Biomedical subjects

Jesús Usón-Gargallo

Publications and source records attributed to Jesús Usón-Gargallo.

11 recordsLinked to original sources

PubMed2006

Bispectral index, spectral edge frequency 95% and median frequency recorded at varying desflurane concentrations in pigs.

The objective of this study is to evaluate the usefulness of bispectral index (BIS), spectral edge frequency 95% (SEF) and median frequency (MED) in relation to a simple descriptive scale (SDS) as indicators of anaesthetic depth at different desflurane concentrations in swine. Sixteen pigs were randomly allocated to four groups. Electroencephalograms (EEG) were recorded during desflurane anaesthesia, and BIS, SEF and MED were calculated from the EEG. The agent was administered in pure oxygen at 1, 1.25, 1.5 and 1.7 MAC in randomized order. Anaesthetic depth was evaluated on a SDS. BIS decreased significantly (P<0.001) at the different anaesthetic dosages used. SEF decreased significantly (P<0.001) from basal to 1 MAC of desflurane. MED decreased significantly (P<0.001) from basal to 1 MAC and from 1 to 1.75 MAC. Good correlation was seen between SDS scores and BIS values and between SDS scores and MED values. BIS appeared to be useful to predict changes in anaesthetic depth at clinically used dosages of inhalant anaesthesia.

Anesthesia↗

PubMed2006

Vascular closure stapler clip anastomosis decreases aortic cross-clamping time compared to interrupted nonabsorbable and running absorbable sutures in growing pigs.

The latest generation in titanium clip application systems, the vascular closure staples (VCS) system avoids intimal lesions and therefore minimizes the subsequent hyperplastic reaction, while at the same time enhancing distensibility and vascular growth. Moreover, VCS clips allow the surgeon to perform vascular anastomosis easily and faster than conventional suture. This system may become the option of choice for vascular reconstruction in pediatric surgery where, as in the case of aortic and transplant surgery, decreasing vascular occlusion times may influence the outcomes. The aim of this study was to determine whether VCS metallic clips would allow shorter anastomosis times than conventional interrupted polypropylene or running Dexon suturing in end-to-end anastomosis performed in the abdominal aorta of young pigs. Twenty-four domestic swine, 45 days old, were used for this study. All animals were subjected to an end-to-end anastomosis in the abdominal aorta using VCS clips, interrupted polypropylene, or running Dexon suture. Aortic cross-clamping time was significantly shorter in the VCS clips group (4.02 +/- 0.72 min), compared to interrupted polypropylene (21.89 +/- 1.93 min) or running Dexon (9.82 +/- 3.97 min) suture. VCS clips are easy to use, and therefore may aid surgeons to significantly decrease the time needed for performing an end-to-end anastomosis in the abdominal aorta, thus decreasing cross-clamping time when compared to interrupted polypropylene or running Dexon sutures.

Anastomosis, Surgical↗

PubMed2006

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.

Anesthesia, General↗

PubMed2005

Vascular closure stapler clips versus polypropylene sutures in end-to-end anastomoses of growing arteries and veins.

Alternatives are still being sought in vascular surgery to avoid the complications caused in growing vessels by the various suture techniques and materials currently in use. A major complication is arrested growth following anastomosis. Opinions differ widely regarding the best approach to this problem, and research is currently underway at our center on the latest generation of clip appliers (vascular closure stapler, or VCS) and their potential application as an alternative to the conventional suture technique in pediatric vascular surgery. This study compared vascular growth and reendothelialization following anastomosis of growing arteries and veins using VCS clips versus the conventional interrupted polypropylene suture technique. 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 the lambs were euthanized. Gross examination of the anastomosis site was followed by histologic examination involving light microscopy, immunohistochemical techniques, and transmission electron microscopy. Although both VCS clips and polypropylene sutures allowed transverse vessel growth, the clips did not penetrate the intima and thus provided enhanced reendothelialization. The satisfactory results obtained here, as in earlier studies, increasingly point to VCS clips as the method of choice in pediatric vascular surgery.

Anastomosis, Surgical↗

PubMed2004

Relationships between a proprietary index, bispectral index, and hemodynamic variables as a means for evaluating depth of anesthesia in dogs anesthetized with sevoflurane.

