I. The concept of precision hepatic resection and its connotation
The term “precision hepatectomy” is used to describe the technical method of hepatectomy surgery, which was first reported in foreign literature, and is a new theory and technical system of hepatic surgery formed against the background of the rise of humanistic and evidence-based medicine in the new century, supported by the current highly developed biomedical and information science and technology. The aim is to pursue the complete removal of the target lesion while ensuring the integrity of the remaining liver anatomy and maximizing the functional volume, and to maximize the control of surgical bleeding and systemic trauma invasion, so that the surgical patient can obtain the best recovery effect.
II. Theoretical basis of precision liver resection
1.The strong compensatory and regenerative potential of the liver is the physiological basis of hepatectomy.
2.The full understanding of functional segmentation of the liver and the segmental distribution pattern of intrahepatic ductal structures and their variation characteristics has laid the anatomical theoretical foundation for precise hepatic resection characterized by anatomical liver surgery. 3.Hepatocellular carcinoma and hepatic metastatic carcinoma are characterized by dissemination within the tumor-bearing liver segment along the portal vein branches of the liver segment, and hepatic bile duct stone disease is characterized by segmental distribution within the liver along the diseased bile duct tree, which determines 4. Hepatectomy often requires blocking liver blood flow to control bleeding: the traditional concept is that the safe time limit for continuous liver blood flow block at room temperature is 15-20 min; recent research data suggest that normal liver can tolerate continuous blood flow block for 60-90 min at room temperature; intermittent liver blood flow block can extend the cumulative blood flow block Intermittent hepatic flow blockade can extend the cumulative flow blockade time limit to more than 2h; it provides a theoretical basis for the rational design of hepatic flow blockade scheme in hepatectomy.
III. Historical evolution of hepatectomy
1.In 1888, German surgeon Langenbuch successfully completed the world’s first liver resection, marking the birth of liver surgery. 2.In 1908, Pringle created the hemostatic technique of temporarily blocking the liver tip. 3.In the middle of the 20th century, the research on the casting of intrahepatic ducts unveiled the mystery of liver anatomy, and regular lobectomy came into being. 4.In the 20th century In the 1980s, with the progress of functional liver anatomy, liver pathology and the support of modern anatomical imaging techniques, hepatic segmental resection came on the stage of surgery. –Both effective removal of liver lesions and preservation of more functional liver tissues improved the precision and efficacy of liver resection from both anatomical and pathological levels.5. In the early 21st century, precision liver resection.
IV. Technical support of precision liver resection
The innovative concept of precision liver resection must rely on the support of current highly developed modern science and technology to be transformed into reality. Modern medical imaging technology has added a wise eye for liver surgeons to see through the anatomical structure and morphology of lesions in the liver. The combined application of ultrasound, CT, MRI and other imaging methods can accurately assess the extent of liver lesions, malignant tumor staging and benign lesion staging, as well as accurately understand the distribution, course and variation of the complex intrahepatic duct system and its adjacent relationship with the lesion, thus providing an important basis for the determination of resectability of liver lesions, the selection of surgical indications and the design of surgical plans. Recently, digital surgery technology, formed by the integration of advanced IT technology with modern medical imaging technology and surgical science, has been applied in surgical clinics. Using the digital surgery technology platform, individual liver tomographic image data can be reconstructed into a digital 3D visualized liver model, which in turn provides accurate quantitative analysis of liver anatomical structure and morphological characteristics of lesions, and combined with virtual reality technology for virtual liver resection and surgical planning. In the past, the assessment of liver reserve function could only rely on crude semi-quantitative methods such as Child grading, and the assessment of reserved liver volume was roughly estimated preoperatively with the help of CT/MRI images and roughly visualized intraoperatively on the liver entity. In recent years, the quantitative liver function assay indocyanine green excretion test (ICG), combined with routine liver biochemical examinations and Child classification, has become the main criterion for comprehensive assessment of liver reserve function. The assessment of liver reserve function combined with accurate computer-assisted liver volume measurement provides a reliable basis for determining the safe limit of hepatic resection and the appropriate extent of hepatic resection.
