Ultrasound-guided thoracic erector spinae plane block: A modified transverse approach.

Sir,

Ultrasound-guided erector spinae plane block (ESPB) has been used for various surgical and nonsurgical analgesia since the first description of parasagittal approach by Forero et al.[1] A transverse approach to this novel technique has also been described in the literature by Hruschka et al.[2] to allow needling from lateral to medial or medial to lateral side. We describe a further modification of this transverse approach to ensure safety along with better ergonomics.

This modified transverse approach of ESPB can be performed with a patient in prone, lateral, or sitting position. The lateral decubitus offers better manipulation of probe and needle and greater comfort to the patient as well as the anesthesiologist [Figure 1a]. Our aim is to identify the transverse process (TP) directly and deposit local anesthetic (LA) into the fascial plane deep to erector spinae muscle [Figure 1b]. We begin the scout scan with a linear probe placed parasagitally in cephalocaudal orientation adjacent to C7 spinous process and the first rib is identified with ultrasound. Then, we can directly count the ribs and come down to desired level of ribs or corresponding TP. This eliminates the problem of determining level of injection by counting spinous process in thoracic region (due to different relationships of spinous process and TP). Once we are on the desired rib, the probe is rotated to a transverse orientation to visualize rib and TP in one frame. Now, lateral end of probe is slided up or down to position it in the intercostal space and the pleura is seen in place of rib. At this point, medial end of footprint of Probe is on TP. The TP and pleura are visualized at the same time with this approach [Figure 1b and c]. Under aseptic precautions, the needle (21 gauge, 80-100 mm short beveled Nerve block needle (preferably echogenic) or a Tuohy needle) is inserted and advanced in in-plane technique from lateral to medial side to contact the TP of the vertebra. After reaching the most lateral and superficial part of the TP, the needle is gradually withdrawn 1–2 mm. At this point, the correct plane is confirmed by hydrodissection and then LA is deposited below the erector spinae muscle and lifting of the erector spinae complex is seen. After negative aspiration, LA is injected in 3–5 ml aliquots. A volume of 20–25 ml of 0.25% (levo) bupivacaine or 0.2% ropivacaine with or without adjuvants can be used for analgesia on each side according to the surgery and requirements.

Figure 1

(a) Patientæs position (Lateral decubitus), probe orientation, and needle entry point. (b) Schematic of ESPB in modified transverse approach. (c) Ultrasound picture of ESPB in modified transverse approach. TM = Trapezius muscle, ESM = erector spinae muscle, LA = local anesthetic, ICM = intercostal muscles, TP = transverse process

These images are from a 42-year-old man undergoing open cholecystectomy. The patient had given consent to share photographs and medical information during preanesthesia check-up. The right TP and pleura are visualized at the same time with this approach [Figure 1a and c]. This patient demonstrated analgesia involving T4–T10 dermatomes lasting for 24 h with a single injection at T7 TP of 25 mL 0.25% bupivacaine with 8 mg dexamethasone.

The transverse approach also helps in the detection of inadvertent LA injection into erector spinae muscle as compared to parasagittal approach.[3] The drug injected in this plane spreads in the longitudinal axis to both cephalad and caudal direction over several levels depending on volume of LA. Although it seems promising, cadaveric dye study as well as randomized controlled trials is warranted to validate its spread, safety, and reliability compared to parasagittal or transverse ultrasound-guided approaches.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initial will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.