US- Guided Femoral Nerve Block

Hi everyone,

Hope everyone is having great holidays!! It's been busy at the new site I have been for the past month. Even though I only do about 4 cases a day unlike 7-8 at the last site, there is still a lot of running around. In all this busy work, I have had some great opportunities to learn how to place femoral nerve blocks using ultrasound (US). Still no where near being an expert at using the US, I have learned to get through it using a few resources like NYSORA website and RKU compact app. The site I am uses a lot of these continuous fem blocks (in conjuction with spinals and TIVA) for post op knee surgeries. So I decided to write a little bit about how I have been taught to place one. I also attached a video for the visual. 

Preoperative :

1) Ensure correct patient and the location of surgery. Check for allergies

2) Check consent. Only absolute contraindication for regional block is patient refusal

3) Equipment: Continuous FNB Tray (2-4mm stimulating needle), dermabond if available, EKG pad for nerve stimulator, sterile gloves. Medications to include Versed and Fentanyl, monitors ( spo2), Ropivacaine 0.5% = 30ml (or similar alternative), another RN or CRNA for assistance. Emergency equipment

4) Inform patient about the procedure. 

Procedure: 

5) Connect monitors, give versed and fentanyl as appropriate. Expose groin/ inguinal area on correct side

6) Don sterile gloves after opening Kit.

7) Prep site with chloroprep as place drape. Prepare local 1% Lidocaine and open femoral Catheter and place it on the sterile portion of drape for easy access.

8) Drop end of the extension cord for assistant to connect and flush stimulating needle with local anesthetic. Do the same to connect nerve stimulator at turn on at 2mA

9) Set up US probe by adding lubricant in the sterile sleeve provided and covering the unsterile probe with sterile sleeve with the help of assisting RN.

10) Place remaining sterile lube at site and orient self to US. Make sure the probe side on your end and on the US screen are matching to avoid confusion.
11) Identify anatomy in the inguinal region. Vein, artery, nerve (medial to lateral). Vein is more compressible when pressure is applied with the probe. Also, identify the two fascias, fascia lata and fascia iliaca that present as white lines under US. Two distinctive "pops" must be observed as these fascias are penetrated.
12) Once structures have been identified, nerve stimulating needle is inserted at 2 mA and patellar "snap" is identified. The bevel of the needle should be facing towards the patients head to ease guiding the catheter. A medial sartorius twitch may by corrected by repositioning the stimulating needle more lateral. Negative aspiration for blood is confirmed as needle is moved. Patellar "snap" should be present up to 0.5 mA of voltage. If still present under 0.2 mA then the needle should be withdrawn slightly as it may be too close to the nerve bundle.

13) When patellar "snap" has been identified and a good view of the needle is seen on the US, 5 cc increments of local anesthetic are injected with periodic checks for negative aspiration.
14) Correct placement of local anesthetic can also be confirmed with the US. Once injected, the needle should be held stable and injecting catheter should be disconnected so that the catheter can be threaded.
15) Correct marking for the catheter may vary but is generally placed at the 15 mark. The catheter cap is applied and it can then be secured with a tegaderm dressing.

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