Jesús Usón-Gargallo

Evaluation of the Effects of Temporary Covered Nitinol Stent Placement in the Prostatic Urethra: Short-Term Study in the Canine Model

PurposeTo evaluate the effect of temporary stent placement on the canine prostatic urethra.MethodsRetrievable PTFE-covered nitinol stents were placed in the prostatic urethras of 8 beagle dogs under fluoroscopic guidance. Retrograde urethrography was obtained before and after stenting. Retrograde urethrography and endoscopy were performed 1 and 2 months after deployment. The endoscopic degree of hyperplasia was rated on a scale of 0 to 4 (0 = absence, 4 = occlusion). On day 60, stents were removed and urethrography was performed immediately before euthanasia. Pathologic analysis was performed to determine the degree of glandular atrophy, periurethral fibrosis, and urethral dilation.ResultsStent deployment was technically successful in 7 animals, and failed in 1 dog due to a narrow urethral lumen. Complete migration was seen in 2 animals at 1 month, and an additional stent was deployed. On day 30, endoscopy showed slight hyperplasia (grade 1) in 3 animals. On day 60, moderate hyperplasia (grade 2) was evidenced in 4 cases. No impairment of urinary flow was seen during follow-up. Retrieval was technically easy to perform, and was successful in all dogs. The major histologic findings were chronic inflammatory cell infiltrates; prostate glandular atrophy, with a mean value of 1.86 (SD 0.90); periurethral fibrosis, with a mean ratio of 29.37 (SD 10.41); and dilatation of the prostatic urethra, with a mean ratio of 6.75 (SD 3.22).ConclusionTemporary prostatic stent placement in dogs is safe and feasible, causing marked enlargement of the prostatic urethral lumen. Retrievable covered stents may therefore be an option for bladder outlet obstruction management in men.

The measurement of neurovegetative activity during anesthesia and surgery in swine: an evaluation of different techniques.

In this study we evaluated, in 10 sevoflurane-anesthetized pigs undergoing abdominal surgery, different techniques for measuring autonomic nervous system (ANS) activity: ANSiscope™ index, spectral analysis of heart-rate variability, hemodynamic variables, and plasma catecholamines and cortisol levels. Animals underwent a 120-min anesthesia during which unilateral ovariectomy was performed. Cardiovascular and respiratory responses were monitored. ANSiscope™ indices (ANSindex™ sympathetic, ANSindex™ parasympathetic and balANSindex™) were used to monitor ANS activity. Spectral analysis was performed using an autoregressive model with a parametric method. The low frequency (LF) and high frequency (HF) components were used to interpret the power spectral density of short-term electrocardiograms (ECGs). The relationship LF/(LF+HF) reflects sympathetic activity, HF/(LF+HF) indicates parasympathetic activity, and the LF/HF ratio gives the predominance of the system. Plasma concentrations of adrenaline, noradrenaline, and cortisol were determined at different times. Correlation (P < 0.01) was found between the balANSindex™ and adrenaline levels and between LF/HF ratio and plasma adrenaline concentrations. Moreover, a significant (P < 0.01) correlation was found between the balANSindex™ and LF/HF ratio. However, no correlation was seen between the registered ANSiscope indices and hemodynamic variables. The correlation seen in this study suggests that the balANSindex™ could be a useful tool to monitor ANS activity during anesthesia and surgery.

Ergonomic analysis of muscle activity in the forearm and back muscles during laparoscopic surgery: influence of previous experience and performed task.

