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Liver surgery in obese and overweight patients
542
Journal of Gastrointestinal Surgery
Abstracts
Robert L. Galloway, PhD, William C. Chapman, MD, Washington University School of Medicine, St. Louis, MO; Vanderbilt University, Nashville, TN; Washington University School of Medcine, St. Louis, MO The purpose of this study was to determine intraoperative factors that will affect the utilization of image-guided surgical techniques during open liver resections. Image-guided surgery (IGS) provides navigational aids to the surgeon by displaying the position of a tracked surgical probe on preoperative tomograms in real time. The ability to link intraoperative presentation to preoperative imaging is achieved through a mapping process known as registration. The registration is established using features on the liver surface. In this study, intraoperative surface data of the liver was acquired from 8 patients undergoing resection for hepatic tumors. Individual points on the liver were digitized over repeated respiratory cycles in order to quantify the motion of the liver while breathing. Shape data was acquired either by sweeping an optically tracked probe across the liver surface, or by using a laser range scanner to rapidly acquire a dense point cloud. Registration was performed between the surface data and preoperative tomograms using the Iterative Closest Point (ICP) methods. Since soft tissue deformation occurs during surgery, the final step was to use a finite element model (FEM) to account for non-rigid components of the registration. Motion in the liver due to respiration was quantified as repeatable and cyclical, primarily along the cranial-caudal axis. Rigid surface registrations resulted in mean residual errors from 2–6 mm. Range scan data provided more robust results compared to the tracked probe. Less error also resulted from capturing featurerich regions such as the inferior liver edge. The registration was able to provide target region errors of less than 1 cm. From visual inspection of the registration data, it appears that the largest source of error was due to deformation of the liver during intraoperative mobilization. Results from FEM studies indicate the model compensates for deformation by warping preoperative tomograms to match intraoperative data. IGS techniques have been developed to improve navigation during liver resection. Liver motion due to respiration has been quantified so that it can be accounted for in future procedures. Laser range scanning provides a rapid means of acquiring intraoperative surface data, necessary for an accurate and robust surface registration. Finite element modeling compensates for non-rigid discrepancies that arise during surgery. Applying IGS concepts will facilitate complex hepatic resections, including living donor transplantations.
55 INLINE MULTIELECTRODE RADIOFREQUENCY ABLATION: A NEW TECHNIQUE TO MINIMIZE BLOOD LOSS IN HEPATIC PARENCHYMAL TRANSECTION David L Morris, PhD, Koroush Shahsavar Haghighi, MBBS, Julie King, RN, Steven Daniel, The University of New South Wales, Sydney, Australia InLine Radiofrequency Ablation (IL-RFA) is a novel modality which aims to reduce blood loss during hepatic resections. We conducted a prospective trial of hepatic resections using IL-RFA. The results of this trial are presented here. The ethics committee of SESAHS approved this study (approval no. 02/07). The InLine RFA device is a 5-cm-long plastic device with 6 electrodes, spaced along the device, each 10 cm long, which can be deployed to varying depths in the hepatic parenchyma. It is then connected to a standard RFA generator. No attempt was made to produce a low CVP and no Pringle inflow inclusion maneuver was performed. The resection plane was ablated with IL-RFA and then resected using the ultrasonic aspirator. Estimated blood loss, resection area, and the time taken for resection were recorded. The volume of intra-operative blood loss was as the
sum of the blood aspirated with the suckers and the blood loss as calculated by weighing the sponges. The surface area for each plane of resection was then measured to allow calculation of the blood loss per cm2 of liver resection. Similar results were seen in cirrhotic vs noncirrhotic livers. Twenty-six patients have so far undergone liver resection using IL-RFA (13 men, 13 women; mean age: 60 years; range 35–84). Mean area resected was 39 cm2 (SD: 9 cm2). Mean blood loss was 227 ml (SD: 278 ml, range: 12–1220 ml). Average blood loss per cm2 was 6 ml/cm2 while average time taken per cm2 was 58 seconds/cm2. InLine RFA significantly reduces bleeding during hepatic parenchymal resections. In comparison to current techniques of hepatic resection, i.e. the jet-cutter (which has been shown to be associated with an average blood loss of 18 ml/cm2) or the CUSA (average blood loss 24 ml/ cm2), blood loss using IL-RFA is far superior. Furthermore, IL-RFA as a tool for resection does not result in a significantly increased time of resection.
