ANAESTHESIA FOR INTRAUTERINE FETAL SURGERY PRESENTED BY- Dr. Anupam MODERATOR- Dr. Yashwant
Fetal surgery is ……….. • Indicated in conditions which interfere with the normal development of the fetus in-utero but • Which when corrected will allow the development of the fetus normally. • It is contraindicated in • conditions that are incompatible with life • medical condition in the mother precluding surgery.
3 types of fetal surgery :- • EXIT (Ex-UteroIntrapartum Treatment Procedure) • Mid gestation Open Surgery • Minimally invasive mid gestation procedures • FETENDO (Fetal Endoscopic Surgery) • FIGS (Fetal Image Guided Surgery)
EXIT ( Ex-uterointrapartum treatment ) :- • Also know as OOPS. • It is the intervention that occurs at the time of delivery • It is primarily used in cases where baby’s airway requires surgical intervention • It starts as a routine LSCS but under GA • Head of the baby is delivered, but the placenta is in situ • The baby gets oxygen from placenta via umbilical cord
Bronchoscopy of the fetal airway • Endotracheal intubation attempted • If unsuccessful then tracheostomy is done • O2 delivery to lungs confirmed • Cord is cut & Baby is delivered
Indications:- • Giant cervical neck mass. • CHAOS (Congenital High Airway Obstruction Syndrome- tracheal atresia) • Removal of balloon after CDH • CCAM (Congenital Cystic Adenomatoid Malformation)
Mid gestational open fetal surgery:- • Surgery performed between 18-26 weeks through hysterotomy. • Fetus exteriorized for surgery then placed back in uterus to mature. Indications :- • CCAM(Congenital Cystic Adenomatoid Malformation of Lung)- Lobectomy • SCT (Sacro-coccygealTeratoma)- Resection • MMC(MeningoMyelocoele)- Repair
FIGS (Fetal Image Guided Surgery) :- • Ultrasound image guided procedure • Least invasive • Least risk of amniotic fluid leak • Least risk of PT labour
Indications :- • Diagnostic :- • ChorionVillus Sampling • Amniocentesis • Cordocentesis • Fetal skin Biopsy • Therapeutic :- • RFA (Radio Frequency Ablation) of anomalous Twins • Cord cauterization in Twins • Vesical / Pleural Shunts • Balloon Dilatation of Aortic Stenosis
FETENDO (Fetal Endoscopic Surgery) :- • Fetoscopic access to the Fetus • The fetal visualisation is a combination of endoscopic and sonographic on two different screens • Less invasive • Less risk of amniotic fluid leak • Less risk of PT labour
Indications :- • CDH (Congenital Diaphragmatic Hernia)-Balloon Occlusion of trachea • TTTS (Twin to Twin Transfusion Syndrome)- Laser coagulation of vessels • Cord ligation in cases of acardiac Twins • Amniotic bands division
ANAESTHETIC CHALLENGES • Those related to any anaesthetic technique in a pregnant female • Techniques used to prevent preterm labour • Maintenance of maternal hemostasis in face of tocolytic techniques • Maintenance of fetal hemostasis • Provision of fetal analgesia.
Anaesthetic considerations :- • Maternal • Fetal • Uteroplacental • Preoperative assessment • Type of anaesthesia • Intraoperative management • Post operative care • complications
Maternal anesthetic considerations:- • Risk of aspiration pneumonitis • Risk of pulmonary edema • Risk of hypoxia • Risk of supine hypotension syndrome • Risk of massive hemorrhage • Myocardial depression, hypotension
Fetal anaesthetic considerations: • Fetal Cardiac Output is sensitive to heart rate changes • Fetus has high vagal tone & low barorecepter sensitivity ,hence responds to stress with precipitous bradycardia. • Fetal circulating volume is low( 110ml/kg), hence little intra-operative bleeding can cause hypovolemia. • Inhalational agents depressess fetal circulation as well-direct myocardial depression, vasodilatation, changes in arterio-venous shunting.
Fetus tends to lose heat much easily from the exposed skin resulting in hypothermia • Immature coagulation system predispose the fetus to bleeding and difficulty in achieving hemostasis. • Maternal anesthesia reduces placental blood flow, this reduces the amount of O2 delivered to the fetus( hypoxia) • Normal Fetal oxygen saturation is 60-70% and the aim is to maintain it above 40% • Intra-operative fetal distress is manifested by bradycardia, decreased fetal oxygen saturation and reduced stroke output.
