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Anaesthesia for-fetal-surgery


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anesthetic consideration of fetal surgery

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Anaesthesia for-fetal-surgery

  1. 1. Dr pramod sarwa Dr jayanth kumar
  2. 2. History of fetal surgery  1965-first intrauterine transfusion…. A.W.Liley  1974-fetoscopy …. Hobbin  1981-fetoscopic transfusion…… Rodeck  1982-first open fetal surgery for obstructive uropathy by Dr. Michael Harrison (father of open fetal surgery), University of California, San Francisco
  3. 3. What is fetal surgery  It is application of established surgical techniques to the unborn baby -During gestation - At the time of delivery
  4. 4. Fetal surgery -prerequisites  Lesion diagnosed accurately severity is assessed correctly defined natural history  Associated anomalies are excluded  Maternal risk is acceptably low  Neonatal outcome would be better than with surgery performed after delivery
  5. 5. fetal surgery  contraindicated  Chromosomal and genetic disorders  Other associated life threatening abnormalities  Timing Usually performed between 24-29 weeks gestation  Requires combined expertise of  Obstetrician  Anaesthesiologist  Neonatologist  Pediatric surgeon
  6. 6. Indications  obstructive uropathy  Congenital diaphragmatic hernia  Cardiac anomalies- complete heart block, AS, PS  Neural tube defects  Thoracic space occupying lesions  Giant neck masses  Tracheal atresia-stenosis  Congenital adenomatoid malformation (CCAM) 1. Anatomic lesions that interfere with development: 2. Anomalies associated with twins • TTS- twin-twin transfusion syndrome • TRAP- twin reverse arterial perfusion 3. Anomalies of placenta, cord or membranes • Amniotic band • Chorioangioma
  7. 7. Types of fetal surgery  Open surgery  FETENDO-Fetal endoscopic surgery or fetoscopy or minimally access fetal surgery (MAFS)  FIGS-Fetal image guided surgery  EXIT-Ex-utero intrapartum treatment procedure
  8. 8. Open surgery  Most definitive and most invasive  Performed – middle of pregnancy  Mother anaesthetised by GA  Uterus opened similar to LSCS  Intraoperative sonography – locate the placenta  Incision taken close to the area of interest  Fetal part is exteriorized  Surgical repair of fetus done
  9. 9. Indication for open fetal surgery Defect Treatment CCAM (Congenital cystic adenomatoid malformation of lung) Lobectomy SCT (Sacro-coccygeal teratoma) Resection MMC (Meningomyelocele) Repair CDH Temporary tracheal occlusion Obstructive hydronephrosis Vesicostomy, ureterostomy
  10. 10. FETENDO-fetal endoscopic surgery or MAFS  Fetoscopic access to the fetus  During or after the 18th week of pregnancy  Useful for treating placental problems  Technically difficult  Maintains fetal position  Under LA with infiltration of both skin and peritoneum+/-sedation  Under epidural, spinal or CSE anaesthesia  High risk for urgent C-section: CSE preferred  Sedation required for maternal anxiolysis
  11. 11. Fetendo Advantages  Less invasive  Avoids maternal hysterotomy  Less risk of amniotic fluid leak  Less blood loss  Less preterm labour and uterine rupture Disadvantages  Uterus irrigated with NS – absorbed to peritoneum through fallopian tubes – pulmonary oedema as mother also receives tocolytics. This can be treated with diuretics
  12. 12. Defect Treatment E.g. CDH( Congenital diaphragmatic hernia) Balloon occlusion of trachea TTTS (Twin-twin transfusion syndrome) Laser coagulation of vessels Acardiac twins in TRAP sequence (twin reverse arterial perfusion) Cord ligation ABS-Amniotic band syndrome Division of amniotic bands BOO-Bladder outlet obstruction Vesicoamniotic shunt
  13. 13. FIGS - fetal image guided surgery  Combination of endoscopic and sonographic method  Ultrasound image guided procedure  Done under RA or LA Advantages  Least invasive  Least risk of amniotic fluid leak of preterm labour
