Erector spinae plane block: Safety in altered anatomy.

Erector spinae plane block (ESPB) could be named as the new popular kid of regional anesthesia. From the first description of the method till now, it attracts clinicians’ interest for the fact that it has proved to be clinically effective in providing postoperative analgesia despite its ease of application.

In this latest issue of Saudi Journal of Anaesthesia, with the case report of Tseng et al.[1], ESP has been highlighted as an analgesia method for multiple rib fracture while it was discussed for its safety in patients with recent laminectomy surgery. Authors explained that they were concerned about epidural spread of local anesthetic (LA) because of this altered anatomy.

Main problem with ESPB is that we are still not sure about the mechanism of action besides the limits of local anesthetic distribution are still not that clear. A recent review has discussed its clinical efficacy and also its mechanism of action according to current literature.[2] Epidural, paravertebral, intercostal, extensive lateral, and longitudinal diffusion were shown as some of the explanations defined by cadaveric, anatomic, and magnetic resonance imaging studies. In spite controversial reports in the literature resulting with different conclusions, the epidural spread seems to be the most plausible explanation according to our current clinical experience. Therefore, we think that the main concern in this case with altered anatomy should not be the epidural LA spread but the catheter placement. It is a known fact that the path of the catheters is not always predictable, especially in the case of laminectomy. As it could be seen in the figure of the report of Tseng et al.,[1] the catheter bends to a different direction instead of going down vertically. Fortunately, there were no adverse effects or any reported complication. Here, we would like to suggest some tips and tricks for safer ESPB and catheter placement for this type of patients.

Different techniques have been described in the literature for both increasing the success and safety for ESPB.[3456] Hruschka et al.[5] described an in-plane transverse approach with a lateral to medial needling technique for laterally positioned patients who were unable to turn or sit because of severe pain. Recently, Narayanan et al.[6] reported the advantage of this technique. As they stated when an inadvertent intramuscular injection is done, a lamination would occur between muscle fibers with a longitudinal approach, while a circumferential spread could be observed with a transverse approach. According to Narayanan et al., both needle and catheter placement would be more accurate with transverse approach. While having agreed with the advantage of the transverse approach, we would like to give our suggestion for the direction of needle placement. Recently, Yörükoǧlu et al.[7] described bilateral ESPB with single needle entry. In this technique, the needle advanced from the midline to lateral while observing the transverse process, spinous process, and also the lamina. Like in this case, where the major concern was the increased spread of LA to epidural space, we think that this needle advancement would be better as it deposits LA away from the midline. With recalling the effects and the advantages of ESPB in patients with rib fracture by the recent study of Adhikary et al.[8] we would like to recommend ESPB application for this group of patients. In addition, in accordance with our clinical experiences, we recommend the transverse approach with advancing the needle from midline to lateral direction.