Non Obstet Surgery


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Non Obstet Surgery

  1. 1. Non-obstetric surgery in pregnancy
  2. 2. Aims <ul><li>Determine the issues relating to the pregnant woman presenting for non- obstetric surgery </li></ul><ul><li>Re-consider the physiological changes that occur through pregnancy and the impact that this might have on your anaesthetic approach to the patient </li></ul><ul><li>Discuss the risks of miscarriage and premature labour in this setting and your management approach to these issues </li></ul><ul><li>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 </li></ul>
  3. 3. Considerations <ul><li>Surgical issues </li></ul><ul><li>Maternal issues </li></ul><ul><li>Foeto-placental issues </li></ul>
  4. 4. Review of Physiological Changes through Pregnancy <ul><li>CVS: </li></ul><ul><ul><li>Hct ^ 15 - 20% @ term </li></ul></ul><ul><ul><li>Plasma vol ^ 45 - 50% @ term </li></ul></ul><ul><ul><li>Dilutional anaemia b/c plasma vol ^ faster than RBC mass -> reduced 02 carriage </li></ul></ul><ul><ul><li>Red plasma oncotic press </li></ul></ul><ul><ul><li>Compensation by: </li></ul></ul><ul><ul><li>^Vm ~50% @ term (P02^10mmHg, PC02 red 32-34mmHg) </li></ul></ul><ul><ul><li>ODC R shifted </li></ul></ul><ul><ul><li>^ CO/ blood flow </li></ul></ul><ul><ul><ul><li>T1 + T2 - CO ^ 30 - 40% </li></ul></ul></ul><ul><ul><ul><li>T3 - CO ^ further 30% </li></ul></ul></ul><ul><ul><ul><li>HR ^ 15%, SV ^ 20% </li></ul></ul></ul><ul><ul><ul><li>Reduced viscosity 2’ haemodil’n, BUT hypercoagulable (^F7,F8,F10,F1) </li></ul></ul></ul><ul><ul><ul><li>Reduced SVR </li></ul></ul></ul><ul><ul><ul><ul><li>Hormone induced vasodil’n </li></ul></ul></ul></ul><ul><ul><ul><ul><li>A-V shunt through placental bed (20% red SVR) </li></ul></ul></ul></ul>
  5. 5. Review of Physiological Changes through Pregnancy <ul><li>Respiratory: </li></ul><ul><ul><li>PVR red 50% </li></ul></ul><ul><ul><li>AWR red ~35% 2’ progesterone </li></ul></ul><ul><ul><li>^V02 ~20% </li></ul></ul><ul><ul><li>ODC R shift </li></ul></ul><ul><ul><li>Vm ^ ~50% (Tv ^ 40%, RR ^ 15% @ term) </li></ul></ul><ul><ul><li>Red FRC 20%, therefore CC > FRC with ^TV -> shunt </li></ul></ul>
  6. 6. Review of Physiological Changes through Pregnancy <ul><li>GIT: </li></ul><ul><li>^ placental gastrin -> red gastric pH </li></ul><ul><li>Red LOS tone </li></ul><ul><li>^ing gravid uterus </li></ul><ul><li>Neuro: </li></ul><ul><li>LA requirements for regional blockade </li></ul><ul><li>Reduced MAC requirement?? </li></ul>
  7. 7. Surgical Issues <ul><li>Requirement for Surgery </li></ul><ul><ul><li>Elective - or where possible, delay until 6/52 post partum </li></ul></ul><ul><ul><li>Semi elective - consider risk/ benefit </li></ul></ul><ul><ul><ul><li>Eg cerebral aneurysm/ cardiac valvular disease/ malignancy </li></ul></ul></ul><ul><ul><li>Emergency - proceed with discussion about realistic expectations </li></ul></ul><ul><li>Pathology </li></ul><ul><ul><li>Intra-abdominal/ Pelvic </li></ul></ul><ul><ul><li>Extra-abdominal </li></ul></ul><ul><li>Current physiological state </li></ul><ul><ul><li>CVS stable/ unstable </li></ul></ul><ul><ul><li>Resp compromise </li></ul></ul><ul><ul><li>GCS </li></ul></ul><ul><ul><li>Infection - local/ systemic </li></ul></ul>
