A virtual simulation approach to assess the effect of trocar-site placement and scar characteristics on the abdominal wall biomechanics.

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.

The effect of thoracic dimensions on compression depth during cardiopulmonary resuscitation.

The effect of the dimensions of the thoracic cage on the resuscitation outcome of cardiopulmonary resuscitation (CPR) maneuvers has long been debated. In this study, the effect of changes in the rib cage dimensions on the achieved compression depth was investigated using finite element simulations. A total of 216 different rib cage geometry models were considered and, in each case, the result of applying different levels of compression force up to 600 N were simulated.

Biomechanical modelling of the pelvic system: improving the accuracy of the location of neoplasms in MRI-TRUS fusion prostate biopsy.

Background: An accurate knowledge of the relocation of prostate neoplasms during biopsy is of great importance to reduce the number of false negative results. Prostate neoplasms are visible in magnetic resonance images (MRI) but it is difficult for the practitioner to locate them at the time of performing a transrectal ultrasound (TRUS) guided biopsy. In this study, we present a new methodology, based on simulation, that predicts both prostate deformation and lesion migration during the biopsy.

Virtual simulation of the biomechanics of the abdominal wall with different stoma locations.

An ostomy is a surgical procedure by which an artificial opening in the abdominal wall, known as a stoma, is created. We assess the effects of stoma location on the abdominal wall mechanics. We perform three-dimensional finite element simulations on an anatomy model which was generated on the basis of medical images.

Biomechanical response of human rib cage to cardiopulmonary resuscitation maneuvers: Effects of the compression location.

The biomechanical response of a human rib cage to cardiopulmonary resuscitation maneuvers was investigated by means of finite element simulations. We analyzed the effect of the location where the force was applied on the achieved compression depths and stress levels experienced by the breastbone and ribs. For compression locations on the breastbone, a caudal shift of the application area toward the breastbone tip resulted in a 17% reduction of the force required to achieve a target 5 cm compression depth.

Hemodynamic effects of blood clots trapped by an inferior vena cava filter.

The alteration of blood flow around an OPTEASE inferior vena cava filter with one or two blood clots attached was investigated by means of computational fluid dynamics. We used a patient-specific vein wall geometry, and we generated different clot models with shapes adapted to the filter and vein wall geometries. A total of eight geometries, with one or two clots and a total clot volume of 0.

Implementation of a new constitutive model for abdominal muscles.

Background And Objective: Abdominal hernia repair is one of the most often performed surgical procedures worldwide. Numerical simulations of the abdominal wall mechanics can be a valuable tool to devise actions aimed at preventing hernia formation. A first step towards this goal is the development of consistent constitutive models for the tissues that form the human abdominal wall.

A comparative CFD study of four inferior vena cava filters.

Computational fluid dynamics was used to simulate the flow of blood within an inferior vena cava (IVC) geometry model that was reconstructed from computed tomography images obtained from a real patient. The main novelty of the present work is that we simulated the implantation of 4 different filter models in this realistic IVC geometry. We considered different blood flow rates in the range between V =20 and V =80 cm /s, and all simulations were performed with both the Newtonian and a non-Newtonian model for the blood viscosity.

Effects of walking in deep venous thrombosis: a new integrated solid and fluid mechanics model.

Deep venous thrombosis (DVT) is a common disease. Large thrombi in venous vessels cause bad blood circulation and pain; and when a blood clot detaches from a vein wall, it causes an embolism whose consequences range from mild to fatal. Walking is recommended to DVT patients as a therapeutical complement.

Effect of anticoagulant treatment in deep vein thrombosis: A patient-specific computational fluid dynamics study.

A methodology that might help physicians to establish a diagnostic and treatment tailored for each specific patient with a pathological thrombus is presented. A realistic model for the geometry of a popliteal vein with a thrombus just above the knee was reconstructed from in vivo computed tomography images acquired from one specific patient and then it was used to perform computational fluid dynamics (CFD) simulations. The wall shear stress (WSS) response to the administration of anticoagulant drugs and the influence of viscosity on the shape of the velocity distribution were investigated.

Computational modeling of electromechanical propagation in the helical ventricular anatomy of the heart.

