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Biomedical subjects

Jesús Usón

Publications and source records attributed to Jesús Usón.

12 recordsLinked to original sources
PubMed2006

Study of laparoscopic forces perception for defining simulation fidelity.

One of the most controversial dilemmas in virtual reality laparoscopic simulators design is the incorporation of force feedback (FF). This issue is approached with an experimental design in which surgeons assess the resistance against pulling of four different tissues, which are characterized with the acquisition of interaction forces. Comparing subjective assessments with objective force parameters we aim to determine the fidelity boundary beyond which no more realism is necessary in simulation. Interaction pulling forces of four tissues have been characterized, which can constitute a basis for requirements of a FF algorithm. Results have also led to the hypothesis that surgeons are able to differentiate tissues and perceive somesthesic information although resulting interaction forces are of the same magnitude than interferences like trocar friction.

Animals↗
PubMed2005

Subxiphoid access to normal pericardium with micropuncture set: technical feasibility study in pigs.

This study was performed with approval from the ethics committee for animal research of the local government. The purpose of the study was to evaluate the technical feasibility of a technique for subxiphoid access to the normal pericardial space with a micropuncture set in 10 large white pigs. With fluoroscopic guidance, a fine needle was inserted through a subxiphoid approach into the anterior mediastinal space to puncture the pericardium, and a micropuncture set was placed in the pericardial space successfully in all animals without complications. Necropsy at 24 hours did not reveal hemomediastinum, hemopericardium, or laceration of the pericardium. Results of the experiments in animals indicated that the technique was feasible and safe.

Animals↗
PubMed2005

Vein and artery growth after anastomosis with vascular closure staple clips vs interrupted polypropylene suture: application in pediatric vascular surgery.

BACKGROUND/PURPOSE: Alternatives are still being sought in vascular surgery to address the problem of arrested growth after anastomosis in growing vessels, and opinions differ widely regarding the most suitable technique. This study compared vascular growth and permeability after anastomosis using the latest-generation vascular closure staple (VCS) system and the conventional suture technique to ascertain which approach yielded better results. METHODS: Thirty 55-day-old lambs underwent end-to-end anastomosis of the carotid artery and jugular vein. Serial ultrasonography and angiography were carried out over the ensuing 6-month growth period, after which lambs were euthanized. RESULTS: Both VCS clips and polypropylene suture allowed longitudinal and transverse vessel growth; however, longitudinal growth was significantly greater in clip-closed vessels than in either sutured or untreated vessels. CONCLUSIONS: The results obtained for vascular growth and permeability suggest that VCS clips may provide a suitable alternative to conventional suture in pediatric vascular surgery.

Anastomosis, Surgical↗
PubMed2005

Metallic ureteral stents versus endoureterotomy as a therapeutic approach for experimental ureteral stricture.

PURPOSE: To determine if the deployment of metallic ureteral stents in benign ureteral stricture is more effective than endoureterotomy. MATERIALS AND METHODS: Twenty pigs were randomly divided in two groups to be treated with endoureterotomy or metallic stents. The internal ureteral diameter 2 cm distal to the ureteropelvic junction, histopathologic changes, ultrasonographic and fluoroscopic studies, urine culture, and serum urea and creatinine levels were analyzed during the phases of the study. The study was divided into three phases. The first included premodel documentation of normal urinary tract and laparoscopic ureteral stricture induction. In the second phase 1 month later, diagnosis and endoureteral treatment were carried out. Twelve weeks after stricture treatment, follow-up imaging studies and postmortem evaluation of all animals were performed. RESULTS: The success rates were 80% for endoureterotomy and 70% for metallic stent implantation. In all animals in the latter group, a ureteral hyperplasic reaction took place that affected the zone of stent implantation. One difference between the groups was the presence of urinary infection in 30% of animals in the endoureterotomy group and in no animals treated with metallic stents. Statistically significant differences in ureteral diameter between the first and second study phases were found within both groups (P < .0001), but not between groups (P = .021). Results from pathologic analysis revealed statistically significant differences between groups (P = .0029). CONCLUSIONS: The interaction among the distal end of the metallic stent, the urothelium, and peristalsis might be the origin of the failure of these devices. Although the deployment of metallic stents is attractive compared with other endourologic techniques like endoureterotomy in cases of benign strictures, certain problems must be resolved to prevent hyperplasia. Until then, this technique will not be a fully reliable therapeutic option for ureteral disorders.