  8. 8. Surgical Issues <ul><li>Surgical intervention during surgery a/w ^ risk LBW (<2500gm); preterm labour and growth-restricted babies </li></ul><ul><li>Most common general surgical procedures in pregnancy: </li></ul><ul><ul><li>Acute appendicitis </li></ul></ul><ul><ul><li>Acute cholecystitis </li></ul></ul><ul><ul><li>(Adhesions -> SBO) </li></ul></ul><ul><li>Ac Appendx </li></ul><ul><ul><li>Rate the same for non pregnant and pregnant 1: 2000 </li></ul></ul><ul><ul><li>Rx the same as non-pregnant appendx </li></ul></ul><ul><li>Ac Chole </li></ul><ul><ul><li>Less surgical intervention 2’ nonsurgical Rx </li></ul></ul><ul><ul><li>Op Chole 1-6:10,000 pregnancy </li></ul></ul><ul><ul><li>Cx GS pancreatitis -> foetal death 10 – 20% </li></ul></ul><ul><li>???Laparoscopic approach </li></ul>
  9. 9. Surgical Issues <ul><li>Pregnancy = RELATIVE C/I to laparoscopy </li></ul><ul><li>BUT </li></ul><ul><ul><li>Potential advantages include : </li></ul></ul><ul><ul><li>Red foetal depression 2’ less maternal opiate </li></ul></ul><ul><ul><li>Red risk wound Cx </li></ul></ul><ul><ul><li>Red maternal post-op hypoventilation </li></ul></ul><ul><ul><li>More rapid maternal recovery: VTE </li></ul></ul><ul><li>Pneumoperitonium -> foetal risks </li></ul><ul><ul><li>Uterine injury at trocar insertion </li></ul></ul><ul><ul><li>Preterm labour 2’ ^ intra-abdominal pressure </li></ul></ul><ul><ul><li>^ foetal acidosis (less with N2O insufflating gas) </li></ul></ul><ul><ul><li>Hypothetical risk red uterine blood flow; but pneumo probably better than open procedure with manual retraction of uterus </li></ul></ul>
  10. 10. Maternal Issues <ul><li>The usual stuff </li></ul><ul><li>Gestation </li></ul><ul><li>Gestational Cx </li></ul><ul><li>Anaesthetic issues for the pregnant pt </li></ul>
  11. 11. Foetal Issues <ul><li>Teratogenicity </li></ul><ul><ul><li>greatest risk T1 = organogenesis </li></ul></ul><ul><ul><li>Less risk T2 = organ development: size and f(n) </li></ul></ul><ul><li>Foeto- placental function : D02 = maternal CO and CaO2 </li></ul><ul><ul><li>BP/ Sp02/ Hb </li></ul></ul><ul><ul><li>Intravascular volume state </li></ul></ul><ul><ul><ul><li>Absolute </li></ul></ul></ul><ul><ul><ul><li>Relative - ACC </li></ul></ul></ul><ul><ul><li>SNS tone </li></ul></ul><ul><li>Spontaneous abortion/ Premature labour </li></ul><ul><ul><li>Depends on gestation/ surgical pathology and location of disease process in relation to uterus </li></ul></ul>
  12. 12. Miscarriage; Preterm Labour (<37/40 G) and Very Preterm Labour(<34/40G) <ul><li>Spontaneous preterm labour and delivery ~33% preterm births </li></ul><ul><li>Preterm birth major contributor to perinatal morbidity and mortality - affecting ~ 6 - 7% births in developed countries </li></ul><ul><li>Rx consists of: bed rest; hydration and pharmacologic interventions </li></ul><ul><li>Tocolysis </li></ul><ul><ul><li>Rx and Mx therapy to terminate preterm labour </li></ul></ul><ul><ul><li>Buy time for foetal lung maturation with a view to delivery </li></ul></ul>
  13. 13. Tocolytics <ul><li>Beta 2 agonists </li></ul><ul><li>CaCB </li></ul><ul><li>MgSO4 </li></ul><ul><li>PG inhibitors </li></ul><ul><li>Oxytocin receptor antagonists </li></ul>