Currently, a series of well-established management methods have been developed for intraoperative hepatic resection bleeding. Since there is a lack of vascular zone in the anatomical gap between the liver segment and the liver lobe, dissociating the liver parenchyma according to the anatomical gap of the liver helps to reduce intraoperative hemorrhage in hepatectomy. The Pringle maneuver is still the most commonly used and effective method for temporary blockage of blood flow to the liver in hepatectomy. Pringle maneuver. Compared with the Pringle maneuver, selective hemihepatic flow blockade can significantly reduce ischemia-reperfusion damage to the liver, which is particularly useful in hepatectomized patients with hepatic impairment or small functional volume of the reserved liver.
The widespread penetration of minimally invasive surgical concepts and techniques in the field of liver surgery has led to the mitigation of residual liver injury and control of systemic trauma response as modern guidelines for liver surgery [3]. Minimally invasive strategies and technical means aimed at reducing the sum of traumatic effects caused by hepatic resection at all levels, including reduction of surgical access trauma, control of intraoperative bleeding and transfusion, maintenance of structural integrity of the remaining liver, reduction of ischemia-reperfusion injury to the remaining liver, and rapid perioperative recovery surgical management have become the core components of precision hepatic resection.
Laparoscopic hepatectomy has the advantage of minimally invasive access compared with open hepatectomy, but the scope and precision of its hepatectomy are somewhat limited. Robot-assisted laparoscopic hepatectomy relies on a high-resolution panoramic 3D image processing system and a flexible robotic arm, which can clearly and precisely perform tissue localization and instrumentation in a small space, overcoming the physiological limitations of conventional laparoscopic instruments and even the human body, making the precision of laparoscopic hepatectomy operation significantly improved, and providing a way to cross the gap between laparoscopic hepatectomy and open hepatectomy and achieve laparoscopic It has opened the way to cross the gap between laparoscopic and open hepatectomy and achieve laparoscopic precision hepatectomy.
V. Surgical strategy of precision hepatectomy
The ideal goal of hepatectomy is the unification of therapeutic effectiveness, surgical safety and minimally invasive intervention. The effectiveness of hepatectomy lies in the complete removal of the target lesion, the safety lies in the adequate compensation of the remaining liver function, and the minimization of invasiveness requires a safe and effective operation with minimal trauma. There is a contradictory conflict between the pathologic requirement to remove a large enough area of liver to completely remove the target lesion and the physiologic principle of maximizing the retention of a sufficient remaining functional liver. Hepatectomy itself is a “double-edged sword” for healing liver disease by causing trauma, and there is a conflict between the requirement for safe and effective healing and the risk of invasive surgical trauma. The core strategy of precision hepatectomy is to achieve the unity of complete removal of lesions, maximum liver protection and minimum invasion with the goal of obtaining the best recovery effect.
(i) Strategy for complete removal of target lesions
Complete removal of the target lesion is a prerequisite for achieving the best recovery effect of precision hepatectomy. The target lesions are all or locally critical lesions that can eliminate symptoms and cure the disease after its resection. For example, for large simple liver cysts, only the cyst wall protruding to the surface of the liver large enough to achieve complete symptom relief and cyst elimination should be removed. For benign liver tumors, complete resection of the lesion along the tumor margin is required, while for malignant liver tumors with infiltrative metastatic characteristics, the peri-cancerous liver tissue that may be infiltrated by the tumor must be removed at the same time.
1.Accurate assessment of target lesion scope: The preoperative assessment of liver lesions is based on medical history, clinical manifestations, imaging, laboratory examination and pathological examination results to systematically understand the nature of the lesion, its distribution inside and outside the liver and the involvement of the hepatic vascular system. For malignant tumors of hepatobiliary system with infiltration and metastasis characteristics, it is still necessary to make reasonable inferences about the invasion range that cannot be identified by existing imaging means according to the biological behavior of various tumors and the tumor stage of individual cases.
