Levent Avtan

A robotic indenter for minimally invasive measurement and characterization of soft tissue response

The lack of experimental data in current literature on material properties of soft tissues in living condition has been a significant obstacle in the development of realistic soft tissue models for virtual reality based surgical simulators used in medical training. A robotic indenter was developed for minimally invasive measurement of soft tissue properties in abdominal region during a laparoscopic surgery. Using the robotic indenter, force versus displacement and force versus time responses of pig liver under static and dynamic loading conditions were successfully measured to characterize its material properties in three consecutive steps. First, the effective elastic modulus of pig liver was estimated as 10-15 kPa from the force versus displacement data of static indentations based on the small deformation assumption. Then, the stress relaxation function, relating the variation of stress with respect to time, was determined from the force versus time response data via curve fitting. Finally, an inverse finite element solution was developed using ANSYS finite element package to estimate the optimum values of viscoelastic and nonlinear hyperelastic material properties of pig liver through iterations. The initial estimates of the material properties for the iterations were extracted from the experimental data for faster convergence of the solutions.

Laparoscopic Vagotomy Using Mini-Instruments in the Rat: A New Laparoscopic Small Animal Model

Purpose:Animal models are necessary for research, technical developments, and training purposes in laparoscopic surgery. Although various operations on small animals have been described, there is still a need for a simple and practical laparoscopic small animal model. We acknowledged truncal vagotomy as a simple procedure, and aimed to develop a model of laparoscopic truncal vagotomy (LTV) in the rat, an inexpensive and easily available animal.Methods:Fifty Wistar rats were randomized into an LTV group (n= 25) and an open truncal vagotomy (OTV) group (n= 25). LTV was effected with two minitrocars inserted into the left upper and right lower quadrants. Two techniques of vagotomy were developed: first, with the esophagus in its anatomical position, and second, with the distal esophagus retracted anteriorly with a grasper inserted into the retroesophageal space. OTV was performed through a midline incision. Animals were sacrificed 24 h post-operatively, and autopsy was performed.Results:The mean ± SD operating time was 8.3 ± 1.4 min in the LTV group and 5.5 ± 0.2 min in the OTV group (P < 0.05). The laparoscopically magnified view provided a better distinction of vagal fibers compared with open surgery, with the second laparoscopic technique providing the best exposure. Complications developed in three rats (12%) from the LTV group and one (4%) from the OTV group (P > 0.05). Vagotomy was confirmed to be complete at autopsy in all of the animals.Conclusion:This is the first technical description of laparoscopic peptic ulcer surgery in the rat. Although subsequent histopathological and physiological studies may be required, technically, laparoscopic vagotomy in the rat seems to be a simple, inexpensive, and expeditious small-animal model for laparoscopic research.

Buttressing the Stapler Line in Laparoscopic Sleeve Gastrectomy; Is It Really Necessary?

Materyal ve Metot: Kliniğimizde Ocak 2014 ve Aralık 2015 tarihleri arasında morbid obezite nedeniyle laparoskopik sleeve gastrektomi uygulanan ve rezeksiyon hattına güçlendirme süturu konulmayan 16 ardışık hastanın dosyası incelendi. Hastaların demografik özellikleri, vücut kitle indeksi (VKİ), ameliyat süreleri, ameliyat öncesi ve ameliyat sonrası 3. gündeki hemoglobin (Hb) değerlerindeki değişim ve ameliyat sonrası gelişen komplikasyonları değerlendirildi. Giriş Morbid obezite günümüzün en sık karşılaşılan sağlık sorunlarından birisidir. Cerrahi tedavi, özellikle de laparoskopik sleeve gastrektomi (LSG) en çok uygulanan yöntemlerden bir tanesidir. LSG’nin ameliyat sonrası yüz güldürücü sonuçları olmasına rağmen başta stapler hattından oluşan kaçak ve kanama gibi ciddi komplikasyonları mevcuttur. Bu komplikasyonların büyük oranda cerrahi teknikle ilişkili olduğu iyi bilinmektedir. Dikiş ve fibrin-yapıştırıcı ile stapler hattını güçlendirme gibi yöntemler önerilse de kesin olarak kabul edilen ve üstünlüğü kanıtlanmış bir yöntem yoktur. Literatürde dikiş hattını güçlendirecek yöntemler kullanılmasına rağmen kaçak oranının %71, kanama oranının ise %8,7’ye2 ulaştığı bildirilmektedir. Ayrıca maliyeti arttırdığı ve ameliyat süresini de uzattığı bir gerçektir3,4. Bu çalışmamızda, LSG esnasında yeni nesil stapler ile rezeksiyon yapılan ve sonrasında hiçbir güçlendirici yöntem kullanmayan hastaların sonuçlarını değerlendirdik. Bulgular: Çalışmaya katılan hastaların ortalama yaşı 44,1±7,2, K/E oranı 12/4 idi. Hastaların ortalama VKİ 49±9 kg/m2 olarak hesaplandı. Ortalama ameliyat süresi 87,9±16,1 dakika olarak hesaplandı. Ameliyat öncesi ortalama Hb değerleri 14,41±0,77 gr/dL, ameliyatın 3. gününde ortalama Hb değerleri 13,91±0,82 gr/dL olarak hesaplandı. Ameliyat sonrası hiçbir hastada major komplikasyon, stapler hattında kaçak veya kanama görülmedi. Tüm ameliyatlar açık cerrahiye geçilmeden laparoskopik olarak sonlandırıldı.

