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ID:9884125
大小:1.81 MB
页数:127页
时间:2018-05-12
《pediatric anatomy, physiology & pharmacology》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、PediatricAnatomy,Physiology&Pharmacology848thFSTIntroductionOfprimaryimportancetothepediatricanesthesiaprovideristherealizationthatinfantsandchildrenarenotsimplyasmalladult.Theiranestheticmanagementdependsupontheappreciationofthephysiologic,anatomicandpharmacologicdifferencesbetw
2、eenthevaryingagesandthevariableratesofgrowth.Alsoofimportanceisageneralknowledgeofthepsychologicaldevelopmentofchildrentoenabletheanesthetisttoprovidemeasurestoreducefearandapprehensionrelatedtoanesthesiaandsurgery.DefinitionsPretermorPrematureInfant:<37weeksTermInfant:38-42weeksg
3、estationPostTermInfant:>42weeksgestationNewborn:upto24hoursoldNeonate:1-30daysoldInfant:1-14monthsoldChild:14monthstopuberty(~12-13years)BodySizeThemostobviousdifferencebetweenchildren&adultsissizeItmakesadifferencewhichfactorisusedforcomparison:anewbornweighing3kgis1/3thesizeofan
4、adultinlength1/9thebodysurfacearea1/21theweightBodysurfacearea(BSA)mostcloselyparallelsvariationsinBMR&forthisreasonBSAisabettercriterionthanageorweightforcalculatingfluid&nutritionalrequirementsBodySizeFetalDevelopmentThecirculatorysystemisthefirsttoachieveafunctionalstateinearly
5、gestationThedevelopingfetusoutgrowsitsabilitytoobtain&distributenutrientsandO2bydiffusionfromtheplacentaThefunctioningheartgrows&developsatthesametimeitisworkingtoservethegrowingfetusAt2monthsgestationthedevelopmentoftheheartandbloodvesselsiscompleteIncomparison,thedevelopmentofth
6、elungbeginslater&isnotcompleteuntilthefetusisneartermFetalCirculationPlacentaGasexchangeWasteeliminationUmbilicalVenousTensionis32-35mmHgSimilartomaternalmixedvenousbloodResult:O2saturationof~65%inmaternalblood,but~80%inthefetalumbilicalvein(UV)LowaffinityoffetalHgb(HgF)for2,3-DPG
7、ascomparedwithadultHgb(HgA)Lowconcentrationof2,3-DPGinfetalbloodO2&2,3-DPGcompetewithHgbforbinding,thereducedaffinityofHgFfor2,3-DPGcausestheHgbtobindtoO2tighterHigherfetalO2saturationFetalCirculationP50is27mmHgforadultHgb,butonly20mmHgforfetalHgbThiscausesaleftshiftintheO2dissoci
8、ationcurveBecausethebridgebetween
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