Preventing the Obturator Nerve Reflex

This study is not yet open for participant recruitment.

Verified March 2012 by Milton S. Hershey Medical Center

Sponsor:

Information provided by (Responsible Party):

Jonathan Anson, Milton S. Hershey Medical Center

ClinicalTrials.gov Identifier:

NCT01547637

First received: February 29, 2012

Last updated: March 7, 2012

Last verified: March 2012

History of Changes

Purpose

The key objective of this study is to compare success rates of ultrasound guided obturator nerve block and anatomic landmark guided obturator nerve block as determined by neuromonitoring endpoints and surgeon observations.

Condition	Intervention
Bladder Injury	Procedure: Obturator nerve block

Study Type:	Interventional
Study Design:	Allocation: Randomized Endpoint Classification: Efficacy Study Intervention Model: Parallel Assignment Masking: Single Blind (Outcomes Assessor) Primary Purpose: Treatment
Official Title:	Preventing the Obturator Nerve Reflex: A Comparison of Ultrasound Guided Obturator Nerve Block and Classic Anatomic Block Technique.

Further study details as provided by Milton S. Hershey Medical Center:

Primary Outcome Measures:

Nerve conduction velocity [ Time Frame: 1 day ] [ Designated as safety issue: Yes ]
Neuromonitoring technician will measure and record obturator nerve conduction velocity in pre-defined time intervals after performance of obturator nerve block.

Estimated Enrollment:	45
Study Start Date:	May 2012
Estimated Study Completion Date:	May 2012
Estimated Primary Completion Date:	May 2012 (Final data collection date for primary outcome measure)

Arms	Assigned Interventions
Experimental: Ultrasound Guided Ultrasound guided obturator nerve block will be performed after induction of general anesthesia. The anterior and posterior divisions of the obturator nerve will be identified with ultrasound. A stimulating needle will be inserted under direct ultrasound visualization. The anterior division will be blocked first. When adductor twitches are present at less than or equal to 0.5 mA, 10 ml of 2% lidocaine will be injected. Next, the needle will be re-directed under direct ultrasound visualization towards the posterior branch of the obturator nerve. After twitches < 0.5 mA are achieved then 10 mL of 2% lidocaine will be injected when the needle tip is visualized in proximity of the posterior branch.	Procedure: Obturator nerve block Ultrasound guided peripheral obturator nerve block Other Name: ultrasound guided obturator nerve block
Experimental: Anatomic landmark Obturator nerve block will be performed after induction of general anesthesia. The adductor magnus tendon approach will be used. A 4 cm insulated stimulating needle will be used to verify location of the obturator nerve by contraction of the thigh adductor group. The needle will be advanced until nerve stimulation is still present at less than or equal to 0.5 mA. When the appropriate nerve stimulation is achieved 10 ml of 2% lidocaine will be injected in divided doses with frequent aspiration. Nerve conduction studies will be repeated once a minute for the first 10 minutes after block completion.	Procedure: Obturator nerve block Peripheral obturator nerve block using 10 ml of 2% lidocaine Other Name: anatomic obturator block

Arms

Assigned Interventions

Experimental: Ultrasound Guided

Ultrasound guided obturator nerve block will be performed after induction of general anesthesia. The anterior and posterior divisions of the obturator nerve will be identified with ultrasound. A stimulating needle will be inserted under direct ultrasound visualization. The anterior division will be blocked first. When adductor twitches are present at less than or equal to 0.5 mA, 10 ml of 2% lidocaine will be injected. Next, the needle will be re-directed under direct ultrasound visualization towards the posterior branch of the obturator nerve. After twitches < 0.5 mA are achieved then 10 mL of 2% lidocaine will be injected when the needle tip is visualized in proximity of the posterior branch.

