***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: 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 Abstract : A study was carried out to determine the effectiveness of low doses of acetazolamide in ameliorating the  symptoms of altitude sickness . Subjects were placed in a low pressure chamber at either 14,000 ft . or 3,000 ft . for 24 hours . Before entering the chamber each subject took a total of 750 mg . of acetazolamide or a placebo . During their 24-hour stay , the subjects filled out a question naire design ed to evaluate their state of well-being . End-tidal PCO2 was measured , and electrodes were applied for monitoring respiratory pattern and EEG . Subjects were given a ranking of 1 ( worst ) to 4 ( best ) comparing individual clinical states . Sample s of arterial blood and cerebrospinal fluid were obtained and analyzed for pH , PO2 , PCO2 , CO2 , HCO3(- ) , and lactate . Twenty-four-hour urine volumes were analyzed for Na , K , and 17-hydroxycorticosteroids .  Acetazolamide significantly lowered arterial and CSF HCO3(- ) , arterial and end-tidal PCO2 , and arterial pH. The mean arterial PO2 was higher in those receiving acetazolamide , but the increase was not significant ( P < .10 ) . Pretreatment with acetazolamide was of sufficient clinical benefit to allow its recommendation prior to altitude exposure . ( Author In this r and omized , double-blind placebo controlled trial our objectives were to determine if acetazolamide is capable of preventing high altitude pulmonary edema ( HAPE ) in trekkers traveling between 4250 m (Pheriche)\4350 m ( Dingboche ) and 5000 m ( Lobuje ) in Nepal ; to determine if acetazolamide decreases pulmonary artery systolic pressures ( PASP ) at high altitude ; and to determine if there is an association with PASP and signs and symptoms of HAPE . Participants received either acetazolamide 250 mg PO BID or placebo at Pheriche\Dingboche and were reassessed in Lobuje . The Lake Louise Consensus Criteria were used for the diagnosis of HAPE , and cardiac ultrasonography was used to measure the velocity of tricuspid regurgitation and estimate PASP . Complete measurements were performed on 339 of the 364 subjects ( 164 in the placebo group , 175 in the acetazolamide group ) . No cases of HAPE were observed in either study group nor were differences in the signs and symptoms of HAPE found between the two groups . Mean PASP values did not differ significantly between the acetazolamide and placebo groups ( 31.3 and 32.6 mmHg , respectively ) . An increasing number of signs and symptoms of HAPE was associated with elevated PASP ( p < 0.01 ) . The efficacy of acetazolamide against acute mountain sickness , however , was significant with a 21.9 % incidence in the placebo group compared to 10.2 % in the acetazolamide group ( p < 0.01 ) . Given the lack of cases of HAPE in either group , we can draw no conclusions about the efficacy of acetazolamide in preventing HAPE , but the absence of effect on PASP suggests that any effect may be minor possibly owing to partial acclimatization during the trek up to 4200 Self-rated moods were determined twice daily with the Clyde Mood Scale on 35 human subjects at 200 m ( baseline ) during a study concerned with evaluating the efficacy of staging plus acetazolamide ( treatment ) for the prevention of acute mountain sickness ( AMS ) . Mood states also were determined on all subjects at 4300 m ( Pikes Peak , Co ) and on 18 of these subjects at 1600 m ( staging site ) . Mood state changes were not observed at 1600 m , but four of the six mood factors were sensitive to the 4300 m altitude . At 4300 m , all subjects , treatment and control , rated themselves as less friendly and clear thinking and more sleepy and dizzy . At 4300 m , the treatment strategy result ed in an improved mood on the friendly , sleepy , and dizzy factors . Altitude-induced changes in clear thinking were not altered by the treatment strategy Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more Acute mountain sickness ( A.M.S. ) and its severe complications , high-altitude pulmonary oedema ( H.A.P.O. ) and cerebral oedema ( C.O. ) , were studied in 278 unacclimatised hikers at 4243 m altitude at Pheriche in the Himalayas of Nepal . The overall incidence of A.M.S. was 53 % , the incidence being increased in the young and in those who flew to 2800 m , climbed fast , and spent fewer nights acclimatising en route . It was unrelated to sex , to previous altitude experience , to the load carried , and to recent respiratory infections . The severity of A.M.S. was inversely related to age ( independent of rate of ascent ) and the highest altitude attained , and was highly ocrrelated with speed of ascent . There were 7 cases of H.A.P.O. and 5 with the more intractable C.O. and , of these 12 , 11 had flown in , 9 had spent only one night at Pheriche , and none were on acetazolamide . 11 required evacuation .  Acetazolamide , compared in a double-blind study with a placebo and also compared with no tablets at all , reduced both the incidence and the severity of A.M.S. in those who flew to 2800 m but not in those who hiked up to that altitude . Prevention consists in slow ascent , rapid recognition of warning signs , and prompt descent to avoid progression BACKGROUND Acute mountain sickness ( AMS ) commonly occurs when unacclimatized individuals ascend to altitudes above 2000 m.  