Saphenous Nerve Block for Foot and Ankle Surgery

A Comparison of Ultrasound-Guided and Ultrasound-Guided With Nerve Stimulation Saphenous Nerve Blockade Utilizing the Transsartorial Approach

Patients undergoing foot and ankle surgery have the option of having a nerve block administered by their Anesthesiologist. The nerve block numbs the foot and results in less post-operative nausea and vomiting, and better pain control. Two different techniques for blocking the saphenous nerve to the foot have been described and are both commonly used at St. Paul's hospital. The goal of this study is to compare the success rates of these two techniques.

Study Overview

• Status: Completed
• Conditions: Saphenous Nerve Block
• Intervention / Treatment: Device: Ultrasound Guidance; Device: Ultrasound guidance + nerve stimulation

Detailed Description

Purpose / Hypothesis This clinical study is a prospective, controlled, randomized, single-blinded trial designed to investigate the hypothesis that ultrasound-guided blockade of the saphenous nerve in conjunction with nerve stimulation has a higher success rate when compared to ultrasound alone. These research interventions represent what is considered to be an improvement on the standard practice at St. Paul's, which is to block the saphenous nerve with one of any number of saphenous nerve blocks, using a number of different techniques (i.e. ultrasound-guided, nerve stimulation, blind field block); the effectiveness of which has been inconsistent. The purpose of this study is to identify if one technique has a great success rate over another, which would ultimately result in increased success rates of saphenous nerve blocks and patient care.

Study Design The study will be a randomized, single-blinded trial of 80 subjects who are undergoing foot and ankle surgery. Informed consent will be obtained from all study subjects. Subjects will be randomized to one of two saphenous nerve block techniques to be administered by an experienced regional anesthesiologist at St. Paul's Hospital. Once the nerve block is completed the success will be evaluated by an investigator blinded to the procedure. Once the 30min evaluation is completed anesthetic care will be provided according to regular institutional practice and at the discretion of the attending anesthesiologist. The subject will then be contacted at 2 and 7 days after block administration to assess for delayed complications.

Intravenous access will be gained and non-invasive blood pressure measurements will be recorded every five minutes. Continuous electrocardiography and oxygen saturation monitoring will be maintained throughout the procedure and for at least 60 minutes afterwards. Light sedation will be provided, with the goal of maintaining verbal contact with the subject throughout the procedure. Where clinically appropriate, the study block may be preceded by an ultrasound-guided popliteal sciatic nerve block at the discretion of the attending anesthesiologist.

Saphenous nerve blockade will be preformed using a transsartorial approach. Subjects in both groups will be positioned prone. The ultrasound probe will be placed in the transverse plane on the medial aspect of the thigh 3-5cm cephalad to the superior border of the patella (area marked). An attempt will then be made to identify the saphenous nerve, which runs deep to the sartorius muscle within the subsartorial fascial plane. The nerve will appear hyperechoic, round or oval shaped. The anesthesiologist will have a maximum scan time of 3 minutes prior to needle entry. Up to 5 mL of 1% Lidocaine will be used for skin infiltration of the injection site. The block will then be preformed as to the protocols below depending on group allocation. A thirty minute evaluation of the saphenous nerve block will occur during the normal monitoring period after the placement of a block.

Following completion of the thirty-minute evaluation, anesthetic care will be provided according to regular institutional practice and at the discretion of the attending anesthesiologist. This may include spinal or general anesthesia.

All subjects will be contacted by telephone at two and seven days post procedure for a follow up interview to assess for delayed complications associated with the procedure.

The medications used for the nerve blocks in the study will include only ropivacaine 0.5% and lidocaine 1%. For subject sedation, midazolam and fentanyl will be used. None of these medications are considered study drugs; rather they are commonly used anesthetic medications. While used in the study, these drugs themselves are not being investigated. The same medications will be used on subjects not enrolled in the study.

Study Treatment Group 1 - Saphenous nerve block using ultrasound guidance The needle will be placed with the needle tip in close proximity (1-2 mm) of the target structures (the saphenous nerve if visible or in the subsartorial facial plane of the sartorius muscle if the nerve is not visible). A total of 10 mL of 0.5% ropivacaine will be used for the block. Before injection of any local anesthetic a gentle aspiration will be preformed, with a second aspiration after 5 mL of ropivacaine has been injected. Once injection of local anesthetic has commenced small needle adjustments are allowed to enhance spread. This will be done at the discretion of the regional anesthesiologist performing the block.