2.Stage reduction treatment of unresectable tumors: For liver malignant tumors with extensive lesions, the invasive range of tumors can be reduced through stage reduction treatment to create conditions for curative liver resection. The descending treatment methods of liver malignant tumor include preoperative hepatic artery embolization chemotherapy, neoadjuvant chemotherapy, precise radiotherapy, etc., which can be applied according to the sensitivity of different tumors to these methods.
3. Follow the principle of tumor-free surgery: Precision hepatectomy should follow the principle of tumor-free to avoid residual tumor and medical dissemination. The whole tumor should be removed from the normal liver tissue without tumor infiltration outside the tumor according to the infiltration and metastasis characteristics of the tumor. In cases of malignant tumors invading important vascular structures in the liver, combined with revascularization and reconstruction can significantly improve the curative resection rate of the tumor. For small residual lesions after resection of the main cancer foci, remedial treatments such as radiofrequency ablation, precise radiotherapy and TACE can be used to achieve complete removal of the tumor.
(II) Strategy to maximize the protection of the remaining liver
The functional volume of the remaining liver and its structural integrity are the key factors to determine the postoperative functional compensation status of the liver and the safety of surgery.
1. Individualized assessment of the safety limit of hepatic resection: the safety limit of hepatic resection is mainly subject to the compensatory limit of liver function and is based on the premise of ensuring the adequate compensation of the remaining liver function. There are great differences in functional liver volume between different individuals or patients with different disease nature of liver disease. Therefore, the safe limit of hepatic resection should not be measured by the amount of hepatic resection, but by the necessary remaining functional liver volume. It is generally accepted that the safe limit of hepatic resection for normal liver is to reserve not less than 25% to 30% of the standard liver volume. Based on clinical studies in Asia, Europe and the United States, the combination of Child classification, signs of portal hypertension and ICG excretion tests can predict the safe limit of hepatic resection in cases with chronic liver disease. Limited hepatectomy or tumor enucleation at the subsegmental level is indicated. For Child A cases without signs of portal hypertension, if the ICG R15 is <10%, the reserved liver volume after hepatectomy should be at least 40%-50% of the standard liver volume; if the ICG R15 is 10%-20%, the reserved liver should be at least 60%-70% of the standard liver volume; if the ICG R15 is 20%-30%, the reserved liver should be at least 70%-80% of the standard liver volume. standard liver volume.
2.Increase the functional volume of the remaining liver: If the functional volume of the reserved liver does not reach the minimum necessary functional volume of the liver, the following ways can be considered to increase the functional volume of the remaining liver: (1) Promote the proliferation of the reserved liver by selective embolization of the portal vein of the segment of the liver to be removed, so that its volume reaches or even exceeds the minimum necessary volume of the liver. (2) Remove reversible liver damage factors and improve the function of the reserved liver. For patients with severe obstructive jaundice requiring massive hepatectomy, preoperative liver function can be improved by selective or total biliary drainage; for simple fatty liver caused by overnutrition, liver damage can be reversed by weight loss. (3) Save functional liver parenchyma while ensuring complete removal of the target lesion. Adopt surgical approaches to save liver parenchyma such as segmental/subsegmental resection or limited partial hepatectomy, choose the smallest tumor-free cutting edge, and avoid large clamping and suturing of liver section tissues.
3.Protection of the remaining liver structure and function: The structural integrity of the four groups of vasculature of the remaining liver is a prerequisite for its full compensatory function, and the absence of any of the vasculature will partially or fully affect the function of the remaining liver. Preoperative evaluation, surgical planning and intraoperative operation should all prioritize the protection and repair and reconstruction of the important vascular tracts of the reserved liver as key elements. Emphasis should also be placed on optimizing the perioperative management plan to prevent residual liver function impairment caused by various factors.
(iii) Strategies to minimize surgical trauma reactions
Minimally invasive strategies and measures covering the whole process of surgical treatment should be implemented, including a series of means to reduce surgical access trauma, control intraoperative bleeding and blood transfusion, reduce residual liver damage, and accelerate surgical treatment for perioperative rehabilitation.
