non obstet surgery

Non-obstetric surgery in pregnancy

AimsAims

Determine the issues relating to the pregnant woman presenting for non- obstetric surgery

Re-consider the physiological changes that occur through pregnancy and the impact that this might have on your anaesthetic approach to the patient

Discuss the risks of miscarriage and premature labour in this setting and your management approach to these issues

Discuss your choice of pharmacological cocktail to achieve your anaesthetic and post operative objectives, the rationale for this and the impact that this might have for mother and foetus

ConsiderationsConsiderations

Surgical issues Maternal issues Foeto-placental issues

Review of Physiological Changes through Pregnancy


CVS: Hct ^ 15 - 20% @ term Plasma vol ^ 45 - 50% @ term Dilutional anaemia b/c plasma vol ^ faster than RBC mass ->

reduced 02 carriage Red plasma oncotic press Compensation by: ^Vm ~50% @ term (P02^10mmHg, PC02 red 32-34mmHg) ODC R shifted ^ CO/ blood flow

T1 + T2 - CO ^ 30 - 40% T3 - CO ^ further 30% HR ^ 15%, SV ^ 20% Reduced viscosity 2’ haemodil’n, BUT hypercoagulable

(^F7,F8,F10,F1) Reduced SVR

Hormone induced vasodil’n A-V shunt through placental bed (20% red SVR)



Respiratory: PVR red 50% AWR red ~35% 2’ progesterone ^V02 ~20% ODC R shift Vm ^ ~50% (Tv ^ 40%, RR ^ 15% @ term) Red FRC 20%, therefore CC > FRC with ^TV -> shunt



GIT: ^ placental gastrin -> red gastric pH Red LOS tone ^ing gravid uterus

Neuro: LA requirements for regional blockade Reduced MAC requirement??

Surgical IssuesSurgical Issues

Requirement for Surgery Elective - or where possible, delay until 6/52 post partum Semi elective - consider risk/ benefit

Eg cerebral aneurysm/ cardiac valvular disease/ malignancy Emergency - proceed with discussion about realistic

expectations Pathology

Intra-abdominal/ Pelvic Extra-abdominal

Current physiological state CVS stable/ unstable Resp compromise GCS Infection - local/ systemic


Surgical intervention during surgery a/w ^ risk LBW (<2500gm); preterm labour and growth-restricted babies

Most common general surgical procedures in pregnancy: Acute appendicitis Acute cholecystitis (Adhesions -> SBO)

Ac Appendx Rate the same for non pregnant and pregnant 1: 2000 Rx the same as non-pregnant appendx

Ac Chole Less surgical intervention 2’ nonsurgical Rx Op Chole 1-6:10,000 pregnancy Cx GS pancreatitis -> foetal death 10 – 20%

???Laparoscopic approach


Pregnancy = RELATIVE C/I to laparoscopy BUT

Potential advantages include: Red foetal depression 2’ less maternal opiate Red risk wound Cx Red maternal post-op hypoventilation More rapid maternal recovery: VTE

Pneumoperitonium -> foetal risks Uterine injury at trocar insertion Preterm labour 2’ ^ intra-abdominal pressure ^ foetal acidosis (less with N2O insufflating gas) Hypothetical risk red uterine blood flow; but pneumo probably

better than open procedure with manual retraction of uterus

Maternal IssuesMaternal Issues

The usual stuff Gestation Gestational Cx Anaesthetic issues for the pregnant pt

Foetal IssuesFoetal Issues

Teratogenicity greatest risk T1 = organogenesis Less risk T2 = organ development: size and f(n)

Foeto- placental function: D02 = maternal CO and CaO2 BP/ Sp02/ Hb Intravascular volume state

Absolute Relative - ACC

SNS tone Spontaneous abortion/ Premature labour

Depends on gestation/ surgical pathology and location of disease process in relation to uterus

Miscarriage; Preterm Labour (<37/40 G) and Very Preterm

Labour(<34/40G)

Miscarriage; Preterm Labour (<37/40 G) and Very Preterm

Labour(<34/40G) Spontaneous preterm labour and delivery ~33%

preterm births Preterm birth major contributor to perinatal morbidity

and mortality - affecting ~ 6 - 7% births in developed countries

Rx consists of: bed rest; hydration and pharmacologic interventions

Tocolysis Rx and Mx therapy to terminate preterm labour Buy time for foetal lung maturation with a view to

delivery

TocolyticsTocolytics

Beta 2 agonists CaCB MgSO4 PG inhibitors Oxytocin receptor antagonists

Tocolytics (?/40 gestation)Tocolytics (?/40 gestation)

