Indigenous technique for continuous perineural catheter insertion and our regime for continuous adductor canal blocks.

Sir,

Regional anesthesia is increasingly becoming important component of perioperative management of surgical patients either for surgical anesthesia or as a component of multimodal analgesia technique due to the tremendous number of benefits it offers in improving patient outcomes. One of the important advances in regional anesthesia which has widened the horizon for peripheral nerve blocks is the continuous perineural blocks (CPNBs), wherein a catheter is threaded in vicinity of nerve bundles to allow local anesthetic infusion and thus, extended benefits of regional anesthesia to the patients.[12] These techniques offer the possibility of prolonging intraoperative anesthesia as well as effective postoperative analgesia while minimizing the risks associated with systemic analgesics and central neuraxial blocks. The peripheral nerve stimulators and ultrasound (USG) aid in precise placement of these catheters in relation to the neural bundle.[12] The catheter placement techniques that are currently used to place the CPNBs are the nonstimulating catheter technique described by Steele et al.[3] and the stimulating catheter technique described by Sarnoff.[4] These involve the use of a stimulating needle with either stimulating or nonstimulating catheters with a stimulating nerve block needle. Typically, the procedure is done using the commercially available equipment (e.g., Contiplex Tuohy needle system, B Braun Melsungen AG, Melsungen, Germany). Nonavailability of the equipment and its high cost is one of the main deterrents to use of continuous blocks.

For USG-guided blocks, nerve stimulation is not a prerequisite. Hence, use of only a needle with suitable catheter can suffice. Tuohy needle and epidural catheter used for epidural block can there be used for continuous catheter technique using USG. Passage of the catheter in proximity to the plexus can be visualized, thereby ensuring a precise placement. We have devised an indigenous technique of continuous nerve block using Tuohy needle [Figure 1]. The equipment required includes 18G Tuohy needle with catheter set, a three-way connector, an extension tubing, an elastometric pump or battery-operated mechanical pumps (when the former is not available or ambulation is not desired), normal saline for hydrodissection, local anesthetic agent (bupivacaine 0.5%/ropivacaine 0.75%), USG machine with suitable probes, and sterile cover for USG probe. We use extension tubing of the stimulating nerve block needles which have been sent for re-sterilization after use by ethylene oxide (ETO). We are routinely using continuous adductor canal blocks for postoperative analgesia in total knee arthroplasty patients. After aseptic preparation and draping of the block site and the USG probe (38-mm linear array transducer, Imagic Agile, Kontron medical, Peachtree city, GA, USA), the adductor canal is visualized in a short-axis view, and the 18G Tuohy needle (Perifix® continuous epidural set, B Braun Melsungen AG, Melsungen, Germany) is advanced in plane toward the adductor canal below the sartorius muscle. Appropriate positioning is confirmed with saline hydrodissection and bolus dose of local anesthetic (16-mL ropivacaine 0.75%) is injected through the extension tubing. Following this, the three-way is turned to the other side and the epidural catheter is advanced 3–5 cm beyond the needle tip. Many-a-times, the catheter gets stuck at the 15-cm mark (corresponding to the tip of Tuohy needle). At this moment, flattening the Tuohy needle, rotating the bevel clockwise or counterclockwise has helped us in majority of cases. Two persons should perform the procedure with one person stabilizing the needle while other performs the injections and threads the catheters. The catheter can be seen jetting out of the Tuohy needle, which confirms its proper placement. Additionally, catheter tip location is confirmed by “air test” (injecting 0.5 mL of air through the catheter under USG).[5] Catheter is carefully aspirated to rule out intravascular placement and 1–2 ml of saline is injected to ensure its free flow through the catheter. Following this, the Tuohy needle is taken out and the catheter is secured in place using a sterile, clear occlusive dressing. The catheter is then connected to elastometric pump (DOSI-FUSER®, Leventon, S.A.U.) containing 0.2% ropivacaine infused at the rate of 3 mL/h, which can be increased to a maximum of 7 mL/h depending on patient response. In addition, all patients received local infiltration analgesia (periarticular injections of ropivacaine 0.2% (70 mL) with epinephrine and ketorolac) at the conclusion of surgery before wound closure. In our experience, this regime has been very effective for postoperative analgesia post-TKR and most patients stay comfortable with only nonopioids, e.g., paracetamol and diclofenac.

Figure 1

(A) Epidural catheter; (B) three-way connector; (C) Tuohy needle; and (D) extension tubing

Attaching and detaching the syringes before catheter threading can lead to needle tip movement and misplacement of the catheter. The advantage of this technique is multifold, i.e., continuous nerve block using easily available equipment, simultaneous hydrodissection using immobile needle technique to aid in correct needle placement and local anesthetic injection with low risk of needle movement or disconnection.

To conclude, this indigenous setup for continuous USG-guided perineural nerve block can be effectively used for providing patients the benefit of continuous nerve blocks when commercial sets are unavailable or cost is prohibitive.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.