  14. 14. Tocolytics (?/40 gestation) <ul><ul><li>Betamimetics : salbutamol/ ritodrine -> terbutaline </li></ul></ul><ul><ul><ul><li>Most widely used in resource poor countries </li></ul></ul></ul><ul><ul><ul><li>Effective v’s placebo at prolonging confinement 48hrs </li></ul></ul></ul><ul><ul><ul><li>Significantly a/w adverse effects +/- w/drawl from Rx </li></ul></ul></ul><ul><ul><ul><ul><li>H’ache/ hypoK+/ ^BSL/ tachycardia - M&F/ arrhythmias/ dyspnoea/ nasal stuffiness/ met acidosis/ myocardial ischaemia/ pulmonary oedema </li></ul></ul></ul></ul><ul><ul><li>CaCB - Nifedipine 20mg; 20” 20mg; 20” 20mg until contractions settle; then 20mg TDS </li></ul></ul><ul><ul><ul><li>12 RCTs, 1029 pt, Cochrane 2003 </li></ul></ul></ul><ul><ul><ul><li>Effective at prolonging confinement, <34/40G </li></ul></ul></ul><ul><ul><ul><li>Reduced adverse effects </li></ul></ul></ul><ul><ul><ul><li>Reduced Hz NRDS/ NEC/ IVH/ NJ </li></ul></ul></ul><ul><ul><li>MgSO4 </li></ul></ul><ul><ul><ul><li>23 trials, 2000pt, Cochrane 2002 </li></ul></ul></ul><ul><ul><ul><li>No effect on delaying birth </li></ul></ul></ul><ul><ul><ul><li>^ risk infant death: RR 2.82 95%CI 1.2 - 6.62 (1 study) </li></ul></ul></ul><ul><ul><ul><li>Overall: no beneficial effect w MgSO4 in neonatal morbidity </li></ul></ul></ul>
  15. 15. Tocolytics (?/40 gestation) <ul><ul><li>PG inhibitors - Indomethacin/ COX 2 selective -> PDA closure 2’ blockade PGE1 </li></ul></ul><ul><ul><ul><li>Conflicting evidence: IVH; NEC; PDA; neonatal mortality </li></ul></ul></ul><ul><ul><ul><li>? ^ BPD; ? ^ Pulm HPT </li></ul></ul></ul><ul><ul><ul><li>Wkly echo suggested </li></ul></ul></ul><ul><ul><li>Oxytocin receptor antagonists : Atosiban </li></ul></ul><ul><ul><ul><li>6 trials, 1695 pts, Cochrane 07/2005 </li></ul></ul></ul><ul><ul><ul><ul><li>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 </li></ul></ul></ul></ul><ul><ul><ul><li>Eur J Obstet Gynaecol Reprod Biol Oct 06 </li></ul></ul></ul><ul><ul><ul><ul><li><28/40: nifedipine better than atosiban w shorter time to onset </li></ul></ul></ul></ul><ul><ul><ul><ul><li>>28/40 CaCB = atosiban, but >er SEs/ neonatal Cx = </li></ul></ul></ul></ul><ul><ul><ul><ul><li>PHx preterm labour: atosiban better than CaCB </li></ul></ul></ul></ul><ul><ul><ul><li>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) </li></ul></ul></ul><ul><ul><ul><li>Real problem = cost and availability! </li></ul></ul></ul>
  16. 16. Delivery <ul><li>Foetal lung maturation >= 24/40G </li></ul><ul><ul><li>Steroids: betamethasone; dexamethasone; hydrocortisone </li></ul></ul><ul><ul><ul><li>Celestone 11.4mg IMI followed by 11.4mg IMI 24hr later </li></ul></ul></ul><ul><ul><ul><li>Aim to delay impending labour by 24 hr to get 2nd dose celestone on board </li></ul></ul></ul><ul><ul><ul><li>Can repeat doses at later date PRN </li></ul></ul></ul><ul><li>Neonatal care/ NICU </li></ul><ul><ul><li>BSL/ temp/ NRDS - surfactant </li></ul></ul><ul><ul><li>Post deliver Ax and review for signs HBI, if significant/ prolonged maternal compromise </li></ul></ul>
