哈尔滨医科大学-临床麻醉学课件-小儿麻醉 2

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1、PediatricAnesthesiaDepartmentofanesthesiologyCuiXiaoGuangTheprovisionofsafeanesthesiaforpediatricpatientsdependsonaclearunderstandingofthephysiologic,pharmacologic,andpsychologicaldifferencesbetweenchildrenandadults.Neonates:0–1monthsInfants:1–12monthsToddlers:1–3yearssmallc

2、hildren:4–12yearsDEVELOPMENTALPHYSIOLOGYOFTHEINFANTThepulmonarysystem1Therelativelylargesizeoftheinfant'stongueThelarynxislocatedhigherintheneckTheepiglottisisshapeddifferently,beingshortandstubbyThevocalcordsareangledTheinfantlarynxisfunnelshaped,thenarrowestportionoccurrin

3、gatthecricoidcartilage:uncuffedendotrachealtubes;patientsyoungerthan6years.Thepulmonarysystem2Alveoliincreaseinnumberandsizeuntilthechildisapproximately8yearsold.Functionalresiduralcapacity(FRC):thesamewithadult;inductionandpalinesthesiaofanesthesiaisrapidA-aDO2islarger:func

4、tionalairwayclosureLimitsoxygenreserves:hypoxemia.Theworkofbreathing:(Inprematureinfants)threetimesofadults,increasedbycoldstressorsomedegreeofairwayobstruction.RR:twotimesofadultsThepulmonarysystem3Tidalvolume(VT)islittle;physiologicaldeadspaceis30%ofVTAirwayresistanceincre

5、asing:secretion,upperairwayinfectionDiaphragmaticandintercostalmusclesdonotachievetheadultconfigurationoftypeImusclefibersuntilthechild2yearsold:apneaorcarbondioxideretentionandrespiratoryfailure.Infantshaveoftenbeendescribedasobligatenasalbreathers:<5monthsofage.TheCardiova

6、scularSystem1Inuterus:foramenovale,ductusarteriosus(right→left)Atbirth:thefetalcirculationbecomesanadult-typecirculation.--transitionalcirculationProlongedtransitionalcirculation:prematurity,infection,acidosis,pulmonarydiseaseresultinginhypercarbiaorhypoxemia(aspirationofmec

7、onium),hypothermia,congenitalheartdisease.TheCardiovascularSystem2Themyocardialstructureoftheheartislessdeveloped,producelesscompliantventriclesThisdevelopmentalmyocardialimmaturity:sensitivitytovolumeloading,poortoleranceofincreasedafterload,heartrate-dependentcardiacoutput

8、.TheCardiovascularSystem3Bradycardiaandprofoundreductionsincardiacoutput:ac