Ø Anaesthesia for Fetoscopy
Ø By: Dr. Nesrine El-Refai
Ø Professor of Anesthesia
Ø Cairo University
Ø Objectives
Ø Introduction.
Ø Techniques of fetal intervention.
Ø General idea about Fetoscopy.
Ø Anesthetic considerations.
Ø Future of fetoscopy.
Ø Anesthetic complications.
Ø Kasr-Aini experience.
Ø Introduction
Ø Anesthesia for fetal surgery involves coordination between the surgical and anesthetic teams.
Ø It is important to understand the maternal, fetal and placental issues to tailor the anesthetic to the surgical plan.
Ø Anesthetic risks for the parturient during nonobstetric surgery include fetal asphyxia , fetal and maternal cardiovascular depression from anesthetics and uterocaval compression, and potential teratogenicity of anesthetic drugs and preterm labor/delivery .
Ø However, fetal surgery also involves repair of the fetal or placental anomaly, and the fetus is usually critically ill, such that survival without the surgery is unlikely.
Ø Factors influencing anesthetic management for fetoscopic surgery include fetal cardiovascular status, history of uterine activity, and location of the placenta relative to the amniotic membranes and umbilical cord.
Ø Cordocentesis and IUT - History
Ø 1963 - First intraperitoneal transfusion (Liley)
Ø 1974 - Fetoscopy to obtain fetal samples (Hobbins, et al)
Ø 1981 - Fetoscopic transfusion (Rodeck, et al)
Ø 1982 - First ultrasound guided IUT (Bang, Bock & Troll)
Ø 1983 - First large study of IUT - 66 cases (Daffos, et al)
Ø
What are the techniques of fetal intervention
Ø Open Fetal Surgery: The most definitive and most invasive.
Ø Fetal endoscopic (Fetendo) Fetal Surgery-Fetoscopy or minimally invasive fetal surgery.
Ø Fetal Image-Guided Surgery (FIGS-IT).
Ø EXIT procedure(Ex Utero Intrapartum Therapy).
Ø
Ø Open Fetal Surgery
Ø It’s performed during the middle of pregnancy.
Ø The mother is anesthetized by GA, the surgical repair of the fetus is completed, the uterus followed by the maternal abdominal wall are closed.
Ø
Fetendo Fetal Surgery(Fetoscopy)
Fetendo Fetal Surgery(Fetoscopy)
Ø “Fetendo” is the fetoscopic intervention that was developed in the 1990s.
Ø The best method of visualizing the fetus in real-time is to use both endoscopic & sonographic techniques. .
Ø Fetendo is technically difficult and required new techniques to allow us to see through the amniotic fluid, maintain the fetal position, and do delicate work within the fetus.
Ø It is particularly useful for treating problems with the placenta, like twin-twin transfusion syndrome.
FIGS-IT
FIGS-IT is a term used for fetal image-guided surgery for intervention .
FIGS-IT is a term used for fetal image-guided surgery for intervention .
Ø It can often be done under a regional anesthesia or even under local anesthesia.
Ø This is the least invasive of the fetal access techniques .
Ø Image-guided intervention can be used for a variety of fetal manipulations including placement of catheter-shunts in the bladder, abdomen &some cardiac manipulation.
It is easiest to think of fetal intervention in terms of invasiveness—open surgery being most invasive; FIGS-IT, least invasive; and Fetendo, in between.
EXIT Procedure
Ø The EXIT : Extra-Uterine Intra-partum.
Ø It is primarily used in cases where the baby's airway requires surgical assistance like CDH Tracheal Occlusion Surgery
Ø The goal with the EXIT is to provide the baby with a functioning airway so that oxygen can be delivered to the lungs after the baby is separated from placenta.
Ø It should be performed with a team consisting of a pediatric surgeon, obstetrician, anesthesiologist, and neonatologist.
Ø The start of the procedure is conducted like a Cesarean section under GA in order to ensure that the uterus is completely relaxed.