Betamimetics: salbutamol/ ritodrine -> terbutaline Most widely used in resource poor countries Effective v’s placebo at prolonging confinement 48hrs Significantly a/w adverse effects +/- w/drawl from Rx

H’ache/ hypoK+/ ^BSL/ tachycardia - M&F/ arrhythmias/ dyspnoea/ nasal stuffiness/ met acidosis/ myocardial ischaemia/ pulmonary oedema

CaCB - Nifedipine 20mg; 20” 20mg; 20” 20mg until contractions settle; then 20mg TDS

12 RCTs, 1029 pt, Cochrane 2003 Effective at prolonging confinement, <34/40G Reduced adverse effects Reduced Hz NRDS/ NEC/ IVH/ NJ

MgSO4 23 trials, 2000pt, Cochrane 2002 No effect on delaying birth ^ risk infant death: RR 2.82 95%CI 1.2 - 6.62 (1 study) Overall: no beneficial effect w MgSO4 in neonatal morbidity

Tocolytics (?/40 gestation)Tocolytics (?/40 gestation)

PG inhibitors - Indomethacin/ COX 2 selective -> PDA closure 2’ blockade PGE1

Conflicting evidence: IVH; NEC; PDA; neonatal mortality ? ^ BPD; ? ^ Pulm HPT Wkly echo suggested

Oxytocin receptor antagonists: Atosiban 6 trials, 1695 pts, Cochrane 07/2005

c/w placebo no red’n preterm birth rates or improve’t in foetal outcome/ Sig more pts <26/40G; lower infant birth wt < 1500gm

Eur J Obstet Gynaecol Reprod Biol Oct 06 <28/40: nifedipine better than atosiban w shorter time to onset >28/40 CaCB = atosiban, but >er SEs/ neonatal Cx = PHx preterm labour: atosiban better than CaCB

Studies failed to demonstrate benefit over other tocolytics -> CCB a/w better foetal outcome and fewer maternal SE (red milk let down -> red lactation -> poorer neonatal survival….in rat models)

Real problem = cost and availability!

DeliveryDelivery

Foetal lung maturation >= 24/40G Steroids: betamethasone; dexamethasone;

hydrocortisone Celestone 11.4mg IMI followed by 11.4mg IMI 24hr later Aim to delay impending labour by 24 hr to get 2nd dose

celestone on board Can repeat doses at later date PRN

Neonatal care/ NICU BSL/ temp/ NRDS - surfactant Post deliver Ax and review for signs HBI, if significant/

prolonged maternal compromise

Anaesthetic ApproachAnaesthetic Approach

Anaesthetic issues for the pregnant pt Airway

Aspiration - Gravid uterus/ LOS tone/ fasting status Failed intubation - oedema

(Blood loss) Conceptus

T1: spontaneous abortion 2’ pathology/ surgery near uterus T1 & T3: Pharmacology

Positioning issues - prone, esp later pregnancy Don’t forget the wedge!

Monitoring: Std and Foetal T1: FHR T2: early = FHR; >26/40 = CTG/ FHR T3: CTG/ FHR CTG

Baseline b-b variab 5 bpm Reactive b-b variab 15bpm b-b variab reduced with GA

GA v’s RegionalGA v’s Regional

Regional preferred , esp toward end T2 when major physiological changes have occurred

Otherwise, GA: Proseal LMA RSI @ 12 - 16/40, or when Sx’atic reflux?

Pharmacology - the good and the bad

Pharmacology - the good and the bad

InductionThio/ Propofol/ ?Ketamine

RelaxantSux ?prolonged effectNDNMJBs

MaintainanceVolatile/ TIVA

AnalgaesiaParacetamol*NSAIDSOpiates*TramadolKetamine

Pharmacology - NSAIDSPharmacology - NSAIDS

T1:* Probable early spont abortion

BMJ 2003 - < 20/40G: prenatal NSAID use at time conception or >1/52 a/w ^ risk miscarriage (HR 1.8 (95% CI 1.0 - 3.2)

* ?? Cardiac malformation: septal defects - not confirmed: Uncertainty -> discourage use thru pregnancy/ Risk: Benefit

