Ultrasound Evaluation of Inferior Vena Cava Compression During Elective Cesarean Delivery.

Ultrasound Evaluation of Inferior Vena Cava Compression During Elective Cesarean Delivery. Comparison of Tilt Versus No Tilt Positioning.

Aortocaval compression by the gravid uterus during the third trimester contributes to decreased venous return to the heart. Neuraxial anesthesia reinforces this hypotension by causing a vasodilatation and venous pooling of blood in the lower limbs. The current practice is to tilt the parturient 15 degrees on the operating table after neuraxial anesthesia in order to decrease this hypotension. Recent meta-analysis suggests there is no conclusive evidence to support the tilt position. The goal of our study is to compare ultrasound vena cava variation measurements in the supine versus the tilt position in third trimester parturients undergoing elective cesarean delivery.

Study Overview

• Status: Completed
• Conditions: Cesarean Section Complications

Detailed Description

Cesarean delivery (CD) is one of the most currently practiced surgeries in the world. In 2013, surgical deliveries represented 32.4% of births in the United States and 26.9% in Canada. Maternal hypotension is a frequent adverse event during CD under spinal anesthesia and can be detrimental to the fetus and mother. Many means have been studied to decrease the incidence of hypotension in this context such as crystalloid/colloid pre-loading and co-loading, vasopressors, and positioning.

Aortocaval compression of the inferior vena cava (IVC) by the gravid uterus is a major contributor to this hypotension and many positions on the operating table have been researched to decrease its influence.Current recommendations for term women undergoing cesarean delivery include left lateral 15 degree tilt in order to reduce aortocaval compression which may cause maternal hypotension and fetal compromise. However, a recent meta-analysis did not show conclusive evidence to favour the tilted versus the supine position. This is probably due to a compensatory mechanism involving venoconstriction of the lower limbs, raising venous pressure and causing flow through collateral channels. Supine hypotensive syndrome with clinically significant effects occurs in 8-10% of women at term, possibly due to less compensatory mechanisms.

Respiratory variations of the IVC diameter measured by an ultrasound may determine the best position on the operating table for term parturients during cesarean delivery. Large variations of IVC diameter during expiration and inspiration have been shown to be related to hypotension in non-pregnant patients.

The primary objective of our project is to compare the collapsibility index of the inferior vena cava during elective cesarean delivery after the administration of spinal anesthesia with a phenylephrine infusion. Each participant will be their own control.

20 patients scheduled for elective cesarean delivery will be included. Each participant will be her own control for the ultrasound measurements of the inferior vena cava, with and without a tilt before and after spinal anesthesia with a phenylephrine infusion. A transcutaneous oximetry monitor (NIRS) will be used in order to measure the upper versus lower body saturation difference. The newborn Apgar score and umbilical cord pH will be noted.

• Study Type: Observational
• Enrollment (Actual): 20

Contacts and Locations

Study Locations

• Canada
  • Quebec
    • Montréal, Quebec, Canada, H1T2M4
      • Maisonneuve-Rosemont

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Female

• Sampling Method: Non-Probability Sample

Study Population

Third trimester parturients with a normal pregnancy and a planned cesarean delivery under spinal anesthesia

Description

Inclusion Criteria:

• ASA 1-2
• Elective cesarean delivery
• Spinal anesthesia
• At least 37 weeks of gestational age
• French speaking patients (able to read and sign the consent form)

Exclusion Criteria:

• Inability to obtain adequate ultrasound mesures before or after spinal anesthesia
• Cardiopathy
• Unexpected difficult spinal anesthesia requiring general anesthesia
• Unexpected complications requiring strong hemodynamic support (transfusions, volume challenges, multiple vasopressors, inotropic drugs...) or requiring anti-hypertensive medication (including magnesium)
• Any contraindication or patient's refusal for spinal anesthesia (e.g. coagulopathy)
• Morbid obesity (IMC over 40 at the time of delivery)
• Active labour
• Emergency cesarean delivery
• Fetal abnormality or prematurity (under 37 weeks of gestational age)
• Multiple gestation
• Inability to cooperate due to langage or physical/mental incapacity

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Control
• Time Perspectives: Prospective

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Collapsibility index of the inferior vena cava after spinal anesthesia.	Comparison of the collapsibility index of the inferior vena cava with and without a tilt after spinal anesthesia.	Day 0

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Collapsibility index of the inferior vena cava before spinal anesthesia.	Comparison of the collapsibility index of the inferior vena cava with and without a tilt before spinal anesthesia.	Day 0
Calf versus arm transcutaneous saturation	Comparison of the calf versus arm transcutaneous saturation values in the tilt versus supine positions before and after spinal anesthesia	Day 0
Impact of the tilt versus no tilt positioning on the Apgar score	Comparison of the Apgar scores of the newborn in regards to the mother's position on the operating table during the C-section: tilt versus supine.	1 hour
Impact of the tilt versus no tilt positioning on the umbilical cord pH	Comparison of the umbilical cord pH of the newborn in regards to the mother's position on the operating table during the C-section: tilt versus supine.	1 month

Collaborators and Investigators

• Sponsor: Ciusss de L'Est de l'Île de Montréal
• Investigators: Principal Investigator: Valerie Zaphiratos, MD, CIUSSS de l'Est de l'Ile de Montréal

Publications and helpful links

General Publications

• Gagne MP, Richebe P, Loubert C, Drolet P, Gobert Q, Denault A, Zaphiratos V. Ultrasound evaluation of inferior vena cava compression in tilted and supine term parturients. Can J Anaesth. 2021 Oct;68(10):1507-1513. doi: 10.1007/s12630-021-02051-w. Epub 2021 Jul 1.

Study record dates

Study Major Dates

• Study Start (Actual): January 29, 2018
• Primary Completion (Actual): March 31, 2018
• Study Completion (Actual): March 31, 2018

Study Registration Dates

• First Submitted: January 18, 2018
• First Submitted That Met QC Criteria: January 24, 2018
• First Posted (Actual): January 25, 2018

Study Record Updates

• Last Update Posted (Actual): April 14, 2021
• Last Update Submitted That Met QC Criteria: April 12, 2021
• Last Verified: April 1, 2021

More Information

Terms related to this study

• Other Study ID Numbers: 2018-1196

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