Ø The head of baby is delivered and the pediatric surgeon uses a bronchoscope through the baby’s mouth & the surgeon attempt to pass an endotracheal tube .
Ø If this is successful, the infant is delivered and the umbilical cord cut.
Ø If a tube cannot be passed from the mouth through the obstruction, the pediatric surgeon will need to place a tracheostomy tube below the level of airway blockage.
Ø Once the tube is placed& functioning , the infant is delivery.
Ø The head of baby is delivered and the pediatric surgeon uses a bronchoscope through the baby’s mouth & the surgeon attempt to pass an endotracheal tube .
Ø If this is successful, the infant is delivered and the umbilical cord cut.
Ø If a tube cannot be passed from the mouth through the obstruction, the pediatric surgeon will need to place a tracheostomy tube below the level of airway blockage.
Ø Once the tube is placed& functioning , the infant is delivery.
Ø
What is fetoscopy?
Ø Fetoscopy is “Minimally Invasive Fetal Surgery”
Ø The procedure is done during or after the 18th week of pregnancy.
Ø In this technique, a fine-caliber endoscope is inserted into the amniotic cavity , under ultrasound guidance, the fetal surgeon can operate on the baby, the umbilical cord or the placenta.
Ø Fetoscopy is associated with a 3-5% risk of miscarriage.
(www.acog.com)
What are the risks?
Ø There is a 12% chance of having a miscarriage, especially if a surgical procedure is done.
Ø There can be infections, excessive bleeding, or leakage of the amniotic fluid.
Ø If there is preterm rupture of the membranes (PROM) then the fetus must be delivered early.
Ø There is a chance of mixing the blood of the mother and fetus.
Ø
Minimally Invasive Fetoscopic Surgery
Minimally Invasive Fetoscopic Surgery
(Fetal Care Center of Cincinnati,2010 )
Ø
Twin-Twin Transfusion syndrome
Ø Occurs in monochorionic twins
Ø Vascular communication in placenta results in imbalance of blood flow.
Ø The vascular connection between twins within the placenta leads to blood flow imbalance between the twins, with(the recipient)having a relative high perfusion of blood and the other,(the donor), being under perfused with blood.
Ø Donor fetus hypoperfused& Recipient twin hyperperfused.
(NHS- 2009)
Ø In TRAP sequence, the indication for umbilical cord coagulation is cardiovascular failure in the pump twin.
Ø In severe TTTS, the indication for umbilical cord coagulation is heart failure in the recipient twin.
Anesthetic Considerations
1) Maternal safety.
2) Avoidance of teratogenic agents.
3) Avoidance of fetal asphyxia.
4) Fetal anesthesia and monitoring.
5) Uterine relaxation.
6) Prevention of preterm labor.
Anaesthetic goals of fetal surgery
Ø Maternal anaesthetic considerations:
1. Precautions should be taken to prevent hypoxaemia and aspiration.
2. Decreases in capillary oncotic pressure and increases in capillary permeability increase the risk of pulmonary edema specially when magnesium sulphate is used for tocolysis.
3. Left uterine displacement to prevent aortocaval compression .
Ø Fetal anaesthetic considerations
Ø It was demonstrated that the human fetal stress response was attenuated by the administration of a narcotic.
Ø Fetal stress to exaggerated pain responses starts in eight week-old infants and may cause pre-term labor.
Ø There is need for fetal anaesthesia in contrast to caesarean section
Ø . Placental transfer of of anaesthetic agents to the fetus is a desirable effect of maternal anaesthesia.
Ø The fetus requires less muscle relaxant and anaesthetic agent.
Ø Although inhaled anaesthetics, rapidly cross the placenta, fetal levels remain below maternal levels for a prolonged period of time.
Ø Anaesthetic-induced decreases in contractility combined with fetal surgical manipulations can result in hypotension, bradycardia, and eventual cardiac collapse.
Ø Because of low circulating blood volume,surgical blood loss is poorly tolerated so trigger for transfusion is low
Ø Hypothermia can be minimized by limiting fetal surgical time and use of warm irrigating fluids.
