Different Approaches Of Serratus Anterior Muscleblock Guided By Ultrasound Study On Diffusion Distribution And Analgesic Effect Of Local Anesthetics

Part Ⅰ:Study on diffusion and distribution of local anesthetics of ultrasound-guided anterior serratus muscle block via different approachesObjective:To observe the diffusion and distribution of local anesthetics by CT scanning and three-dimensional reconstruction after the performance of anterior serratus muscle block via different approaches in pulmonary nodule patients undergoing CT-guided puncture and localization,so as to provide imaging reference for anterior serratus plane block.Methods:The subjects of the study were 36 patients who required elective thoracic surgery for CT-guided puncture and localization of pulmonary nodules in the Second Affiliated Hospital of Soochow University from July 2021 to December 2021.The included patients were 18-75 years old,had ASA classification of grade Ⅰ-Ⅱ and BMI of ≤30 kg/m2.According to different approaches,the enrolled patients were divided into three groups:the anterior axillary line approach group,mid-axillary line approach group and posterior axillary line approach group for anterior serratus muscle block.Under the guidance of ultrasound,all patients in the three groups underwent in-plane needle insertion at the level of the 6th rib to perform a corresponding plane block using the block solution of 0.25%ropivacaine(20 ml)containing 30mg/ml of iohexol.Furthermore,the diffusion of local anesthetics containing contrast agents was studied based on CT three-dimensional reconstruction.Results:There was no significant difference among the three groups in the average age,gender,BMI and the average diameter of nodules(all P>0.05).According to the CT imaging,no drug liquid penetrated corresponding muscular spaces and diffused to the deep or superficial part.Meanwhile,within the diffusion range of local anesthetics of the anterior serratus muscle,both superficial block and deep block could realize better diffusion.Among them,the diffusion range of superficial block anesthetics through the posterior axillary line approach(R4～R8)was the largest,followed by deep block via the posterior axillary line approach(R5～R8)and deep block via the anterior axillary line approach(R4～R7);and superficial block via the anterior axillary line approach(R4～R6),superficial block via the mid-axillary line approach(R6～R8)and deep block(R5～R7)were the last.Conclusion:For the ultrasond-guided serratus anterior plane block at the level of the sixth rib;1.the diffusion range of the drug solution in the posterior axillary line approach was wider than that in the anterior axillary line and the midaxillary line;2.the diffusion range of the drug solution in the superficial block was wider than that in the deep block.Part Ⅱ:Study on the analgesic effect of local anesthetics of ultrasound-guided anterior serratus muscle block via different approachesObjective:To explore the analgesic effect of local anesthetics of ultrasound-guided anterior serratus muscle block via different approaches based on the results of Part Ⅰ,so as to provide a potential reference for pain intervention during thoracic surgery clinically.Methods:The subjects of the study were 120 patients who required elective thoracic surgery for CT-guided puncture and localization of pulmonary nodules in the Second Affiliated Hospital of Soochow University from July 2021 to December 2021.The included patients were 18-75 years old.had ASA classification of grade Ⅰ-Ⅱ and BMI of ≤30 kg/m2.According to different approaches,the enrolled patients were divided into three groups:the anterior axillary line approach group,mid-axillary line approach group and posterior axillary line approach group for anterior serratus muscle block.Under the guidance of ultrasound,all patients in the three groups underwent in-plane needle insertion at the level of the 6th rib to perform a corresponding plane block using the block solution of 0.25%ropivacaine(20 ml).Furthermore,the diffusion of local anesthetics containing contrast agents was studied based on CT three-dimensional reconstruction.The scores by using the visual analog scale(VAS)of pain were recorded and compared at the three-time points during puncture and localization when changing body position and at rest.In addition,the range of decline in temperature sensation in each group was determined and compared using the coated ice measurement method,in which the transparent film was attached to the patients’ body surface and the ice was used to slide on the film to record and measure the area coverage with temperature change perceived by the patients.Results:There was no significant difference among the three groups in the average age,gender.BMI and the average diameter of nodules(all P>0.05).Meanwhile,no statistically significant difference was found in VAS scores of superficial block and deep block via different approaches(all P>0.05).When changing body position and at rest,the VAS score of the posterior axillary line approach was lower than that of the anterior axillary line and mid-axillary line approach,and the VAS score of the deep block was lower than that of the superficial block,with statistically significant differences(all P<0.05).Furthermore,the posterior axillary line approach had the largest range of decline in temperature sensation,and the superficial block was superior to the deep block,with statistically significant differences(all P<0.05).Besides,in the three groups,4 patients had nausea and vomiting,and 2 patients had hematoma at the puncture site;and there was no pneumothorax or other related complications,without statistically significant differences(all P>0.05).Conclusion:For the ultrasond-guided serratus anterior plane block at the level of the sixth rib;1.The VAS score and hypothermia range of the retroaxillary approach were better than those of the anterior and midaxillary approach;2.The VAS score of deep block in the retroaxillary approach was lower than that of superficial block.