anaesthetic management during foetal surgery


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1 : Anaesthesia for foetal surgery Speaker : Dr.Avinash.K Moderator : Dr.S.Manimala Rao
2 : Prenatal diagnosis improves perinatal care. Severe lesions detected early enough may lead to termination of pregnancy. Most correctable defects are best managed by maternal transport to an appropriate center and delivery near term. Some may benefit from change in the timing or mode of delivery.
3 : Serial study of affected fetuses may help unravel the developmental pathophysiology of some surgically correctable lesions and thus lead to improved treatment before or after birth.
4 :
5 : Diagnosis Ultrasonography/ MRI Alpha-Fetoprotein neural tube defects , omphalocele, gastroschisis and sacrococcygeal teratoma. Fetal Sampling : karyotyping and DNA- based diagnosis, for genetic defects and inherited metabolic abnormalities
6 : Fetal Sampling Chorionic villus sampling- first trimester Amniocentesis – second trimester PUBS percutaneous umbilical cord sampling ( rapid karyotyping 2 days versus 7 days for amniocentesis) Fetoscopy / ultrasound fetal skin or liver biopsies Risk of fetal loss from fetal sampling 1-5%.
7 : Future of diagnosis & Rx of Foetus
8 : Prenatal diagnosis and management DEFECTS USUALLY MANAGED BY ELECTIVE ABORTION DEFECTS DETECTED IN UTERO BUT BEST CORRECTED AFTER TERM DELIVERY DEFECTS THAT MAY LEAD TO CAESAREAN DELIVERY DEFECTS THAT MAY LEAD TO INDUCED PRETERM DELIVERY Defects that may benefit from Fetal intervention and Fetal surgery
9 : DEFECTS USUALLY MANAGED BY ELECTIVE ABORTION Anencephaly, holoprosencephaly Severe chromosomal anomalies (trisomy 13) Bilateral renal agenesis, infantile polycystic kidney Severe untreatable inherited metabolic disorders (Tay-sachs disease) Lethal bone dysplasias (recessive osteogenesis imperfecta)
10 : DEFECTS DETECTED IN UTERO BUT BEST CORRECTED AFTER TERM DELIVERY Oesophageal , duodenal, and Intestinal atresia Meconium ileus Enteric and Duplication cysts Small intact omphalocele, meningocele Unilateral, hydronephrosis, multicystic kidney Small sacrococcygeal teratoma, cystic hygroma, Benign cysts (ovarian, mesenteric, choledochal) Craniofacial, limb, and chest wall deformities
11 : DEFECTS THAT MAY LEAD TO CAESAREAN DELIVERY Conjoined twins Giant omphalocele, ruptured omphalocele. Gastroschisis Severe hydrocephalus, large or ruptured meningomyelocele Large sacrococcygeal teratoma or cervical cystic hygroma
12 : DEFECTS THAT MAY LEAD TO INDUCED PRETERM DELIVERY Obstructive hydronephrosis Obstructive hydrocephalus Gastroschisis or ruptured omphalocele Intestinal volvulus with ischemia Immune hydrops fetalis Intrauterine growth retardation Arrhythmias (supraventicular tachycardia with failure)
13 : Malformations that may benefit from treatment before birth Potentially lethal defects those that interfere with fetal organ development and that if alleviated, would allow normal development to proceed. Nonlethal defects; myelmeningocele, cleft lip and palate Metabolic and cellular defects ; stem cell, enzyme defects, predictable organ failure.
14 : Potentially lethal defects Urinary tract obstruction (urethral valves) Cystic adenomatoid malformation Diaphragmatic hernia Sacrococcygeal teratoma Twin-twin transfusion syndrome Aqueductal stenosis Complete heart block Pulmonary/ aortic obstruction Tracheal atresia /stenosis
15 : NON-LETHAL DEFECTS Myelomeningocele Spinal cord damage- paralysis, neurogenic bladder Cleft lip and palate Facial defect-persistent deformity
16 : METABOLIC AND CELLULAR DEFECTS Stem cell or enzyme defects Hemoglobinopathy- anemia Immunodeficiency- infection Storage disease – retardation Organ failure Hypoplastic heart/ lung/ kidney
17 : Foetal surgery requires analgesia,sedation & paralysis of both The mother & The foetus Hence need for understanding physiology of both foetus & mother
18 : Maternal physiologic changes & anaesthetic risks
19 : Foetal physiology & anaesthetic risks
20 : Foetal monitoring
21 : Foetal SPO2 < 30% suggests hypoxia and predicts imminent bradycardia and collapse. Foetal ABG ccan be sampled from umbilical artery. Foetal Hb monitored as needed by use of microcuvette with drop of blood from head or palm.
