Anesthetic Considerations of Physiological Changes During Pr

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Anesthetic ConsiderationsAnesthetic Considerationsof Physiological Changesof Physiological Changes

During PregnancyDuring Pregnancy

Presented by:Mona Abdelsamie

Assistant lecturer of AnesthesiologyUnder Supervision of:Prof. Dr. Hoda Omar

Professor of Anesthesiology !ntensive careAnesthesiology Department

Ain Shams University


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OBJECTIVES OBJECTIVES

Maternal physiology duringMaternal physiology duringpregnancy.pregnancy.Uteroplacental circulation.Uteroplacental circulation.

Placental transfer of anestheticPlacental transfer of anestheticagents.agents."ffect of labor on maternal"ffect of labor on maternalphysiology.physiology.


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Anaesthesia for parturient

What is the difference?

Physiologicalchanges

Alter the usualresponse

to anaesthesia

2Patients are cared#or simultaneously

Mother #etus


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Maternal Physiology during PregnancyMaternal Ph

ysiology during Pregnancy

1) Progressive MAC.1) Progressive MAC. by 40% at termby 40% at term Returns to normal by 3Returns to normal by 3 rdrd dayday

postpartum.postpartum.

$%S

Progesterone increases20times normal

level at term

&' endorphin surge during labor delivery


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2( ↑Sensitivity to Local Anesthetics.LA requirements

during RA ↓ by 30%

Hormonally Mediated

"ngorged "pidural(enous Ple)us

↓ F Volume

↓olume o!"idural "ace

↑"idural s"ace#ressure


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*espiratorysystem

↑ygen consum"tion20–40%

↑inute Ventilation40–50%↑↑' ( ) RR

&↑*0 +30 mm,g- )a$ .

↓aCo. +./ 3. mm,g-Com"ensatory ↓ ,Co 3ˉ

#rogesterone↑$. #roduction


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!*(!*(

+,,,+,,,mlml

++5%5%

!$+- ,

ml+15%

($($/ ,,/ ,,

mlml%o%o

$hange$hange

01$01$2 ,2 ,

mlml--5%5%

(0(0 - ,ml- ,ml++45%45%

"*("*( 3 ,ml3 ,ml--25%25%

#*$#*$

45,,45,,mlml--20%20%

*(*( 4, ,4, ,mlml

--15%15%

(olumes $apacities

1ung volumes&capacities at termgestation in absolutevolumes as thepercentage changefrom non'pregnant(alues


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↓RC 1 )$ . Consum"tion

!Ra"id desaturation during

"eriods o a"nea

☼re o ygenation "rior to 2A is mandatory.☼arturient hould not lie lat ithout

su""lemental o ygen.

↓RC ( )&V ↑☼"ta5e o 6nhalational nesthetics.


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,ormonal ChangesCa"illary engorgement ores"iratory tract mucosa

1"↑ncidence o di icult intubation.2(rauma and bleeding during

endotracheal intubation.

☼se a small !'' +7 8 9 mm-during 2A


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,ematologicalChanges

! : ) :lood Volume + u" to ;0ml< =g-#by 4,,, 6 4 ,, ml at term

*eturns to normal 4 6 + 7ee8spostpartum

↑lasma Volume > ) R:C mass+

!

Dilutional anemia ↓ blood viscosity

#acilitates maternal fetale)change of respiratory gases$

nutrients metabolites

↓m"act o maternal bloodloss at delivery


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66 ? ,y"ercoagulable state

↑ibrinogen@ actors V66@ V666@ 6 @ ( 66

↓actor 6

666 ? $ther changes

9 1eucocytosis up to +4 ooo;


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$(S↑$# by E0% at term

↑R * 8 30% ↑V 30%Returns to normal 2 ee!s postpartum.

SVR ↓ S:# ( ↓↓ D:#@ the res"onse to adrenergic and vasoconstric

agents is decreased.

C"P# PAP# PA$P unchanged.


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u"ine ,y"otension syndrome

$OP ↓ in su"ine "osition a ter ./th

ee5 o gestation.$ccurs in .0% o omen at term

Com"ression o 6VC Com"ression o lo er aorta

Aortocaval com"ression

lood lo to 5idneys$

tero"lacental circulation&

o er e tremeties

↓R ↓ C$# by .E% at term.