Study Treatment Group 2 - Saphenous nerve blockade using ultrasound guidance and nerve stimulation The needle will be place with the needle tip in close proximity (1-2 mm) of the target structure (the saphenous nerve if visible or in the subsartorial fascial plane if the nerve is not visible). The Pajunk MultiStim SENSOR nerve stimulator will then be turned on, starting at 1.0 milliamp (mA) until a tapping sensation is elicited in the medial or anterior aspect of the ankle. The amplitude of the nerve stimulator will then be gradually decreased with maintenance of the tapping sensation by making small adjustments in needle location. The end-point for nerve localization will be a tapping sensation in the area of the medial malleolus at ≤ 0.6 mA. The anesthesiologist will have a maximum search time of 5 minutes from needle entry to elicitation of the tapping sensation. Once a tapping sensation is elicited in the ≤ 0.6 mA range, 10 mL of 0.5% ropivacaine will be injected at the site. If a tapping sensation is elicited but not ≤ 0.6 mA within 5 minutes then 10 mL of 0.5% ropivacaine will be injected at the site where the lowest amplitude tapping sensation was elicited. If no tapping sensation is elicited from the subject after 5 minutes, an injection of 10 mL of ropivacaine will be made below the Sartorius muscle in the subsartorial fascial plane. Before injection of any local anesthetic a gentle aspiration will be preformed, with a second aspiration after 5 mL of ropivacaine has been injected. Once injection of local anesthetic has commenced small needle adjustments are allowed to enhance spread. This will be done at the discretion of the regional anesthesiologist performing the block.

• Study Type: Interventional
• Enrollment (Actual): 80
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • British Columbia
    • Vancouver, British Columbia, Canada, V6Z 1Y6
      • St. Paul's Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 19 years to 80 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

1. Subjects undergoing foot and ankle surgery
2. Aged 19-80
3. Normal sensation in saphenous nerve distribution in both legs
4. Provided written informed consent.
5. Body Mass Index <38 kg/m2

Exclusion Criteria:

1. Subject refusal
2. A known history of allergy, sensitivity or any other form of reaction to local anesthetics of amide type
3. Suspected inability to comply with study procedures, including language difficulties or medical history and/or concomitant disease (i.e. skin infection as the site of needle insertion), as judged by the investigator. Reason for exclusion will be recorded.
4. A neurological and/or vascular condition, which may preclude eligibility for peripheral nerve blockade (i.e. peripheral neuropathy) as judged by the investigator. Reason for exclusion will be recorded.
5. Subjects on therapeutic anticoagulation or coagulopathy at the time of nerve blockade.
6. Previous inclusion in this study.
7. Participation in other clinical studies during this study or in the 14 days prior to admission to this study.
8. Surgeon refusal (e.g. the surgeon does not want a nerve block for the subject). Reason for exclusion will be recorded.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Ultrasound Guidance; Saphenous nerve block placed using ultrasound guidance alone	Device: Ultrasound Guidance; Ultrasound guidance will be used to place a saphenous nerve block
Experimental: Ultrasound Guidance + nerve stimulation; Saphenous nerve block placed using ultrasound guidance and nerve stimulation	Device: Ultrasound guidance + nerve stimulation; Ultrasound guidance and nerve stimulation will be used to place a saphenous nerve block

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Block Success	Complete absence of sensation to pinprick at two different anatomic areas of the saphenous nerve at thirty minutes	30 minutes post nerve block

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Block Failure Rate	Persistent sensation in the saphenous nerve distribution at 30 minutes (i.e., absence of any evidence of blockade [decreased or complete absence of sensation] at both areas: normal sensation.	30 minutes post nerve block
Any Evidence of Blockade (Decreased or Complete Absence of Sensation)	Participants with any evidence of blockade (decreased or complete absence of sensation) at the two different anatomic areas in the distribution of the saphenous nerve (2 cm proximal to the medial malleolus and 10 cm distal to the medial tibial condyle)	30 min
Incomplete Block Rate	incomplete [decreased only] loss of sensation in the saphenous nerve distribution at 30 minutes at both areas of assessment	30 minutes post nerve block
Speed of Onset for Nerve Block (Complete Blockade)	Median (Kaplan-Meier curve "survival") time required to reach complete absence of sensation to pinprick at the two different anatomic areas of assessment in the distribution of the saphenous nerve (2 cm proximal to the medial malleolus and 10 cm distal to the medial condyle of the tibia).	30 minutes post nerve block
Rate of Success of Elicitation of a Tapping Sensation	successful elicitation of any "tapping" sensation in the saphenous nerve distribution within the 5 min stimulation time limit	5 minutes
Mean Minimum Stimulation Current	the mean minimum stimulation current magnitude to elicit "tapping" sensation in the saphenous nerve distribution (cf. 3.2.3 below)	5 minutes
Rate of Success of Elicitation of a Tapping Sensation at < 0.6 Milliampere (mA)	Successful elicitation of "tapping" sensation in the saphenous nerve distribution at ≤ 0.6 mA	5 minutes
Time Required to Administer Block	The time required for the block to be completed (from scanning to removal of needle)	10 minutes
Immediate Complications	Any complications as a result of block placement (e.g. local anesthetic toxicity, hematoma, pain etc.)	60 minutes post block completion
Delayed Complications	Any complication as a results of nerve block placement (e.g. persistent paresthesia, nerve injury)	7 days post operative