Purpose: The first aim of this study is to analyze the muscle activity in back and forearm muscles in surgeons during laparoscopic dissection and suturing maneuvers. The second aim is to determine the influence of the surgeons’ previous experience in laparoscopic surgery. Methods: A total of 30 laparoscopic surgeons were divided in 3 groups: novice suturing, novice dissecting, and experts suturing. Electromyography data were collected from the trapezius, forearm flexors, and forearm extensors muscles, during the proposed tasks on physical simulator. Results: Muscle activity was significantly lower in the expert group. Moreover, muscle activity in the trapezius was significantly higher during the completion of intracorporeal suturing when compared with that during dissection. Conclusions: Results obtained in this study show that the surgeons with a higher degree of laparoscopic experience exhibit a lower level of muscle activity when compared with the novice surgeons. Moreover, in accordance to our results, laparoscopic suturing involves a higher degree of muscle effort than during laparoscopic dissection.

Learning curves of basic laparoscopic psychomotor skills in SINERGIA VR simulator.

PurposeSurgical simulators are currently essential within any laparoscopic training program because they provide a low-stakes, reproducible and reliable environment to acquire basic skills. The purpose of this study is to determine the training learning curve based on different metrics corresponding to five tasks included in SINERGIA laparoscopic virtual reality simulator.MethodsThirty medical students without surgical experience participated in the study. Five tasks of SINERGIA were included: Coordination, Navigation, Navigation and touch, Accurate grasping and Coordinated pulling. Each participant was trained in SINERGIA. This training consisted of eight sessions (R1–R8) of the five mentioned tasks and was carried out in two consecutive days with four sessions per day. A statistical analysis was made, and the results of R1, R4 and R8 were pair-wise compared with Wilcoxon signed-rank test. Significance is considered at P value <0.005.ResultsIn total, 84.38% of the metrics provided by SINERGIA and included in this study show significant differences when comparing R1 and R8. Metrics are mostly improved in the first session of training (75.00% when R1 and R4 are compared vs. 37.50% when R4 and R8 are compared). In tasks Coordination and Navigation and touch, all metrics are improved. On the other hand, Navigation just improves 60% of the analyzed metrics. Most learning curves show an improvement with better results in the fulfillment of the different tasks.ConclusionsLearning curves of metrics that assess the basic psychomotor laparoscopic skills acquired in SINERGIA virtual reality simulator show a faster learning rate during the first part of the training. Nevertheless, eight repetitions of the tasks are not enough to acquire all psychomotor skills that can be trained in SINERGIA. Therefore, and based on these results together with previous works, SINERGIA could be used as training tool with a properly designed training program.

Physiologic Responses to Infrarenal Aortic Cross-Clamping during Laparoscopic or Conventional Vascular Surgery in Experimental Animal Model: Comparative Study

The aim of this study was to compare the hemodynamic and ventilatory effects of prolonged infrarenal aortic cross-clamping in pigs undergoing either laparotomy or laparoscopy. 18 pigs were used for this study. Infrarenal aortic crossclamping was performed for 60 minutes in groups I (laparotomy, n = 6) and II (laparoscopy, n = 6). Group III (laparoscopy, n = 6) underwent a 120-minute long pneumoperitoneum in absence of aortic clamping (sham group). Ventilatory and hemodynamic parameters and renal function were serially determined in all groups. A significant decrease in pH and significant increase in PaCO2 were observed in group II, whereas no changes in these parameters were seen in group I and III. All variables returned to values similar to baseline in groups I and II 60 minutes after declamping. A significant increase in renal resistive index was evidenced during laparoscopy, with significantly higher values seen in Group II. Thus a synergic effect of pneumoperitoneum and aortic cross-clamping was seen in this study. These two factors together cause decreased renal perfusion and acidosis, thus negatively affecting the patients general state during this type of surgery.