Animals↗
PubMed2004

Treatment of experimental ureteral strictures by endourological ureterotomy and implantation of stents in the porcine animal model.

The objective of this study is to evaluate the dilation of the ureter using endoureterotomy and an expanding-sheath double pigtail ureteral stent in the treatment of experimentally induced ureteral strictures in the porcine animal model. This is a new treatment in the ureteral strictures resolution in Veterinary Urology, although it is not a common affection, it usually appears as a consequence of ureteritis and in the iatrogenic female genital surgery. The experimental study is design in three phases: induction of experimental stricture, diagnosis and treatment of the stricture and follow-up. We have used 10 healthy Large White female pigs. The internal ureteral diameter was measured prior to laparoscopic ligature stricture induction using retrograde ureteropyelography (RUPG). Experimental stricture was diagnosed 4 weeks after intervention, using RUPG and ultrasound, and treated by endoureterotomy and subsequent placement of a double pigtail ureteral stent, which was removed 6 weeks later. The study finished 4 weeks later with measurement of ureteral diameters using RPUG and ultrasound evaluation. Except in one case, all ureters displayed permanent dilation of the strictured area for 10 weeks after treatment (6 weeks with ureteral stent and 4 more weeks without stent). Finally, this technique proved to be effective in cases of short-length and short-living ureteral strictures, and represents a viable alternative to conventional surgery in animals.

Animals↗
PubMed2002

Fine-needle percutaneous transhepatic parenchymal portal venography by using carbon dioxide: a pilot study in pigs.

Our purpose was to evaluate the feasibility and safety of carbon dioxide (CO(2)) in fine-needle percutaneous transhepatic parenchymal portal venography and its potential clinical applications. Three Belgian landrace pigs received fine-needle percutaneous transhepatic parenchymal portal venography by using CO(2) as a contrast agent. Under fluoroscopic and B-mode ultrasonic guidance, right or left lobe of liver was punctured with a 22-G Chiba needle, through which CO(2) was injected with a dedicated CO(2) injector at injection rate of 20 ml/s for 20 ml, 40 ml/s for 40 ml, 40 ml/s for 60 ml, and 40 ml/s for 80 ml, respectively. The portal venograms were obtained by use of digital subtraction angiography (DSA) system with animal in supine position. In one pig transarterial portal venography was performed, in addition, using iodinated contrast agent. The portal vein was visualized in each run of venography. Optimal images of portal tree structure up to four-order branches were obtained in all those with CO(2) injection rate of 40 ml/s, which appeared much better in quality than those obtained by cranial mesenteric arteriography with iodinated contrast agent. No extravasation of CO(2), liver laceration, or any other complication occurred during the procedures. The technique we proposed demonstrated optimal portography, which appeared to be safe, minimally invasive, less time-consuming, cost-effective, and easy to perform, with great potential in clinical applications.

Angiography, Digital Subtraction↗
PubMed2002

End-to-end anastomosis in growing vessels using a novel suturing technique: VCS metallic staples.

For pediatric transplants, a suturing technique is needed that allows the vessel to grow along with better healing of the anastomosis, through eliminating exogenous and thrombogenic material in the intimal side, thus minimizing the risk of vascular stenosis. In this study, 12 55-day-old lambs were subjected to end-to-end anastomosis of the right carotid artery and external jugular vein using vascular closure staple (VCS) clips (the vessels from the left side served as controls). Animals were followed up with duplex ultrasound. After 6 months, angiography was performed and animals were euthanized for microscopic study of the vessels. Duplex ultrasonography and angiography showed all vessels to be patent, with no flow disturbances and no stenosis at the anastomotic site at 6 months. Stenotic segments caudal to the anastomosis site were seen in two veins. No significant changes were seen macroscopically in any of the veins, whereas one of the arteries developed a pseudoaneurysm at the anastomotic site. Histological structure was normal in all the studied veins. Arteries showed different degrees of modifications that did not affect patency or flow in any case. Measurements taken after 6 months confirm that this technique allows the vessel to grow. This technique may be useful in vascular pediatric surgery.

