A mathematical model of the laparoscopic manipulating space (original) (raw)
Related papers
Elasticity of the living abdominal wall in laparoscopic surgery
Journal of Biomechanics, 2006
Laparoscopic surgery requires inflation of the abdominal cavity and this offers a unique opportunity to measure the mechanical properties of the living abdominal wall. We used a motion analysis system to study the abdominal wall motion of 18 patients undergoing laparoscopic surgery, and found that the mean Young's modulus was 27.774.5 and 21.073.7 kPa for male and female, respectively. During inflation, the abdominal wall changed from a cylinder to a dome shape. The average expansion in the abdominal wall surface was 20%, and a working space of 1.27 Â 10 À3 m 3 was created by expansion, reshaping of the abdominal wall and diaphragmatic movement. For the first time, the elasticity of human abdominal wall was obtained from the patients undergoing laparoscopic surgery, and a 3D simulation model of human abdominal wall has been developed to analyse the motion pattern in laparoscopic surgery. Based on this study, a mechanical abdominal wall lift and a surgical simulator for safe/ergonomic port placements are under development. r
Surgical Endoscopy and Other Interventional Techniques, 2006
Background Carbon dioxide insufflation of the peritoneal cavity for laparoscopic surgery offers a unique opportunity to measure some mechanical properties of the human abdominal wall that hitherto have been difficult to obtain. Methods The movement and change of the abdominal wall during insufflation to a pressure of 12 mmHg was studied in 18 patients undergoing laparoscopic surgery using a remote motion analysis
Compliance of the abdominal wall during laparoscopic insufflation
Surgical Endoscopy, 2016
Background To provide adequate workspace between the viscera and abdominal wall, insufflation with carbon dioxide is a common practice in laparoscopic surgeries. An insufflation pressure of 15 mmHg is considered to be safe in patients, but all insufflation pressures create perioperative and postoperative physiologic effects. As a composition of viscoelastic materials, the abdominal wall should distend in a predictable manner given the pressure of the pneumoperitoneum. The purpose of this study was to elucidate the relationship between degree of abdominal distention and the insufflation pressure, with the goal of determining factors which impact the compliance of the abdominal wall. Methods A prospective, IRB-approved study was conducted to video record the abdomens of patients undergoing insufflation prior to a laparoscopic surgery. Photo samples were taken every 5 s, and the strain of the patient's abdomen in the sagittal plane was determined, as well as the insufflator pressure (stress) at bedside. Patients were insufflated to 15 mmHg. The relationship between the stress and strain was determined in each sample, and compliance of the patient's abdominal wall was calculated. Subcutaneous fat thickness and rectus abdominus muscle thickness were obtained from computed tomography scans. Correlations between abdominal wall compliances and subcutaneous fat and muscle content were determined. Results Twenty-five patients were evaluated. An increased fat thickness in the abdominal wall had a direct exponential relationship with abdominal wall compliance (R 2 = 0.59, p \ 0.05). There was no correlation between muscle and fat thickness. Conclusion All insufflation pressures create perioperative and postoperative complications. The compliance of patients' abdominal body walls differs, and subcutaneous fat thickness has a direct exponential relationship with abdominal wall compliance. Thus, insufflation pressures can be better tailored per the patient. Future studies are needed to demonstrate the clinical impact of varying insufflation pressures.
Surgical Endoscopy, 2014
Background Determinants of working space in minimal access surgery have not been well studied. Using computed tomography (CT) to measure volumes and linear dimensions, we are studying the effect of a number of determinants of CO 2 working space in a porcine laparoscopy model. Here we report the effects of pre-stretching of the abdominal wall. Methods Earlier we had noted an increase in CO 2 pneumoperitoneum volume at repeat insufflation with an intraabdominal pressure (IAP) of 5 mmHg after previous stepwise insufflation up to an IAP of 15 mmHg. We reviewed the data of this serendipity group; data of 16 pigs were available. In a new group of eight pigs, we also explored this effect at repeat IAPs of 10 and 15 mmHg. Volumes and linear dimensions of the CO 2 pneumoperitoneum were measured on reconstructed CT images and compared between the initial and repeat insufflation runs. Results Previous stepwise insufflation of the abdomen with CO 2 up to 15 mmHg significantly (p \ 0.01) increased subsequent working-space volume at a repeat IAP of 5 mmHg by 21 %, 7 % at a repeat IAP of 10 mmHg and 3 % at a repeat IAP of 15 mmHg. The external anteroposterior diameter significantly (p \ 0.01) increased by 0.5 cm (14 %) at repeat 5 mmHg. Other linear dimensions showed a much smaller change. There was no statistically significant correlation between the duration of the insufflation run and the volume increase after prestretching at all IAP levels.
