An Improved Cryosurgical Probe Testbed Based on Convective Exchange Boundary Conditions

2012 ◽  
Author(s):  
Michael L. Etheridge ◽  
Jeunghwan Choi ◽  
Stephanie Zastrow ◽  
Satish Ramadhyani ◽  
John C. Bischof
Keyword(s):  
Thermal Properties ◽  
Treatment Outcome ◽  
Minimally Invasive ◽  
Boundary Conditions ◽  
Predictive Modeling ◽  
Invasive Technique ◽  
Key Factors ◽  
Temperature Dependent ◽  
Freezing Medium ◽  
Convective Exchange

Cryosurgery has demonstrated significant capabilities as a minimally invasive technique for treating cancer and other conditions [1], but has been limited by the ability to accurately predict treatment outcome and damage to surrounding tissues. Contributing to this problem has been the accuracy of predictive modeling and translating this to effective pretreatment planning. The two key factors in accurately modeling cryosurgical freezing are the temperature-dependent thermal properties of the freezing medium and cryoprobe boundary conditions. Both of these issues are considered in this study.

scholarly journals Methods for Characterizing Convective Cryoprobe Heat Transfer in Ultrasound Gel Phantoms

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Michael L. Etheridge ◽  
Jeunghwan Choi ◽  
Satish Ramadhyani ◽  
John C. Bischof
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Boundary Conditions ◽  
Detailed Knowledge ◽  
Temperature Dependent ◽  
Convective Boundary ◽  
Convective Coefficient ◽  
Tissue Phantom ◽  
Convective Exchange ◽  
Transient Variations

While cryosurgery has proven capable in treating of a variety of conditions, it has met with some resistance among physicians, in part due to shortcomings in the ability to predict treatment outcomes. Here we attempt to address several key issues related to predictive modeling by demonstrating methods for accurately characterizing heat transfer from cryoprobes, report temperature dependent thermal properties for ultrasound gel (a convenient tissue phantom) down to cryogenic temperatures, and demonstrate the ability of convective exchange heat transfer boundary conditions to accurately describe freezing in the case of single and multiple interacting cryoprobe(s). Temperature dependent changes in the specific heat and thermal conductivity for ultrasound gel are reported down to −150 °C for the first time here and these data were used to accurately describe freezing in ultrasound gel in subsequent modeling. Freezing around a single and two interacting cryoprobe(s) was characterized in the ultrasound gel phantom by mapping the temperature in and around the “iceball” with carefully placed thermocouple arrays. These experimental data were fit with finite-element modeling in COMSOL Multiphysics, which was used to investigate the sensitivity and effectiveness of convective boundary conditions in describing heat transfer from the cryoprobes. Heat transfer at the probe tip was described in terms of a convective coefficient and the cryogen temperature. While model accuracy depended strongly on spatial (i.e., along the exchange surface) variation in the convective coefficient, it was much less sensitive to spatial and transient variations in the cryogen temperature parameter. The optimized fit, convective exchange conditions for the single-probe case also provided close agreement with the experimental data for the case of two interacting cryoprobes, suggesting that this basic characterization and modeling approach can be extended to accurately describe more complicated, multiprobe freezing geometries. Accurately characterizing cryoprobe behavior in phantoms requires detailed knowledge of the freezing medium's properties throughout the range of expected temperatures and an appropriate description of the heat transfer across the probe's exchange surfaces. Here we demonstrate that convective exchange boundary conditions provide an accurate and versatile description of heat transfer from cryoprobes, offering potential advantages over the traditional constant surface heat flux and constant surface temperature descriptions. In addition, although this study was conducted on Joule–Thomson type cryoprobes, the general methodologies should extend to any probe that is based on convective exchange with a cryogenic fluid.

scholarly journals Gastric tube necrosis following minimally invasive oesophagectomy is a learning curve issue

2013 ◽  
Vol 95 (5) ◽  
pp. 329-334 ◽  
Author(s):  
L Ramage ◽  
J Deguara ◽  
A Davies ◽  
A Hamouda ◽  
K Tsigritis ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Learning Curve ◽  
Gastric Tube ◽  
Invasive Technique ◽  
Ischaemic Preconditioning ◽  
Inpatient Mortality ◽  
Key Factors ◽  
Ultrasonic Dissector ◽  
Prophylactic Measures ◽  
Minimally Invasive Oesophagectomy

