Fetal heart rate changes after fetal intravascular treatment with pancuronium bromide.

Because of recurrent needle dislodgement secondary to fetal movement, we have altered our intravascular transfusion technique by replacing maternal premedication (meperidine and diazepam [group 1]) with fetal intravascular infusion of pancuronium bromide (Pavulon [group 2]), a nondepolarizing neuromuscular blocking agent. Baseline fetal heart rate, number of accelerations, and variability were assessed before and after transfusion in both groups. Whereas there were no changes after transfusion in the former group, those fetuses who received pancuronium bromide demonstrated a dramatic abolishment of accelerations and decrease in variability, with the heart rate pattern often appearing "sinusoidal-like." These alterations in fetal heart rate were temporary changes that reverted to normal once the fetus "awakened" from the neuromuscular blockade. We speculate that these changes in fetal heart rate are secondary to the interaction of the reported hypertensive and vagolytic effects of pancuronium bromide.

Intrauterine neuromuscular blockade in fetus.

Antenatal intrauterine fetal therapy has now become the target of numerous invasive diagnostic and therapeutic maneuvers. Fetal motion during intrauterine fetal therapy not only makes these procedures technically more difficult but also increases the likelihood of trauma to the umbilical vessels and the fetus. Combination of high doses of sedatives, tranquilizers, and narcotics rarely results in adequate suppression of fetal movement. Such medication puts the mother at risk of respiratory depression, regurgitation and aspiration. The use of pancuronium or atracurium to temporarily arrest fetal movement in ten fetus is reported. After an initial ultrasound assessment of fetal lie, placental location, and umbilical cord insertion site, the fetal weight was calculated by the ultrasound parameters of biparietal diameter and abdominal circumference. Under ultrasound guidance, we injected pancuronium 0.15 mg/kg or atracurium 1.0 mg/kg using a 23-gauge spinal needle into the fetal gluteal muscle. Short-term paralysis of the fetus was induced in all cases. Fetal movement stopped by sonographic observation within 5.8 +/- 2.3 min in the pancuronium group and 4.7 +/- 1.8 min in the atracurium group. Fetal movements returned both to maternal sensation or ultrasonic observation by 92 +/- 23 min in the first group and 36 +/- 11 min in the second group. No adverse effect of the relaxant has been observed in any of the mothers. There was no evidence of local soft tissue, nerve or muscle damage at the site of injection on initial examination of the neonates after delivery. The use of neuromuscular relaxant in fetus was a safe and useful method.

Anestesia en cirugía fetal intrauterina / Anesthesia in fetal surgery

El diagnóstico intrauterino y el tratamiento de las anormalidades, tales como hidrocefalia obstructiva congénita, hidronefrosis y hernia diafragmática, mediante cirugía fetal, han obtenido grandes adelantos desde el punto de vista clínico y continúan en evolución. La anestesia para estos procedimientos tiene como objetivo provocar mínimos riesgos para la madre y el feto. Por esta razón, la ténica anestésica debe incluir un monitoreo materno-fetal exhaustivo, durante y después del procedimiento. Las técnicas percutáneas, frecuentemente, requieren anestesia local con sedación. Sin embargo, ésta no provee anestesia adecuada para procedimientos que requieren histerectomía o fetoscopía. Su empleo proporciona confort materno, pero no produce suficiente relajación uterina ni adecuada anestesia fetal. Con el empleo de anestesia general, la tocolisis se mantiene con agentes halogenados y útero-inhibidores, mientras que la anestesia en el feto se logra con el uso de opioides y relajantes musculares, siendo esta técnica segura para ambos. El uso de fármacos útero-inhibidores debe mantenerse durante y después de la histerotomía, que, junto con la analgesia epidural mediante colocación de un catéter, contribuyen a disminuir el riesgo de parto prematuro, logrando el control eficaz del dolor postoperatorio.