Distribution of regions of ultrasound-guided erector spinae plane block at the level of T5 transverse process

Objective To study the distribution of the regions of ultrasound-guided erector spinae plane block (ESPB) at the level of T5 transverse process. Methods Thirty male patients, aged 18-64 yr, with body mass index of 18-24 kg/m2, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective thoracotomy, were enrolled in this study.ESPB was conducted with 0.5% ropivacaine hydrochloride 0.4 ml/kg at the level of T5 transverse process under ultrasound guidance before induction of general anesthesia.Blocks in each thorax and back region (the left side of the body was divided into 18 different regions based on the anatomical landmarks on the body surface, No.1-18) were assessed by cold stimulation.Effective block in each region was recorded at 10, 15, 20, 25, 30, 40 and 50 min after administration.The adverse reactions such as pneumothorax, puncture hematoma and local anesthetic intoxication were recorded. Results The blocking range was basically fixed at 30 min after a single ESPB injection at the level of T5 transverse process, and the regions covered from the sternal angle to the level of the rib arch.The regions of effective block were No.1-3 and 5-7 in ≥95% patients, and the regions of effective block were No.1-15 and 17 in patients ≥90% and < 95%.No patients developed adverse reactions such as pneumothorax, puncture hematoma or local anesthetic intoxication. Conclusion The regions of effective ultrasound-guided ESPB at the level of T5 transverse process are mainly distributed in T2-T8 thoracodorsal skin areas. Key words: Nerve block; Back muscles; Tissue distribution