Objective To study clinical data retrospectively and demonstrate the optimal injection site of adductor canal block by performing a cadaveric study.Methods Clinical part:clinical data from 19 patients,11 males and 8 females,aged 21 85 years,ASA physical status Ⅰ-Ⅲ,who received ultrasound guided adductor canal block were retrospectively collected.Among whom 9 received a mid-distance injection of 10 ml of 0.5％ ropivacaine and 10 received an injection of the same medication at the outlet of adductor canal.The primary endpoint was complete absence of cold sensation to ice cube on the medial side of calf at 30 minutes and 24 hours after injection.Cadaveric part:40 lower limbs,20 males and 20 females,were finally analyzed in the study.The distances from the anterior superior iliac spine (ASIS) to the medial tibial condyle,from ASIS to the entrance of the adductor canal,from ASIS to the exit of the canal (adductor tendinous opening),from ASIS to the site where sa phenous nerve emerges through the aponeurotic covering were measured respectively.The length of adductor canal,the relative location of adductor canal and the site where saphenous nerve pierces in the lower limbs were calculated.Results Clinical part:all 19 cases were successfully recorded with complete absence of cold sensation at 30 minutes after injection of local anesthetic and complete sensory recovery at 24 hours after injection.Cadaveric part:in all specimens,saphenous nerve enters adductor canal and coursed down until emerging at very close to the distal end of the canal with the saphenous branch of descending genicular artery.The length of the adductor canal was (10.0±2.1) cm.The entrance and the exit of adductor canal and the emerging site of the saphenous nerve located along the (54.7±3.0) ％,(76.0％±3.8) ％ and (74.1±3.2) ％ of sartorius muscle,respectively.Conclusion Performing ultrasound-guided adductor canal block at either the outlet of adductor canal or mid-distance of thigh can achieve comparable blockade of saphenous nerve.Cadaveric study implicated that the optimal injection site for adductor canal block should be the lower one-third of sartorius muscle.Ultrasound-guided injection of local anesthetics next to the descending genicular artery may possibly become a promising new method of saphenous nerve block.

【Objective】 To investigate the perioperative rate of allogeneic red blood cell (RBC) transfusion in patients who underwent total knee arthroplasty (TKA) and its risk factors, and to identify its cross-match to transfusion ratio (C∶T ratio). 【Methods】 Anesthetic data of patients who underwent TKA from January 2014 to October 2019 in Peking Union Medical College Hospital were collected and analyzed retrospectively. Perioperative allogeneic RBC transfusion rate was calculated, and binary Logistic regression analysis was performed to identify its risk factors in these patients. The overall C∶T ratio was calculated and divided into subgroups based on surgery type and age group. 【Results】 The study enrolled 2 903 patients. The perioperative rate of allogeneic RBC transfusion in TKA patients was 10.9% (95% CI 9.8%~12.0%) and overall C∶T ratio was 5.6∶1. The independent risk factors leading to perioperative allogeneic RBC transfusion included advanced age(OR=1.025, 95% CI 1.009~1.042, P<0.01), preoperative hemoglobin level(OR=0.966, 95% CI 0.954~0.978, P<0.001), preoperative anemia(OR=3.543, 95% CI 2.052~6.119, P<0.001), hematological diseases(OR=6.462, 95% CI 2.479~16.841, P<0.001), bilateral surgery(OR=7.681, 95% CI 5.759~10.245, P<0.01) and revision surgery(OR=9.584, 95% CI 4.360~21.065, P<0.001). 【Conclusion】 The risk factors for perioperative allogeneic RBC transfusion in TKA patients included advanced age, preoperative low hemoglobin level, preoperative anemia, hematological diseases, bilateral surgery and revision surgery. Only type and screen tests are recommended if patients receiving unilateral primary TKA surgery are less than 75 years old without anemia and hematological diseases, while at least one to four units of blood should be cross-matched if patients are with preoperative anemia and hematological diseases or will receive bilateral and revision arthroplasty.

Objective Although intraoperative cell salvage (ICS) has been widely used to reduce the demand for allogeneic blood transfusion, patients who use ICS approach still have not completely avoided chances of blood transfusion. This study aims to investigate the rate of allogeneic red blood cell(RBC) transfusion in patients receiving ICS, and to evaluate irrationality of allogeneic RBC transfusion and its risk factors.Methods Medical records of all patients associated with ICS approach from January 2013 to July 2014 were retrospectively reviewed. Theoretical hemoglobin level after reinfusion of salvaged RBC at the end of operations was estimated. Irrational transfusion was defined as initiating allogeneic transfusion with theoretical hemoglobin above 100 g/L. The clinical variables, including the surgical department, gender, age, body weight, ratio of blood loss to estimated blood volume(EBV), salvaged blood volume and preoperative hemoglobin level were subsequently compared between patients who received rational transfusion and those did not. Logistic regression was performed to identify the risk factors for irrationality of allogeneic RBC transfusion in these patients.Results Of 1487 patients with ICS approach in this study, the rate of allogeneic RBC transfusion was 31.4%(467/1487), and the rate of irrational allogeneic RBC transfusion was 26.0% (341/1313). Patients with irrational transfusion were younger (t=4.656, P<0.001), with lower body weight (t=3.910, P<0.001) and slightly lower preoperative HGB level (t=2.822, P=0.005) than those with rational transfusion, but had significantly larger salvaged blood volume (U=-10.926, P<0.001) and higher ratio of blood loss to EBV (U=-17.067, P<0.001), disregarding whether they preoperatively met anemia criteria or not (U=-1.396, P=0.163). Preoperative hemoglobin level (OR=1.975, P=0.005) and the ratio of blood loss/EBV (OR=5.392, P<0.001) were independent risk factors leading to the irrational allogeneic RBC transfusion.Conclusions The irrationality of allogeneic RBC transfusion existed in ICS patients, which may be associated with the preoperative hemoglobin level and the ratio of blood loss to EBV. Determining the HGB levels before transfusion is required to avoid unnecessary blood administration. Doctors should keep their knowledge in blood management updated and improve their awareness of rational transfusion for a better patients care.