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ANAESTHESIA FOR FETAL SURGERY

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  1. ANAESTHESIA FOR FETAL SURGERY By: Anuradha Patel Moderator: Dr. R.S.Rautela, Dr. Rashmi University College of Medical Sciences & GTB Hospital, Delhi email: anaesthesia.co.in@gmail.com www.anaesthesia.co.in

  2. History of fetal surgery • 1965-first intrauterine transfusion for hydrops due to Rh incompatibility by A.W.Liley • 1974-fetoscopy to obtain fetal samples by Hobbin • 1981-fetoscopic transfusion by Rodeck • 1982-first open fetal surgery for obstructive uropathy by Dr. Michael Harrison (father of open fetal surgery), University of California, San Francisco

  3. What is fetal surgery • It is application of established surgical techniques to the unborn baby -During gestation - At the time of delivery

  4. Indication for fetal surgery • Indicated in defects which can be accurately identified antenatally and which cause progressive and permanent damage to the fetus if not corrected • Which when corrected will allow normal development of the fetus, improve postnatal outcome, prevent death and reduces long term morbidity • Intervention to be taken only when there is a reasonable probability of fetal benefit and minimal maternal risk

  5. Fetal surgery -prerequisites • Lesion is diagnosed accurately • Lesion’s severity is assessed correctly • Lesion should have a defined natural history and cause progressive injury to the fetus that is irreversible after delivery • Associated anomalies that contraindicate intervention are excluded • Maternal risk is acceptably low • Neonatal outcome would be better with in utero surgery than with surgery performed after delivery

  6. Contraindication for fetal surgery • Conditions incompatible with life • Chromosomal and genetic disorders • Other associated life threatening abnormalities • Usually performed between 24-29 weeks gestation • Requires combined expertise of • Obstetrician • Anaesthesiologist • Neonatologist • Pediatric surgeon

  7. Fetal malformations managed by selective abortion • Anencephaly, porencephaly, encephalocele, giant hydrocephalus • Chromosomal anomalies-trisomy 13, trisomy 18 • Renal agenesis or bilateral polycystic kidney disease • Inherited nontreatable metabolic and hematologic abnormalities-Tay Sachs disease • Lethal bone dysplasias-recessive osteogenesis imperfecta

  8. Indications For Fetal Surgery • Bilateral obstructive hydronephrosis or lower urinary tract obstruction • Obstructive hydrocephalus • Congenital diaphragmatic hernia(CDH) • Cardiac anomalies-complete heart block, AS, PS • Neural tube defects –spina bifida, sacrococcygeal teratoma, myelomeningocele • Skeletal defects • Gastroschisis • Thoracic space occupying lesions • Giant neck masses • Tracheal atresia-stenosis • Congenital cystic pulmonary adenomatoid malformation(CCAM) • Craniosynostosis • Cleft lip and palate • Hydrothorax 1. Anatomic lesions that interfere with development:

  9. 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

  10. Deficiencies and malfunctions requiring medical treatment in utero • Deficient pulmonary surfactant • Anemia due to erythroblastosisfetalis and hydrops • Endocrine deficiency-hypothyroidism, goiter, adrenal hyperplasia • Metabolic block-B12 dependent methylmalonicacidemia, biotin dependent multiple carboxylase deficiency • Nutritional deficiency-IUGR • Cardiac arrhythmias • Inherited defects potentially curable by stem cell transplantation

  11. Types of fetal surgery • Open surgery-the most definitive • FETENDO-Fetal endoscopic surgery or fetoscopy or minimally access fetal surgery (MAFS) • FIGS-Fetal image guided surgery • EXIT-Ex-utero intrapartum treatment procedure

  12. 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

  13. 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

  14. 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

  15. 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

  16. TTTS

  17. 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 • Least risk of preterm labour

  18. Both diagnostic and therapeutic uses

  19. Ex-utero intrapartum treatment (EXIT) procedure • Also known as 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

  20. 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

  21. 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

  22. Challenges before the field of fetal surgery • Ethical dilemma • Maternal risk • Fetal risk • Maternal anaesthesia • Fetal anaesthesia • Post surgical tocolysis

  23. Challenges before the field of fetal surgery • Ethical dilemma • Maternal risk • Fetal risk • Maternal anaesthesia • Fetal anaesthesia • Post surgical tocolysis