The classical interpretation of myocardial activation assumes that the myocardium is homogeneous and that the electrical propagation is radial. However, anatomical studies have described a layered anatomical structure resulting from a continuous anatomical helical disposition of the myocardial fibers. To further investigate the sequence of electromechanical propagation based on the helical architecture of the heart, a simplified computational model was designed.

Calculation of human femoral vein wall parameters in vivo from clinical data for specific patient.

A common problem in the elaboration of biomechanical models is determining the properties and characteristics (measures) of the physical behavior of in vivo tissues in the human body. Correct estimates must be made of the tissue's physical properties and its surroundings. We suggest a method to compute the constitutive modeling of venous tissue, for every specific patient, from clinically registered ultrasounds images.

Simulation and study of the geometric parameters in the inguinal area and the genesis of inguinal hernias.

We are interested in studying the genesis of a very common pathology: the human inguinal hernia. How the human inguinal hernia appears is not definitively clear, but it is accepted that it is caused by a combination of mechanical and biochemical alterations, and that muscular simulation plays an important role in this. This study proposes a model to explain how some physical parameters affect the ability to simulate the region dynamically and how these parameters are involved in generating inguinal hernias.

Simulation and study of the behaviour of the transversalis fascia in protecting against the genesis of inguinal hernias.

Simulating the muscular system has many applications in biomechanics, biomedicine and the study of movement in general. We are interested in studying the genesis of a very common pathology: human inguinal hernia. We study the effects that some biomechanical parameters have on the dynamic simulation of the region, and their involvement in the genesis of inguinal hernias.

A simulation finite element model for the mechanics of the internal oblique muscle: a defense mechanism against inguinal hernia formation?

Simulation of the human muscular system has multiple applications in biomechanics, biomedicine and in the study of motion in general. Mechanical alterations of the normal functioning in the inguinal area ("inguinal shutter") seems to be involved in the genesis of hernias in adults, but the role of this anatomical mechanisms is poorly understood. A finite element model for the mechanics of the internal oblique muscle allowed creating a dynamic model of the inguinal region applicable to the study of the shutter mechanism as a defence mechanism of contention of the abdominal viscera against development of an inguinal hernia.

Effectiveness of a clinical guide for the treatment of postoperative pain in a major ambulatory surgery unit.

A retrospective study to evaluate a clinical guide for the treatment of postoperative pain in our One Day Surgery Unit (ODSU) is presented. A total of 2783 patients, treated during 1 year, were studied. Postoperative pain was evaluated 24 h after surgery by phone-call using a visual analogue scale (VAS) and a verbal response scale (VRS).

[Evaluation of the system of direct purchase and distribution of urinary incontinence pads in primary care centers].

Objective: To evaluate the impact of the pilot experience of direct purchase and distribution of incontinence diapers in primary health care centres of the Balearic Islands after 10 months of implementation.

Design: Comparison of diapers's public expenditures and use during 10 months of pilot experience (9/1/1994-6/30/1995: POSTC) to a same length period prior to pilot experience implementation (11/1/1993-8/31/1994: PREC).

Setting: Primary health care centres of the Balearic Islands (Spain).

Effect of cyclosporin A on proteinuria in patients with Alport's syndrome.

Eight patients with Alport's syndrome and massive proteinuria (129 +/- 60.57 mg/m2 per hour) were treated with cyclosporin A (CyA) for 8 months. The average dose of CyA administered to all patients was 4.

[Tubular handling of potassium in cystinosis].

Seven patients with cystinosis (Ccr between 30 and 90 ml/m/1.73 m2), were studied attempting to delineate renal tubular handling of potassium. Ks, Ck/Ccr X 100, Aldou and UAldo V/Ks were determined in basal conditions; tubular handling of water and sodium, and clearance of potassium were studied during hypotonic saline diuresis.

Hepatitis B virus infection and vaccination in children undergoing hemodialysis.

Among 54 patients, between 2 and 18 years of age, submitted to hemodialysis due to severe chronic renal failure, the prevalence of hepatitis B virus markers was 66.7% and that of HBsAg was 13.0%.