Comparison of the distance of the erector spina muscle from the skin at different thoracal levels and different positions under ultrasonography.

Introduction and Purpose: With the increase in the use of USG, peripheral nerve blocks have become widespread. With the use of USG, the application of ESP block, one of the interfacial plane blocks, has also come to the fore. Facial plane blocks are used both for anesthetic purposes and in the treatment of acute and chronic pain. ESPB; It has been successfully applied for analgesia in various indications from chronic shoulder pain to hip surgery such as thoracotomy, breast surgery, cardiac surgery, vertebral surgery, cholecystectomy, inguinal hernia repair, hip surgery. ESPB can be performed in different positions (sitting-lateral-prone) and at different thoracic levels. In our study, we aimed to calculate the most ideal measurement of the distance of the erector spina muscle to the skin, accompanied by ultrasonography at different thoracic vertebral levels (T1-T2, T5-T6, T11-T12) and in different positions (lateral-sitting-prone) in order to improve the quality of block in patients who will undergo Erector Spina Plan block. we aimed. Method: This study was conducted prospectively in the Department of Anesthesiology and Reanimation, Faculty of Medicine, Harran University. The study was approved by the Harran University Faculty of Medicine Clinical Research Ethics Committee (Decision dated 06.09.2021 and numbered 21.15.13). Patients in surgeries involving the upper-middle-lower thoracic region were included in the study. ASA I-II 40 women aged 18- 65 years. A total of 80 patients, including 40 men and 40 men, participated in the study. Firstly, the patients were tied on the navel area and their right sides were sitting in an upright position, secondly, they were lying on their left sides in the lateral decubitus position, with their hands at their sides, and thirdly, their hands were extended to their sides in the prone position, their heads were turned to the left and they were on their right sides. He was examined under ultrasound guidance. Spinous processes of the relevant vertebrae (T1-T2, T5-T6, T11-T12) are determined, in lateral and prone positions, and the probe is rotated 90 degrees when the transverse process is detected by moving it 3 cm laterally until the transverse process is visible. The high-frequency 10-15 mmhz linear probe of the IC was taken to the sagittal position, and the subcutaneous tissue, rhomboid, trapezoidal ius. Erector spinae muscles were determined on the USG screen. After the erector spinae muscle and the process connected to the related vertebrae are determined, the clearest image is obtained and the distance from the upper middle point of the screen to the vertebral process is measured and recorded by freezing the USG. Thus, these different measurements are compared among themselves. Findings: A weak correlation was found between the distance of the erector spina muscle to the skin with increasing age. There is a strong relationship between the increase in BMI and the distance of the erector spina muscle to the skin (p=0.001; p<0.01). In T1-T2, T5-T6, T11-T12, the distance from the skin of the cases with prone stance was found to be significantly lower than the cases whose stance was sitting and lateral (p=0.001; p=0.001; p<0.01). In the sitting-lateral-prone positions, the distance from the skin of the cases with thoracic level T5-T6 was found to be significantly lower than the cases with thoracic level T1-T2 and T11- T12 (p=0.001; p=0.001; p<0.01). Likewise, the distance from the skin of the cases with thoracic level T1-T2 was found to be significantly lower than the cases with thoracic level T11-T12 (p=0.001; p<0.01). Conclusion: The distance of the erector spina muscle from the skin varies depending on age, weight and BMI. The distance from the skin to the skin varies according to the difference in the applied thoracic level and the difference in the application position. As a result, the erector spina muscle was found closer to the skin when the patients were in the prone position. Levels From the point of view, at the T5-T6 level, the erector spina muscle is at the closest distance to the skin. At the T11-T12 level, the erector spina muscle is at the furthest distance. As a result, an ESP block applied in the prone position and at the T5-T6 thoracic level will be easier. Key words: Erector spina plane block, erector spina muscle, peripheral nerve block, interfacial plane block.