ControlledHypotension

Introduction

1.history：

1917，theconceptwasfirstproposedbyCushing；

1946，wasintroducedintoclinicalpracticebyGardner1948，Griffiths-“hypotensivespinaltechnique”；1950，ganglionicblockade-pentamethonium；

1962，sodiumnitroprousside；

Subsequenttechniques:β-adrenergicreceptorblockingdrugs,acombinationofα-andβ-adrenergicreceptorblockingdrugs,volatileanesthetics,

purinederivativesIntroduction

2.Controlled/Induced/DeliberatedHypotension

3.Purpose：（1）decreasebloodloss（2）improvedvisibilityoftheoperativefield（3）decreasingtheneedforbloodtransfusions（4）decreasingthetransmittingdiseasebybloodtransfusion

Rationaleofcontrolledhypotension1.Majorfactorsofmaintainbloodpressure（1）cardiacoutput（CO）（2）totalsystemicvascularresistance（TSVR）（3）bloodvolume（4）bloodviscosity（BV）

組織血液灌流量=（π×MAP×血管內(nèi)徑4）（8×血液粘度×血管長(zhǎng)度）

Rationaleofcontrolledhypotension

2.Controlledhypotension：（1）TSVR：

①Tensionofvascularsystem

②MAP≥32mmHg-sufficienthemoperfusion

③Safelimit：MAP≥60mmHg

Older≥80mmHg（2）CO：

①Venoussystem：capacitancevessel

70%totalbloodvolume

②Venousdilatation→returnedbloodvolume↓

→CO↓→MAPEffectofhypotensiononorgansfunction一、CentralNervousSystem：1.Changesincerebralhemodynamics（CBF）（1）AutoregulationofCBF：60~150mmHg（2）MAP<60mmHg→Autoregulation

deprivation（3）↑FiO2→Toleranceforhypoxia↑（4）PaCO22.Changesofusingsodiumnitroprussideandtrimethaphan

3.Changesofusingisoflurane

Effectofhypotensiononorganfunction

二、Heart：

1.Maintenanceofanoxygensupplysufficient：

2.Autoregulationofcoronarycirculation：

3.Suppresstachycardia：β1-receptor-esmolol

labetalol

、urapidil4.Reducemetabolicrequirements：nitroglycerin

Effectofhypotensiononorganfunction三、Kidneys：

1.AutoregulationofKidneys：80~180mmHg2.SBP↓75mmHg→GFR↓→anuresis3.SufficientOxygensupplykidneyvasodilatation4.Normalrenalfunction→albuminuria、cast、

redcell5.Nephropathy→severdisadvantage、

renalinadequacyAutoregulationof

renalbloodflow543210100200平均動(dòng)脈壓（mmHg)腎血流(ml/min/g腎重)Effectofhypotension

onorganfunction四、SplanchnicCirculation：

1.liverhypoxichazard2.gastrointestinaltract五、Eye：六、SkinandMuscle：IndicationsandContraindications

一、Indications：1.Operationsoftissueandorganwhichbloodsupplyabundantly：headandneck2.Cardiovascularoperations：

aorticaneurysm、

patentductus

arteriosus、

intracranialvascularmalformation3.Lossoflargevolumeblood：

surgeryonlargetumors、

totalhiparthroplastyIndicationsandContraindications

4.Clear

operatingfield：middleear、

microsurgery5.Hypertension、intracranialhypertension

intraocularhypertension

duringanesthesiawhichcausingsevereharmfulconsequence6.Contraindicationsforbloodtransfusion7.Religiousbeliefs：precludebloodtransfusion

IndicationsandContraindications

二、Contraindications：

1.Absolutecontraindications：（1）Organicdisease：cerebrovasculardiseaserenaldysfunctionliverdysfunctionseverecoronaryarterydiseaselong-termhypertensionarteriosclerosisIndicationsandContraindications

（2）Hypovolemia

、severeanemia、

andrespiratoryinsufficiency（3）Aspectoftechnique：notfamiliarwiththetheoryandtechniqueof

controlledhypotensionIndicationsandContraindications

2.Relativecontraindications：（1）Elderlypatientorbaby；（2）Chronicoxygendeficiency；（3）Ischemicperipheralangiopathy：

severeperipheralclaudication；（4）Phlebitis、thrombus；（5）GlaucomaCOMPLICATIONS

1.Complications：（1）Cerebralinfarction、cerebralanoxia（2）Coronaryarteryembolization、

cardiacfailure（3）Renaldysfunction,anuriaandoliguria（4）Respiratoryinsufficiency（5）Embolism（6）Postoperativebleeding（7）Persistencehypotension（8）AnalepsiadelayCOMPLICATIONS2.Reason：Hypotension→perfusionpressure↓→slowbloodflow→thrombogenesis3.Correlationfactors：（1）Donotcontroltheindicationsstrictly（2）Hypotensionandpersistencetimetoolong（3）Faultoftechnicalmanagement（4）Insufficienttransfusion→hypovolemia（5）Respiration

managementimproperly（6）PostoperativecareisnotstrictCOMPLICATIONS

4.PreventionandManagement：（1）Controltheindicationsstrictly

（2）Keepveinopen、fluidinfusionintime

preciseestimatedblood

loss、

（3）Appropriatehypotension

adaptiveprocess（4）Enhancerespiration

managementmaintainPaCO2normalkeeptheairwayunobstructed（5）Enhance

postoperativecareTECHNIQUESTOINDUCECONTROLLEDHYPOTENSION一、PharmacologicTechniques

：

1.Medicationcombination：

fastandshort-actingvasoactivedrug

volatileanesthetic+/orβ-receptorblocker2.Forte：enhancehypotensioneffect→↓drug

consumption→preventadverseeffect

（reflextachycardia、reboundhypertension、drugfast）

TECHNIQUESTOINDUCECONTROLLEDHYPOTENSION二、CommonlyUsedDrugs：

1.SodiumNitroprusside：firstselect0.01%0.5~8.0μg/kg/minivgtttotalamount≤1.5mg/kg2.Nitroglycerin：

3.VolatileAnestheticDrugsTECHNIQUESTOINDUCECONTROLLEDHYPOTENSION4.α-Adrenergicreceptor-blockingdrug：

phentolamine、urapidil5.

PurineDerivatives：ATP6.

Esmolol：short-actingcardioselectiveβ-adrenergicreceptor-blockingdrug7.

Labetalol：blockbothα1-andβ1-receptorsalsoblocksβ2-receptors8.

Nicardipine：calciumchannelblockingdrug600~800μg/kg/hTECHNIQUESTOINDUCECONTROLLEDHYPOTENSION三、CommonlyUsedTechniques：

1．VolatileAnestheticDrugs：（1）Halothane：deepanesthesia→inhibitmyocardium→CO↓（2）Enflurane：dilateperipheralvessels（3）Isoflurane：dilateperipheralvesselsTECHNIQUESTOINDUCECONTROLLEDHYPOTENSION

2.Angiotenic：（1）SodiumNitroprusside：①Note：Solutioninstability→protectfromlightSuddenlywithdrawal→reboundhypertension

→captoprillong-termuse→quicklydrugtolerance

compensatorytachycardia→propranolol②Cyanidepoisoning：largedoseorlongtime

→cyanate

cumulationTECHNIQUESTOINDUCECONTROLLEDHYPOTENSION