Ø Maintenance of uteroplacental circulation is vital for successful outcome of the procedure.
Ø Fetal oxygenation is dependent on both blood oxygenation and placental blood flow.
Ø Since uteroplacental flow is influenced by vascular resistance therefore uterus must remain relaxed.
Ø Kinking of umbilical cord must be avoided and corrected if this has occurred during changing position of the fetus.
Ø Increase of maternal pH and hypocapnia result in reduced umbilical blood flow and fetal hypoxia.
(Indian J Anaesth. 2009)
Preoperative preparation
Ø Preanaesthetic checkup to evaluate the mother including airway evaluation and concurrent medical problems.
Ø The placental location and fetal cardiovascular function are evaluated by ultrasonography, ECHO&MRI.
Ø The operating room is warmed to 80°F and type specific packed red cells for the mother and O-negative packed red cells for the fetus are made available.
Ø
Ø Monitoring
Ø Maternal Monitors:
Ø Two pulse oximeters,.
Ø An arterial pressure transducer
Ø Cardiac monitor for the mother
Ø Sodium bicitrate is given orally and metoclopramide given intravenously as prophylaxis for aspiration.
Ø An indomethacin suppository is administered for postoperative tocolysis .
Fetal monitoring
Ø If the fetal extremity is accessible, a pulse oximeter probe is placed on the limb .
Ø Normal fetal arterial saturation is 60–70% and values above 40% during surgery represent adequate saturation.
Ø Echocardiography is used to monitor fetal heart rate and stroke volume.
Ø Fetal arterial or venous blood gas samples may be obtained by the surgeons through umbilical or central vessel puncture.
Ø Warmed, fresh O-negative blood can be administered to the fetus to correct anaemia.
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Ø
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Ø Monitoring the Fetus During Fetoscopic Surgery
Ø Fetoscopic Placental Vessel Catheterization
. A “fetal IV” and/or arterial line would allow fetal blood sampling, pressure monitoring, administration of blood products, intravenous fluids and pharmacologic agents.
Ø Fetoscopic Surgery Monitoring
Ø A variety of monitoring parameters during human fetoscopic surgery have been used:
Ø Periodic sonography monitors heart rate and contractility.
Ø Direct uterine palpation is required to assess the degree of uterine distention and intrauterine fluid balance is adjusted accordingly.
Ø The irrigating solution is warmed and maintained at 37oC -38oC.
Anesthesia For Minimally Invasive Surgery
Ø In fetoscopy, normal saline irrigation is used inside the uterus.
Ø It can be performed under local anaesthesia with infiltration of both skin and peritoneum.
Ø Intravenous sedation should be given for maternal anxiolysis .
Ø Midazolam, fentanyl, remifentanil or propofol infusion may be used but deep sedation should be avoided to prevent aspiration.
Ø The uterus is irrigated with normal saline in this procedure and this can be absorbed to peritonium through the fallopian tubes.
Ø This can lead to pulmonary edema as the patient is also receiving tocolytics. This can be treated with diuretics .
Ø Most fetoscopy procedures involve manipulation of placenta and umbilical cord and there is no fetal incision therefore fetal anesthesia is not required.
Ø Epidural anesthesia has the advantage of minimal effects on fetal hemodynamic,on uteroplacental blood flow &postoperative uterine activity.
The disadvantages include lack of uterine relaxation, lack of fetal anesthesia, and difficulty manipulating the uterus and cord while the fetus may be moving.
A balanced inhaled-opioid anesthetic has the advantage of allowing uterine manipulation with an immobile-anesthetized fetus &less fetal cardiovascular depression than deep inhaled anesthesia.
The potential disadvantage of this technique is an inability to fully relax the uterus to access difficult cord positions.
Deep inhaled anesthesia has the advantage of profound uterine relaxation.
Ø Disadvantages:fetal cardiac depression and decreased
uteroplacental blood flow. (Anesth Analg 2000)
Ø Comparison of different anesthetic Techniques (Epidural anesthesia)
Ø Advantages:
q Minimal effects on:
1. fetal hemodynamic
2. uteroplacental blood flow .