  17. 17. Anaesthetic Approach <ul><li>Anaesthetic issues for the pregnant pt </li></ul><ul><ul><li>Airway </li></ul></ul><ul><ul><ul><li>Aspiration - Gravid uterus/ LOS tone/ fasting status </li></ul></ul></ul><ul><ul><ul><li>Failed intubation - oedema </li></ul></ul></ul><ul><ul><li>(Blood loss) </li></ul></ul><ul><ul><li>Conceptus </li></ul></ul><ul><ul><ul><li>T1: spontaneous abortion 2’ pathology/ surgery near uterus </li></ul></ul></ul><ul><ul><ul><li>T1 & T3: Pharmacology </li></ul></ul></ul><ul><ul><li>Positioning issues - prone, esp later pregnancy </li></ul></ul><ul><ul><li>Don’t forget the wedge! </li></ul></ul><ul><li>Monitoring: Std and Foetal </li></ul><ul><ul><li>T1: FHR </li></ul></ul><ul><ul><li>T2: early = FHR; >26/40 = CTG/ FHR </li></ul></ul><ul><ul><li>T3: CTG/ FHR </li></ul></ul><ul><ul><li>CTG </li></ul></ul><ul><ul><ul><li>Baseline b-b variab 5 bpm </li></ul></ul></ul><ul><ul><ul><li>Reactive b-b variab 15bpm </li></ul></ul></ul><ul><ul><ul><li>b-b variab reduced with GA </li></ul></ul></ul>
  18. 18. GA v’s Regional <ul><li>Regional preferred , esp toward end T2 when major physiological changes have occurred </li></ul><ul><li>Otherwise, GA: </li></ul><ul><ul><li>Proseal LMA </li></ul></ul><ul><ul><li>RSI @ 12 - 16/40, or when Sx’atic reflux? </li></ul></ul>
  19. 19. Pharmacology - the good and the bad <ul><li>Induction </li></ul><ul><ul><li>Thio/ Propofol/ ?Ketamine </li></ul></ul><ul><li>Relaxant </li></ul><ul><ul><li>Sux ?prolonged effect </li></ul></ul><ul><ul><li>NDNMJBs </li></ul></ul><ul><li>Maintainance </li></ul><ul><ul><li>Volatile/ TIVA </li></ul></ul><ul><li>Analgaesia </li></ul><ul><ul><li>Paracetamol* </li></ul></ul><ul><ul><li>NSAIDS </li></ul></ul><ul><ul><li>Opiates* </li></ul></ul><ul><ul><li>Tramadol </li></ul></ul><ul><ul><li>Ketamine </li></ul></ul>
  20. 20. Pharmacology - NSAIDS <ul><li>T1: </li></ul><ul><li>* Probable early spont abortion </li></ul><ul><ul><li>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) </li></ul></ul><ul><li>* ?? Cardiac malformation: septal defects - not confirmed: Uncertainty -> discourage use thru pregnancy/ Risk: Benefit </li></ul><ul><li>* Aspirin exposure -> ^ risk gastroschisis </li></ul><ul><li>T3: </li></ul><ul><li>Vascular effects( renal & cardiac): constriction DA and renal arteries -> renal bld flow// discontinue @ 32/40G </li></ul><ul><li>Conflicting evidence: </li></ul><ul><ul><li>IVH; NEC; PDA; neonatal mortality; ? ^ BPD; ? ^ Pulm HPT </li></ul></ul><ul><ul><li>Am J Obs Gynae 1997: 193 echo/ 72 foetuses </li></ul></ul><ul><ul><ul><li>NSAIDS -> ductal constriction 50% foetuses 24.7 - 35/40 @ av 5+/- 6 days after Rx initiated </li></ul></ul></ul><ul><ul><ul><li>By 31/40 - 70% ductal constriction </li></ul></ul></ul><ul><ul><ul><li>Cessation Rx -> ALL rtn to N ductal flow velocities </li></ul></ul></ul><ul><li>*Discontinue 6 - 8 weeks before delivery </li></ul><ul><li>*Non selective OK with lactation/ ^ risk jaundice and kernicterus/ ?? COX - 2 </li></ul>
  21. 21. Pharmacology - Tramadol <ul><ul><li>Tramadol is Pregnancy Category C. </li></ul></ul><ul><ul><li>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. </li></ul></ul><ul><ul><li>No harm to the foetus due to tramadol was seen at doses that were not maternally toxic. </li></ul></ul><ul><ul><li>No drug-related teratogenic effects were observed in progeny of mice, rats or rabbits treated with tramadol by various routes </li></ul></ul><ul><ul><li>Embryo and foetal toxicity consisted primarily of decreased foetal weights, skeletal ossification and increased supernumerary ribs at maternally toxic dose levels. </li></ul></ul><ul><ul><li>Transient delays in development or behavioural parameters were also seen in pups from rat dams allowed to deliver </li></ul></ul>
