The Effect of Fluids on Aortic VTI During C-section

April 19, 2024 updated by: Amy Lee, Baylor College of Medicine

The Influence of Intravascular Fluid Administration on Aortic Velocity Time Integral in Obstetric Patients Undergoing Cesarean Section

Pregnancy is associated with a myriad of physiologic changes, including expansion of blood volume, decrease in oncotic pressure, and increased cardiac output. The obstetric population is associated with intrapartum hemorrhage. Accordingly, it is important to have an accurate method to assess fluid status in intrapartum patients. The use of standard volume assessment tools including arterial lines and central venous catheters is limited given the brevity of obstetric procedures and the morbidity of these techniques on the awake patients, and the costs. Non-invasive methods to assess volume status (carotid dopplers, direct measurement of blood loss, bio-impedance devices) are imperfect. Echocardiography is an attractive tool to measure fluid status in experienced operators such as anesthesiologists. IVC diameter and variation of aortic velocity time integral are two measures that can be obtained via echocardiography and been studied in spontaneously breathing patients. The purpose of this study is to determine whether these measurements can be used in the assessment of volume status in the laboring patient.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Pregnancy is associated with a myriad of physiologic changes, including expansion of blood volume, decrease in oncotic pressure, and increased cardiac output. Comorbidities including maternal hypertension, renal or cardiac disease may further complicate the assessment of volume status and are associated with increased risks related to fluid administration (c). In addition, the majority of obstetric patients receive neuraxial analgesia or anesthesia to facilitate both vaginal and operative delivery. These techniques are associated with hemodynamic changes including maternal hypotension secondary to a decrease in SVR and CO. These changes may in turn be associated with a reduction in placental blood flow affecting fetal outcome, and may also cause maternal nausea, vomiting and dizziness. Further, the obstetric population is high risk for intrapartum hemorrhage. As such, it is critical to have an accurate method to assess fluid status in intrapartum patients.

The use of invasive volume assessment tools including arterial lines and central venous catheters is limited given the brevity of obstetric procedures, the morbidity of these invasive techniques for the awake patient, and the associated time and costs (b). Non-invasive methods that assess volume status in the obstetric population include techniques such as direct measurement of blood loss (g), carotid dopplers (c), bio-impedence devices (f); However these methods have been shown to be imperfect and are not widely used.

Echocardiography is a non-invasive, widely-available tool that can provide rapid information for experienced operators such as anesthesiologists. Respiratory variations in inferior vena cava diameter (IVCd) and variation in aortic velocity time integral (∆VTI) following passive leg raise have been extensively studied in spontaneously breathing patients. IVCd has been shown to predict fluid responsiveness, however requires a high threshold (>40-50% collapsibility) to detect a difference. IVCd may also change with diaphragmatic motion, thus results may be confounded if the patient becomes tachypneic (d) or is spontaneously breathing (g). In contrast, aortic velocity time integral (∆VTI) may be a more sensitive indicator of volume status. Lamia et al showed a 12% change in VTI as 77% sensitive and 100% specific for a 15% change in cardiac output following 500 mL volume expansion in ICU patients with shock (both spontaneously breathing and mechanically ventilated, e). While there are some studies of IVC collapsibility in the obstetric population, there are limited data on VTI as a measure of volume status in laboring patients.

The purpose of this study is to determine whether the aortic velocity time integral (VTI) is influenced by intravascular fluid administration during cesarean section. Secondary aims include determining whether inferior vena cava diameter (IVCd), blood pressure, and heart rate are influenced by intravascular fluid administration during cesarean section. Additionally, total amount of vasopressor agents administered during the procedure will be recorded.

Study Type

Observational

Enrollment (Estimated)

50

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • United States
    • Texas
      • Houston, Texas, United States, 77030
        • Recruiting
        • Ben Taub General Hospital
        • Contact:
        • Principal Investigator:
          • Amy Lee, MD
        • Sub-Investigator:
          • Yi Deng, MD
        • Contact:
        • Sub-Investigator:
          • Claudia Wei, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 35 years (Adult)

Accepts Healthy Volunteers

Yes

Sampling Method

Probability Sample

Study Population

All patients ages 18-35 undergoing elective cesarean section with planned spinal anesthetic at Ben Taub General Hospital (BTGH) will be screened. Consenting patients will undergo spinal anesthetic prior to planned procedure. All subjects will receive the same 1L fluid bolus intraoperatively.