1. Control of intraoperative bleeding: Minimizing intraoperative bleeding is a basic requirement for precise hepatectomy, and priority should be given to controlling major bleeding in particular in terms of strategies and methods. The level of hepatic resection that circumvents large blood vessels should be chosen as much as possible to prevent collateral damage to important vessels; at the same time, the application of blood flow blocking methods should be reasonably chosen, and the vascular structures in the liver section should be precisely dissected and treated in the process of dissociating the liver parenchyma.
2.Reducing tissue damage: The liver should be cherished and human tissues should be carefully cared for during surgery to reduce surgical trauma as much as possible. Operate gently, dissect delicately, reveal and precisely deal with the vascular structures on the section when dissecting the liver parenchyma one by one. Avoid ligating large pieces of tissues and avoiding “brutal” operations such as rough pulling and squeezing of organs.
3.Accelerate recovery: Based on the concept of accelerated recovery surgery, we adopt a series of perioperative treatment methods such as early enteral nutrition to accelerate the healing of trauma and reduce the reaction of trauma, so as to accelerate the recovery of patients. For patients with risk factors that induce liver failure, including pre-existing liver parenchymal lesions, low preoperative liver reserve function, functional volume of the remaining liver close to the safety limit, long-time blood flow blockage in the liver, intraoperative hemorrhage, abdominal infection, sepsis, etc., it is more important to pay high attention to perioperative management and develop a perfect management plan.
VI. Surgical planning of precision hepatectomy
The surgical planning of precision hepatectomy follows the principles of evidence-based medicine and is highly individualized. On the one hand, the patient is accurately evaluated preoperatively to obtain empirical evidence of the condition from all aspects of anatomy, physiology and pathology, and on the other hand, the best available evidence on the evaluation of various hepatectomy techniques is fully utilized and combined with traditional liver surgery experience to develop the best surgical plan for individual cases. The core elements include: determining the extent of resection necessary for complete removal of the target lesion; determining the extent of preservation necessary to ensure functional compensation of the remaining liver; determining the appropriate extent of hepatic resection and the appropriate surgical approach; evaluating and protecting the reserved liver volume, structure and function; setting the optimal parenchymal segmentation plane; anticipating the vascular structures to be resected/reconstructed; assessing the surgical risks and developing appropriate management responses; and determining the surgical The procedure, key technical approaches and perioperative management points are determined.
The necessary extent of resection is the sum of the diseased liver tissue involved in the target lesion and the non-diseased liver tissue that will be structurally and functionally destroyed after resection of the lesion. The optimal curative hepatic resection and the appropriate extent of hepatic resection are determined within the resectable range of the liver between the necessary resection range and the required preservation range, based on the principle of maximizing the functional volume of the remaining liver and the assessment of the difficulty, risk, and safety of the various surgical options available. Anatomic segmental hepatectomy is consistent with the concept of precision hepatectomy and can be the procedure of choice for the surgical treatment of many limited liver lesions. In cases with poor liver reserve and the need to preserve more functional liver tissue, subsegmental hepatectomy or irregular partial hepatectomy may be considered.
A comprehensive assessment of the four sets of vascular structures of the reserved liver and their anatomical relationship to the lesion should be performed and a well-targeted surgical management plan should be developed according to the precise analysis of 2D images and panoramic view of 3D images. Smooth hepatic venous return and structural integrity of the Glission system are equally important for the remaining liver function. Virtual surgery with the aid of a computer-assisted surgical planning system allows quantitative assessment of the vessels of interest and their branches and prediction of the possible areas and extent of ischemia and stasis within the reserved liver, which helps to determine the appropriate extent of hepatic resection and to develop a management plan for the involved vessels.
The selection of the liver parenchymal segmentation plane requires a combination of the following factors: obtaining adequate tumor-free cut margins, conserving functional liver parenchyma, gaping along segments lacking vascular structures, and avoiding damage to the vascular structures of the reserved liver. The optimal segmentation plane is determined by continuous tracking analysis of multiple frames of 2D images, or virtual surgery based on 3D reconstructed images, comparing the condition of the margins when different virtual sections are taken, the ducts involved in the section, the volume of the resected liver, the volume of the remaining liver and its structural integrity.
