Determination of ED90 of Intrathecal Lidocaine for Adequate Anesthesia for Elective Cervical Cerclage Surgery
Status:
Terminated
Trial end date:
2016-08-01
Target enrollment:
Participant gender:
Summary
Cervical incompetence complicates approximately 1 in 500 pregnancies . Those women with
cervical incompetence are at risk for second trimester spontaneous abortion and preterm
labor. Cervical cerclage reduces these risks but must be performed under general or neuraxial
anesthesia. Some anesthesiologists prefer neuraxial anesthesia, as it reduces fetal exposure
to medications and avoids the risks associated with loss of maternal airway reflexes under
general anesthesia. Spinal anesthesia, in particular, has the added advantage of being
technically simple while still providing a rapid, dense sensory block. For cerclage
placement, patients require a sensory block from the T10 to S4 dermatome in order to cover
sensation from the cervix as well as the vagina and perineum. Patients presenting for
cerclage under spinal anesthesia pose a dosing challenge given the physiologic changes
associated with pregnancy. As women progress with their pregnancy, they require lower doses
of intrathecal local anesthetic to achieve similar block level. Multiple studies have
demonstrated that these changes start during the second trimester. Inadequate sensory
coverage with a spinal anesthetic typically necessitates conversion to general anesthesia,
causing additional time wasted and added risk to the patient and fetus. Anecdotally, this is
the reason why some anesthesiologists choose general anesthesia for patients undergoing
cerclage over a spinal anesthetic. As there is currently no literature determining the
correct dosage for these patients, we propose a dose-response study to determine the ED90 of
intrathecal lidocaine for adequate anesthesia for elective cervical cerclage placement.The
findings of this study will help determine the minimum dose of intrathecal lidocaine
necessary to provide adequate spinal anesthesia for cervical cerclage for 90% of women. This
will help decrease the frequency of inadequate anesthesia for cervical cerclage.