Browsing by Autor "Juan Daniel Pedraza"

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Association between clinical and surgical variables with postoperative outcomes in patients treated for intestinal obstruction for non-malignant conditions: a cross-sectional study
(Research Square (United States), 2022) Felipe Girón; Carlos Eduardo Rey Cháves; Lina Rodríguez; Roberto Javier Rueda‐Esteban; Ricardo E. Núñez-Rocha; Juan Daniel Pedraza; Danny Conde; Marco Vanegas; Ricardo Nassar; Juan David Hernández
Abstract Background: Intestinal obstruction is considered a frequent surgical pathology related to previous surgical procedures. Many different factors can lead to different outcomes when surgical management is needed. Therefore, we aim to describe the factors related to morbidity and mortality in surgical management of IO in a single-center experience. Methods: Retrospective observational study with a prospective database, in which we described patients who underwent surgical management due to intestinal obstruction between 2004 and 2015. Demographics, perioperative data, surgical outcomes, morbidity, and mortality were described. Results: 366 patients were included. Female were 54.6%. Mean age was 61.26. Laparoscopic approach was done in 21.8 % and the conversion rate was 17.2%. Intestinal resection was performed in 37.9% of the cases. Postoperative complications were observed in 18.85%. Reintervention and mortality were 9.5% and 4.1% respectively. Laparoscopic approach shows lesser time of intestinal transit (mean 28.67 vs mean 41.95 hours), and restart of oral intake after surgery (mean 96.06 vs mean 119.65) compared with open approach. Increased heart rate and intensive care unit length of stay were related with mortality (p 0.01 and 0.000 respectively). For morbidity, laparotomy and need and duration of ICU stay were related with any complication statistically significant (p 0.02, 0.008, 0.000 respectively). Conclusion: Patients with increased heart rate in the emergency room, decreased amount of intravenous fluids, need and higher length of stay in the intensive care unit, and delay in resuming oral intake after surgery appear to have poor outcomes. Laparoscopic approach seems to be a safe and feasible approach for intestinal obstruction.
Isopropyl Alcohol and Methylene Chloride as Alternatives for pre‐plastination Dehydration and Defatting processes
(Wiley, 2020) Juan Sebastián López-McCormick; Juan Daniel Pedraza; Roberto Javier Rueda‐Esteban
Plastination as a technique creates durable, long lasting, realistic specimens with a high value in anatomy teaching and research. While the original protocol using Acetone has shown great results, the use of this substance is restricted in some countries due to socioeconomical or governmental limitations. The aim of this work is to develop a protocol in which acetone has been replaced as a dehydration and defatting medium. Three groups of specimens were procured. Each of them had a sample of abdominal organs with varying fragility (kidney‐liver‐small intestine), skeletal muscle and brain tissue. Group 1 and 2 (G1–G2) were previously fixated with formaldehyde 4%, while group 3 (G3) was preserved in a glycerin‐based formaldehyde free solution. A conventional plastination technique was carried out including fixation, dehydration, defatting, forced impregnation and curing. All groups were fixated with formaldehyde 10%, although G3 required cleansing with a 50% ethylic alcohol (EA) solution to remove the glycerin. G1 was dehydrated and defatted with EA. G2 & G3 were dehydrated with isopropyl alcohol (IA), and defatted with methylene chloride (MC). All groups were impregnated in low temperatures with 1% S3–S10 Biodur silicone‐cross linker mixture. Finally, curing was divided in two steps, passive curing for 6 months and S6 cross linking. The specimens were analyzed based on tissue retraction, color degradation, morphological alterations and final specimen pliability. G1 showed maximum tissue shrinkage, morphological alteration and color degradation acquiring a brownish tone. G2 & G3 suffered less tissue retraction, color degradation was minimal, morphological alteration was not observed. Specimen pliability remained the same across the three groups, specific tissues such as skeletal muscle, blood vessels and intestine were more pliable. Lesser tissue retraction and increased color preservation were obtained with the use of IA and MC for dehydration and defatting, compared with exclusive use of EA for both steps. Specimens previously preserved with glycerin‐based formaldehyde free solutions where successfully plastinated with this technique. While this study serves as a proof of concept that IA and MC are viable substitutes for Acetone in the dehydration and defatting steps, the lack of objective measurements and a control group with acetone are strong limitations of this study. Future studies with a higher number of standardized specimens and controls are needed to determine the impact of the proposed replacement in the plastination protocol.
MATLAB Tool for Color Comparative Analysis in Fixed Specimens. A Five Solution Single Blind Controlled Trial
(Wiley, 2020) Gabriel Mateo Mejia; Juan Daniel Pedraza; Roberto Javier Rueda‐Esteban
Formaldehyde fixation avoids decomposition process of cadaveric specimens , making them useful for anatomy teaching and research . However, formaldehyde leads to fresh appearance loss in the tissue, which reduces its academical value. Although some color recovery solutions have been presented , , no standardized method for quantitative color assessment in fixed tissues has been proposed. Our aim of is to present a MATLAB tool for color recovery analysis in formaldehyde fixed tissues. Four different animal tissues (cardiac and skeletal muscle, kidney and liver), previously fixed with 10% formaldehyde (v/v) were treated in five different solutions (mineral staining, sodium bisulfite, sodium bicarbonate, GERDEX and modified Chilean solution ). Tissues were photographed at different stages of preservation. Analysis was carried out in two different spaces of chromatic representation (RGB and HSV). A computerized color comparison tool was developed allowing visualization of the chromatic presence in RGB color space through a three‐dimensional distribution (color cloud). Besides color cloud intersection percentage, frequency histograms of RGB distributions and the color saturation (S) distribution were used to generate performance metrics based on the Bhattacharyya distance. Each metric addressed one specific desired characteristic of a color recuperated specimen. Mineral staining proved to be the solution with the best overall performance across most of the proposed metrics, significantly recovering the color compared to fresh tissue. Although significant results were obtained, future works implementing more robust methods of comparison, that involve metrics based on multiple desirable characteristics of a specimen are necessary. The MATLAB tool developed showed to be useful for the quantitative color analysis and comparison in formaldehyde fixed tissues. Further studies should be done to standardize quality metrics of existing and upcoming preservation techniques. Support or Funding Information Anatomy Laboratory, School of Medicine, Universidad de los Andes.