Collaborators and Investigators

• Sponsor: University of British Columbia
• Investigators: Principal Investigator: Scott Bell, MD, University of British Columbia

Publications and helpful links

General Publications

• Tsui BC, Ozelsel T. Ultrasound-guided transsartorial perifemoral artery approach for saphenous nerve block. Reg Anesth Pain Med. 2009 Mar-Apr;34(2):177-8; author reply 178. doi: 10.1097/AAP.0b013e31819a273e. No abstract available.
• Horn JL, Pitsch T, Salinas F, Benninger B. Anatomic basis to the ultrasound-guided approach for saphenous nerve blockade. Reg Anesth Pain Med. 2009 Sep-Oct;34(5):486-9. doi: 10.1097/AAP.0b013e3181ae11af.
• Head SJ, Leung RC, Hackman GP, Seib R, Rondi K, Schwarz SK. Ultrasound-guided saphenous nerve block--within versus distal to the adductor canal: a proof-of-principle randomized trial. Can J Anaesth. 2015 Jan;62(1):37-44. doi: 10.1007/s12630-014-0255-1. Epub 2014 Oct 22.
• Lopez AM, Sala-Blanch X, Magaldi M, Poggio D, Asuncion J, Franco CD. Ultrasound-guided ankle block for forefoot surgery: the contribution of the saphenous nerve. Reg Anesth Pain Med. 2012 Sep-Oct;37(5):554-7. doi: 10.1097/AAP.0b013e3182611483.
• Chen J, Lesser J, Hadzic A, Resta-Flarer F. The importance of the proximal saphenous nerve block for foot and ankle surgery. Reg Anesth Pain Med. 2013 Jul-Aug;38(4):372. doi: 10.1097/AAP.0b013e318295596a. No abstract available.
• Benzon HT, Sharma S, Calimaran A. Comparison of the different approaches to saphenous nerve block. Anesthesiology. 2005 Mar;102(3):633-8. doi: 10.1097/00000542-200503000-00023.
• Chi J, Greensmith JE. Saphenous nerve block technique with neurostimulation. Reg Anesth Pain Med. 2007 Nov-Dec;32(6):548-9. doi: 10.1016/j.rapm.2007.08.007. No abstract available.
• Comfort VK, Lang SA, Yip RW. Saphenous nerve anaesthesia--a nerve stimulator technique. Can J Anaesth. 1996 Aug;43(8):852-7. doi: 10.1007/BF03013038.
• van der Wal M, Lang SA, Yip RW. Transsartorial approach for saphenous nerve block. Can J Anaesth. 1993 Jun;40(6):542-6. doi: 10.1007/BF03009739.
• Montgomery SH, Shamji CM, Yi GS, Yarnold CH, Head SJ, Bell SC, Schwarz SK. Effect of Nerve Stimulation Use on the Success Rate of Ultrasound-Guided Subsartorial Saphenous Nerve Block: A Randomized Controlled Trial. Reg Anesth Pain Med. 2017 Jan/Feb;42(1):25-31. doi: 10.1097/AAP.0000000000000522.

Study record dates

Study Major Dates

• Study Start: February 1, 2015
• Primary Completion (Actual): October 1, 2015
• Study Completion (Actual): October 1, 2015

Study Registration Dates

• First Submitted: February 18, 2015
• First Submitted That Met QC Criteria: March 2, 2015
• First Posted (Estimate): March 9, 2015

Study Record Updates

• Last Update Posted (Actual): April 2, 2018
• Last Update Submitted That Met QC Criteria: September 6, 2017
• Last Verified: September 1, 2017

More Information

Terms related to this study

• Keywords: Nerve Block; Regional Anesthesia; Ropivacaine; Neurostimulation; Ultrasound guided; Saphenous Nerve; Foot Surgery; Nerve Stimulation; Ankle Surgery
• Other Study ID Numbers: H14-02912

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No