Introduction Gastric tube necrosis following oesophagectomy is thought to have an increased association with a minimally invasive technique. Some suggest gastric ischaemic preconditioning may reduce ischaemic complications. We discuss our series of 155 consecutive minimally invasive oesophagectomies (MIOs), including a number of cases of gastric tube ischaemia, of which 4 (2.6%) developed conduit necrosis. Methods Data were collected prospectively of MIOs carried out by a single surgeon between 2005 and 2011. Cases of gastric tube necrosis were identified. Results Overall, 155 patients were identified. The inpatient mortality rate was 2.6%. Gastric tube necrosis occurred in four patients (2.6%). An ultrasonic dissector injury to the gastroepiploic arcade had occurred in two cases. In another case, the gastric tube was strangulated in the hiatus. In the remaining case, no clear mechanical cause was identified. All 4 cases occurred within the first 73 cases. The gastric tube necrosis rate of the first 50 cases versus cases 51–155 was 4% and 2% respectively (p=0.5948). The anastomotic leak rate in these two cohorts was 18% and 7% respectively (p=0.0457). There was a significant reduction in overall gastric tube complications from 22% to 10% following the learning curve of the initial 50 cases (p=0.0447). Conclusions In our series, gastric tube necrosis appears to be a learning curve issue. Prophylactic measures such as ischaemic preconditioning become less relevant as the operating surgeon’s experience increases. Instead, meticulous attention to preserving the gastroepiploic arcade, avoidance of tension in the tube and careful positioning of the gastric conduit through an adequately sized hiatus are key factors.

scholarly journals Microsurgical unilateral laminotomy for bilateral decompression of degenerative lumbar canal stenosis: a comparative study

2019 ◽  
Vol 55 (1) ◽  
Author(s):  
Mohamed I. Refaat ◽  
Amr K. Elsamman ◽  
Adham Rabea ◽  
Mohamed I. A. Hewaidy
Keyword(s):  
Patient Satisfaction ◽  
Blood Loss ◽  
Minimally Invasive ◽  
Invasive Technique ◽  
Decompression Surgery ◽  
Microsurgical Decompression ◽  
Significant Difference ◽  
Duration Of Surgery ◽  
Group A ◽  
Group B

Abstract Background The quest for better patient outcomes is driving to the development of minimally invasive spine surgical techniques. There are several evidences on the use of microsurgical decompression surgery for degenerative lumbar spine stenosis; however, few of these studies compared their outcomes with the traditional laminectomy technique. Objectives The aim of our study was to compare outcomes following microsurgical decompression via unilateral laminotomy for bilateral decompression (ULBD) of the spinal canal to the standard open laminectomy for cases with lumbar spinal stenosis. Subjects and methods Cases were divided in two groups. Group (A) cases were operated by conventional full laminectomy; Group (B) cases were operated by (ULBD) technique. Results from both groups were compared regarding duration of surgery, blood loss, perioperative complication, and postoperative outcome and patient satisfaction. Results There was no statistically significant difference between both groups regarding the improvement of visual pain analogue, while improvement of neurogenic claudication outcome score was significant in group (B) than group (A). Seventy-three percent of group (A) cases and 80% of group (B) stated that surgery met their expectations and were satisfied from the outcome. Conclusion Comparing ULBD with traditional laminectomy showed the efficacy of the minimally invasive technique in obtaining good surgical outcome and patient satisfaction. There was no statistically significant difference between both groups regarding the occurrence of complications The ULBD technique was found to respect the posterior spinal integrity and musculature, accompanied with less blood loss, shorter hospital stays, and shorter recovery periods than the open laminectomy technique.

scholarly journals Endovascular Bariatric Surgery as Novel Minimally Invasive Technique for Weight Management in the Morbidly Obese: Review of the Literature

Nutrients ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 2541
Author(s):  
Giuseppe Massimo Sangiorgi ◽  
Alberto Cereda ◽  
Nicola Porchetta ◽  
Daniela Benedetto ◽  
Andrea Matteucci ◽  
...  
Keyword(s):  
Bariatric Surgery ◽  
Minimally Invasive ◽  
Weight Management ◽  
World Health ◽  
Invasive Technique ◽  
Morbidly Obese ◽  
World Population ◽  
Obese Patients ◽  
The World ◽  
Open Bariatric Surgery