Anastomosis, Surgical↗
PubMed2002

Design of a new suture practice card for microsurgical training.

Suturing technique is of paramount importance in microsurgery. Basic training in this technique can be done using the practice card, a purpose-made polyurethane card. A practice card has been designed in the Minimally Invasive Surgery Centre to closely resemble microsurgical requirements in order to practice and learn correct microsuturing maneuvers. This practice card is a key part of microsurgical training. After many years of experience, and based on a survey we conducted, we can conclude that this practice card is essential for step-by-step microsurgical training. Using this card, the number of animals required to attain necessary microsurgical skills is reduced significantly. Furthermore, costs are also reduced, and the trainee can avoid mistakes during training with live animals, thus optimizing results.

Animals↗
PubMedDate not supplied

Comparative study of ureteral stents following endoureterotomy in the porcine model: 3 vs 6 weeks and 7F vs 14F.

The aim of the study was to determine the optimal stent size and stenting duration following retrograde endoureterotomy of experimental ureteral strictures. Twenty healthy Large White female pigs were randomly divided into four groups, depending on stent size (7F vs 14F) and stenting duration (3 weeks vs 6 weeks). Three additional pigs were used as the control group. The internal ureteral diameter was measured 2 cm below the lower pole of the right kidney. Histopathological changes of the urinary tract, ultrasonographic and fluoroscopic studies, urine culture, and serum urea and creatine levels were analyzed during the different phases of the study. The study was divided into three phases. Phase I included premodel documentation of the normal urinary tract and laparoscopic ureteral stricture creation. During the second phase 1 month later, the diagnosis and endourologic treatment of strictures were performed. Phase III began 4 weeks after stent removal; follow-up imaging studies and postmortem evaluation of all animals were performed. Ureteral strictures developed in all animals 4 weeks after model creation. Results from ureteral diameter measurements and pathological studies revealed no statistically significant intergroup differences. However, prevalence of urinary infection proved to be directly related to stent size (14F) and permanence (6 weeks). The chi square results suggest a statistically significant relationship between the urinary tract infection and recurrent strictures (alpha = 0.046). We recommend the use of 7F stents for a period of 3 weeks or less, as these are more easily positioned and result in the reduction of secondary side effects (lower infection rate, less intramural ureteral lesions). A significant relationship between urinary tract infection and stricture recurrence was found in this experimental study.

Animals↗
PubMedDate not supplied

Angiographic study and therapeutic embolization of soft-tissue fibrosarcoma in a dog: case report and literature.

A case of soft-tissue fibrosarcoma with pulmonary metastases in a dog is reported. Although three attempts of fine-needle aspiration (FNA) biopsy failed to provide definitive tumor diagnosis, results of angiography strongly indicated a soft-tissue sarcoma. Transcatheter arterial embolization (TAE) using particles of gelatin sponge was performed following selective angiography. The mass was decreased in size on reevaluation 2 weeks after embolization. The dog was euthanized on the request of the owners due to overall failing health. Necropsy and pathological study confirmed the diagnosis of soft-tissue fibrosarcoma with pulmonary metastases. In a review of the literature, angiographic findings of soft-tissue sarcoma in the dog of this report were similar to those in human beings, suggesting a potential role for angiography in the differential diagnosis of suspect soft-tissue fibrosarcomas and for guiding FNA or surgical biopsy. Previous reports have also shown therapeutic embolization to be an effective treatment both in experimental animal study and in clinical practice in the human; therefore, TAE could be an effective adjunctive treatment of soft-tissue fibrosarcoma in the dog.

Animals↗