3. postoperative uterine activity.
Ø Disadvantages:
q lack of :
1. uterine relaxation
2. fetal anesthesia,
3. difficulty manipulating the uterus and cord while the fetus may be moving.
Ø Comparison of different anesthetic Techniques (Deep inhaled anesthesia )
Ø Advantages:
profound uterine relaxation.
Ø Disadvantages:
fetal cardiac depression decreased uteroplacental blood flow.
Ø Comparison of different anesthetic Techniques (A balanced inhaled-opioid anesthetic )
Ø Advantages:
1. allowing uterine manipulation with an immobile-anesthetized fetus .
2. less fetal cardiovascular depression than deep inhaled anesthesia
Ø Disadvantages:
q inability to fully relax the uterus to access difficult cord positions.
Ø
Ø Some new researches
Ø Remifentanil produces improved fetal immobilization with good maternal sedation and only minimal effects on maternal respiration. (Anesth Analg 2005).
Ø In mid-gestational women undergoing fetoscopic interventions under GA, cardiopulmonary function remained stable. However a moderate increase in extra vascular lung water EVLW and pulmonary vascular permeability indicates an increased risk for maternal pulmonary oedema.(Br J Anaesth 2009).
Ø Continuous fentanyl infusion with midazolam provided acceptable maternal analgesia and sedation during fetoscopy. (Masui. 2008).
Ø
Working Medium/Irrigation System
Working Medium/Irrigation System
Ø A specially designed fetoscopic irrigation system is used to deliver high flows at constant physiologic temperatures (37˚ C).
Ø Despite high volumes of fluid perfused into the uterus (up to 40 L/per operation), less than 3% was systematically absorbed and maternal hypervolemia or altered maternal electrolytes was not noted.
Working Medium/Irrigation System
A specially designed fetoscopic irrigation system is used to deliver high flows at constant physiologic temperatures (37˚ C).
Despite high volumes of fluid perfused into the uterus (up to 40 L/per operation), less than 3% was systematically absorbed and maternal hypervolemia or altered maternal electrolytes was not noted.
Important Anesthetic Complication
Maternal Pulmonary Edema During Fetoscopic Surgery (Anesth Analg 2008):
q Patient received combined spinal-epidural anesthesia .
q pulmonary edema resulted from irrigating fluid (totaling net 8 L) absorbed IV, through myometrial venous channels accessed by passage of the operating trocars.
q We have not proceeded with surgery after achieving a 2 liter discrepancy since our index case; no further episodes of pulmonary edema have been encountered.
Kasr Aini Experience
The fetoscopy team performed 11cases, one diagnostic & 10 laser.
Success rate was 50%. (International results are 60%).
One case TRAP & others were Twin-Twin Transfusio Syndrome.
All patients received epidural except for one who had GA.
References
Anesth Analg 2000;91:1394–7 ANESTHESIA FOR FETOSCOPIC SURGERY.
Operative Fetoscopy." Florida Institute for Fetal Diagnosis and Therapy March 11, 2003 [cited March 12, 2003]. http://www.fetalmd.com.
GALINKIN ET AL. Anesth Analg 2000;91:1394–7 ANESTHESIA FOR FETOSCOPIC SURGERY.
Indian J Anaesth. 2009 October; 53(5): 554–559.Anaesthesia for Fetal Surgeries.
Operative Fetoscopy chapter;Craig T. Albanese in Pediatric laparoscopy,edited by Thom E Lobe. ©2003 Landes Bioscience.
(Anesth Analg 2005;101:251–8).
Maternal haemodynamics and lung water content during percutaneous fetoscopic interventions under general anaesthesia.(Br J Anaesth 2009; 102: 523–7).
Epidural versus general anesthesia for twin-twin transfusion syndrome requiring fetal surgery. Fetal Diagn Ther. 2004 May-Jun;19(3):286-91.
Maternal Pulmonary Edema During Fetoscopic Surgery (Anesth Analg 2008;107:1978 –80):
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