Procedure: Obturator nerve block

Ultrasound guided peripheral obturator nerve block

Other Name: ultrasound guided obturator nerve block

Experimental: Anatomic landmark

Obturator nerve block will be performed after induction of general anesthesia. The adductor magnus tendon approach will be used. A 4 cm insulated stimulating needle will be used to verify location of the obturator nerve by contraction of the thigh adductor group. The needle will be advanced until nerve stimulation is still present at less than or equal to 0.5 mA. When the appropriate nerve stimulation is achieved 10 ml of 2% lidocaine will be injected in divided doses with frequent aspiration. Nerve conduction studies will be repeated once a minute for the first 10 minutes after block completion.

Procedure: Obturator nerve block

Peripheral obturator nerve block using 10 ml of 2% lidocaine

Other Name: anatomic obturator block

Detailed Description:

Transurethral resection of bladder tumor (TURBT) is a urologic surgery used in the treatment of non-muscle invasive bladder cancer. A potential complication of this procedure is bladder rupture or injury secondary to adductor muscle contraction from obturator nerve stimulation. This risk is increased in resection of lateral wall tumors, as electrosurgical resection of these lesions is more likely to inadvertently stimulate the obturator nerve.

There are several mechanisms for preventing the obturator reflex. Pharmacologic paralysis can reliably inhibit thigh adduction. However, TURBT is often a short procedure that is not amendable to intermediate duration neuromuscular blocking medications. The use of succinylcholine is another option but is limited by its short duration of action which may not be adequate for the time needed to resect the tumor. Additionally, many patients have contraindications to the use of succinylcholine. Spinal anesthesia does not reliably prevent the obturator reflex.

Regional anesthesia is another potential treatment modality to prevent the obturator reflex during TURBT. Motor blockade of the obturator nerve will prevent this adduction in the event of inadvertent nerve stimulation. Peripheral blockade of the obturator nerve can be combined with either general or spinal anesthesia. Historically, obturator nerve block (ONB) has been considered a technically challenging procedure. Recently, however, successful ultrasound guided ONB techniques have been reported. To the best of our knowledge there has been no study to date comparing the effectiveness of ONB achieved by anatomic landmarks (with nerve stimulation) versus ultrasound guided ONB (with nerve stimulation) at preventing the obturator reflex during TURBT surgery.

The key objective of this study is to compare success rates of ultrasound guided obturator nerve block and anatomic guided obturator nerve block as determined by neuromonitoring endpoints and surgeon observations.

Eligibility

Ages Eligible for Study:	35 Years and older
Genders Eligible for Study:	Both
Accepts Healthy Volunteers:	No

Criteria

Inclusion Criteria:

Patients undergoing TURBT for lateral wall bladder tumors at risk for electrical stimulation as determined by the attending surgeon.

Exclusion Criteria:

Pre-existing obturator nerve injury
Thigh adductor muscle weakness
Neuropathy
Local anesthetic allergy
Infection at the site of injection
Abnormal coagulation studies
use of neuromuscular blocking medications (if deemed necessary by attending anesthesiologist caring for the patient).

Contacts and Locations

Please refer to this study by its ClinicalTrials.gov identifier: NCT01547637

Locations

United States, Pennsylvania
Penn State Milton S. Hershey Medical Center	Not yet recruiting
Hershey, Pennsylvania, United States, 17033
Contact: Jonathan A Anson, MD 717-531-6597 janson@hmc.psu.edu
Principal Investigator: Jonathan A Anson, MD

Sponsors and Collaborators

Milton S. Hershey Medical Center

Investigators

Principal Investigator:

Jonathan A Anson, MD

Milton S. Hershey Medical Center

More Information

No publications provided

Responsible Party:	Jonathan Anson, Assitant professor of Anesthesiology, Milton S. Hershey Medical Center
ClinicalTrials.gov Identifier:	NCT01547637 History of Changes
Other Study ID Numbers:	Not Assigned yet
Study First Received:	February 29, 2012
Last Updated:	March 7, 2012
Health Authority:	United States: Institutional Review Board

Keywords provided by Milton S. Hershey Medical Center:

Obturator nerve block
Regional anesthesia
TURBT

ClinicalTrials.gov processed this record on May 19, 2013

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