Acetazolamide and Ginkgo biloba have both been recommended for AMS prophylaxis ; however , there is conflicting evidence regarding the efficacy of Ginkgo biloba use . We performed a r and omized , placebo-controlled trial of acetazolamide vs Ginkgo biloba for AMS prophylaxis . METHODS We r and omized unacclimatized adults to receive acetazolamide , Ginkgo biloba , or placebo in double-blind fashion and took them to an elevation of 3800 m for 24 hours . We grade d AMS symptoms using the Lake Louise Acute Mountain Sickness Scoring System ( LLS ) and compared the incidence of AMS ( defined as LLS score > or =3 and headache ) . RESULTS Fifty-seven subjects completed the trial ( 20 received acetazolamide ; 17 , Ginkgo biloba , and 20 , placebo ) . The LLS scores were significantly different between groups ; the median score of the acetazolamide group was significantly lower than that of the placebo group ( P=.01 ; effect size , 2 ; and 95 % confidence interval [ CI ] , 0 to 3 ) , unlike that of the Ginkgo biloba group ( P=.89 ; effect size , 0 ; and 95 % CI , -2 to 2 ) . Acute mountain sickness occurred less frequently in the acetazolamide group than in the placebo group ( effect size , 30 % ; 95 % CI , 61 % to -15 % ) , and the frequency of occurrence was similar between the Ginkgo biloba group and the placebo group ( effect size , -5 % ; 95 % CI , -37 % to 28 % ) . CONCLUSIONS In this study , prophylactic acetazolamide therapy decreased the symptoms of AMS and trended toward reducing its incidence . We found no evidence of similar efficacy for Ginkgo biloba Previous attempts to detect global cerebral hemodynamic differences between those who develop headache , nausea , and fatigue following rapid exposure to hypoxia [ acute mountain sickness ( AMS ) ] and those who remain healthy have been inconclusive . In this study , we investigated the effects of two drugs known to reduce symptoms of AMS to determine if a common cerebral hemodynamic mechanism could explain the prophylactic effect within individuals . With the use of r and omized , placebo-controlled , double-blind , crossover design , 20 healthy volunteers were given oral acetazolamide ( 250 mg ) , dexamethasone ( 4 mg ) , or placebo every 8 h for 24 h prior to and during a 10-h exposure to a simulated altitude of 4,875 m in a hypobaric chamber , which included 2 h of exercise at 50 % of altitude-specific VO(2max ) . Cerebral hemodynamic parameters derived from ultrasound assessment s of dynamic cerebral autoregulation and vasomotor reactivity were recorded 15 h prior to and after 9 h of hypoxia . AMS symptoms were scored using the Lake Louise Question naire ( LLQ ) . It was found that both drugs prevented AMS in those who became ill on placebo ( ~70 % decrease in LLQ ) , yet a common cerebral hemodynamic mechanism was not identified . Compared with placebo , acetazolamide reduced middle cerebral artery blood flow velocity ( 11 % ) and improved dynamic cerebral autoregulation after 9 h of hypoxia , but these effects appeared independent of AMS . Dexamethasone had no measureable cerebral hemodynamic effects in hypoxia . In conclusion , global cerebral hemodynamic changes result ing from hypoxia may not explain the development of AMS During an expedition to the Himalayas , we studied the  sleep and respiration of six climbers . Three ingested acetazolamide ( 500 mg ) daily throughout the climb and the other three ingested placebo . At high altitude ( 4,150 - 4,846 m ) , each subject ingested temazepam ( 10 mg ) for one night and placebo for another . Acetazolamide improved sleep above 2,750 m , but it is uncertain whether this was due to sedation or to improvements in arterial oxygen saturation . Sleep was markedly disturbed in all subjects above 4,000 m.  Temazepam  improved sleep , and in subjects taking acetazolamide , it reduced sleep-onset latencies and increased sleep efficiency close to that of sea level values . These observations suggest that the prophylactic use of acetazolamide is likely to improve sleep in climbers and that a low dose of a benzodiazepine such as temazepam ( 10 mg ) may be beneficial at high altitude . Studies are now needed to exclude any possibility of respiratory impairment at altitude before a firm recommendation can be made regarding the routine use of this hypnotic Abstract Objective To evaluate the efficacy of ginkgo biloba , acetazolamide , and their combination as prophylaxis against  acute mountain sickness . Design Prospect i ve , double blind , r and omised , placebo controlled trial . Setting Approach to Mount Everest base camp in the Nepal Himalayas at 4280 m or 4358 m and study end point at 4928 m during October and November 2002 . Participants 614 healthy western trekkers ( 487 completed the trial ) assigned to receive ginkgo , acetazolamide , combined acetazolamide and ginkgo , or placebo , initially taking at least three or four doses before continued ascent . Main outcome measures Incidence measured by Lake Louise acute mountain sickness score ≥ 3 with headache and one other symptom . Secondary outcome measures included blood oxygen content , severity of syndrome ( Lake Louise scores ≥ 5 ) , incidence of headache , and severity of headache . Results Ginkgo was not significantly different from placebo for any outcome ; however participants in the acetazolamide group showed significant levels of protection . The inc 
    Output:
    
RESULTS Acetazolamide prophylaxis was associated with a 48 % relative-risk reduction compared to placebo .
There was no evidence of an association between efficacy and dose of acetazolamide .
Adverse effects were often not systematic ally reported but appeared to be common but generally mild .
Acetazolamide is effective prophylaxis for the prevention of symptoms of  AMS  in those going to high altitude .
A dose of 250 mg/day has similar efficacy to higher doses and may have a favorable side-effect profile