Uteroplacental considerations:- • Maternal hyperventilation is avoided as maternal hypocapnia causes fetal placental vasoconstriction and fetal hypoxia. • Maternal BP & myometrial tone correlates with uterine artery blood flow. • Maintenance of patent UA & maintenence of maternal BP with in 10% of baseline is critical.
Pre-operative assessment:- • Assessment of the mother for fitness for anaesthesia • Assessment of the fetus • Detailed USG to r/o other malformations • 3D and 4D examination-Detailed examination of affected organ system • Detailed Fetal Echocardiography, Amniocentesis, Localization of placenta • Fetal MRI • Maternal blood cross matched- arrange blood for mother and fetus.
Anaesthesia for open fetal surgery:- • Pre-operative preparation- • OT warmed • Blood arranged • Monitors and syringes • Prophylaxis for Aspiration • Lumber epidural inserted & tested • Indomethacin suppository administered • Positioning done
The fetus is monitored with • Fetal Echocardiography • Pulse Oximetry • PO2 from Cord Blood • Fetal Hb from Cord Blood
TYPES OF MATERNAL ANAESTHESIA :- • Regional Anaesthesia-Lumbar Epidural • Deep GA-(Sodium Pentothal + Scoline) + (Isoflurane + Fentanyl+O2 + Vecuronium) • GA with N2O- (Sodium Pentothal + Scoline) + (Isoflurane + N2O + Vecuronium)
Intraoperative management:- • Rapid sequence induction with thiopentone & Sch. • Maintenence – Nitrous plus oxygen plus 0.5 MAC (isoflurane, desflurane) • Invasive arterial line, secure 2nd venous catheter, NG tube & Foley's catheter insertion. • Fetal status monitored by sterile intraop echocardiography.
Restrict fluids in mother ( post op PE ) • Before hysterotomy, nitrous turned off & deepen the patient by increasing inhalational agents to 2 MAC • Maintain maternal BP – ephedrine/PE • Fetus is given I/M opioids b4 incision. • Fetal monitoring with Miniature pulse oximeter & echocardiography done. • Blood gas samples help guide therapy during period of fetal distress. • Following closure of uterus, anaesthesia converted to regional based technique.( LA,opioids through epidural catheter)
Tocolysis instituted via MgSo4 loading dose followed by infusion. • Patient extubated and shifted to recovery. Post-op management:- • Tocolysis for at least 18-24 hours. • Adequate maternal pain relief with epidural.
Anaesthesia for EXIT :- • No tocolysis • One additional OT for possible fetal sugery • Desflurane inhalational agent of choice. • During hysterotomy, only partial exposure of fetus done. • DL / intubation done by surgeon or anaesthesiologist. • If baby cant be intubated , tracheostomy done. • After assuring adequate fetal oxygenation cord clamped & fetus delivered.
The timing of cord clamping with respect to administration of oxytocin, methergin and carboprost as well as decreasing volatile agents must be coordinated between anaesthesiologist and surgeon . • Blood loss is monitored and cross matched blood is administered if needed. • If surgery is not required immediately, a neonatology team resuscitates and transports the neonate to NICU.
Fetoscopic surgery:- • Epidural anaesthesia:- less effect on fetal hemodynamics & UP circulation & post op uterine activity but lack of uterine relaxation, lack of fetal anesthesia hence, difficulty manipulating the uterus & cord while baby is still moving. • Balanced inhalation-opioid anaesthesia:- it eliminates anxiety, nausea, emesis and allows immobile anaestheized fetus, less CV effects than deep inhalational, but provides no uterine relaxation.
Deep inhalational anaesthesia:- provides profound uterine relaxation but affect fetal hemodynamics & UPBF
Maternal complications: - • Tocolytic therapy can cause pulmonary edema • Subsequent delivery by LSCS • Massive hemorrhage • Amniotic fluid leak • Wound infection • Intra uterine infection • “Maternal Mirror Syndrome” in cases of fetal Hydrops ( mother mirrors the symptoms that fetus is experiencing) • Chorio-amniotic membrane separation
Fetal complications:- • Prematurity • Intra Uterine Infection • Fetal vascular embolic events • Intestinal atresia • Renal agenesis • Premature closure of DuctusArteriosus • CNS injuries due to maternal hypoxia or fetal circulatory disturbance • Bleeding