A New Model of Abdominal Aortic Aneurysm with Gastric Serosa Patch: Surgical Technique and Short-Term Evaluation

The purpose of this work was to develop an abdominal aortic aneurysm (AAA) model that resembles human aneurysms with potential for further growth, patent collateral vessels, and a predictable tendency to rupture, and that can be used in the development of new endoprostheses and implant training. An infrarenal AAA model was created in five domestic swine using an autologous gastric serosal patch. Pre- and postsurgical digital substraction aortograms (DSA) were obtained to document the appearance and dimensions of the aneurysm. Animals were followed up with DSA and ultrasonography on days 7, 14, 30, 45, 60, and 90 after model creation. Aneurysmal diameters were measured with both techniques in all examinations. On day 90, animals were euthanized, target arteries were harvested, and pathological evaluation was performed. The nonparametric Wilcoxon test was used to assess any differences in measured diameters. All the animals survived the surgical procedure. The aneurysmal diameters increased from 8.14± 2.15 to 13.28± 1.18 mm immediately after surgery (p <. 05), but no subsequent significant growth of the aneurysmal sac was seen during follow-up. In this experimental setting, measurements obtained with DSA were slightly larger than those obtained with ultrasound. Two animals died of AAA rupture on days 6 and 10 (40% rupture rate). Pathological examination showed lack of elastic laminae and increased collagen content in the aortic patch. Thus, model showed a tendency to rupture, but no significant potential for further aneurysmal growth. It might be useful for training in endovascular therapies, but its usefulness for preclinical endovascular device testing is limited by its lack of growth potential.

Validation of SINERGIA as training tool: a randomized study to test the transfer of acquired basic psychomotor skills to LapMentor.

PurposeLaparoscopic surgery is commonly used in many surgical procedures but requires a learning process to develop the necessary skills. Virtual reality simulators play an essential role within the training curricula. This paper aims to determine whether training in SINERGIA VR simulator allows novice surgeons to improve their basic psychomotor laparoscopic skills.MethodsForty-two people participated in this study, including 28 unexperience medical students and 14 expert surgeons who developed previously more than 100 laparoscopic procedures. Medical students made a pre-training test in LapMentor II; then, they trained in SINERGIA and they finally accomplished a post-training test in LapMentor II. Experts just made one trial in LapMentor II. A statistical analysis was carried out and results of pre- and post-training tests of novices were compared with Wilcoxon signed-rank test. Pre- and post-training tests of novices were also compared with results of experts with Mann–Whitney U test.ResultsMost metrics provided by LapMentor II and included in this study show significant differences when comparing pre- and post-training tests of novices. Analysis of pre-training test of novices and experts results show significant differences in all analyzed metrics for all studied tasks. On the other hand, LapMentor was not able to distinguish between experts and novices after training in SINERGIA for any metric in the camera manipulation task and for some metrics of the other tasks.ConclusionsTraining in SINERGIA VR simulator allows improvement of basic psychomotor laparoscpic skills and transferring them to another virtual simulator. Therefore, it could be used in laparoscopic surgery training programs.

Anaesthetic Considerations during Laparoscopic Surgery

Laparoscopic surgery has improved greatly during the last years, mainly thanks to advances in both anaesthetic and surgical techniques (Llagostera-Pujol et al., 2002). Abdominal laparoscopy is normally perceived to be associated with few risks. However, clinicians should be aware of inherent dangers such as gaseous embolism, a potential inability to control haemorrhage, an increase in carbon dioxide arterial partial pressure, and changes in arterial blood pressure and heart rate. The hemodynamic and respiratory alterations associated with abdominal laparoscopy are caused by the high intraabdominal pressure brought over by pneumoperitoneum creation. The most relevant hemodynamic changes are a decrease in venous return secondary to Inferior Vena Cava compression and increases in central venous pressure and arterial blood pressure in absence of heart rate changes. Regarding respiratory adjustments, cranial displacement of the diaphragm causes a restrictive respiratory syndrome with decreased pulmonary compliance and increased pulmonary pressures and inspiratory peak (Carrasco et al., 1998; Joris et al., 1999). Anesthesia in laparoscopic procedures it’s complicated by the pathophysiologic changes developed because of the pneumoperitoneum creation and the required positioning of the patient. It’s also considered a potentially high risk procedure because of other inherent conditions: The duration of procedures is usually longer, there is a risk of visceral injury and it’s difficult to estimate the amount of blood loss when hemorrhage occurs. The anesthesiologist must have a deep understanding of the pathophysiological consequences derived from the pneumoperitoneum, to be prepared to prevent, detect and address the possible alterations that can occur during the intervention. The physiological changes and complications derived from the pneumoperitoneum are the first topics described. The postoperative benefits of laparoscopy regarding some postoperative aspects will be described in second place. A lot of studies have been published about the advantages and effects of laparoscopic surgeries during the last 35 years, but anaesthetic techniques and laparoscopic conditions have change a lot during the last 15 years, so this review we’ll be focused on those modern techniques and conditions.