56 LIVER SURGERY IN OBESE AND OVERWEIGHT PATIENTS Silvio Balzan, MD, Olivier Farges, MD, PhD, C. Yigitler, MD, Jacques Belghiti, MD, PhD, Beaujon Hospital, Hepato-Pancreatico-Biliary Surgery, Clichy, France Obesity is associated with an increased risk of diabetes, systemic arterial hypertension, and malignancies. Also, obese patients are penalized by a higher risk of postoperative complications (although recently questioned in the context of abdominal surgery) and reluctance of some surgeons to operate on them. This might especially be the case in the context of liver surgery as obesity is also associated with NAFLD. We analyzed the characteristics of patients undergoing hepatectomies and the influence of the Body Mass Index (BMI) on the postoperative course.The 683 patients undergoing elective hepatectomies between 1999 and 2003 were stratified according to their BMI (in kg/m2, range 15–44) into lean (BMI ⬍25), overweight (BMI 25 to 29) and obese (BMI ⭓30). Minor (38%) and major hepatectomies (62%, including 271 right hepatectomies) were compared separately. Intraoperative ventilation parameters of obese patients undergoing major resections were in addition compared to those of patients with a BMI ⬍30. Overweight (34%) and obesity (14%) were somewhat more frequent than in the general population and were associated with an increased risk of diabetes (15 and 14 vs. 7%), systemic arterial hypertension (39 and 34 vs. 16%), malignancies, steatosis, and liver fibrosis. Fibrosis in obese patients was more frequent than steatosis (58 vs. 39%). The BMI had no influence on in-hospital mortality (overall 3%), the incidence of postoperative liver failure, or the kinetics of bilirubin or prothrombin time. In contrast, morbidity (notably pulmonary complications) was increased in overweight patients following major hepatectomies (OR: 2.4) and in obese patients following both minor and major resections (OR: 2.5 and 3). This resulted in an increase of in-hospital stay. Intraoperative transfusion in major hepatectomies was more frequent in obese than in lean or overweight patients (45 vs. 17 and 23%, P ⬍ .01), despite higher preoperative hemoglobin levels and both more frequent and more prolonged use of portal clamping. Despite greater intraoperative peak inspiratory airway pressures (18 vs. 15 mmHg, P ⬍ .05), obese patients had smaller respiratory volumes (6 vs. 9 ml/kg, P ⬍ .001). Almost half of the patients undergoing liver resections are either overweight or obese. Neither increased the mortality of the procedure and the BMI should therefore not interfere with the indication for, or extent of the resection. Patients with increased BMI are however at increased risk of pulmonary complications and intraoperative bleeding; both are partly explained by the inability to achieve adequate intraoperative respiratory volumes despite increased ventilation (and therefore hepatic vein) pressure, respectively.
Journal of Gastrointestinal Surgery
Abstracts
Robert L. Galloway, PhD, William C. Chapman, MD, Washington University School of Medicine, St. Louis, MO; Vanderbilt University, Nashville, TN; Washington University School of Medcine, St. Louis, MO The purpose of this study was to determine intraoperative factors that will affect the utilization of image-guided surgical techniques during open liver resections. Image-guided surgery (IGS) provides navigational aids to the surgeon by displaying the position of a tracked surgical probe on preoperative tomograms in real time. The ability to link intraoperative presentation to preoperative imaging is achieved through a mapping process known as registration. The registration is established using features on the liver surface. In this study, intraoperative surface data of the liver was acquired from 8 patients undergoing resection for hepatic tumors. Individual points on the liver were digitized over repeated respiratory cycles in order to quantify the motion of the liver while breathing. Shape data was acquired either by sweeping an optically tracked probe across the liver surface, or by using a laser range scanner to rapidly acquire a dense point cloud. Registration was performed between the surface data and preoperative tomograms using the Iterative Closest Point (ICP) methods. Since soft tissue deformation occurs during surgery, the final step was to use a finite element model (FEM) to account for non-rigid components of the registration. Motion in the liver due to respiration was quantified as repeatable and cyclical, primarily along the cranial-caudal axis. Rigid surface registrations resulted in mean residual errors from 2–6 mm. Range scan data provided more robust results compared to the tracked probe. Less error also resulted from capturing featurerich regions such as the inferior liver edge. The registration was able to provide target region errors of less than 1 cm. From visual inspection of the registration data, it appears that the largest source of error was due to deformation of the liver during intraoperative mobilization. Results from FEM studies indicate the model compensates for deformation by warping preoperative tomograms to match intraoperative data. IGS techniques have been developed to improve navigation during liver resection. Liver motion due to respiration has been quantified so that it can be accounted for in future procedures. Laser range scanning provides a rapid means of acquiring intraoperative surface data, necessary for an accurate and robust surface registration. Finite element modeling compensates for non-rigid discrepancies that arise during surgery. Applying IGS concepts will facilitate complex hepatic resections, including living donor transplantations.