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Com"ensatory mechanisms inunanaesthetised Gomen

Venous Collaterals

#aravertebral

Venous "le usAbdominal

all

↑VR ( ,R

Reduced during generalor regional anesthesia

evere ,y"otension

#ro ound Fetal ,y"o ia


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Ho oman in late "regnancy should lie su"ine ithout shi ting

the uterus o the great abdomino "elvic vessels.

Le t lateral decubitus

'ilting the tableLe t side do n

Rigid edge under'he right hi"

Fluid "reloading be ore neuroa ial anesthesia6t does not com"letely avoid maternal hy"otension but

it) maternal C$# "reserve utero"lacentalblood lo.


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>!0

☼p ard displa&ement o' t(e stoma&( by t(euterus 6ncom"etence o gastroeso"hageals"hincter 2astroeso"hageal re lu ( eso"hagitis.

'he "arturient should be considered a ull stomach "atient uring most o gestation

☼ ↑#rogesterone ↓ tone o gastroeso"hageal s"hincter.☼#lacental 2astrin ,y"ersecretion o gastric acid.

☼2astric em"tying Delayed ith labor.


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#harmacological "ro"hyla is against as"irationHo "ositive "ressure ventilation be ore intubation

Ra"id sequence induction ellic5Is maneouvre

For 2A


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Renal ystem

♦:F ( 2FR ) by *0% at st trimester but returns tonormal in 3 rd trimester.

♦↑enin ( Aldosterone Ha + retention.

♦rB Creatinine ( :4H may ↓ to 0B* 8 0B7mg


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,e"atic! ects

♦e"atic unction ( he"atic blood lo unchanged

♦inor ) in rB 'ransaminases ( LD, in 3 rd trimester.

♦↑rB Al5aline "hos"hatase +"lacental-.

♦ild ↓ in rB albumin +dilutional-.

♦25–30%↓n "seudocholine estrase activity.

#rogesterone levels inhibit release o cholecysto5inin incomem"tying o gall bladder altered bile acid com"osition ormo cholesterol stones.


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&etabolic! ects

#regnancy is Diabetogenic

,uman #lacental lactogen relative insulin resistance.

tarvation li5e state

↓lood 2lucose ( Amino Acid levels.↑ree Fatty Acids@ =etones ( triglycerides.

↑strogen levels 'hyroid gland hy"ertrohy ) ' 3 ( ' E

↑:2 Free '3@ '

E ( ' , remain normal


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4tero"lacental Circulation

At term? uterine bloodlo is 0% o C$#

'(00 )*00l


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ally dilated uterine vasculature ith absent autoregulation

4terine :lood Flo

Directly "ro"ortional to di erence bet een

uterine arterial and venous "ressure

6nversely "ro"ortional to uterine ascular resistance

Abundant K adrenergic ( some adrenergic rece"tors.

#reviously @ vasoconstrictor agents ith "redominant adrenergic actiBgB !"hedrine",ere of choice for hy otension during regnancy

Recent studies sho that K adrenengic drugs +eBgB#henyle"hrine- have etter e ects.


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.aMor actors ↓ uterine blood lo during "regnancy

ystemic,y"otension

4terineVasoconstriction Uterine$ontractions

♦ortocaval com"ression.

♦y"ovolemia.

♦ym"athetic bloc5ith regional anesthesia.

♦tress induced endogenousCatecholamines during labor.

♦adrenergic agonists.

♦ocal anesthetic agents.

♦y"ertensive disorders→eneraliNed vasoconstriction.

♦abor.

♦ytocin in usions.

♦treme hy"oca"nia#aC$. J .0 mmhg.

♦arbiturates&#ro"o ol.


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#lacental trans er o anesthetic agents

#lacental trans er o drugs de"ends on

1olecular eight ? J *00 Da cross easily

2rotein binding

Li"id solubility? ,ighly ioniNed substances have "oor li"id sol

4aternal ( etal ", ? a ect ioniNation o the drug

5aternal drug concentration? a ected by dose givenand route o administration

(iming o administration


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6nhalational Agents

Cross "lacentareely

Limited e ects i J&AC ( delivery ithin0 minB o inductionntravenous Agents

'hi"ental@ 5etamine( "ro"o ol

Limited etal e ectsin usual inductiondoses

rug distribution@metabolism ( "lacentalu"ta5e"

