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NCT Number: NCT05512065

Changes in Velocimetric Indices of Uterine and Umbilical Arteries Before and After Combined Spinal-epidural Analgesia in Laboring Women

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.

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Key information

Conditions

Labor Pain Neurologic Manifestations Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–50 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Mount Sinai Hospital

Toronto, Ontario, M5G1X5, Canada

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Written informed consent
  • Term pregnant patients requesting labor analgesia
  • Singleton pregnancy
  • Term pregnant patients in active labor
  • ASA<4
  • No evidence of fetal congenital anomalies, fetal compromise or fetal decelerations prior to CSE

Exclusion criteria

  • Refusal to consent for the study
  • Known spinal deformities
  • Previous back instrumentation
  • Patients with BMI>50 kg/㎡ due to anticipated technical challenges in Doppler studies

Treatment and study plan

Ultrasound

Device

Ultrasound scan of the right and left uterine arteries and umbilical artery.

Primary outcomes

  1. Uterine artery velocimetric index - systolic/diastolic ratio (S/D) at baseline

    Time frame: 5 minutes

    Uterine artery velocimetric index - systolic/diastolic ratio (S/D) will be measured at baseline (prior to combined spinal epidural).

  2. Uterine artery velocimetric index - systolic/diastolic ratio (S/D) at 10 minutes

    Time frame: 5 minutes

    Uterine artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 10 minutes after combined spinal epidural

  3. Uterine artery velocimetric index - systolic/diastolic ratio (S/D) at 30 minutes

    Time frame: 5 minutes

    Uterine artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 30 minutes after combined spinal epidural

  4. Uterine artery velocimetric index - pulsatility index (PI) at baseline

    Time frame: 5 minutes

    Uterine artery velocimetric index - pulsatility index (PI) will be measured at baseline (prior to combined spinal epidural).

  5. Uterine artery velocimetric index - pulsatility index (PI) at 10 minutes

    Time frame: 5 minutes

    Uterine artery velocimetric index - pulsatility index (PI) will be measured 10 minutes after combined spinal epidural

  6. Uterine artery velocimetric index - pulsatility index (PI) at 30 minutes

    Time frame: 5 minutes

    Uterine artery velocimetric index - pulsatility index (PI) will be measured 30 minutes after combined spinal epidural

  7. Uterine artery velocimetric index - resistance index (RI) at baseline

    Time frame: 5 minutes

    Uterine artery velocimetric index - resistance index (PI) will be measured at baseline (prior to combined spinal epidural).

  8. Uterine artery velocimetric index - resistance index (RI) at 10 minutes

    Time frame: 5 minutes

    Uterine artery velocimetric index - resistance index (PI) will be measured 10 minutes after combined spinal epidural

  9. Uterine artery velocimetric index - resistance index (RI) at 30 minutes

    Time frame: 5 minutes

    Uterine artery velocimetric index - resistance index (PI) will be measured 30 minutes after combined spinal epidural

  10. Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at baseline

    Time frame: 5 minutes

    Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured at baseline (prior to combined spinal epidural).

  11. Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 10 minutes

    Time frame: 5 minutes

    Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 10 minutes after combined spinal epidural

  12. Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 30 minutes

    Time frame: 5 minutes

    Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 30 minutes after combined spinal epidural

  13. Umbilical artery velocimetric index - pulsatility index (PI) at baseline

    Time frame: 5 minutes

    Umbilical artery velocimetric index - pulsatility index (PI) will be measured at baseline (prior to combined spinal epidural).

  14. Umbilical artery velocimetric index - pulsatility index (PI) at 10 minutes

    Time frame: 5 minutes

    Umbilical artery velocimetric index - pulsatility index (PI) will be measured 10 minutes after combined spinal epidural

  15. Umbilical artery velocimetric index - pulsatility index (PI) at 30 minutes

    Time frame: 5 minutes

    Umbilical artery velocimetric index - pulsatility index (PI) will be measured 30 minutes after combined spinal epidural

  16. Umbilical artery velocimetric index - resistance index (PI) at baseline

    Time frame: 5 minutes

    Umbilical artery velocimetric index - resistance index (PI) will be measured at baseline (prior to combined spinal epidural).