  14. 14.  Both diagnostic and therapeutic uses Diagnostic Therapeutic -Chorion villus sampling -Amniocentesis -Cordocentesis -Fetal skin biopsy -RFA of anomalous twins -Cord cauterization in twins -Vesical/pleural shunts/catheter -Balloon dilatation of aortic stenosis
  15. 15. Ex-utero intrapartum treatment (EXIT) procedure OOPS-operation on placental support  Intervention occurring at the time of delivery  Used in cases where baby’s airway requires surgical intervention  Provide the baby with patent airway that can provide oxygen to the lungs after separation of placenta  Starts as a routine LSCS but under GA with maximum volatile agent(>2 MAC)  Head of the baby is delivered, but placenta is in situ  Baby gets oxygen from placenta via umbilical cord
  16. 16.  Surgeon removes the occlusive device  Bronchoscopy of fetal airway  Endotracheal intubation done  If unsuccessful, then tracheostomy tube below the level of airway blockage is placed  Oxygen delivery to lungs confirmed  Umbilical cord is clamped  Baby delivered
  17. 17. Defect Treatment CHAOS – Congenital high airway obstruction syndrome Tracheostomy CDH (Congenital diaphragmatic hernia) Removal of tracheal balloon Giant cervical neck masses Resection CCAM (Congenital cystic adenomatoid malformation) Resection
  18. 18. Considerations during EXIT procedure  Uterus needs to stay relaxed to permit placental perfusion  Uterus needs to contract at end to limit bleeding  Needs hemostatic hysterotomy  May permit upto 2 hours of ongoing placental perfusion
  19. 19. Challenges before the field of fetal surgery  Ethical dilemma  Maternal risk  Fetal risk  Maternal anaesthesia  Fetal anaesthesia  Post surgical tocolysis
  20. 20. Anaesthesia -basic considerations  Pre operative evaluation and preparation  Relief of anxiety  Avoidance of fetal asphyxia  Adequate analgesia  Uterine relaxation  Prevention of preterm labour  Maternal safety  Avoidance of teratogenic agents  Fetal anaesthesia and monitoring
  21. 21. Fetal assessment  Detailed USG to rule out other malformations  Fetal echocardiography  Fetal MRI  3D and 4D examination  Detail examination of affected organ system  Amniocentesis  Localisation of placenta and umbilical cord  Volume of amniotic fluid
  22. 22. Pre-operative preparation  Consent for caesarean delivery  Maternal blood cross matched  Availability of O-negative, CMV-negative, irradiated, cross matched blood against the maternal antibodies  Adequate aspiration prophylaxis  Indomethacin rectal suppository for postoperative tocolysis  Epidural catheter-postoperative pain control  Operating room temp
  23. 23. Avoidance of fetal asphyxia  Avoidance of maternal hypoxia  Avoidance of maternal hypercapnea  Quick treatment of maternal hypotension  Fluid boluses  Vasopressors  Decreasing anaesthetic concentration
  24. 24. Adequate analgesia  Local anaesthesia-0.5 ml 1% lidocaine-infiltration of both skin and peritoneum  Field block  CSE
  25. 25. Prevention and treatment of preterm labour  Tocolytic agent  indomethacin (rectal)  magnesium sulfate  terbutaline (subcutaneous)  nitroglycerine  Halogenated agents-halothane, isoflurane, sevoflurane  Vascular stasis during hysterotomy-special stapling device  Postoperative pain control-epidural catheter
  26. 26. Maternal sedation and local anaesthesia  Indicated in percutaneous needle aspirations or catheter insertions  Drug of choice-BZD(diazepam, midazolam), narcotics(fentanyl, remifentanil) for maternal anxiety  Disadvantages:  increased hypoxia  unprotected airway; aspiration risk  presence of foetal movements  Close monitoring for 3-4 hrs required
  27. 27. Regional anaesthesia  Indicated in MAFS(Minimal access fetal surgery)  Lumbar epidural, spinal or CSE anaesthesia  Advantages:  excellent analgesia and good muscle relaxation  avoids GA  keeps mother awake and alert  minimal effects on fetal hemodynamics, uteroplacental blood flow and uterine activity  Disadvantages:  Hypotension  lack of fetal anaesthesia, difficulty manipulating uterus and cord while the fetus may be moving