Nowadays, obesity represents one of the most unresolved global pandemics, posing a critical health issue in developed countries. According to the World Health Organization, its prevalence has tripled since 1975, reaching a prevalence of 13% of the world population in 2016. Indeed, as obesity increases worldwide, novel strategies to fight this condition are of the utmost importance to reduce obese-related morbidity and overall mortality related to its complications. Early experimental and initial clinical data have suggested that endovascular bariatric surgery (EBS) may be a promising technique to reduce weight and hormonal imbalance in the obese population. Compared to open bariatric surgery and minimally invasive surgery (MIS), EBS is much less invasive, well tolerated, with a shorter recovery time, and is probably cost-saving. However, there are still several technical aspects to investigate before EBS can be routinely offered to all obese patients. Further prospective studies and eventually a randomized trial comparing open bariatric surgery vs. EBS are needed, powered for clinically relevant outcomes, and with adequate follow-up. Yet, EBS may already appear as an appealing alternative treatment for weight management and cardiovascular prevention in morbidly obese patients at high surgical risk.

scholarly journals Microendoscopy-assisted extraforaminal lumbar interbody fusion for treating single-level spondylodesis

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Motohide Shibayama ◽  
Guang Hua Li ◽  
Li Guo Zhu ◽  
Zenya Ito ◽  
Fujio Ito
Keyword(s):  
Minimally Invasive ◽  
Spinal Canal ◽  
Interbody Fusion ◽  
Facet Joint ◽  
Clinical Results ◽  
Invasive Technique ◽  
Clinical Effects ◽  
Lumbar Interbody Fusion ◽  
Disc Space ◽  
Single Level

Abstract Background Lumbar interbody fusion is a standard technique for treating degenerative lumbar disorders involving instability. Due to its invasiveness, a minimally invasive technique, extraforaminal lumbar interbody fusion (ELIF), was introduced. On surgically approaching posterolaterally, the posterior muscles and spinal canal are barely invaded. Despite its theoretical advantage, ELIF is technically demanding and has not been popularised. Therefore, we developed a microendoscopy-assisted ELIF (mELIF) technique which was designed to be safe and less invasive. Here, we aimed to report on the surgical technique and clinical results. Methods Using a posterolateral approach similar to that of lateral disc herniation surgery, a tubular retractor, 16 or 18 mm in diameter, was placed at the lateral aspect of the facet joint. The facet joint was partially excised, and the disc space was cleaned. A cage and local bone graft were inserted into the disc space. All disc-related procedures were performed under microendoscopy. The spinal canal was not invaded. Bilateral percutaneous screw-rod constructs were inserted and fixed. Results Fifty-five patients underwent the procedure. The Oswestry Disability Index and visual analogue scale scores greatly improved. Over 90% of the patients obtained excellent or good results based on Macnab’s criteria. There were neither major adverse clinical effects nor the need for additional surgery. Conclusions mELIF is minimally invasive because the spinal canal and posterior muscles are barely invaded. It produces good clinical results with fewer complications. This technique can be applied in most single-level spondylodesis cases, including those involving L5/S1 disorders.

The Emerging Role of Robotic Single-site Approach for Myomectomy: A Systematic Review of the Literature

2021 ◽  
pp. 155335062098822
Author(s):  
Eirini Giovannopoulou ◽  
Anastasia Prodromidou ◽  
Nikolaos Blontzos ◽  
Christos Iavazzo
Keyword(s):  
Blood Loss ◽  
Minimally Invasive ◽  
Complication Rate ◽  
Operative Time ◽  
Intraoperative Complications ◽  
Single Site ◽  
Minimally Invasive Technique ◽  
Invasive Technique ◽  
Robotic Myomectomy ◽  
The Mean