55 INLINE MULTIELECTRODE RADIOFREQUENCY ABLATION: A NEW TECHNIQUE TO MINIMIZE BLOOD LOSS IN HEPATIC PARENCHYMAL TRANSECTION David L Morris, PhD, Koroush Shahsavar Haghighi, MBBS, Julie King, RN, Steven Daniel, The University of New South Wales, Sydney, Australia InLine Radiofrequency Ablation (IL-RFA) is a novel modality which aims to reduce blood loss during hepatic resections. We conducted a prospective trial of hepatic resections using IL-RFA. The results of this trial are presented here. The ethics committee of SESAHS approved this study (approval no. 02/07). The InLine RFA device is a 5-cm-long plastic device with 6 electrodes, spaced along the device, each 10 cm long, which can be deployed to varying depths in the hepatic parenchyma. It is then connected to a standard RFA generator. No attempt was made to produce a low CVP and no Pringle inflow inclusion maneuver was performed. The resection plane was ablated with IL-RFA and then resected using the ultrasonic aspirator. Estimated blood loss, resection area, and the time taken for resection were recorded. The volume of intra-operative blood loss was as the
sum of the blood aspirated with the suckers and the blood loss as calculated by weighing the sponges. The surface area for each plane of resection was then measured to allow calculation of the blood loss per cm2 of liver resection. Similar results were seen in cirrhotic vs noncirrhotic livers. Twenty-six patients have so far undergone liver resection using IL-RFA (13 men, 13 women; mean age: 60 years; range 35–84). Mean area resected was 39 cm2 (SD: 9 cm2). Mean blood loss was 227 ml (SD: 278 ml, range: 12–1220 ml). Average blood loss per cm2 was 6 ml/cm2 while average time taken per cm2 was 58 seconds/cm2. InLine RFA significantly reduces bleeding during hepatic parenchymal resections. In comparison to current techniques of hepatic resection, i.e. the jet-cutter (which has been shown to be associated with an average blood loss of 18 ml/cm2) or the CUSA (average blood loss 24 ml/ cm2), blood loss using IL-RFA is far superior. Furthermore, IL-RFA as a tool for resection does not result in a significantly increased time of resection.
56 LIVER SURGERY IN OBESE AND OVERWEIGHT PATIENTS Silvio Balzan, MD, Olivier Farges, MD, PhD, C. Yigitler, MD, Jacques Belghiti, MD, PhD, Beaujon Hospital, Hepato-Pancreatico-Biliary Surgery, Clichy, France Obesity is associated with an increased risk of diabetes, systemic arterial hypertension, and malignancies. Also, obese patients are penalized by a higher risk of postoperative complications (although recently questioned in the context of abdominal surgery) and reluctance of some surgeons to operate on them. This might especially be the case in the context of liver surgery as obesity is also associated with NAFLD. We analyzed the characteristics of patients undergoing hepatectomies and the influence of the Body Mass Index (BMI) on the postoperative course.The 683 patients undergoing elective hepatectomies between 1999 and 2003 were stratified according to their BMI (in kg/m2, range 15–44) into lean (BMI ⬍25), overweight (BMI 25 to 29) and obese (BMI ⭓30). Minor (38%) and major hepatectomies (62%, including 271 right hepatectomies) were compared separately. Intraoperative ventilation parameters of obese patients undergoing major resections were in addition compared to those of patients with a BMI ⬍30. Overweight (34%) and obesity (14%) were somewhat more frequent than in the general population and were associated with an increased risk of diabetes (15 and 14 vs. 7%), systemic arterial hypertension (39 and 34 vs. 16%), malignancies, steatosis, and liver fibrosis. Fibrosis in obese patients was more frequent than steatosis (58 vs. 39%). The BMI had no influence on in-hospital mortality (overall 3%), the incidence of postoperative liver failure, or the kinetics of bilirubin or prothrombin time. In contrast, morbidity (notably pulmonary complications) was increased in overweight patients following major hepatectomies (OR: 2.4) and in obese patients following both minor and major resections (OR: 2.5 and 3). This resulted in an increase of in-hospital stay. Intraoperative transfusion in major hepatectomies was more frequent in obese than in lean or overweight patients (45 vs. 17 and 23%, P ⬍ .01), despite higher preoperative hemoglobin levels and both more frequent and more prolonged use of portal clamping. Despite greater intraoperative peak inspiratory airway pressures (18 vs. 15 mmHg, P ⬍ .05), obese patients had smaller respiratory volumes (6 vs. 9 ml/kg, P ⬍ .001). Almost half of the patients undergoing liver resections are either overweight or obese. Neither increased the mortality of the procedure and the BMI should therefore not interfere with the indication for, or extent of the resection. Patients with increased BMI are however at increased risk of pulmonary complications and intraoperative bleeding; both are partly explained by the inability to achieve adequate intraoperative respiratory volumes despite increased ventilation (and therefore hepatic vein) pressure, respectively.