Combined spinal-epidural (CSE) for labor analgesia has been used for many years and is practiced commonly at our institution, especially when the patient requests immediate pain relief. CSE is not only beneficial for its faster onset of analgesia, but also it is favorable in relation to the need for rescue analgesia, urinary retention, and rate of instrumental delivery compared to the traditional epidural. Despite its beneficial effects, there is a risk of about 15-30% of developing abnormal fetal heart rate following CSE. This is self-resolving with minimal or no intervention. Although the cause of fetal bradycardia is not fully elucidated, variations in uterine artery blood flow after epidural analgesia are thought to be due to the interaction of numerous events related to blockade of sympathetic innervations, fluid administration, maternal hypotension, uterine vascular effects of sympathetic block, fluctuations in circulating catecholamines, and possibly the effect of opioids. Similar mechanism is thought to be a cause of fetal bradycardia after the CSE with its faster onset and superior block. Maternal or fetal circulation during labor can be assessed using continuous-wave Doppler ultrasound to monitor maternal uterine artery (UtA) and fetal umbilical artery (UmA) velocity waveforms to detect changes in blood flow. The velocimetry indices mentioned above have been often used to assess the changes in the blood flow before and after the induction of epidural analgesia during labor in several studies. Although there are some studies regarding the effect of labor epidural analgesia using velocimetry indices, but there is currently no published study evaluating velocimetry indices of uterine and umbilical arteries before and after the induction of CSE. Thus, the aim of this study is to investigate the impact of CSE to maternal and fetal blood flow to evaluate the relationships. The investigators hypothesize that both uterine artery and umbilical artery blood flow are reduced after the induction of CSE, which may be responsible for the occurrence of fetal bradycardia.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
30
Ultrasound scan of the right and left uterine arteries and umbilical artery.
Mount Sinai Hospital
Toronto, Ontario, Canada
Uterine artery velocimetric index - systolic/diastolic ratio (S/D) at baseline
Uterine artery velocimetric index - systolic/diastolic ratio (S/D) will be measured at baseline (prior to combined spinal epidural).
Time frame: 5 minutes
Uterine artery velocimetric index - systolic/diastolic ratio (S/D) at 10 minutes
Uterine artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 10 minutes after combined spinal epidural
Time frame: 5 minutes
Uterine artery velocimetric index - systolic/diastolic ratio (S/D) at 30 minutes
Uterine artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 30 minutes after combined spinal epidural
Time frame: 5 minutes
Uterine artery velocimetric index - pulsatility index (PI) at baseline
Uterine artery velocimetric index - pulsatility index (PI) will be measured at baseline (prior to combined spinal epidural).
Time frame: 5 minutes
Uterine artery velocimetric index - pulsatility index (PI) at 10 minutes
Uterine artery velocimetric index - pulsatility index (PI) will be measured 10 minutes after combined spinal epidural
Time frame: 5 minutes
Uterine artery velocimetric index - pulsatility index (PI) at 30 minutes
Uterine artery velocimetric index - pulsatility index (PI) will be measured 30 minutes after combined spinal epidural
Time frame: 5 minutes
Uterine artery velocimetric index - resistance index (RI) at baseline
Uterine artery velocimetric index - resistance index (PI) will be measured at baseline (prior to combined spinal epidural).
Time frame: 5 minutes
Uterine artery velocimetric index - resistance index (RI) at 10 minutes
Uterine artery velocimetric index - resistance index (PI) will be measured 10 minutes after combined spinal epidural
Time frame: 5 minutes
Uterine artery velocimetric index - resistance index (RI) at 30 minutes
Uterine artery velocimetric index - resistance index (PI) will be measured 30 minutes after combined spinal epidural
Time frame: 5 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at baseline
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured at baseline (prior to combined spinal epidural).