OBJECTIVE: To evaluate relationships among various techniques for monitoring anesthetic depth in sevoflurane-anesthetized dogs undergoing orthopedic surgery. ANIMALS: 10 dogs. PROCEDURE: Dogs were medicated with acepromazine (0.05 mg/kg, IM), buprenorphine (0.01 mg/kg, IM), and atropine (0.04 mg/kg, IM). Anesthesia was induced and maintained with sevoflurane. Cardiovascular and respiratory responses were monitored. Anesthetic depth was monitored by use of the bispectral index (BIS), and a proprietary index was used to monitor activity of the autonomic nervous system. RESULTS: A significant decrease in BIS was seen after induction but concurrent changes were not observed for the other techniques. The proprietary index increased significantly after intubation, but no changes were seen for the other techniques. No significant changes were detected during incision or when higher nociceptive stimuli were applied. We did not identify a correlation between BIS and the proprietary index, the proprietary index and hemodynamic variables, or the BIS and hemodynamic variables during induction and maintenance. A significant increase in the proprietary index and BIS was detected at the time of resumption of reflexes. During anesthetic recovery, a correlation was found between the proprietary index and BIS but not between hemodynamic variables and the other techniques. CONCLUSIONS AND CLINICAL RELEVANCE: A significant increase in the proprietary index, but not the BIS or hemodynamic variables, was detected during intubation. Anesthetic induction with sevoflurane did not prevent the sympathetic stimulus attributable to tracheal intubation. Monitoring of hemodynamic variables does not provide sufficient information to allow clinicians to evaluate stress during anesthetic recovery.

Acepromazine↗

PubMed2004

Assessment of the relationship of bispectral index values, hemodynamic changes, and recovery times associated with sevoflurane or propofol anesthesia in pigs.

OBJECTIVE: To evaluate bispectral index (BIS) values in pigs during anesthesia maintained with sevoflurane-fentanyl or propofol-fentanyl as a predictor of changes in hemodynamic parameters and duration of recovery from anesthesia. ANIMALS: 12 pigs. PROCEDURE: Pigs were randomly allocated to undergo 1 of 2 anesthetic regimens. Anesthesia was induced with propofol (2 mg/kg, i.v.); 6 pigs were administered sevoflurane via inhalation (1 minimum alveolar concentration [MAC] at a fresh gas flow rate of 3 L/min; group I), and 6 were administered propofol (11 mg/kg/h, i.v.; group II). All pigs received fentanyl (2.5 mg/kg, i.v., q 30 min). After abdominal surgery, pigs were allowed to recover from anesthesia. Cardiovascular variables and BIS values were recorded at intervals throughout the procedure; duration of recovery from anesthesia was noted. RESULTS: No correlation was established between arterial blood pressure and BIS and between heart rate and BIS. Mean BIS at discontinuation of administration of the anesthetic agent was greater in group-II pigs (65.2 +/- 10.6 minutes) than in group-I pigs (55.8 +/- 2.9 minutes). However, recovery from anesthesia was significantly longer in group II (59.80 +/- 2.52 minutes) than in group I (9.80 +/- 2.35 minutes). CONCLUSIONS AND CLINICAL RELEVANCE: In swine anesthetized with sevoflurane or propofol and undergoing abdominal surgery, the BIS value derived from an electroencephalogram at the end of anesthesia was not useful for predicting the speed of recovery from anesthesia. Moreover, BIS was not useful as a predictor of clinically important changes in arterial blood pressure and heart rate in those anesthetized pigs.

Analysis of Variance↗

PubMed2003

Comparison of ultrasonographic characteristics of the gastroduodenal junction during pyloroplasty performed laparoscopically or via conventional abdominal surgery in dogs.

OBJECTIVE: To evaluate the use of ultrasonography to detect morphologic changes in the pylorus during pyloroplasty performed laparoscopically or via conventional abdominal surgery in dogs. ANIMALS: 10 healthy mixed-breed dogs. PROCEDURE: Laparoscopic ultrasonography of the pylorus was performed in 5 dogs during laparoscopic pyloroplasty (LP), and ultrasonography of the pylorus was performed in 5 dogs during pyloroplasty via conventional abdominal surgery (CAP group). Appearance and dimensions of the pyloric sphincter were evaluated by use of a 7.5-MHz flexible laparoscopic linear-transducer probe. RESULTS: Mean +/- SD duration of the ultrasonographic procedure was 11 +/- 3.04 minutes (range, 6 to 18 minutes). In the CAP group, cross-sectional views of the pylorus revealed significant differences between the overall transverse external diameter, overall craniocaudal external diameter, and transverse diameter of the pyloric lumen. After surgery, the pyloric area was significantly increased. Longitudinal views of the pylorus revealed that width of the pyloric ring was significantly less after surgery. Transverse views of the pylorus for the LP group revealed a significant increase in the transverse diameter and craniocaudal diameter of the pyloric lumen after LP. The pyloric area was also significantly increased after surgery. Longitudinal views of the pylorus revealed that width of the pyloric ring was significantly less after surgery. Transverse diameter of the pyloric lumen was significantly increased after LP. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study suggests that ultrasonography is useful for detecting relevant morphologic changes in the pyloric sphincter after pyloroplasty.

