Agreement Between Laterality of Tsui Test and Laterality of Color Flow Doppler Signals During Labor Epidural Analgesia

Agreement Between Laterality of Tsui Test and Laterality of Color Flow Doppler Signals During Labor Epidural Analgesia: a Prospective Observational Study

Epidural analgesia for relief of labor pain is a very common, safe and reliable technique that requires placement of a catheter in the epidural space. About 5% of labor epidural catheters may need to be re-sited due to failure of analgesia. This is often caused by malposition of the epidural catheter. Many factors may influence the position of the tip of the epidural catheter and the resulting spread of local anesthetic solution within the epidural space and consequently the quality of labor pain management. The electrical stimulation of the epidural catheter, commonly known as Tsui test, can reliably confirm its positioning within the epidural space if this stimulus produces a muscular twitch under a certain current amplitude threshold. This muscular response is unilateral in 90% of the cases, not having any relationship between unilaterality and unsatisfactory catheter performance. It is unknown if this unilateral response has any correlation with the actual position of the catheter tip in terms of right or left side of the epidural space. Furthermore, the Tsui test does not give any information on the spread of anesthetic solution into the epidural space. Recent investigation shows that color flow doppler ultrasound during fluid injection through the epidural catheter may be helpful in determining the laterality of the tip of the epidural catheter; furthermore it may be able to inform about the spread the anesthetic solution, which is a limitation of the Tsui test. The investigators will perform an observational study to investigate the response patterns of Tsui test and Color flow Doppler ultrasound in the obstetric population. Women who have delivered under epidural analgesia will be approached for the study before the epidural catheter is removed. The investigators aim to characterize the laterality and current thresholds of Tsui test response and the laterality of the lumbar epidural catheter tip by color doppler ultrasound. The investigators hope to describe the findings and to correlate them with other clinical outcomes.

Study Overview

• Status: Completed
• Conditions: Labor Pain
• Intervention / Treatment: Device: Doppler ultrasonography; Device: Tsui test

• Study Type: Observational
• Enrollment (Actual): 25

Contacts and Locations

• Study Contact: Name: Jose CA Carvalho, MD; Phone Number: 2681 416-586-4800; Email: jose.carvalho@sinaihealth.ca

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5G1X5
      • Mount Sinai Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 55 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Female

• Sampling Method: Non-Probability Sample

Study Population

Women who have delivered vaginally under epidural analgesia will be approached for the study before the epidural catheter is removed.

Description

Inclusion Criteria:

• Patients who have delivered vaginally under epidural anesthesia

Exclusion Criteria:

• Patients who refuse, are unable to give or have withdrawn consent
• Patients unable to communicate fluently in English.
• Patients who experience fetal or maternal complications during delivery.

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Patients who had an epidural placed for labour; Patients who had an epidural placed for labour may take part. Study procedures will take place after delivery and prior to removal of the epidural catheter.	Device: Doppler ultrasonography; color flow Doppler ultrasonography; Device: Tsui test; The stimulator is set at frequency of 1Hz with 0.2 msec pulse width and the current output ranging from 0 to 20 mA. The current output will be carefully increased from zero until motor activity is detected up to a maximum of 20 mA.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Tsui test motor response: questionnaire	Tsui test motor response will be recorded as either: left, right or bilateral	5 minutes
Colour flow Doppler ultrasound assessment: questionnaire	Colour flow Doppler ultrasound assessment will be recorded as either: left, right or bilateral	5 minutes

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Tsui test current threshold amplitude	Epidural catheter stimulation will be performed in all patients with a 0.2 msec pulse width and 1 Hz frequency. The current will be increased from 0 mA until a motor response is observed or until the maximum current of 20 mA is reached.	5 minutes
Tsui test motor response dermatome: abdomen, thigh, leg, feet	The muscle group involved in the response will be documented as: abdomen, thigh, leg, feet. Whether right, left or bilateral will also be recorded.	5 minutes
Location of epidural catheter tip flow as detected by Doppler	Location (interspace) of epidural catheter tip flow as detected by Doppler.	5 minutes
Need for catheter mobilization: questionnaire	The need for catheter mobilization, including replacement (at any time after it is placed) will be documented as yes or no.	12 hours
Presence of asymmetric block: questionnaire	The presence of asymmetric block (>=2 segments difference) will be documented as yes or no.	12 hours

Collaborators and Investigators

• Sponsor: Samuel Lunenfeld Research Institute, Mount Sinai Hospital

Study record dates

Study Major Dates

• Study Start (Actual): June 8, 2022
• Primary Completion (Actual): January 30, 2023
• Study Completion (Actual): January 30, 2023

Study Registration Dates

• First Submitted: March 7, 2022
• First Submitted That Met QC Criteria: March 7, 2022
• First Posted (Actual): March 16, 2022

Study Record Updates

• Last Update Posted (Estimate): February 23, 2023
• Last Update Submitted That Met QC Criteria: February 22, 2023
• Last Verified: February 1, 2023

More Information

Terms related to this study

• Keywords: ultrasound; epidural analgesia; labor epidural; Doppler; epidural catheter; Tsui test
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Labor Pain
• Other Study ID Numbers: 22-01

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No