Validation of a Realistic Simulator for Veterinary Gastrointestinal Endoscopy Training

This article reports on the face, content, and construct validity of a new realistic composite simulator (Simuldog) used to provide training in canine gastrointestinal flexible endoscopy. The basic endoscopic procedures performed on the simulator were esophagogastroduodenoscopy (EGD), gastric biopsy (GB), and gastric foreign body removal (FBR). Construct validity was assessed by comparing the performance of novices (final-year veterinary students and recent graduates without endoscopic experience, n=30) versus experienced subjects (doctors in veterinary medicine who had performed more than 50 clinical upper gastrointestinal endoscopic procedures as a surgeon, n=15). Tasks were scored based on completion time, and specific rating scales were developed to assess performance. Internal consistency and inter-rater agreement were assessed. Face and content validity were determined using a 5-point Likert-type scale questionnaire. The novices needed considerably more time than the experts to perform EGD, GB, and FBR, and their performance scores were significantly lower (p<.010). Inter-rater agreement and the internal validity of the rating scales were good. Face validity was excellent, and both groups agreed that the endoscopy scenarios were very realistic. The experts highly valued the usefulness of Simuldog for veterinary training and as a tool for assessing endoscopic skills. Simuldog is the first validated model specifically developed to be used as a training tool for endoscopy techniques in small animals.

Physiological responses to different ischemic periods during laparoscopic infrarenal aortic cross-clamping: evaluation in an experimental animal model.

Our aim was to study the physiological repercussions of varying ischemic times during laparoscopic aortic surgery. After quarantine, laparoscopy was performed in 24 healthy pigs, which were randomly allocated to four study groups: group I (n=6), laparoscopic infrarenal abdominal aortic surgery with 30 min of crossclamping; group II (n=6), laparoscopic infrarenal abdominal aortic surgery with 60 min of cross-clamping; group III (n=6), laparoscopic infrarenal abdominal aortic surgery with 120 min of cross-clamping; group IV (n=6), 120 min pneumoperitoneum in the absence of aortic cross-clamping (control group). Hematological, biochemical, hormone, hemodynamic, and ventilatory studies were conducted during and after surgery; and a postoperative neurological evaluation was performed 10 days after surgery. Group III evidenced an increase in arterial blood pressure and heart rate that was significantly higher than those present in the other groups. Significant decreases in pH were observed in groups II and III, whereas no changes in this parameter were seen in groups I and IV. Catecholamine levels during surgery were similar in all groups (a significant [p<0.001] increase in plasmatic adrenaline and noradrenaline was seen immediately after pneumoperitoneum creation in all groups). A positive association was found between the duration of aortic clamping and hormone values at 30 and 60 min after declamping but not after 24hr. A significant increase in the renal resistive index (RRI) and a significant decrease in urine output were evidenced during laparoscopy, with significantly lower RRI values seen in group IV immediately after surgery. Thus, a synergic effect of pneumoperitoneum and aortic cross-clamping was seen in this study. These two factors together cause a hemodynamic compromise, with decreased renal perfusion and acidosis, thus negatively affecting the patients general state during this type of surgery. Despite being well tolerated in healthy pigs, a laparoscopic aortic cross-clamping time over 60min produces significant hemodynamic, metabolic, and hormonal changes. Careful patient selection is mandatory to avoid any severe complications.