Characteristics Of Changes In Cardiovascular Systems At The Earlier Stage For Healthy Young Adults Who Rapidly Travel To Plateau And Their Impacts On Altitude Acclimatization Capability

Objective and backgroundThere are more than140million people worldwide living on plateau2500metersabove sea level, among which80million live in Asia.In China,1/6of the land is plateau.With the development and opening up of plateau area, more and more people move thereliving and working. How ever,due to such unique plateau climate as hypobaria hypoxia、cold and dry weather，most healthy people will have some physiopathologic changes.Thechanges of cardiovascular(CVS) will bring about most side effect on people’s health.Studying the rules of CVS change could help us to reduce the incidence of disease likeacute mountain sickness (AMS) and cardiovascular accident (CVA). There were lots ofstudies about the cardiovascular change for people arriving high altitudes rapidly，but moststudies just focus on one or two index. Studies about both the cardiac function (CF) andblood pressure (BP) changes and the interactions between them in a same object occurringafter initial transition from lower altitude localities to high altitude localities were rare. Ourstudy is to understand the CF, BP, C-reactive protein(CRP), endothelin-1(ET-1), nitrogenmonoxidum (NO) changes in47healthy young after initial transition from lower altitudelocalities to high altitude localities， at constant altitude after varied timeintervals(1day/1week/1month after entry onto highlands),and grasp their basic patterns. Wehope this study could offer some evidence for the further researches on the rule of CVSchanges of people who enter plateau rapidly.Object and methodObjectOur study object include47healthy young of18.27±0.9years old，168.15±4.16cmheight and58.67±7.11kg weight. They all lived in area of400m height above sea level before entering the plateau. They transited to plateau by plane at same time, and it was thevery first time for them to arriving plateau. The average altitude of their destination is3680m.According to Lake Louise AMS score system, none of them have got AMS.Method1. Investigation methodWe analyzed the whole variation tendency of BP, CF on47objects, and grasped theirbasic patterns.Then they were divided into two groups according the BP on the first daythey arrived plateau. Those whose systolic pressure(SP) decreased on the first day weredivided into group A(11person), those whose SP increased in the first day were dividedinto group B(36person).The BP changes on both of the two groups have significantdifference from they were in plain area(P＜0.05).There are no significant difference onmean age, mean height, mean body weight, Body Mass Index (BMI)and surface areabetween two groups(P＞0.05).2. MeasurementsUse the desk model sphygmomanometer(JB3053-91YuYue, Jiangsu, China) tomeasure the stationary blood pressure in brachial arteries on47healthy young adults byfive person for four times(on plains,1day,1week,1month after arrival on highlands).Use the doppler echocardiography (MMX SonoSite,USA) to measure theinterventricular septum thickness and amplitude(IVST＆IVSA), the posterior left ventriclethickness and amplitude(PLVT＆PLVA), left ventricular end-diastolic diameter(LVEDD)、the left ventricular end-diastolic volume (LVEDV), the left ventricular end-systolic volume(LVESV) and pulmonary artery pressure (PAP) on47healthy young adults by a sameperson each time. We calculate the values of Left ventricular ejection fraction (LVEF), leftventricular minor axis decurtation (LVMAD,△D%), Stroke Volume(SV), pulmonaryartery pressure (PAP) and cardiac output(CO) each time.Use electrocardiogram ECG(7101FuTian,Beijing,China) to get the ECG of47healthyyoung adults four times, calculate the values of heart rate(HR) each time.Statisticalanalysis performed on the four result sets were obtained.Drawing vein blood on47healthy young adults with empty stomach，and taking bloodserum after centrifuging before we preserved the blood serum at the temperature of－20℃.Use automatic biochemistry analyzer(7180Hitachi,Japan)to measure the values of CRP on47healthy young adults. Use NO kit (Provided by JianCheng Technology LimitedCompany, Nanjing) to measure the values of NO on47healthy young adults by nitric acidreducing enzyme method. Use ET-1kit (Provided by HuaYing Technology LimitedCompany，Beijing) to measure the values of NO on47healthy young adults.3. Statistical methodAnalysis of variance(ANOVA) on repeated measures data(SPSS17.0， α=0.05)；Compare means one by one(SPSS17.0α=0.05).Test of normality on each index.Using one-sample Kolmogorov-SmirnovTest(SPSS17.0，α=0.05)；Comparing group A and group B to find visible difference. ChoseIndependent-Sample T-test or Mann-Whithey U-test according to whether the indexobeying normal distribution(SPSS17，α=0.05)Result1.When study on the whole object, Comparing with plain area, there are significantincrease of the BP,HR,PAP,CO(P＜0.05), there are significant decrease of the SV(P<0.05)，there are no significant difference of the CO(P＞0.05)1day after arriving onhighlands(P<0.05), there are significant increase of the HR,PAP(P＜0.05), decrease of theLVEF,△D%,SV(P<0.05)，no significant difference of the BP,CO(P＞0.05)1week afterarriving on highlands(P<0.05); there are significant increase of the CO,PAP(P＜0.05),decrease of theBP, LVEF,△D%、SV(P<0.05)，no significant difference of the HR(P＞0.05)1month after arriving on highlands(P<0.05).Comparing with1day after arriving onhighlands, there are significant decrease of the BP, HR, LVEF,△D%, SV, CO(P<0.05), nosignificant difference of the PAP(P＞0.05)1week after arriving on highlands, there aresignificant increase of the PAP(P＜0.05), decrease of the BP,HR,CO(P<0.05)， nosignificant difference of the LVEF,△D%, SV(P＞0.05)1month after arriving onhighlands;Comparing with1week after arriving on highlands, there are significant increaseof the LVEF,△D%,SV,CO(P＜0.05), decrease of the BP,HR(P<0.05)，no significantdifference of the PAP(P＞0.05)1month after arriving on highlands.2. The variation of BP, CF on two groups appeared similar tendency, just like thewhole tendency on all object. The variation tendency of CRP, NO, ET-1on two groupsappear difference. With regard to CRP, there are significant increase (P＜0.05)on group B1day and1week after arriving on highlands comparing with plain area. On group A, comparing with plain area, there are no significant difference(P＞0.05)1day after arrivingon highlands,there are significant increase (P＜0.05)1week after arriving on highlands. TheCRP decrease on both of the two groups, approximately to the level on plain area.Withregard to ET-1, there are significant decrease (P＜0.05)on group A1month after arrivingon highlands comparing with plain area and1week after arriving on highlands(P＜0.05);There are no significant difference (P＞0.05)on group B each time.There are no significantdifference of the NO(P＞0.05)on both groups each time.3.On the1st day after arriving on highlands, comparing the indexes between the twogroups, the HR and CO of group B are significantly higher than group A(P＜0.05). As tothe other indexes, there are no significant differences between the two groups.Conclusion1. In general, the changes of CVS are mainly on the early period after arriving athighlands (within1week),so we should pay more attention to AMS and CVA’s precaution inthis period.1month later, we can acclimatization with the highlands climate， thoseindividuals who are still have significant dysfunction on CF may be considered assusceptible population about Chronic Mountain Sickness (CMS).2. We divide our study abject into two groups according to the BP variation in the firstday they arrived at plateau.We found no matter whether the BP increased or decreased inthe1st day, their CF changed in a same way. Those changes ensured life-sustaining oxygendelivery to the tissues despite a reduction in the partial pressure of inspired oxygen.3. People whose blood pressure increase at the very first time after transferring to highaltitudes have superior acclimatization capability than those whose blood pressure decreaseat the very first time after transferring to high altitudes. They may be considered as lowersusceptible population about CMS.