Abstract】 With the development of living liver transplantation, precision hepatectomy with the concept of most complete lesion removal, minimal trauma, maximum liver function protection and fastest health recovery has been accepted and mastered by more and more hepatic surgeons, and the related techniques have been more and more widely used in routine liver surgery. Especially in some complex liver surgeries, it can improve the radical resection rate of liver tumors and the safety of surgery, reduce the traumatic impact on the body and decrease the incidence of complications, which will further improve the prognosis and quality of life of hepatic surgery patients. Keywords: living liver transplantation; precise hepatectomy Since the successful completion of the world’s first hepatectomy by Langerbuch, with the continuous improvement in the understanding of liver anatomy and function and the continuous improvement of hepatectomy techniques, the surgical exclusion zone of the liver no longer exists, and the perioperative morbidity and mortality rate of liver surgery has been reduced to 1%-5%. However, on the premise of ensuring the thoroughness and safety of surgery, how to perform a wider range of radical hepatectomy for tumors or complex hepatectomy for special anatomical locations with limited liver reserve function has put forward higher requirements for contemporary hepatic surgeons. In 1989, the world’s first living liver transplantation using a living left outer lobe donor was successfully performed, and in 1993, Makuuchi successfully performed the world’s first adult living liver transplantation using a left hemi-liver. In 1996, Fan Shangda successfully performed the first living liver transplantation with a right hemihepatic vein (MHV). Behind the success of these procedures was a deeper understanding of the structure and function of the liver and a further improvement in hepatic surgery techniques. In recent years, the development of living liver transplantation in mainland China has been rapid, with more than 1400 cases performed. To complete a successful living liver transplantation, the anatomy of the donor liver needs to be carefully analyzed and evaluated, and the plan of liver division and reconstruction needs to be accurately formulated according to the needs of both donors and recipients, and to be able to strictly follow the predetermined plan during the operation in an orderly manner, so that the two parts of the liver to be divided can undergo minimal trauma and maximum functional protection, ultimately ensuring the success of the operation. It is important to apply the concept and techniques of living liver transplantation to routine liver resection surgery, especially to some complex liver resection surgeries. 2.1 The importance of preoperative evaluation and surgical planning As with living liver transplantation, accurate preoperative evaluation is a prerequisite for successful liver resection, including preoperative imaging of the patient’s liver anatomical features and lesions and accurate assessment of the liver reserve function. Modern imaging technology has provided surgeons with a “third eye”, allowing us to “see” the anatomy of the liver, the lesion, and its relationship to the surrounding vital structures preoperatively through a multi-angle “perspective” using 3D reconstructed images from CT or MRI. Based on the above information, a surgical plan is developed in advance, a computerized virtual hepatectomy is performed, and the results of the resection are evaluated. For hepatic resection of hepatocellular carcinoma, the extent of anatomical resection should be determined based on the location of the tumor and its lobe, and the volume of the liver to be resected should be calculated accordingly. For example, if a right hemicolectomy is proposed for a tumor adjacent to the middle hepatic vein, but the patient’s liver reserve is not able to tolerate the right hemicolectomy with MHV, the operation must be chosen to carefully separate and preserve the MHV while ensuring radical treatment, or to partially or completely remove the MHV and reconstruct the return pathway with a venous bridge, in order to avoid the postoperative impaired return of the remaining left hemicolectomy IV, which may lead to liver dysfunction due to insufficient effective residual liver. The liver insufficiency may occur due to insufficient effective residual liver. Because of its strong functional reserve and regenerative capacity, the normal liver can tolerate 75% to 80% of the volume resected and can rapidly regenerate and recover 2 to 4 weeks after surgery. Because fatty liver can lead to a decrease in liver reserve, the potential degree of fatty infiltration of the donor liver is often analyzed during the quality assessment of the donor liver for living liver transplantation, and the donor liver resection protocol is developed accordingly. The majority of livers requiring conventional hepatectomy have varying degrees of chronic injury or even cirrhosis, and their reserve function and regenerative capacity are greatly reduced. The indocyanine green excretion test (ICG) is an important method for the quantitative determination of liver function, which is more accurate than the traditional liver function Child classification to determine the reserve function of the liver and the safe limit of hepatic resection. The ICG 15 min retention rate (ICG?R15) combined with 3D CT liver volume calculation can provide a reliable basis for the safe hepatic resection range. If ICG?R15<10%, 60% total liver volume resection can be performed; if ICG?R15 10%-20%, 30%-40% total liver volume resection can be performed; if ICG?R15 20%-30%, 20%-30% total liver volume resection can be performed; if ICG?R15 >30%, only partial resection or enucleation of tumor is allowed. 