  24. Ethical considerations and dilemma • Not all procedures are performed regularly • The results are not guaranteed • Risk to both mother and fetus • Surgical animal models do not always replicate in human beings • Use of neuromuscular relaxants to immobilize the fetus • Psychological and neuro developmental consequences of fetal surgery • Fetus is sacrificed to improve the outcome of in utero sibling • Ethical dilemma-should a procedure which is not guaranteed to produce results be performed on the insistence of mother

  25. Challenges before the field of fetal surgery • Ethical dilemma • Maternal risk • Fetal risk • Maternal anaesthesia • Fetal anaesthesia • Post surgical tocolysis

  26. Maternal risks • Tocolytic therapy can cause pulmonary oedema (MgSO4) • Increased uterine activity • Uterine rupture • Subsequent delivery by LSCS • Blood loss • Maternal aspiration • Maternal hypotension • Maternal hypocarbia or hyperventilation • Amniotic fluid leak

  27. Wound infection • Intrauterine infection • Mixing of blood of mother and fetus • Chorioamnionic membrane separation • Deep anaesthesia - fetal and myocardial depression and can affect placental perfusion • Operative risk of GA and a midgestation hysterotomy • Risk of compromising future reproductive potentials

  28. Challenges before the field of fetal surgery • Ethical dilemma • Maternal risk • Fetal risk • Maternal anaesthesia • Fetal anaesthesia • Post surgical tocolysis

  29. Fetal risks • Prematurity • Preterm labour • PROM • Decreased uterine blood flow • Fetal asphyxia • Teratogenecity of anaesthetic drugs • Post-operative abortion-12%

  30. Partial placental separation-compromised foetus • Intrauterine infection • Fetal vascular embolic events-intestinal atresia, renal agenesis • Premature closure of ductus arteriosus • CNS injuries due to maternal hypoxia or fetal circulatory disturbance • Death or long term morbidity • Failure or lack of improvement

  31. Challenges before the field of fetal surgery • Ethical dilemma • Maternal risk • Fetal risk • Maternal anaesthesia • Fetal anaesthesia • Post surgical tocolysis

  32. Anaesthesia for fetal surgery-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

  33. Pre-operative evaluation • Counselling of families: • Potential fetal benefit • Maternal risks • Standard alternatives • Assessment of mother for fitness for anaesthesia • h/o uterine activity • airway examination • concurrent medical problems

  34. Assessment of fetus: • 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

  35. 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-sodium citrate orally and metoclopramidei.v. • Indomethacin rectal suppository for postoperative tocolysis • Epidural catheter-postoperative pain control • Operating room is warmed to 80°F

  36. Relief of anxiety • Providing complete information about the procedure • Allowing husband or relative during minor procedures • Mild sedation with BZD or barbiturates • Reduction of environmental stimuli-noise, pressure, pain, cold

  37. Avoidance of fetal asphyxia • Avoidance of maternal hypoxia • Avoidance of maternal hypercapnea • Quick treatment of maternal hypotension • Fluid boluses • Vasopressors • Decreasing anaesthetic concentration

  38. Adequate analgesia • Local anaesthesia-0.5 ml 1% lidocaine-infiltration of both skin and peritoneum • Field block • CSE

  39. Prevention and treatment of preterm labour • Tocolytic agents • beta adrenergic agonists • indomethacin (rectal) • magnesium sulfate • terbutaline (subcutaneous) • nitroglycerine • Halogenated agents-halothane, isoflurane, sevoflurane • Vascular stasis during hysterotomy-special stapling device • Postoperative pain control-epidural catheter

  40. Anaesthetic techniques • Maternal sedation and local anaesthesia • Local anaesthesia with foetal paralysis • Regional anaesthesia • General anaesthesia

  41. 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

  42. Local anaesthesia with fetal paralysis • Indicated in fetal umbilical vein blood sampling • For fetal paralysis, NDMR given via umbilical vein or intramuscularly into fetal thigh or shoulder • Advantages • Loss of fetal movements for 2-4 hrs without any danger of maternal NMB • Disadvantages • If fetus requires an emergency delivery, NMB will produce paralysed fetus and will require respiratory assistance

  43. 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

  44. Disadvantages: • Hypotension • lack of fetal anaesthesia, difficulty manipulating uterus and cord while the fetus may be moving

  45. 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

  46. 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

  47. General anaesthesia • Advantages: • Profound uterine relaxation • Allowing uterine manipulation with an immobile anaesthetised fetus • Disadvantages: • Fetal cardiac depression • Decreased uteroplacental blood flow

  48. Maternal monitoring • Pulse oximeter • ECG • HR • BP monitoring • Capnography • Temperature