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NCT Number: NCT06655675

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

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 Cardiovascular Diseases Hypertension Neurologic Manifestations Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms Vascular Diseases

Age range

18 year–50 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Mount Sinai Hospital

Toronto, Ontario, M5G1X5, Canada

Location status: Recruiting

Location contact

Amir Siddiqui, MD

SUB_INVESTIGATOR

Claudia Jimenez, MD

SUB_INVESTIGATOR

Cristian Arzola, MD

SUB_INVESTIGATOR

Fernanda Lanza Oliveira, MD

SUB_INVESTIGATOR

Javiera Vargas Zuniga, MD

SUB_INVESTIGATOR

Kristi Downey, MSc

SUB_INVESTIGATOR

Mrinalini Balki, MD

CONTACT

[email protected]

416-586-4800 ext. 5270

Sebastian Hobson, MD

SUB_INVESTIGATOR

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
  • Patients with and without diagnosed hypertensive disorders of pregnancy

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 umbilical artery

Primary outcomes

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

    Time frame: 10 minutes

    Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 10 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

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

    Time frame: 10 minutes

    Umbilical artery velocimetric index - pulsatility index (PI) will be measured 10 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

  3. Umbilical artery velocimetric index - resistance index (RI) at 10 minutes

    Time frame: 10 minutes

    Umbilical artery velocimetric index - resistance index (RI) will be measured 10 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

Secondary outcomes

  1. 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 prior to combined spinal epidural, with the uterus in relaxed and contracted states.

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

    Time frame: 5 minutes

    Umbilical artery velocimetric index - pulsatility index (PI) will be measured prior to combined spinal epidural, with the uterus in relaxed and contracted states.

  3. Umbilical artery velocimetric index - resistance index (RI) at baseline

    Time frame: 5 minutes

    Umbilical artery velocimetric index - resistance index (RI) will be measured prior to combined spinal epidural, with the uterus in relaxed and contracted states.

  4. Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 5 minutes

    Time frame: 5 minutes

    Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 5 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

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

    Time frame: 5 minutes

    Umbilical artery velocimetric index - pulsatility index (PI)will be measured 5 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

  6. Umbilical artery velocimetric index - resistance index (RI) at 5 minutes

    Time frame: 5 minutes

    Umbilical artery velocimetric index - resistance index (RI) will be measured 5 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

  7. Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) at 20 minutes

    Time frame: 20 minutes

    Umbilical artery velocimetric index - systolic/diastolic ratio (S/D) will be measured 20 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

  8. Umbilical artery velocimetric index - pulsatility index (PI) at 20 minutes

    Time frame: 20 minutes

    Umbilical artery velocimetric index - pulsatility index (PI) will be measured 20 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

  9. Umbilical artery velocimetric index - resistance index (RI) at 20 minutes

    Time frame: 20 minutes

    Umbilical artery velocimetric index - resistance index (RI) will be measured 20 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

  10. 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, with the uterus in relaxed and contracted states.

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

    Time frame: 30 minutes

    Umbilical artery velocimetric index - pulsatility index (PI) will be measured 30 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

  12. Umbilical artery velocimetric index - resistance index (RI) at 30 minutes

    Time frame: 30 minutes

    Umbilical artery velocimetric index - resistance index (RI) will be measured 30 minutes after combined spinal epidural, with the uterus in relaxed and contracted states.

  13. Pain score at baseline - questionnaire

    Time frame: 1 minute

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

  14. Pain score at 10 minutes - questionnaire

    Time frame: 10 minutes

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

  15. Pain score at 30 minutes - questionnaire

    Time frame: 30 minutes

    Pain score - verbal numeric rating scale (0-10) at 30 minute3 after combined spinal epidural

  16. Sensory block level at 10 minutes

    Time frame: 10 minutes

    Sensory block level at 10 minutes following combined spinal epidural

  17. Sensory block level at 30 minutes

    Time frame: 30 minutes

    Sensory block level at 30 minutes following combined spinal epidural

  18. frequency of uterine contractions

    Time frame: 10 minutes

    The number of contractions on the monitor in a 10 minute period.

  19. Presence of prolonged hypertonic uterine contractions- questionnaire

    Time frame: 30 minutes

    Presence of prolonged hypertonic uterine contractions as measured by the monitor

  20. 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

  21. 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

  22. 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

  23. Desaturation: oxygen level <95%

    Time frame: 30 minutes

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

  24. fetal heart rate at baseline

    Time frame: 5 minutes

    fetal heart rate at baseline, prior to combined spinal epidural

  25. 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

  26. presence of fetal bradycardia - questionnaire

    Time frame: 30 minutes

    presence of fetal bradycardia (fetal heart rate <110)

  27. presence of fetal prolonged deceleration - questionnaire

    Time frame: 30 minutes

    presence of fetal prolonged deceleration (fetal heart rate <110/min lasting less than 10 minutes)

  28. presence of fetal persistent late decelerations - questionnaire

    Time frame: 30 minutes

    presence of fetal persistent late decelerations will be recorded

  29. presence of fetal non-reassuring variable deceleration - questionnaire

    Time frame: 30 minutes

    presence of fetal non-reassuring variable deceleration will be recorded

  30. presence of fetal salutatory variability - questionnaire

    Time frame: 30 minutes

    presence of fetal salutatory variability (FHR change>25beats) will be recorded

  31. Neonatal weight

    Time frame: up to 24 hours

    Neonatal weight measured after delivery in grams minutes

  32. Apgar score at 1 minute

    Time frame: 1 minute

    Apgar score at 1 minute

  33. Apgar score at 5 minutes

    Time frame: 5 minutes

    Apgar score at 5 minutes

  34. Mode of delivery - questionnaire

    Time frame: up to 24 hours

    Mode of delivery will be recorded as vaginal, assisted (forceps or vacuum), or cesarean

Study contacts

Contact information is provided by the study sponsor or research team.

Mrinalini Balki, MD

CONTACT

[email protected]

416-586-4800 ext. 5270

Sponsors and collaborators

Lead sponsor

Samuel Lunenfeld Research Institute, Mount Sinai Hospital

Other

Registry information

Official study title

Changes in Velocimetric Indices of Uterine and Umbilical Arteries Before and After Combined Spinal-epidural Analgesia in Laboring Women (PART I and PART II)

Important dates

Study start
2024
Primary completion
2026
Study completion
2026
First posted
Oct 23, 2024
Registry last updated
Jul 11, 2025

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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