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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.56 no.3 Campinas May/June 2006
Anesthesia for ex utero intrapartum treatment of fetus with prenatal diagnosis of cervical hygroma. Case report*
Anestesia para tratamiento intraparto extraútero en feto con diagnóstico prenatal de higroma en la región cervical. Relato de caso
Angélica de Fátima de Assunção Braga, TSAI; José Aristeu F. Frias, TSAII; Franklin S. da Silva BragaIII; Monique Sampaio RousseletII; Ricardo BariniIV; Lourenço SbragiaV; Juliana GuarizeVI; Larissa C.C.GilVII
Associada do Departamento de Anestesiologia da FCM-UNICAMP
IIAnestesiologista do CAISM
IIIProfessor Doutor do Departamento de Anestesiologia da FCM-UNICAMP
IVProfessor Associado do Departamento de Ginecologia da FCM-UNICAMP
VProfessor Associado do Departamento de Cirurgia da FCM-UNICAMP
VIME2 do CET do Departamento de Anestesiologia da FCM-UNICAMP
VIIME3 do CET do Departamento de Anestesiologia da FCM-UNICAMP
OBJECTIVES: Ex utero intrapartum treatment (EXIT) is a procedure performed
during Cesarean section with preservation of fetal-placental circulation, which
allows the safe handling of fetal airways with risk of airways obstruction.
This report aimed at describing a case of anesthesia for EXIT in a fetus with
cervical cystic hygroma.
CASE REPORT: Female patient, 22 years old, 37 weeks gestation without anesthetic background, physical status ASA I, submitted to EXIT for airway handling and tracheal intubation of fetus at risk for airway obstruction. Procedure was performed under general anesthesia associated to continuous epidural anesthesia. Patient was premedicated with intravenous metoclopramide (10 mg) and ranitidine (50 mg). Epidural 0.25% bupivacaine with epinephrine (30 mg) associated to fentanyl (100 µg) was administered, followed by cephalic catheter for postoperative analgesia. Uterus was displaced to the left. Anesthesia was induced in rapid sequence with fentanyl, propofol and rocuronium and was maintained with isoflurane in 2.5 at 3% in O2 and N2O (50%). After hysterotomy, fetus was partially released assuring uterus-placental circulation, followed by fetal laryngoscopy and tracheal intubation. Then fetus was totally released with umbilical cord clamping, administration of oxytocin (20 UI) in continuous infusion, followed by intravenous methyl-ergonovine (0.2 mg). Maternal systolic pressure was maintained above 100 mmHg during the procedure with bolus ephedrine (5 mg) and crystalloids (3000 mL). Isoflurane concentration was gradually decreased during uterine closure. At surgery completion neuromuscular block was reversed and morphine (2 mg) was injected through the epidural catheter for postoperative analgesia.
CONCLUSIONS: Major recommendations for EXIT are maternal-fetal safety, uterine relaxation to maintain uterine volume and uterus-placental circulation, and fetal immobility to help airway handling.
Key Words: ANESTHESIA, Obstetric; ANESTHETIC TECHNIQUES, General, Regional: epidural combined; COMPLICATIONS: cystic hygroma, ventilatory; SURGERY, Obstetric:ex utero treatment, intrapartum.
Y OBJETIVOS: El tratamiento intraparto extraútero (EXIT) constituye
un procedimiento realizado durante la cesária, con preservación
de la circulación feto-placentaria, que permite el manejo seguro de la
vía aérea del feto, con riesgo de obstrucción de las vías
aéreas. El objetivo de este relato fue el de presentar un caso de anestesia
para EXIT, en feto con higroma cístico en la región cervical.
RELATO DEL CASO: Paciente con 22 años, 37 semanas de gestación, sin antecedentes anestésicos, estado físico ASA I, sometida a EXIT para manejo de vía aérea e intubación traqueal en feto con riesgo para obstrucción de vías aéreas. El procedimiento se realizó bajo anestesia general asociada a peridural continua. En el preoperatorio fueron utilizados metoclopramida (10 mg) y ranitidina (50 mg), por vía venosa. En el espacio peridural se administró bupivacaína a 0,25% con adrenalina (30 mg) asociada a fentanil (100 µg), seguida de la introducción de catéter cefálico, para analgesia postoperatoria. El útero fue desplazado para la izquierda. La inducción anestésica se hizo en secuencia rápida, con fentanil, propofol y rocuronio y el mantenimiento con isoflurano en 2,5% a 3%, en O2 y N2O (50%). Después de la histerotomía, se procedió a la liberación parcial del feto, asegurando la circulación útero placentaria, siguiendo las maniobras de laringoscopia e intubación traqueal fetal. A continuación se realizó la liberación total del feto, con pinzamiento del cordón umbilical, administración de ocitocina (20 UI) en infusión venosa continua seguida de metil-ergonovina (0,2 mg) por vía venosa. Durante el procedimiento, la presión arterial sistólica materna se mantuvo por encima de 100 mmHg, con efedrina en bolus (5 mg) y cristaloide (3000 mL). La concentración del isoflurano disminuyó gradualmente durante el cierre uterino. Al final de la intervención quirúrgica el bloqueo neuromuscular fue revertido y se inyectó morfina (2 mg) por el catéter peridural para analgesia posoperatoria.