Animals↗

PubMed2003

Bispectral index, spectral edge frequency 95%, and median frequency recorded for various concentrations of isoflurane and sevoflurane in pigs.

OBJECTIVE: To evaluate bispectral index (BIS), spectral edge frequency 95% (SEF), and median frequency (MED) in relation to a visual analogue scale (VAS) as indicators of anesthetic depth for various concentrations of sevoflurane and isoflurane in pigs. ANIMALS: 32 pigs. PROCEDURE: Pigs were randomly allocated to 8 groups (4 pigs/group). An electroencephalogram (EEG) was recorded in each conscious pig. Pigs were then anesthetized by use of sevoflurane (n = 16) or isoflurane (16). Agents were administered in oxygen at minimum alveolar concentrations (MACs) of 1, 1.25, 1.5, and 1.75 MAC in a randomized order. End-tidal sevoflurane and isoflurane concentrations were maintained for 30 minutes, after which an EEG was recorded for 5 minutes; BIS, SEF, and MED were then calculated. Anesthetic depth was evaluated by use of the VAS. Cardiovascular and EEG responses to nociceptive stimuli were evaluated for each anesthetic agent. RESULTS: BIS decreased significantly for the various concentrations of each anesthetic. At equivalent MACs, BIS values were significantly higher during sevoflurane-induced anesthesia than during isoflurane-induced anesthesia. Values of MED and SEF decreased significantly from basal values to 1 MAC of sevoflurane and isoflurane. For both agents, there was good correlation between VAS scores and BIS values and between VAS scores and SEF values. CONCLUSIONS AND CLINICAL RELEVANCE: BIS was useful for predicting changes in anesthetic depth at clinical dosages of inhalant anesthetics. Values of BIS, SEF, and MED were significantly higher during anesthesia induced by administration of sevoflurane than during anesthesia induced by administration of isoflurance at equivalent MACs.

Anesthesia↗

PubMedDate not supplied

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 subtraction 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.

Animals↗

PubMedDate not supplied

Laparoscopic sonography in the urinary system.

This work reports the use of laparoscopic-transducer sonography for the examination of the urinary system in a swine model. Animals underwent a two-phase study. In the first phase, the urinary system was examined using laparoscopic sonography. In the second a partial ureteral obstruction was induced, and sonographic changes were recorded and evaluated. Sonography was used to evaluate kidneys, ureters, and bladder. Anatomic structures were evaluated and the following pathological findings were identified: renal cysts, one polycystic kidney, dilation of the renal pelvis, hydronephrosis, and one perirenal pseudocyst. Where necessary, contrast digital fluoroscopy (excretory urography and retrograde ureteropyelography) was also performed. Laparoscopic sonography mainly is used for evaluation prior to laparoscopic surgery to guide decisions relating to surgery. The quality of the images obtained laparoscopically is superior to that of percutaneous or transabdominal images, because artifacts are reduced and the contact surface of the transducer is placed directly over the study area. Laparoscopic sonography proved highly effective for studying renal and ureteral disorders prior to minimally invasive surgery.

Animals↗

PubMedDate not supplied

Comparison of the effect of laparoscopic and conventional pyloric surgery on gastric emptying in dogs.

The effect of a laparoscopic approach and pyloric surgery on canine gastrointestinal activity, particularly gastric emptying time, is not well understood. The purpose of this study was to compare the effect of laparoscopic and conventional pyloric surgery, in Ramstedt pyloromyotomy and Heineke-Mikulicz pyloroplasty, on complete gastric emptying time in 20 clinically normal dogs. Dogs were divided into four groups of five animals: dogs with laparoscopic Ramstedt pyloromyotomy, conventional Ramstedt pyloromyotomy, or laparoscopic Heineke-Mikulicz pyloroplasty, and the conventional Heineke-Mikulicz pyloroplasty group. Gastric emptying time using barium sulfate mixed with dry kibble dog food was measured fluoroscopically before and 1 month after surgery. Gastric emptying of solids was significantly enhanced in the pyloroplasty groups in the postoperative period compared with preoperative emptying. Just as after conventional pyloromyotomy, gastric emptying time after laparoscopic pyloromyotomy was not statistically different as compared with preoperative values. This study indicates that the fluoroscopic test meal is a valuable tool for defining complete gastric emptying time in normal dogs. We conclude that pyloromyotomy was less effective in decreasing complete gastric emptying time than Heineke-Mikulicz pyloroplasty in normal dogs. The possibility of decreasing complete gastric emptying time by laparoscopic surgery suggests a potential clinical application for this technique in small animals.

Animals↗