Comparison of Lichtenstein, Laparoscopic Transabdominal Preperitoneal, and Laparoscopic Totally Extraperitoneal Groin Hernia Repair and our experience with 104 Patients

Objective: The aim of this study was to compare the results of Lichtenstein repair (LR) and transabdominal preperitoneal (TAPP) and totally extraperitoneal (TEP) laparoscopic repair in groin hernias. Methods: The medical records of 104 patients who underwent groin hernia repair between January 2011 and December 2015 were retrospectively analyzed. Patients who underwent LR were defined as group 1 (n=29); those who underwent TAPP laparoscopic repair were defined as group 2 (n=42), and those who underwent TEP laparoscopic repair were defined as group 3 (n=33). The patients in the groups were compared according to their demographic findings, body mass index, operative time, and post-operative complications. Results: One patient in group 1, 10 patients in group 2, and seven patients in group 3 had bilateral groin hernias. Four patients in group 2 and two in group 3 had recurrent hernia and a history of previous LR. The mean operation time was 50.13±14.28 min in group 1, 69.61±22.19 min in group 2, and 63.87±18.09 min in group 3. The mean hospital stay was 1.4 days in group 1, 1.2 days in group 2, and 1.1 days in group 3. No major complication was encountered in early post-operative period in all groups. Discussion: Laparoscopic procedures are commonly used in hernia surgery, particularly in recurrent and bilateral cases. However, in primary and unilateral cases, LR and laparoscopic procedures have similar results. From the findings of this study, in laparoscopic hernia repair, the most important factor affecting the selection of the method is the experience of the surgeon.

Creating the Pneumoperitoneum

This chapter focuses on starting the pneumoperitoneum and is a guide to prevention and management of access and exposure-related risk factors and complications; it also deals with pneumoperitoneum-associated alterations and complications. Main subtitles of this chapter are as below: Access to Peritoneal Cavity and Exposure Noninsufflated entry method Trocar placement without prior pneumoperitoneum Open method Pre-insufflated entry method with Veress needle Visual entry method (with or without pre-insufflation) Access and Exposure-Related Risk Factors Improper placement of Veress needle Sudden uncontrolled entry into the peritoneal cavity High-pressure reading Poor visualisation Risks related with port location Uncontrolled entry Removal of cannulas (Video 1.1) Access and Exposure-Related Complications Preperitoneal insufflation (Video 1.2) Piercing the greater omentum with Veress needle Puncture of a hollow organ with Veress needle Complications of Potential Space Exposure Complications of Trocar Placement Abdominal wall haemorrhage Major vascular injury Bowel injury Bladder injury Trauma related with the type of port (Video 1.3) Pneumoperitoneum-Associated Complications Cardiopulmonary trouble Gas embolisation Deep vein thrombosis Postoperative shoulder or subphrenic pain Pneumoperitoneum-Associated Physiologic Alterations Mechanical effects of increased intra-abdominal pressure Direct systemic effects of absorbed CO2 Pneumoperitoneum and Abdominal Sepsis

Teletraining in Minimal Access Surgery

Over the last two decades, minimal access surgery (MAS) has become an indispensable alternative to conventional open surgery. Nowadays many surgical techniques are developing in MAS and many surgeons feel compelled learn these procedures. Appropriate training and education are therefore essential, but, time, monetary and geographical constraints of many surgeons often limit opportunities to gain new surgical knowledge, skills and techniques.

Reparation Laparoscopique D’une Recidive D’herniorraphie Ombilicale Ouverte

Une recidive d’herniorraphie par voie ouverte peut parfaitement etre reparee par voie laparoscopique. La pratique d’une hernioplastie laparoscopique utilisant une prothese biface est une technique efficace et de plus en plus repandue.

TAPP Avec Tissucol® Pour Recidive Tep

La technique TAPP peut etre un bon choix, pour la reparation d’une recidive de TEP. La fixation de la prothese peut etre effectuee par un encollage avec du Tissucol.