CONCLUSIONES: Las principales recomendaciones para la realización del EXIT son seguridad materno-fetal, relajamiento uterino para el mantenimiento del volumen uterino y de la circulación útero placentaria y el no movimiento fetal para facilitar el manejo de las vías aéreas.
Advances of prenatal diagnostic exams, such as high-resolution ultrasound and MRI, have increasingly diagnosed fetal anatomic malformations involving face or neck, which offer higher risk of airway obstruction and are associated to high morbidity/mortality rates 1-5. Early fetal airway obstruction diagnosis has allowed the development of strategic treatment for its effective perinatal handling. Ex utero intrapartum treatment (EXIT) was initially proposed to revert tracheal occlusion in fetuses with congenital diaphragmatic hernia and has the advantage of preserving uterus-placental circulation and maintaining fetal oxygenation during airway evaluation and maintenance 6.
EXIT anesthesia involves two patients, mother and fetus, so care to assure maternal-fetal safety should be considered. As opposed to a simple Cesarean section, uterine relaxation is critical during ex utero intrapartum procedures to prevent placental detachment and fetal hypoxemia by uterine blood flow impairment 1,2,7.
This report aimed at presenting a case of anesthesia for EXIT in fetus with cervical cystic hygroma.
After information and explanation about the anesthetic procedure, a female patient, 22 years old, 62 kg, 156 cm, gestation 1 to 0, with 37 weeks gestation, without anesthetic background, physical status ASA I, was submitted to Cesarean section under general anesthesia with mechanically controlled ventilation associated to continuous epidural anesthesia for ex utero intrapartum treatment (EXIT). The procedure was proposed to assure airway maintenance of fetus with giant cervical cystic hygroma, diagnosed in the prenatal period (Figure 1) with high risk of airway obstruction at birth. Monitoring consisted of cardioscope at DII lead, noninvasive blood pressure, pulse oximetry, capnography and neuromuscular block evaluation by acceleromyography. Patient was premedicated with intravenous metoclopramide (10 mg) and ranitidine (50 mg), 30 minutes before anesthesia. Upper limb vein was catheterized in the OR at room temperature with disposable 14G catheter for volume replacement and drug administration. With patient in the sitting position, puncture was performed at L3-L4 interspace with disposable 16G Tuohy needle and, after epidural space identification by the loss of resistance to air technique, 0.25% bupivacaine with 1:200,000 epinephrine (3 mg) associated to fentanyl (100 µg) were injected, followed by cephalic catheter insertion for postoperative analgesia.
Patient was placed in the supine position and uterus was displaced to the left with the aid of Crawfords wedge. General anesthesia was induced in rapid sequence, oxygenation with 100% oxygen under mask, intravenous fentanyl (250 µg), propofol (120 mg) and rocuronium (50 mg), Sellik maneuver and tracheal intubation. Anesthesia was maintained with isoflurane in 2.5% concentration at 3% through gauged vaporizer and administered in mixture of O2 and N2O (50%). Fetal was partially released (head, shoulders and upper limbs) after hysterotomy and, after assuring fetal-placental circulation, fetal laryngoscopy and tracheal intubation were performed with the aid of rigid bronchoscope (Figures 2 and 3).
Oxygen peripheral saturation and fetal pulse frequency were continuously evaluated during the procedure with the aid of pulse oximetry and sterile sensor placed on right hand, which were maintained in approximately 70% and 108 bpm, respectively. After tracheal intubation SpO2 has increased to 90% and pulse frequency was maintained in approximately 100 bpm. Fetus was then totally released, umbilical cord was clamped and uterus was continuously sutured. Isoflurane concentration was gradually decreased and oxytocin (20 UI) continuous infusion and intravenous methyl-ergonovine (0.2 mg) were administered to reestablish uterine tone. Maternal systolic blood pressure was maintained above 100 mmHg with bolus ephedrine (5 mg) in a total dose of 20 mg and crystalloids (3000 mL).
