Popliteal Nerve Block Periprocedural Care

Informed or written consent must be obtained. The patient should have the risk and benefits discussed with them as well as the positioning and what to expect.

Needed equipment includes the following:

• An ultrasound machine with a probe of 10–12 MHz frequency.

• An 80-mm 22 gauge needle, depth 3–4 cm.

• Standard monitors: EKG, pulse oximeter, and blood pressure cuff.

• Local anesthetic to inject and for the skin wheal.

• Sterile prep, ChloraPrep preferred.

• Ultrasound gel, not necessarily sterile since needle inserted away from probe.

• Tegaderm to place on tip of probe.

• Echogenic non stimulating needles.

• An insulated stimulating needle (which can be connected to a nerve stimulator if wanted; these needles tend not to be very echogenic).

• Nerve stimulator (if wanted in adjunct to ultrasound images or if an ultrasound is not available): A 21-gauge or 22-gauge insulated needle, nerve stimulator set at 1–1.5 mA, pulse frequency of 1 Hz, and pulse duration of 0.1 msec. Attach needle to nerve stimulator and place grounder on patient.

• Local anesthetic (see Anesthesia in Patient Preparation): If a good image exists, 20 cc is all that’s necessary with the use of an ultrasound. Increasing the volume may increase the duration of the block but also increases the chance of complications. Maximum of 40 cc, also need to consider weight-based toxicity of local anesthetic used.

• Rescusitation equipment and lipid emulsion must be readily available.

Anesthesia

For surgical anesthesia in adults, a single shot of 30 cc of 1.5% mepivacaine plain provides close to immediate (5 min) to 2–3 hrs of surgical analgesia. For longer surgical anesthesia up to 3–4 hrs, 1:400,000 epinephrine is added to the solution. If a longer block is needed, adding tetracaine at 2 mg/cc (0.2%) prolongs the block to 4–6 hrs. Also consider 15 ccl of 1.5% mepivicaine with 15 cc of 0.5% bupivicaine injected, this will give you immediate surgical anesthesia and longer-acting analgesia, over 12 hours.

For longer postoperative analgesia, 0.25% ropivacaine or bupivacaine is used and should provide more than 12 hours of pain relief. ^[5] The onset is delayed from 5 minutes to about 20 minutes. This can be used for both perioperative and postoperative pain control. Once again, 20–40 cc depending on patient's weight and anatomy.

Positioning

For the popliteal block, the patient can be in 3 different positions: supine, lateral, and prone. The preferred position depends on patient comfort and the clinician’s experience.

Minimum of pulse oximetry and preferably 3- or 5-lead EKG, blood pressure cuff.

Sedation for the patient—versed and fentanyl, if patient will tolerate and if needed. Usually only needed if done before surgery. 

Oxygen by nasal cannula if patient if being sedated. 

Patients are usually monitored for at least 30 minutes after the block is done before being discharged.