22 : Avoidance of foetal asphyxia Maternal hypoxia to be avoided ( hyperoxia not a problem) . CO2 readily crosses membranes , hence foetal Pco2 reflects maternal Pco2. Maternal hypoventilation will lead to foetal hypercarbia and respiratory acidosis.
23 :
24 :
25 : Uterine vasculature fully dilated during pregnancy- recieves 10% of CO. 70-90% of it goes to placenta. Therefore uterine perfusion ~ perfusion pressure ( maternal BP )
26 : Any intervention causing maternal hypotension to be promptly corrected by Fluid administration ? Anaesthetic conc (done carefully because may cause uterine contractions ) Vasoactive agents- eg Ephedrine Foetal surgery pts have tendency for pulmonary edema – because of tocolytics – so restrict fluid.
27 : Analgesia for minor surgical interventions Local anaesthesia with lignocaine 1% infilteration for minor procedures like Percutaneous placement of large bore needles Diagnostic needle insertion Therapeutic needle insertion Systemic analgesia not required.
28 : Risk of preterm labour Preterm labour has been described as the ‘Achilles heel’ of fetal surgery. Invasive foetal interventions may increase uterine stimulation inducing uterine contractions. Intra-op or post-op contractions is a function of degree of invasiveness and gestational age. >27 wks uterus more irritable- aggressive tocolysis < 20 wks uterine contractility is less a problem
29 : Prevention & treatment of premature labour Tocolytic agents : ß- adrenergic agonists Rectal indomethacin Prostaglandin synthetase inhibitors High conc of halogenated agents-halo,iso,sevo When uterine closure is initiated a loading dose of MgSo4 - 4 gm over 20 min with continous infusion 2 gm/hr. When immediate tocolysis is required bolus dose of NTG 50-200 ug can be given when uterus refilled with saline to replace lost amniotic fluid Post-op pain relief – Epidural – prevent preterm
30 : Anaesthetic techniques Maternal sedation & local anaesthesia Local anaesthesia & foetal paralysis Regional anaesthesia General anaesthesia
31 : Maternal sedation & local anaesthesia This for percutaneous needle aspirations or catheter placements Choice of drugs for maternal sedation Benzodiazepines-diazepam,midazolam Narcotics – morphine,fentanyl Major disadvantages- ? chances of hypoxia Aspiration of gastric contents Presence of foetal movements Mothers to be monitored closely for 3-4 hrs for ventilation,respiration,hemodynamics
32 : Local anaesthesia & foetal paralysis This technique specifically indicated in procedures like foetal umbilical vein blood sampling. Advantages Minimal parental analgesia provides adequate pain relief Neuromuscular blockers do not cross placenta so no maternal paralysis Disadvantages No foetal analgesia or anaesthesia May lead to emergency delivery – if done so foetus will be paralysed and hence needs repiratory assistance
33 : Regional anaesthesia It is an acceptable technique Only disadvantage maternal hypotension
34 : General anaesthesia Lighter level of anaesthesia with 1 MAC with brief exposure to deep plane 2 MAC is advocated Rather than continuous deep plane of anaesthesia Aggressive monitoring required
35 : Videoendoscopic Fetal Surgery FETENDO Obviate need for uterine incision Obstacles Fix amniotic membranes Perfuse amniotic cavity with fluid rather than gas Position and stabilize the fetus It is called FETENDO because the movements are like the children’s video game NINTENDO
36 : EXIT (Ex-utero Intrapartum treatment procedure) It is the intervention that occurs at the time of delivery It is primarily used in cases where baby’s airway requires surgical intervention Provide the baby with patent airway that can provide O2 to the lungs after separation of placenta
37 : Examples CHAOS (Congenital High Airway Obstruction Syndrome) Removal of balloon after CDH Pulmonary Sequestration CCAM (Congenital Cystic Adenomatoid Malformation)
38 : 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
39 :
40 : Bronchoscopy of the fetal airway Endotracheal intubation attempted If unsuccessful then tracheostomy is done O2 delivery to lungs confirmed
41 : Cord is cut Baby is delivered
42 : thank you

 

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