Procedure went on without maternal-fetal intercurrences. At surgery completion, morphine (2 mg) was injected through the epidural catheter for postoperative analgesia. After neuromuscular block recovery, patient was extubated when T4:T1 > 0.9 (acceleromyography), maintaining 98% hemoglobin peripheral saturation in room air. Fetal airway handling and tracheal intubation were performed in 3 minutes, with total surgery duration of 80 minutes. Newborn presented Apgar scores of 6 and 9 at 1 and 5 minutes, respectively, being referred to neonatal ICU with spontaneous ventilation. Parturient was referred to the post-anesthetic recovery unit conscious and hemodynamically stable.
Congenital cervical, head and face tumors are major causes of fetal airway obstruction and may be potentially lethal, requiring tracheal intubation at birth 1,4,5,8. With the advances on diagnostic methods, these abnormalities are often diagnosed in the prenatal period allowing a procedure planning for the adequate airway control at birth 3. Lymphatic malformations, as in our case, are macrocystic (cystic hygroma CH) and microcystic (lymphangiomas), which may even be simultaneous and contain other vascular elements.
The incidence of cystic hygroma is 1:12,000 neonates being developed in the posterior cervical region in 75% of cases. Large hygromas involve the whole cervical region, the face and other structures including mediastinum, and may be associated to hydrops and diffuse limphangiomatosis 9.
Obstructed airway diagnostic is in general obtained in the 30th gestational week with the aid of ultrasound and MRI for detailed injury evaluation as well as its relation with airways. As from diagnosis, Cesarean section is normally scheduled for after the 35th gestational week to prevent prematurity problems, such as respiratory distress syndrome. Although prematurity is not a counterindication for the procedure, treatment with surfactant should be started before birth 2,3,10-12.
EXIT, for maintaining uterus-placental circulation and, as a consequence, adequate fetal oxygenation during the time needed for airway handling (laryngoscopy, bronchoscopy, tracheal intubation or tracheotomy), is a common procedure in such situations 1,2,4-6,8,10.
Maternal care during EXIT is equal to that considered for open fetal procedures and, in addition to changes inherent to pregnancy, uterine relaxation and abruptio placental prevention are of primary importance. As to fetal care, one may stress anesthesia, immobility and prevention of fetal asphyxia 1,2,10-14.
Increased uterine tone as a consequence of uterine incision and handling is a major cause of abruptio placental, decreased placental blood flow and fetal anoxia. Its prevention is critical for surgical procedure success. Concomitant perioperative tocolytic drugs may be needed in addition to high concentration of volatile agents used to obtain adequate uterine relaxation for the procedure 2,7,12,13,15,16.
Bolus nitroglycerin (50 to 100 µg) followed by continuous infusion (15 to 20 µg.kg-1.min-1) has been often used in the perioperative period due to advantages such as fast excretion, short duration and prompt tocolytic effect recovery after infusion withdrawal. Adequate tocolytic effect may also be obtained with magnesium sulfate alone or associated to nitroglycerin 2,7. Although useful, those drugs are not free from side effects such as hypotension, arrhythmias, pulmonary edema, metabolic changes and interaction with neuromuscular blockers 2,7,10-13.
Similarly to open fetal surgeries, this procedure is performed under general anesthesia with high volatile agent concentrations to promote uterine relaxation needed to maintain maternal-fetal circulation, to decrease maternal stress and to contribute to fetal anesthesia 2,10-13. However, as opposed to intra utero fetal surgery, where uterine relaxation is critical, EXIT peaks with birth, with no need for postoperative tocolytic treatment 2,10,13,16.
It is also different from standard Cesarean section, where low volatile agent concentrations are used to prevent uterine atonia and potential risk of bleeding. In addition, it is desirable that time between beginning of anesthesia and umbilical cord clamping is decreased to decrease fetal exposure to anesthetic agents. Neonate depression during EXIT is not a problem because the procedure is ended with tracheal intubation and ventilation 2,17.
Another important EXIT aspect is related to uterine volume maintenance in adequate levels to preserve placental perfusion. Fetus is partially released (head, chest and upper limbs) after hysterotomy with umbilical cord maintained within the uterine cavity. This prevents heat loss by fluid evaporation, in addition to preventing umbilical cord exposure to cold and dry air, which could activate prostaglandin synthesis with consequent vasoconstriction and decreased blood flow through the cord. So, fetal airway handling, if needed, may last up to 60 minutes or more without impairing maternal-fetal circulation 2,6.
Uterine tone recovery is mandatory after airway handling, total fetal release and umbilical cord clamping. Inhalational anesthesia depth may be decreased, followed by the administration of oxytocin for tone recovery and to decrease uterine bleeding. However, as a consequence of prolonged uterine relaxation, uterine atonia may persist and become a severe complication. In these cases, muscular or intravenous methyl-ergonovine is indicated in addition to volume replacement 2,11.