  22. 22. Pharmacology - Tramadol <ul><li>Lactation </li></ul><ul><ul><li>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. </li></ul></ul><ul><li>Labour and Delivery </li></ul><ul><ul><li>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. </li></ul></ul><ul><ul><li>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. </li></ul></ul><ul><ul><li>The effect of tramadol, if any, on the later growth, development, and functional maturation of the child is unknown. </li></ul></ul><ul><ul><li>However, there are studies looking at the effect of tramadol in labour c/w pethidine, and advocating the effectiveness and use of tramadol </li></ul></ul>
  23. 23. Pharmacology - Ketamine <ul><ul><li>Use In Pregnancy - Category B3 </li></ul></ul><ul><ul><li>Limited studies in animals have not shown that ketamine causes birth defects; however, it crosses the placenta . </li></ul></ul><ul><ul><li>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 ; </li></ul></ul><ul><ul><li>Ketamine administration to pregnant monkeys near term was associated with increased blood Pco2 and a dose-dependent respiratory depression in neonates </li></ul></ul><ul><ul><li>With the exception of administration during surgery for abdominal delivery or vaginal delivery, no controlled clinical studies in pregnancy have been conducted </li></ul></ul><ul><ul><li>The safe use of ketamine in pregnancy has not been established, and such use is not recommended . </li></ul></ul>
  24. 24. Pharmacology - Ketamine <ul><ul><li>Use in Lactation </li></ul></ul><ul><ul><li>Ketamine is likely to be excreted in breast milk and therefore breastfeeding should be discontinued when ketamine is in use </li></ul></ul>
  25. 25. Pharmacology - Thromboembolic Px <ul><ul><li>Common risk factors for VTE during pregnancy: </li></ul></ul><ul><ul><ul><li>35yoa </li></ul></ul></ul><ul><ul><ul><li>Obesity </li></ul></ul></ul><ul><ul><ul><li>Operative delivery </li></ul></ul></ul><ul><ul><ul><li>Thrombophilia </li></ul></ul></ul><ul><ul><ul><li>FHx or PHx VTE </li></ul></ul></ul><ul><ul><li>VTE in pregnancy = anticoagulation throughout pregnancy and continued for at least 6/52 post partum/ 6/12 Rx </li></ul></ul><ul><ul><li>UFH </li></ul></ul><ul><ul><ul><li>Does not X placenta </li></ul></ul></ul><ul><ul><ul><li>Previously drug of choice for VTE/ cardiac valvular disease </li></ul></ul></ul><ul><ul><li>LMWH </li></ul></ul><ul><ul><ul><li>Does not X placenta </li></ul></ul></ul><ul><ul><ul><li>Now the drug of choice for VTE Px in pregnant pt </li></ul></ul></ul><ul><ul><li>Warfarin </li></ul></ul><ul><ul><ul><li>X placenta </li></ul></ul></ul><ul><ul><ul><li>Embryopathy occurs if administered b/n 6th and 12th wk gestation </li></ul></ul></ul><ul><ul><ul><li>Avoided if heparin substituted for warfarin by 6 wks gestation </li></ul></ul></ul>
  26. 26. Summary <ul><li>Stabilize pt </li></ul><ul><li>Appropriateness for surgery </li></ul><ul><ul><li>…… ..elective/ semi-elective/ emergency </li></ul></ul><ul><li>Anaesthesia for……surgery </li></ul><ul><li>Anaesthesia for……the pregnant pt </li></ul><ul><li>Anaesthetic considerations…..for the well being of the foetus </li></ul><ul><li>Ask for help/ advice from appropriate other specialties! </li></ul>