Objective. To review the existing studies on single-site robotic myomectomy and test the safety and feasibility of this innovative minimally invasive technique. Data Sources. PubMed, Scopus, Google Scholar (from their inception to October 2019), as well as Clinicaltrials.gov databases up to April 2020. Methods of Study Selection. Clinical trials (prospective or retrospective) that reported the outcomes of single-site robotic myomectomy, with a sample of at least 20 patients were considered eligible for the review. Results. The present review was performed in accordance with the guidelines for Systematic Reviews and Meta-Analyses (PRISMA). Four (4) studies met the inclusion criteria, and a total of 267 patients were included with a mean age from 37.1 to 39.1 years and BMI from 21.6 to 29.4 kg/m2. The mean operative time ranged from 131.4 to 154.2 min, the mean docking time from 5.1 to 5.45 min, and the mean blood loss from 57.9 to 182.62 ml. No intraoperative complications were observed, and a conversion rate of 3.8% was reported by a sole study. The overall postoperative complication rate was estimated at 2.2%, and the mean hospital stay ranged from 0.57 to 4.7 days. No significant differences were detected when single-site robotic myomectomy was compared to the multiport technique concerning operative time, blood loss, and total complication rate. Conclusion. Our findings support the safety of single-site robotic myomectomy and its equivalency with the multiport technique on the most studied outcomes. Further studies are needed to conclude on the optimal minimally invasive technique for myomectomy.

Minimally invasive permanent pacemaker implantation immediately after birth: from delivery room to heart surgery

2021 ◽  
pp. 1-3
Author(s):  
Mehmet Taşar ◽  
Nur Dikmen Yaman ◽  
Burcu Arıcı ◽  
Ömer Nuri Aksoy ◽  
Huseyin Dursin ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Atrioventricular Block ◽  
Heart Surgery ◽  
Pacemaker Implantation ◽  
Skin Incision ◽  
Permanent Pacemaker ◽  
Invasive Technique ◽  
Permanent Pacemaker Implantation ◽  
Congenital Atrioventricular Block ◽  
The Right

Abstract Introduction: Congenital atrioventricular block is diagnosed in uterine life, at birth, or early in life. Atrioventricular blocks can be life threatening immediately at birth so urgent pacemaker implantation techniques are requested. Reasons can be cardiac or non-cardiac, but regardless of the reason, operations are challenging. We aimed to present technical procedure and operative results of pacemaker implantation in neonates. Materials and methods: Between June 2014 and February 2021, 10 neonates who had congenital atrioventricular block underwent surgical operation to implant permanent epicardial pacemaker by using minimally invasive technique. Six of the patients were female and four of them were male. Mean age was 4.3 days (0–11), while three of them were operated on the day of birth. Mean weight was 2533 g (1200–3300). Results: Operations were achieved through subxiphoidal minimally skin incision. Epicardial 25 mm length dual leads were implanted on right ventricular surface and generators were fixed on the right (seven patients) or left (three patients) diaphragmatic surface by incising pleura. There were no complication, morbidity, and mortality related to surgery. Conclusion: Few studies have characterised the surgical outcomes following epicardial permanent pacemaker implantation in neonates. The surgical approach is attractive and compelling among professionals so we aimed to present the techniques and results in patients who required permanent pacemaker implantation in the first month of life.

scholarly journals 689 Silac (Sinus Laser-Assisted Closure) For Pilonidal Sinus: Our NHS Experience

2021 ◽  
Vol 108 (Supplement_2) ◽  
Author(s):  
S Kalaskar ◽  
J Adamek
Keyword(s):  
Minimally Invasive ◽  
Success Rate ◽  
Pilonidal Disease ◽  
Surgical Excision ◽  
Pilot Project ◽  
Invasive Technique ◽  
Recurrence Rates ◽  
Pilonidal Cyst ◽  
Primary Wound Closure

Abstract Introduction The accepted treatment of pilonidal disease still consists of surgical excision with primary wound closure. This treatment has complications such as excessive pain, delayed wound healing, and recurrence. We introduced this technique using a radial laser probe (SiLaCTM, Biolitec, Germany). Previous studies have shown encouraging results with respect to safety, patient satisfaction, and minimal recurrence rates. Method The pilot project was planned with the objectives to assess postoperative complications and reoperation rates. All operations were performed as day case procedures under general anaesthesia. We studied the data of our first 25patients operated with this technique between January 2019 and December 2019 using a prospective database and outpatient clinic follow up. Results The median follow up duration was 13 months. The initial success rate was 64%(16/25), reoperation was required in 32%(8/25) and one patient was lost to follow up. one patient returned with abscess formation in the postoperative period. Conclusions SiLaC is a safe and minimally invasive technique for the destruction of the pilonidal cyst and sinus. The success rate is modest, making this new therapy a minimally invasive option for the majority of the patients with pilonidal disease but it should be offered with caution.

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