Regional anesthesia (spinal or epidural) has been reported as single technique for this procedure, however unsuccessfully, because fetuses cried and moved during tracheal intubation attempt before umbilical cord clamping 2. Respiratory movements with consequent decrease in pulmonary resistance and increase in peripheral vascular resistance result in arterial canal closing and loss of adequate fetal circulation to maintain fetal oxygenation, limiting the time needed for the procedure 2,15.
To prevent fetal breathing and moving, some authors suggest that fetuses should receive muscular opioids and neuromuscular blockers 2,12,13,18-20. Notwithstanding the rapid crossing of placental barrier by volatile gases, fetal concentration remains lower than maternals even after long exposure periods, not assuring fetal anesthesia and immobility to allow the EXIT procedure. Fentanyl (5 to 20 µg.kg-1) is the opioid of choice due to the efficacy and safety observed in premature neonates submitted to anesthesia 10-12,21. Fetal movements have been safely assured with pancuronium (0.2 to 0.3 mg.kg-1), pipecuronium (0.2 mg.kg-1) or vecuronium (0.2 mg.kg-1) 1,12,13,18. Due to its vagolytic activity, pancuronium increases cardiac rate, which is a desirable effect to maintain fetal cardiac output 22.
In our case, after cord clamping, placental expulsion and oxytocin administration, epidural anesthesia associated to general anesthesia has allowed for the gradual decrease in volatile agent concentration maintaining adequate surgical analgesia with increased tone and decreased risk of uterine bleeding.
Volatile agents are potent uterine muscle relaxants and 2 to 3 MAC concentrations are needed for adequate tocolytic effect 1,10,20,23. Halothane is the agent with higher utero-relaxant properties, however it is not recommended especially due to its cardiopulmonary depressing effects. The choice is, then, isoflurane and sevoflurane, for their low blood-gas coefficient, which contributes to fast recovery and minor cardiopulmonary depressing effects 2,10,19,20,23.
However, high volatile agent concentrations may promote maternal hypotension which associated to uterine bleeding results in utero-placental perfusion impairment, leading to decreased cardiac output and fetal hypoxemia. It is then critical to control maternal repercussions with uterine displacement to the left and the use of hemostatic staplings which minimize hysterotomy-related bleeding in the presence of uterine atonia 1,14-16.s
Additionally, moderate crystalloids and colloids infusion and vasopressor amines are useful to control hypotension, maintaining systolic blood pressure always above 100 mmHg. In spite of controversies on the use of these drugs to treat maternal hypotension, ephedrine, although potentially promoting fetal acidosis is still the most popular vasopressor due to its beta-adrenergic effect and minor action on uterine blood flow 1,24. Some authors recommend phenylephrine because even in high doses (1000 µg) it does not promote clinically significant vasoconstriction and placental perfusion decrease. So, it may be considered adequate to correct vasodilation secondary to spinal anesthesia 24. Angiotensin II (10 to 15 µg.kg-1.min-1) has also been used because it does not cross placental barrier and does not promote uterine vasoconstriction 2.
Fetal monitoring is fundamental during EXIT, since any instability, such as bradycardia and hypoxemia, may be sign of poor placental perfusion, which should be early detected. So, monitoring with ECG, cardiac ultrasound and pulse oximetry is recommended; however, due to installation and observation difficulties, pulse oximetry is more practical and feasible. During upper airway handling, fetal SpO2 varies from 38% to 95%, with mean values close to 70%. Fetal heart rate should be maintained between 130 and 140 bpm. Oxygen peripheral saturation below 50% and heart rate below 120 pbm are indications of fetal-placental flow and fetal oxygenation impairment. So, maneuvers to control such intercurrences should be instituted, such as improved fetalplacental flow and prompt airway control by tracheal intubation or tracheotomy 2.
Considering the circumstances inherent to fetal intervention (EXIT), the anesthesiologist should participate in a multidisciplinary team with a strategy based on maternal-fetal safety and neonate pulmonary ventilation viability. In our case, the anesthetic technique has promoted uterine relaxation and maintenance of adequate uterine volume for fetal partial exposure and immobility, preserving placental perfusion, which are critical conditions for a successful procedure.
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Dra. Angélica de Fátima Assunção Braga
Rua Luciano Venere Decourt, 245 Cidade Universitária
13084-040 Campinas, SP
Submitted for publication
09 de novembro de 2005
Accepted for publication 06 de fevereiro de 2006
* Received from Centro de Atenção Integral à Saúde da Mulher (CAISM) da Faculdade de Ciências Médicas da Universidade de Campinas (FCM-UNICAMP), Campinas, SP.