Time frame: 5 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 10 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 10 minutes after combined spinal epidural
Time frame: 5 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 30 minutes
Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 30 minutes after combined spinal epidural
Time frame: 5 minutes
Umbilical artery velocimetric index - pulsatility index (PI) at baseline
Umbilical artery velocimetric index - pulsatility index (PI) will be measured at baseline (prior to combined spinal epidural).
Time frame: 5 minutes
Umbilical artery velocimetric index - pulsatility index (PI) at 10 minutes
Umbilical artery velocimetric index - pulsatility index (PI) will be measured 10 minutes after combined spinal epidural
Time frame: 5 minutes
Umbilical artery velocimetric index - pulsatility index (PI) at 30 minutes
Umbilical artery velocimetric index - pulsatility index (PI) will be measured 30 minutes after combined spinal epidural
Time frame: 5 minutes
Umbilical artery velocimetric index - resistance index (PI) at baseline
Umbilical artery velocimetric index - resistance index (PI) will be measured at baseline (prior to combined spinal epidural).
Time frame: 5 minutes
Umbilical artery velocimetric index - resistance index (PI) at 10 minutes
Umbilical artery velocimetric index - resistance index (PI) will be measured 10 minutes after combined spinal epidural
Time frame: 5 minutes
Umbilical artery velocimetric index - resistance index (PI) at 30 minutes
Umbilical artery velocimetric index - resistance index (PI) will be measured 30 minutes after combined spinal epidural
Time frame: 5 minutes
Pain score at baseline - questionnaire
Pain score - verbal numeric rating scale (0-10) prior to combined spinal epidural
Time frame: 1 minute
Pain score at 10 min - questionnaire
Pain score - verbal numeric rating scale (0-10) at 10 min after combined spinal epidural
Time frame: 1 minute
Pain score at 30 min - questionnaire
Pain score - verbal numeric rating scale (0-10) at 30 min after combined spinal epidural
Time frame: 1 minute
Hypotension: systolic blood pressure less than 80% of baseline
Systolic blood pressure \< 80% of baseline, monitored q5 for 30 minutes following combined spinal epidural
Time frame: 30 minutes
Hypertension: systolic blood pressure greater than 120% of baseline
Systolic blood pressure \> 120% of baseline, monitored q5 for 30 minutes following combined spinal epidural
Time frame: 30 minutes
Bradycardia: heart rate less than 70% of baseline
Heart rate \< 70% of baseline or a heart rate \< 50bpm, monitored q5 for 30 minutes following combined spinal epidural
Time frame: 30 minutes
Desaturation: oxygen level <95%
Oxygen level \<95%, monitored q5 for 30 minutes following combined spinal epidural
Time frame: 30 minutes
Sensory block level at 10 minutes
Sensory block level at 10 minutes following combined spinal epidural
Time frame: 10 minutes
Sensory block level at 30 minutes
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Sensory block level at 30 minutes following combined spinal epidural
Time frame: 30 minutes
Duration of labour
Onset of labour until delivery of the placenta
Time frame: up to 24 hours
Type of delivery
Type of delivery will be recorded: vaginal, cesarean section, instrumental delivery
Time frame: up to 24 hours
Presence of hypertonic uterine contractions
Presence of hypertonic uterine contractions as noted by the nursing or obstetric team.
Time frame: up to 24 hours
fetal heart rate at baseline
fetal heart rate at baseline, prior to combined spinal epidural
Time frame: 5 minutes
fetal heart rate q5 min up to 30 minutes
fetal heart rate q5 min up to 30 minutes following combined spinal epidural
Time frame: 30 minutes
presence of fetal bradycardia - questionnaire
presence of fetal bradycardia (fetal heart rate \<110)
Time frame: up to 24 hours
presence of fetal tachycardia - questionnaire
presence of fetal tachycardia (fetal heart rate \>160)
Time frame: up to 24 hours
Neonatal weight
Neonatal weight measured after delivery in grams
Time frame: 2 minutes
Apgar score at 1 minute
Apgar score at 1 minute
Time frame: 1 minute
Apgar score at 5 minutes
Apgar score at 5 minutes
Time frame: 5 minute2