Opioids Cross "lacentareely

Variable e ects

&orhine&ost signi icant res"iratory de"ressant

e ects&e"eridinee"eridine igni icant res"iratory de"ression "ea5ing

3 h a ter administration

Fentanyl &inimal e ect i J Og


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Local anesthetics #lacental trans er de"ends on:

1=a

2aternal ( etal ", ? Fetal acidosis higher etal to

maternal

drug ratios B :inding o hydrogen ions to the nonioniNed orm

tra""ing

o local anesthetic in etal circulation.egree o "rotein binding ? highly "rotein bound agents

di use "oorly across the "lacentaChloro"rocaine has the least "lacental trans er as it is ra"idlbro5en do n by "lasma cholinestrase in the maternal circulatio


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Most of anesthetic agents sho7 significant placental transfer

#etal effects of drugs administered to parturient depend on

1Maturity of fetal organs substantial fetal hepaticupta8e of many drugs

2Dilution of the umbilical venous blood by venous blood from lo7er half of fetal body modify fetal

drug distribution.


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! ect o labor on maternal "hysiology

tages o labor

st stage . nd stage 3rd stage

tarts ith true labor"ains@ ends by ullcervical dilation

tarts ith ull cervical ilation@ etal descent

ccurs@ ends ith com"letedelivery o etus

! tends rom birth o tbaby to delivery o the"lacenta

Latent "hase Active "hase

#rogressive cervical e acement&inor dilataton +. 8 E cm-

#rogressive cervical dilatationu" to 0 cm

/ 8 . h in nulli"arous* 8 / h in multi"arousB

Contractions are B* . mina"art@ last 8 B* min

15 )120in

15 ).0in


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6ntense "ain ul contractions

&aternalhy"erventilation&V ) u" to 300%

↑. consum"tion 70%

above 3rd

trimester values

#Co. J .0 mm,g

4terine VC Fetal acidosis

+#eriods o hy"oventilation transientmaternal ( etal hy"o emia in bet eenContractions.


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!ach contraction

Dis"laces 300 8 *00ml blood rom

terus to central circulation

C$# ) E*% above 3 rd trimesteric value.

&a imum strain on the heart occurs immediatelya ter delivery

4terine intense involution sudden relieve o 6VC

→ ↑$# /0% above "relabor values.


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Discussioniscussion


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Puestions


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Fetal blood concentrations o lidocaineetal blood concentrations o lidocaineollo ing maternal administration ould beollo ing maternal administration ould be

higher than e "ected?igher than e "ected?BB 6 administered during uterine contractionB administered during uterine contractionB

.BB 6n the "resence o umbilical cordn the "resence o umbilical cordcom"ressionBom"ressionB

3BB 6n the "resence o maternal acidosisBn the "resence o maternal acidosisB

EBB 6n the "resence o etal acidosisBn the "resence o etal acidosisB

*BB 6n the "resence o increased maternaln the "resence o increased maternalmetabolismBetabolismB

√


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B 'otal "eri"heral resistance decreasesB.B ,b concentration decreasesB3B #lasma cholinestrase concentration increasesBEB :lood glucose concentration increasesB*B Functional residual ca"acity increasesB

During "regnancyuring "regnancy

√√


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'he dose o bu"ivacaine required or s"inalhe dose o bu"ivacaine required or s"inalanesthesia is reduced in the "regnant "atient atnesthesia is reduced in the "regnant "atient at

term because o decreasederm because o decreased

B C F volumeB.B "inal cord blood lo B3B &etabolism o bu"ivacaineB

EB C F "ressureB*B 'urnover o C FB

√


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B &aternal arterial ",B.B Fetal cerebral blood lo B3B &aternal cerebral blood lo BEB &aternal uterine artery lo B*B Fetal arterial #$ .B

ternal hy"erventilation "roduces a decrease inernal hy"erventilation "roduces a decrease in

√

√


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'he ollo ing substances trans er reely acrosshe ollo ing substances trans er reely acrossthe "lacenta?he "lacenta?

BB HeostigmineBeostigmineB.BB 6nsulinBnsulinB3BB #ancuroniumBancuroniumBEBB Atro"ineBtro"ineB

*BB glyco"yrolateBlyco"yrolateB

√

√


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Anesthetic Considerations of Physiological Changes During Pr

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