  28. 28. General anaesthesia  Aspiration prophylaxis-sodium citrate, ranitidine, metoclopramide  Prevention of supine hypotensive syndrome-left lateral tilt  Short acting amnestic-thiopentone  Short acting muscle relaxant-succinylcholine for RSI  Maintenance - 100% O2 with low levels of inhalational(isoflurane) or 50% O2 and 50% N2O with low inhalational + vecuronium + fentanyl  Maternal and fetal monitoring
  29. 29.  Uterus opened similar to LSCS  Fetal part is exteriorized  Special stapling device  Surgical repair of fetus done  Warmed Ringer Lactate along with antibiotics infused to replace amniotic fluid  At the time of closure, i.v. MgSO4 6 gm over 20 minutes  During extubation, coughing or straining avoided to maintain integrity of uterine closure
  30. 30. General anaesthesia • Advantages: • Profound uterine relaxation • Allowing uterine manipulation with an immobile anaesthetised fetus • Disadvantages: • Fetal cardiac depression • Decreased uteroplacental blood flow
  31. 31. Maternal monitoring  Pulse oximeter  ECG  HR  BP monitoring  Capnography  Temperature
  32. 32. Fetal monitoring  Blood gas, pH, pO2  Blood glucose  Electrolytes  Fetal Hb from cord blood  Electronic measurements of foetal heart rate, blood pressure and umbilical blood flow  Foetal heart rate cardiotachometer- FHR, temperature  Foetal ECG  Foetal echocardiography
  33. 33. Fetal anaesthetic considerations  Fetal organ systems are immature  Fetal cardiac output is sensitive to HR changes  Fetus has high vagal tone and thus response to stress with precipitous bradycardia  Fetal circulatory blood volume is low, hence little intra-operative bleeding can cause hypovolemia, so trigger for transfusion is low  During prolonged surgery, fetus need to be transfused O-negative blood
  34. 34. Fetal pain  Not possible to assess fetal pain directly  Assessed indirectly by ability of fetus to mount a stress response to noxious stimulus-increased fetal cortisol, beta-endorphins and central sparing hemodynamic changes  Fetal administration of narcotic inhibits cortisol and beta-endorphin release but does not inhibit central sparing hemodynamic changes  Fetal stress to pain starts in 8 weeks gestation age and may cause preterm labour
  35. 35. Advantages of fetal surgery  In utero environment supports rapid post-operative healing  Rapid healing, fostered by fetal growth factor  Infections are combated by passage of maternal immune factors  Umbilical circulation meets nutritional and respiratory needs without outside assistance  Medical agents given directly to fetus have greater efficacy at reduced doses
  36. 36. Postsurgical tocolysis  High risk of preterm labour  Pre-operative: rectal indomethacin  MgSO4 is tocolytic of choice and maintained for 2-3 days-3 gm/hr infusion  Adequate maternal analgesia as maternal pain can cause preterm labour and fetal distress  Epidural analgesia (PCEA) for 24-48 hrs is recommended to prevent uterine contractility
  37. 37. New researches  Remifentanil produces improved fetal immobilization with good maternal sedation and only minimal effects on maternal respiration (Anesth Analg, 2005)  Continuous fentanyl infusion with midazolam provides acceptable maternal analgesia and sedation during fetoscopy(Masui, 2008)  In fetoscopic interventions under GA, cardiopulmonary functions remain stable. However, a moderate increase in extravascular lung water(EVLW) and pulmonary vascular permeability indicates an increased risk for maternal pulmonary oedema(Br J Anaesth, 2013) Future possibilities  Stem cells or DNA to treat sickle cell anaemia or other genetic conditions  More potent tocolytics to control preterm labour  Improved techniques of fetoscopic visualisation