* Aspirin exposure -> ^ risk gastroschisisT3: Vascular effects( renal & cardiac): constriction DA and renal arteries ->

renal bld flow// discontinue @ 32/40G Conflicting evidence:

IVH; NEC; PDA; neonatal mortality; ? ^ BPD; ? ^ Pulm HPT Am J Obs Gynae 1997: 193 echo/ 72 foetuses

NSAIDS -> ductal constriction 50% foetuses 24.7 - 35/40 @ av 5+/- 6 days after Rx initiated

By 31/40 - 70% ductal constriction Cessation Rx -> ALL rtn to N ductal flow velocities

*Discontinue 6 - 8 weeks before delivery*Non selective OK with lactation/ ^ risk jaundice and kernicterus/ ?? COX - 2

Pharmacology - TramadolPharmacology - Tramadol

Tramadol is Pregnancy Category C. There are no adequate and well-controlled studies with

tramadol in pregnant women. Tramadol should be used during pregnancy only if the potential benefit outweighs the potential risk to the foetus because safe use in pregnancy has not been established.

No harm to the foetus due to tramadol was seen at doses that were not maternally toxic.

No drug-related teratogenic effects were observed in progeny of mice, rats or rabbits treated with tramadol by various routes

Embryo and foetal toxicity consisted primarily of decreased foetal weights, skeletal ossification and increased supernumerary ribs at maternally toxic dose levels.

Transient delays in development or behavioural parameters were also seen in pups from rat dams allowed to deliver

Pharmacology - TramadolPharmacology - Tramadol

Lactation Tramadol is not recommended for obstetric preoperative

medication or for post-delivery analgesia in nursing mothers because its safety in infants and newborns has not been studied. Low levels of tramadol have been detected in breast milk. Following a single intravenous 100mg dose of tramadol, the cumulative excretion in breast milk within 16 hours post-dose was 100 mcg of tramadol (0.1% of the maternal dose) and 27 mcg of M1.

Labour and Delivery Tramadol should not be used in pregnant women prior to or

during labour unless the potential benefits outweigh the potential risks, because safe use in pregnancy has not been established.

Tramadol has been shown to cross the placenta. The mean ratio of serum tramadol in the umbilical veins compared to maternal veins was 0.83 for 40 women given tramadol during labour.

The effect of tramadol, if any, on the later growth, development, and functional maturation of the child is unknown.

However, there are studies looking at the effect of tramadol in labour c/w pethidine, and advocating the effectiveness and use of tramadol

Pharmacology - KetaminePharmacology - Ketamine

Use In Pregnancy - Category B3 Limited studies in animals have not shown that ketamine

causes birth defects; however, it crosses the placenta. Histological changes in the heart (degeneration and oedema

of cardiac muscle), liver (diffuse haemopoietic cell infiltration, parenchymal cell degeneration) and kidneys (proximal convoluted tubule degeneration) were observed in fetuses following administration of ketamine to pregnant rats during the period of organogenesis at doses similar to the maximum human dose, on a body surface area basis;

Ketamine administration to pregnant monkeys near term was associated with increased blood Pco2 and a dose-dependent respiratory depression in neonates

With the exception of administration during surgery for abdominal delivery or vaginal delivery, no controlled clinical studies in pregnancy have been conducted

The safe use of ketamine in pregnancy has not been established, and such use is not recommended.

Pharmacology - KetaminePharmacology - Ketamine

Use in Lactation Ketamine is likely to be excreted in breast milk and

therefore breastfeeding should be discontinued when ketamine is in use

Pharmacology - Thromboembolic Px

Pharmacology - Thromboembolic Px

Common risk factors for VTE during pregnancy: 35yoa Obesity Operative delivery Thrombophilia FHx or PHx VTE

VTE in pregnancy = anticoagulation throughout pregnancy and continued for at least 6/52 post partum/ 6/12 Rx

UFHDoes not X placentaPreviously drug of choice for VTE/ cardiac valvular disease

LMWHDoes not X placenta Now the drug of choice for VTE Px in pregnant pt

WarfarinX placentaEmbryopathy occurs if administered b/n 6th and 12th wk gestationAvoided if heparin substituted for warfarin by 6 wks gestation

SummarySummary

Stabilize pt

Appropriateness for surgery……..elective/ semi-elective/ emergency

Anaesthesia for……surgery

Anaesthesia for……the pregnant pt

Anaesthetic considerations…..for the well being of the foetus

Ask for help/ advice from appropriate other specialties!

non obstet surgery

Health & Medicine