The design of the surgical procedure and the selection of key techniques depend on the complexity of the liver lesion and the procedure, the functional volume of the liver reserved, and the status of important vascular involvement. Anatomic segmental resection of the liver often begins with dissection and blockage of the liver tip of the target liver segment, showing the ischemic border of the segment to be resected before dissection of the liver parenchyma. In complex cases where the lesion involves the hilum, making it difficult to dissect and separate the hepatic tissues on the side to be resected, the hepatic tissues of the reserved liver can be dissected first to confirm the hepatic tissues, and then the liver parenchyma can be dissected along the ischemic border. For huge liver tumors, in order to avoid the hematogenous spread of cancer cells caused by squeezing the tumor when freeing the liver, an anterior approach to hepatectomy can be used, i.e., first ligating and severing the liver tip of the tumor-bearing liver, then severing the liver parenchyma and hepatic vein, and finally freeing the perihilar ligament and removing the tumor.
For hepatic resection with normal parenchyma and adequate reserved liver functional volume, intraoperative bleeding can be controlled by reducing central venous pressure (<5 cmH2O) combined with hepatic flow block; for cases with severe parenchymal damage and marginal reserved liver functional volume, hepatic resection without hepatic flow block or with selective hemihepatic flow block should be considered. For difficult hepatectomy, hepatectomy under total hepatic vascular isolation and cold perfusion may be considered when the anticipated need for blocking hepatic blood flow exceeds the limit of hepatic tolerance to ischemia. For those with involvement of the main hepatic vein and posterior inferior hepatic vena cava requiring resection and reconstruction, hepatic resection under total hepatic blood flow blockade or extracorporeal hepatic resection may be required.
The choice of liver parenchymal dissection method is based on the experience of the surgeon, the availability of equipment and the requirement for fine intraoperative dissection. In superficial areas of the liver without important vascular structures, the liver parenchyma can be dissected by clamping and crushing and electrocoagulation, or directly by thermal coagulation such as ultrasonic hemostasis knife or PK knife. The liver parenchyma can be dissected near the hilum and the travels of important vasculature by combining electrocoagulation with precision instruments such as ultrasonic scalpel and waterjet that help in precise dissection and bleeding control.
Traditional liver surgery plans are based on two-dimensional ultrasound and CT/MRI imaging assessments as well as semi-quantitative assessment of liver function, and it is difficult to quantify the anatomical localization of the lesion and the adjacent relationship with intrahepatic vascular structures as well as liver reserve function. The final decision on the surgical plan can be made only after the abdominal dissection, especially for complex liver resection cases. The computer-aided surgical planning system based on the digital surgical platform can provide a three-dimensional perspective of liver anatomy, accurately grasp the boundaries of liver segments, accurately measure the functional volume of liver segments and even arbitrary vessels, accurately locate the lesion and its anatomical relationship with adjacent vasculature, and then accurately determine the resectability of the lesion. The virtual liver resection allows comparison, screening and optimization of different surgical options. Especially for complex liver resections with large resection areas, involving or adjacent to important anatomical structures, the computer-aided surgical planning system appears to be of more practical value.
In summary, precision liver resection is a new concept and technical system of liver surgery based on the modern integrated medical model, which embodies the humanistic surgical concept and minimally invasive surgical guidelines to obtain the best recovery results with minimal invasion and maximum liver protection. Precision hepatectomy is a clinical practice that follows the principles of evidence-based medicine, obtaining empirical evidence of the disease through precise evaluation of anatomy, physiology and pathology, combining the best available evidence on the evaluation of various hepatectomy techniques and traditional surgical methods for individualized surgical planning, and formulating the best surgical treatment plan for each individual case. Precision liver resection emphasizes the rational application of advanced technological methods and tools to achieve the ideal goals of “therapeutic effectiveness, surgical safety, and minimally invasive intervention” through precise preoperative evaluation, sophisticated surgical planning, refined surgical operation, and excellent postoperative management. The application of the concept and technology of precision liver resection will further significantly improve the prognosis and quality of life of liver surgery patients.