Description

Inclusion Criteria:

  • healthy nulliparous or multiparous pregnant women with a term (>37 weeks gestation)
  • age 18-35
  • singleton pregnancy
  • scheduled for Cesarean delivery with planned neuraxial spinal or combined spinal epidural anesthesia
  • American Society for Anesthesiologists physical status 2

Exclusion Criteria:

  • Patients without ability to provide informed consent
  • American Society for Anesthesiologists physical status 3 or 4
  • Emergency cesarean section
  • BMI>40
  • Known cardiac and pulmonary comorbidities including chronic hypertension, preeclampsia, gestational hypertension, diabetes, asthma, renal disease
  • Age > 35

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
0 mL crystalloid
These are the measurements (aortic velocity time integral, inferior vena cava diameter, vital signs) that will be taken at time 0, at which time 0 mL of fluids will have been administered.
Drug: lactated ringers
the intervention is one liter fluid bag of lactated ringers which is routinely used as a fluid coload for spinal anesthesia. All patients will receive the same amount of fluids however this will be paused at various time points in order to perform the echocardiogram.
Other Names:
  • crystalloid
250 mL crystalloid.
These are the measurements (aortic velocity time integral, inferior vena cava diameter, vital signs) that will be taken at time 1, after the spinal has been placed and approximately 250 mL fluids has been administered.
Drug: lactated ringers
the intervention is one liter fluid bag of lactated ringers which is routinely used as a fluid coload for spinal anesthesia. All patients will receive the same amount of fluids however this will be paused at various time points in order to perform the echocardiogram.
Other Names:
  • crystalloid
500 mL crystalloid
These are the measurements (aortic velocity time integral, inferior vena cava diameter, vital signs) that will be taken at time 2, at which time 500 mL of fluids will have been administered.
Drug: lactated ringers
the intervention is one liter fluid bag of lactated ringers which is routinely used as a fluid coload for spinal anesthesia. All patients will receive the same amount of fluids however this will be paused at various time points in order to perform the echocardiogram.
Other Names:
  • crystalloid
1000 mL crystalloid
These are the measurements (aortic velocity time integral, inferior vena cava diameter, vital signs) that will be taken at time 3, at which time 1000 mL of fluids will have been administered.
Drug: lactated ringers
the intervention is one liter fluid bag of lactated ringers which is routinely used as a fluid coload for spinal anesthesia. All patients will receive the same amount of fluids however this will be paused at various time points in order to perform the echocardiogram.
Other Names:
  • crystalloid

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
aortic velocity time integral
Time Frame: at baseline measure, right after spinal placement (250mL LR), at 500mL LR infusion, and at 1 L LR infusion (approximately 20mins)
the percent change in aortic velocity time integral as measured by transthoracic echo
at baseline measure, right after spinal placement (250mL LR), at 500mL LR infusion, and at 1 L LR infusion (approximately 20mins)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
inferior vena cava collapsibility
Time Frame: at baseline measure, right after spinal placement (250mL LR), at 500mL LR infusion, and at 1 L LR infusion (approximately 20mins)
the percent change in diameter of inferior vena cava as measured by transthoracic echo
at baseline measure, right after spinal placement (250mL LR), at 500mL LR infusion, and at 1 L LR infusion (approximately 20mins)
change in systolic blood pressure
Time Frame: every 2.5 mins for 20 mins (when 1L LR is administered) once the pt has a spinal placement
percent change in systolic blood pressure
every 2.5 mins for 20 mins (when 1L LR is administered) once the pt has a spinal placement
change in heart rate
Time Frame: every 2.5 mins for 20 mins (when 1L LR is administered) once the pt has a spinal placement
percent change in heart rate
every 2.5 mins for 20 mins (when 1L LR is administered) once the pt has a spinal placement

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Baylor College of Medicine

Investigators

  • Principal Investigator: Amy Lee, MD, Baylor College of Medicine
  • Study Director: Yi Deng, MD, Baylor College of Medicine
  • Principal Investigator: Claudia Wei, MD, Baylor College of Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 25, 2020

Primary Completion (Estimated)

December 31, 2025

Study Completion (Estimated)

December 31, 2025

Study Registration Dates

First Submitted

March 28, 2020

First Submitted That Met QC Criteria

March 31, 2020

First Posted (Actual)

April 1, 2020

Study Record Updates

Last Update Posted (Actual)

April 22, 2024

Last Update Submitted That Met QC Criteria

April 19, 2024

Last Verified

April 1, 2024

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • H45744

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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