Scientific reports, 2024
Analyses of registries and medical imaging suggest that laparoscopic surgery may be penalized with a high incidence of trocar-site hernias (TSH). In addition to trocar diameter, the location of the surgical wound (SW) may affect TSH incidence. The intra-abdominal pressure (IAP) exerted on the abdominal wall (AW) might also influence the appearance of TSH. In the present study, we used finite element (FE) simulations to predict the influence of trocar location and SW characteristics (stiffness) on the mechanical behavior of the AW subject to an IAP. Two models of laparoscopy patterns on the AW, with trocars in the 5-12 mm range, were generated. FE simulations for IAP values within the 4 kPa-20 kPa range were carried out using the Code Aster open-source software. Different stiffness levels of the SW tissue were considered. We found that midline-located surgical wounds barely deformed, even though they moved outwards along with the regular LA tissue. Laterally located SWs hardly changed their location but they experienced significant variations in their volume and shape. The amount of deformation of lateral SWs was found to strongly depend on their stiffness. Trocar incisions placed in a LA with non-diastatic dimensions do not compromise its mechanical integrity. The more lateral the trocars are placed, the greater is their deformation, regardless of their size. Thus, to prevent TSH it might be advisable to close lateral trocars with a suture, or even use a prosthetic reinforcement depending on the patient's risk factors (e.g., obesity). The prevalence of trocar-site hernias (TSH) is not clear 1. Analysis of registries suggests a high incidence of TSH 2 and that, depending on their location, reparation of these hernias can be complex 3. Moreover, the recently updated guidelines for closure of abdominal wall incisions 4 provide no support to the notion that the fascial closure at the trocar site can benefit TSH prevention. These guidelines also mention that there is no evidence supporting the best trocar location and they recommend suturing the fascial defect for trocar sites of 10 mm or larger, and for trocars located at the umbilical site 4. Finite element (FE) simulations may strengthen our understanding of how surgical wounds (SWs) alter the mechanical behavior of the abdominal wall (AW) 5,6. Our key assumption is that the response of the AW to intraabdominal pressure (IAP) sometime after surgery will depend on the mechanical properties of the tissue regrown at the surgical sites, that is, the tissue conforming the SWs, and the laparoscopy pattern used in the surgery. The resilience of the AW to an applied IAP value, P a , is mostly due to the stiffness of its tissues, which are of muscular or tendinous nature. Both types of tissue are characterized by the presence of fibers in their architecture 7. The new SW tissue might be weak and, from a mechanical point of view, softer than expected 8. On the other hand, the regrown tissue in the SW might become scarred 9,10 and exceedingly stiff 11. In silico analysis could help to virtually simulate the influence of trocar location or trocar scar characteristics on the mechanical behavior of the AW. However, to the best of our knowledge, there is no study on how the SW
Virtual simulation of the biomechanics of the abdominal wall with different stoma locations
Scientific Reports, 2022
developed by Tuset et al. 21 to investigate the effect of different transperitoneal stoma locations on the biomechanical behavior of the AW. We considered seventeen different locations for stoma incisions and we focused our analysis in two aspects. First, we assessed whether the response of the AW to a certain level of intraabdominal pressure (IAP), measured in terms of both the deformation and stress levels experienced by the tissues, is affected by the presence of a stoma. In addition, we analyzed the corresponding enlargements and deformations experienced by the trephine. Enlargement of the stoma incision is generally considered a risk factor for PH, even though statistical analyses of patient data on the subject might be inconclusive 2 .
Computer simulation for ergonomic improvements in laparoscopic surgery
Applied Ergonomics, 2006
It is the aim of this study to reduce the stress and strain of the medical staff during laparoscopic operations, and, simultaneously, to increase the safety and efficiency of an integrated operation room (OR) by an ergonomic redesign. This was attempted by a computer simulation approach using free modelling of the OR and 3D human models (manikins). After defining ergonomically ''ideal'' postures, optimal solutions for key elements of an ergonomic design of the OR (position and height of the image displays, height of the OR table and the Mayo stand) could be evaluated with special regard to the different individual body size of each member of the team. These data should be useful for the development of team adapted, user friendly integrated OR suites of the future. r
Forces and displacements in colon surgery
Surgical Endoscopy, 2002
Background: This study aims to ®nd criteria for designing safer laparoscopic graspers for manipulation of delicate tissues. Since the experiment was performed in an open-surgery setup without any movement restrictions, the results are relevant to general surgery as well as laparoscopic. Method: Four surgeons were asked to apply via two clamps enough force to a pig's colon to stretch the mesocolon for dissection. Directions, magnitudes, and application points of the forces were recorded. Results: The surgeons applied per clamp on average 2.5 N and maximally 5 N to the colon. These forces were at an angle of about 40°to 70°relative to the horizontal plane and approximately 60°relative to each other.
Simulation of pneumoperitoneum for laparoscopic surgery planning
Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention, 2012
Laparoscopic surgery planning is usually realized on a preoperative image that does not correspond to the operating room conditions. Indeed, the patient undergoes gas insufflation (pneumoperitoneum) to allow instrument manipulation inside the abdomen. This insufflation moves the skin and the viscera so that their positions do no longer correspond to the preoperative image, reducing the benefit of surgical planning, more particularly for the trocar positioning step. A simulation of the pneumoperitoneum influence would thus improve the realism and the quality of the surgical planning. We present in this paper a method to simulate the movement of skin and viscera due to the pneumoperitoneum. Our method requires a segmented preoperative 3D medical image associated to realistic biomechanical parameters only. The simulation is performed using the SOFA simulation engine. The results were evaluated using computed tomography [CT] images of two pigs, before and after pneumoperitoneum. Results...
Journal of the Mechanical Behavior of Biomedical Materials, 2021
The study concerns mechanical behaviour of a living human abdominal wall. A better mechanical understanding of a human abdominal wall and recognition of its material properties is required to find mechanically compatible surgical meshes to significantly improve the treatment of ventral hernias. A non-invasive methodology, based on in vivo optical measurements is proposed to determine strains of abdominal wall corresponding to a known intraabdominal pressure. The measurement is performed in the course of a standard procedure of peritoneal dialysis. A dedicated experimental stand is designed for the experiment. The photogrammetric technique is employed to recover the three-dimensional surface geometry of the anterior abdominal wall at the initial and terminal instants of the dialysis. This corresponds to two deformation states, before and after filling the abdominal cavity with dialysis fluid. The study provides information on strain fields of living human abdominal wall. The inquiry is aimed at principal strains and their directions, observed at