2.2 Rational use of surgical techniques related to living liver transplantation How to complete hepatectomy with minimal bleeding, minimal trauma and maximum protection of liver function is the goal of both living liver transplantation and conventional hepatectomy, and in order to achieve these goals, the techniques used in living liver transplantation can be used in conventional hepatectomy, especially in some more complicated hepatectomies. To maximize the protection of the remaining liver function after hepatectomy, ischemia-reperfusion injury to the portion of the liver to be preserved should be avoided as much as possible. Therefore, Pringle total hepatic flow block should generally be avoided. To reduce intraoperative bleeding, only part of the hepatic blood flow to the area to be resected can be blocked, and the central venous pressure can be controlled to less than 5 cmH2O (1 cmH2O=0.098 kPa), and the hepatic venous return can be kept as smooth as possible, thus reducing bleeding from the hepatic venous system. In right hepatectomy, if the inflow to the right hepatic vein is completely blocked, the right hepatic vein can be considered to be blocked in order to avoid the return of tumor through the right hepatic vein during hepatectomy, and the right liver can be resected in an almost bloodless state, but in left hepatectomy, obstruction of the middle hepatic vein during hepatectomy should be avoided to avoid the obstruction of the return of hepatic V and VIII segments and increase the bleeding from the MHV system with increased pressure during hepatic parenchymal separation. The hemorrhage from the MHV system with increased pressure during parenchymal separation should be avoided. If bleeding is still high despite these measures, further blockade of either the hepatic arterial flow or portal venous flow to a portion of the liver may be attempted to minimize the ischemia-reperfusion injury caused by complete blockade of the inflow to the liver. Although there are many expensive liver parenchymal dissection devices available, such as the CUSA and the spiral waterjet, the clamping technique remains the most cost-effective technique. The key is that the surgery must be performed methodically without ischemic time limitation, and each intrahepatic ductal structure must be carefully exposed and treated exactly, and different methods such as electrocoagulation, titanium clamps and sutures can be used to treat different ductal structures of different diameters to ensure that the surgical wound does not bleed and bile leak. Since most patients with hepatocellular carcinoma in China have developed on the basis of hepatitis B cirrhosis, the texture of liver tissue is relatively hard, so it is slower to use CUSA or waterjet to separate normal liver texture and more likely to bleed. In general, if there are no important structures within 1 to 2 cm of the liver surface, clamping can be used as the main method, but when important structures such as large blood vessels are close, CUSA can be used to carefully dissect and identify the structures before cutting and separating. The author believes that there are various methods of hepatic parenchymal dissection and a variety of equipment and instruments, and the operator can be flexible according to the conditions of his hospital and his familiarity with different surgical methods and surgical instruments, but the key is that the surgical method must be based on the concept of delicacy and accuracy. The protection of residual liver function is carried out throughout the entire surgical procedure, including preoperative imaging assessment and surgical planning, intraoperative hepatic blood flow control and parenchymal dissection, and disposal of the remaining liver. Because of the delicate and precise technique used to manage the intrahepatic ductal structures during parenchymal dissection, the remaining liver is generally flat and does not require additional suture closure. Reconstruction of the MHV and its major branches is a common technique used in living liver transplantation. Reconstruction of MHV and its major branches is a common technique for living liver transplantation and is not required for most routine hepatectomies. However, when the reserve function of the remaining liver is critical after partial hepatectomy, it is particularly important to ensure effective blood supply and venous outflow tract patency to the entire remaining liver. The author has tried to use frozen cadaver revascularization to expand MHV after hemihepatectomy, and achieved good results. 3, the era of precision liver surgery With the continuous development of living liver transplantation, the surgical concept has been accepted and mastered by more and more liver surgeons, and related techniques are increasingly applied in routine liver surgery, with the most thorough lesion removal, minimal trauma, maximum liver function protection and the fastest health recovery as the treatment concept of precision liver surgery is emerging. Our initial experience has shown that the use of precision hepatic resection techniques in routine liver resection, especially in some complex liver resection procedures, can improve the resection rate and surgical completeness of hepatocellular carcinoma, reduce surgical trauma including systemic inflammatory response and liver tissue damage, thereby allowing more patients to undergo radical liver tumor resection, and further improve surgical safety and reduce surgical complications. This will further improve the safety of surgery and reduce surgical complications, thus benefiting more patients.