Aortocaval Compression Clinical Trial
Official title:
Neonatal Acid-base Status After Elective Cesarean Delivery Under Spinal Anesthesia - a Comparison of Maternal Supine Horizontal Position Versus Left Lateral Table Tilt
This study aims to compare the neonatal acid-base status of women who remain supine horizontal, with women who are tilted to the left side by 15° during elective cesarean delivery at term under spinal anesthesia, with systolic BP maintained at baseline with a phenylephrine (PE) infusion. The null hypothesis is that the position of the patient (supine horizontal or tilted) during cesarean section will make no difference to neonatal wellbeing. The primary outcome will be the neonatal umbilical arterial base deficit (BD) at birth. The investigators will also examine the effects of maternal position during cesarean section under spinal anesthesia on maternal cardiac output (CO) and whether these changes have a correlation with the neonatal umbilical cord blood acid-base status. The secondary outcome will be the total phenylephrine dose requirement at 15 minutes after spinal injection.
Methods: This will be a randomized trial structured as an equivalence trial. Subjects will
be American Society of Anesthesiologists (ASA) I and II women aged ≥18 years, non-laboring,
at term (>37 weeks gestation) with singleton pregnancies in cephalic presentation, scheduled
for elective cesarean delivery under spinal anesthesia. Patients will receive spinal
anesthesia for cesarean section in the sitting position, after which they will lay either
supine horizontal or the surgical table will be tilted to the left by 15°, depending on the
group to which they were randomized (SUPINE or TILT). An IV phenylephrine infusion will be
administered to maintain systolic BP at baseline until delivery. A noninvasive hemodynamic
monitoring system (NICOM, Cheetah Medical Inc., Vancouver, WA, USA) will continuously
monitor CO and stroke volume. Neonatal umbilical vein and arterial blood gas results will be
recorded.The null hypothesis is that the position of the patient (supine horizontal or
tilted) during cesarean section will make no difference to neonatal wellbeing.
Statistical Design: The estimated sample size is the minimum number of study subjects
required for rejecting the alternative hypothesis (i.e., accepting the null hypothesis). A
significant difference between groups in the primary outcome, umbilical artery BD (which is
a measure of fetal well being at the time of delivery and an indirect indicator of the
adequacy of uteroplacental perfusion) would be of the order of magnitude of 2 mmol/L.
Standard deviation of BD tends to be of this magnitude also. It would therefore require 22
subjects per group for 90% power to detect this magnitude of difference with alpha 0.05.
Because BD is often not normally distributed, it is appropriate to increase sample size by
10-20%, and because the investigators have important secondary outcomes (PE usage, UA and UV
pH, UV BD) the investigators intend to recruit 50 subjects per group to allow sufficient
power for analysis of these secondary outcomes with appropriate correction for multiple
comparisons, and allowing for 10% dropout. PE usage in the investigators previous study
tends to have a standard deviation of about 30% of the mean, also roughly the magnitude of a
clinically significant difference.
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Allocation: Randomized, Endpoint Classification: Safety Study, Intervention Model: Factorial Assignment, Masking: Open Label, Primary Purpose: Treatment
| Status | Clinical Trial | Phase | |
|---|---|---|---|
| Completed |
NCT05427968 -
Comparison of Hypotension During Spinal Anaesthesia for C-section
|