  17. Umbilical artery velocimetric index - resistance index (PI) at 10 minutes

    Time frame: 5 minutes

    Umbilical artery velocimetric index - resistance index (PI) will be measured 10 minutes after combined spinal epidural

  18. Umbilical artery velocimetric index - resistance index (PI) at 30 minutes

    Time frame: 5 minutes

    Umbilical artery velocimetric index - resistance index (PI) will be measured 30 minutes after combined spinal epidural

Secondary outcomes

  1. Pain score at baseline - questionnaire

    Time frame: 1 minute

    Pain score - verbal numeric rating scale (0-10) prior to combined spinal epidural

  2. Pain score at 10 min - questionnaire

    Time frame: 1 minute

    Pain score - verbal numeric rating scale (0-10) at 10 min after combined spinal epidural

  3. Pain score at 30 min - questionnaire

    Time frame: 1 minute

    Pain score - verbal numeric rating scale (0-10) at 30 min after combined spinal epidural

  4. Hypotension: systolic blood pressure less than 80% of baseline

    Time frame: 30 minutes

    Systolic blood pressure < 80% of baseline, monitored q5 for 30 minutes following combined spinal epidural

  5. Hypertension: systolic blood pressure greater than 120% of baseline

    Time frame: 30 minutes

    Systolic blood pressure > 120% of baseline, monitored q5 for 30 minutes following combined spinal epidural

  6. Bradycardia: heart rate less than 70% of baseline

    Time frame: 30 minutes

    Heart rate < 70% of baseline or a heart rate < 50bpm, monitored q5 for 30 minutes following combined spinal epidural

  7. Desaturation: oxygen level <95%

    Time frame: 30 minutes

    Oxygen level <95%, monitored q5 for 30 minutes following combined spinal epidural

  8. Sensory block level at 10 minutes

    Time frame: 10 minutes

    Sensory block level at 10 minutes following combined spinal epidural

  9. Sensory block level at 30 minutes

    Time frame: 30 minutes

    Sensory block level at 30 minutes following combined spinal epidural

  10. Duration of labour

    Time frame: up to 24 hours

    Onset of labour until delivery of the placenta

  11. Type of delivery

    Time frame: up to 24 hours

    Type of delivery will be recorded: vaginal, cesarean section, instrumental delivery

  12. Presence of hypertonic uterine contractions

    Time frame: up to 24 hours

    Presence of hypertonic uterine contractions as noted by the nursing or obstetric team.

  13. fetal heart rate at baseline

    Time frame: 5 minutes

    fetal heart rate at baseline, prior to combined spinal epidural

  14. fetal heart rate q5 min up to 30 minutes

    Time frame: 30 minutes

    fetal heart rate q5 min up to 30 minutes following combined spinal epidural

  15. presence of fetal bradycardia - questionnaire

    Time frame: up to 24 hours

    presence of fetal bradycardia (fetal heart rate <110)

  16. presence of fetal tachycardia - questionnaire

    Time frame: up to 24 hours

    presence of fetal tachycardia (fetal heart rate >160)

  17. Neonatal weight

    Time frame: 2 minutes

    Neonatal weight measured after delivery in grams

  18. Apgar score at 1 minute

    Time frame: 1 minute

    Apgar score at 1 minute

  19. Apgar score at 5 minutes

    Time frame: 5 minute2

    Apgar score at 5 minutes

Sponsors and collaborators

Lead sponsor

Samuel Lunenfeld Research Institute, Mount Sinai Hospital

Other

Registry information

Important dates

Study start
2022
Primary completion
2024
Study completion
2024
First posted
Aug 23, 2022
Registry last updated
Oct 24, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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