Notes from the Palo Alto VA CPNB Course

 

Ta Prohm - photo by JoAnn Sturman

Scott Sturman, M.D.

General Considerations:

Although the course emphasized the merits of CPNB, a number of points were made which apply to single shot PNB techniques, as well.

In this VA center ultrasound guided nerves blocks are the norm, and nerve stimulation is seldom used.  In most cases the longer linear probe is used for both upper and lower extremity blocks.  The 20 gauge Tuohy needle is preferred for single shot procedures, while the 17 gauge Tuohy is reserved for continuous blocks.  The larger caliber and lack of an insulated coating make the needle more visible, while the blunt tip is thought to be less likely to damage nerves.  With the larger orifice it is easier to determine if the injection pressures are truly high and not a result of attempting to empty a 20 ml syringe via a 22 gauge needle.

Although an epidural kit with a 17 gauge Tuohy and floppy catheter can be used, the center coordinated with Arrow to construct a kit which contains only the equipment necessary for the block, including a Stat Lock for the epidural catheter.

When blocking the lower extremity, fall prevention is of great concern.  In fact no patient is sent home with a lower extremity block unless they are “non weight bearing.”  The Morse Fall Scale Assessment is routinely used by the staff.

Prior to surgery all patients receive an information sheet from the surgeon’s office describing the nerve block they will receive during the peri operative period.  The consent process allows for the anesthesiologist to perform the nerve block prior to surgeon arrival, since the surgeon or a designee can confirm the procedure and mark the patient.  For further patient education, the anesthesia department devotes a portion of their web site to information regarding regional anesthesia. 

Clinical Recommendations:

The blocks follow a rigid protocol which rely heavily on CPNB.  Sterile gloves and draping are standard, but gowns are not.  Patients receive Mepivacaine 1.5% initially followed by a catheter infusing Ropivacaine 0.2%, generally at 6-8 cc/hr.  Faculty at the center prefer to avoid prolonged dense motor blocks and rarely use bupivacaine or ropivacaine.  No additives are combined routinely with the local anesthetic.

For both single shot and continuous blocks the short axis-in plane technique is used.  Only two blocks require tunneling to secure the catheter–the FICB and the adductor canal block.

The following are some Tricks of the Trade which are used at the Palo Alto VA:

When preforming the SCB, be sure to inject below the brachial plexus near the first rib to block C8-T1.

The brachial plexus is more easily instrumented from the ICB approach by having the patient abduct the upper arm 90 degrees and bend the elbow 90 degrees placing the palm near the head facing upwards.  This makes the course of the subclavian-axillary artery nearly a straight line and easier to locate.

Both the subcostal and inferior TAP blocks require the needle to enter the skin at a 45 degree angle.  Note the depth of the target on ultrasound examination, then plan the needle entry point that same distance from the center of the probe.

The FICB is accessed only 2-3 centimeters lateral to the femoral nerve.  The fascia iliaca is identified in relation to the nerve, then the probe is moved laterally keeping the fascial plane in sight.  The probe is then rotated 90 degrees and the local anesthetic injected superiorly.

The center’s TKA protocol curiously uses general anesthesia in conjunction with multimodal RX, intra operative wound infiltration with 150 cc of Ropivacaine 0.2%, and continuous adductor canal block.

The sciatic nerve block at the popliteal is managed in the prone position.  Even with appropriate placement of the local, the block is notorious for its slow onset. 

Billing:

The is no distinction made between IV general anesthesia and inhalational anesthesia.  Therefore, the block is billed for post op pain RX and not the primary anesthetic, as long as the IV anesthesia is sufficiently deep to warrant the distinction of IV general anesthesia.

Internet Information:

Lastly, another web site resource was recommended which addresses pertinent issues and serves as another resource for regional anesthesia information.

Ultrasoundblock

 Tibet - photo by JoAnn Sturman