Jonathan A. Schoen

Major mesh-related complications following hernia repair: events reported to the Food and Drug Administration.

Mesh material affects complications following hernia repair. Medical device reports on the use of surgical mesh for hernia repair were reviewed from the Food and Drug Administration’s (FDA) Manufacturer User Facility Device Experience Database from January 1996 to September 2004. We analyzed 252 adverse event reports related to the use of surgical mesh for hernia repair. Adverse events included infection (42%, 107 reports), mechanical failure (18%, 46), pain (9%, 23), reaction (8%, 20), intestinal complications (7%, 18), adhesions (6%, 14), seroma (4%, 9), erosion (2%, 6), and other (4%, 9). Compared to all other mesh types, Sepra/polypropylene mesh had more mechanical failures (80 vs 14%, p < 0.05), biomaterial mesh had more reactions (57 vs 7%, p < 0.05), polytetrafluoroethylene (PTFE)/polypropylene mesh had more intestinal complications (14 vs 7%, p < 0.05), and PTFE mesh tended to have more infections (75 vs 41% all other, p = 0.07). Death occurred in 2% (5). We conclude that specific mesh materials are related to specific complications.

Wireless Tissue Palpation for Intraoperative Detection of Lumps in the Soft Tissue

In an open surgery, identification of precise margins for curative tissue resection is performed by manual palpation. This is not the case for minimally invasive and robotic procedures, where tactile feedback is either distorted or not available. In this paper, we introduce the concept of intraoperative wireless tissue palpation. The wireless palpation probe (WPP) is a cylindrical device (15 mm in diameter, 60 mm in length) that can be deployed through a trocar incision and directly controlled by the surgeon to create a volumetric stiffness distribution map of the region of interest. This map can then be used to guide the tissue resection to minimize healthy tissue loss. The wireless operation prevents the need for a dedicated port and reduces the chance of instrument clashing in the operating field. The WPP is able to measure in real time the indentation pressure with a sensitivity of 34 Pa, the indentation depth with an accuracy of 0.68 mm, and the probe position with a maximum error of 11.3 mm in a tridimensional workspace. The WPP was assessed on the benchtop in detecting the local stiffness of two different silicone tissue simulators (elastic modulus ranging from 45 to 220 kPa), showing a maximum relative error below 5%. Then, in vivo trials were aimed to identify an agar-gel lump injected into a porcine liver and to assess the device usability within the frame of a laparoscopic procedure. The stiffness map created intraoperatively by the WPP was compared with a map generated ex vivo by a standard uniaxial material tester, showing less than 8% local stiffness error at the site of the lump.

Surgical evaluation of a novel tethered robotic capsule endoscope using micro-patterned treads.

BackgroundThe state-of-the-art technology for gastrointestinal (GI) tract exploration is a capsule endoscope (CE). Capsule endoscopes are pill-sized devices that provide visual feedback of the GI tract as they move passively through the patient. These passive devices could benefit from a mobility system enabling maneuverability and controllability. Potential benefits of a tethered robotic capsule endoscope (tRCE) include faster travel speeds, reaction force generation for biopsy, and decreased capsule retention.MethodsIn this work, a tethered CE is developed with an active locomotion system for mobility within a collapsed lumen. Micro-patterned polydimethylsiloxane (PDMS) treads are implemented onto a custom capsule housing as a mobility method. The tRCE housing contains a direct current (DC) motor and gear train to drive the treads, a video camera for visual feedback, and two light sources (infrared and visible) for illumination.ResultsThe device was placed within the insufflated abdomen of a live anesthetized pig to evaluate mobility performance on a planar tissue surface, as well as within the cecum to evaluate mobility performance in a collapsed lumen. The tRCE was capable of forward and reverse mobility for both planar and collapsed lumen tissue environments. Also, using an onboard visual system, the tRCE was capable of demonstrating visual feedback within an insufflated, anesthetized porcine abdomen.ConclusionProof-of-concept in vivo tRCE mobility using micro-patterned PDMS treads was shown. This suggests that a similar method could be implemented in future smaller, faster, and untethered RCEs.

Laparoscopic sleeve gastrectomy: long-term weight loss outcomes

BACKGROUND Laparoscopic sleeve gastrectomy (LSG) has become an increasingly popular stand-alone weight loss surgery, but there is a paucity of long-term efficacy data. OBJECTIVE To determine long-term outcomes for patients undergoing LSG. SETTING Tertiary care university hospital in the United States. METHODS This study presents a case series of the first 16 patients undergoing LSG at our institution. Inclusion criteria were accepted indications for bariatric surgery, and exclusion criteria were any prior bariatric surgery, gastrectomy, substance abuse, uncontrolled psychiatric illness, end-stage organ disease, or advanced-stage cancer. Patients were followed for 7 years. Outcomes included percent excess weight loss (%EWL), percent weight loss (%WL), resolution of co-morbidities, and major and minor complications. RESULTS Patients enrolled in this study had a mean body mass index (BMI) of 43.5 kg/m(2) and a mean age of 49, and 14 of 16 patients were women. Fourteen of 16 patients had 7-year follow-ups with a mean %WL of 29.6%±8.95 and a mean %EWL of 59.6%±89.9%. At 7 years, 11 of 14 patients achieved>50% EWL. One-year follow-up data revealed a mean EWL of 72%±20%, which was significantly greater than the %EWL at 7 years (P = .005). Complications included 1 partial obstruction at the gastric incisura angularis and 1 subacute leak; both were managed endoscopically. There were no reoperations and no deaths. Five of 14 patients experienced new-onset gastroesophageal reflux disease. CONCLUSIONS At 7 years postoperative, the LSG remained a durable and successful operation.

Preliminary Mechanical Characterization of the Small Bowel for In Vivo Robotic Mobility

In this work we present test methods, devices, and preliminary results for the mechanical characterization of the small bowel for intra luminal robotic mobility. Both active and passive forces that affect mobility are investigated. Four investigative devices and testing methods to characterize the active and passive forces are presented in this work: (1) a novel manometer and a force sensor array that measure force per cm of axial length generated by the migrating motor complex, (2) a biaxial test apparatus and method for characterizing the biomechanical properties of the duodenum, jejunum, and ileum, (3) a novel in vitro device and protocol designed to measure the energy required to overcome the self-adhesivity of the mucosa, and (4) a novel tribometer that measures the in vivo coefficient of friction between the mucus membrane and the robot surface. The four devices are tested on a single porcine model to validate the approach and protocols. Mean force readings per cm of axial length of intestine that occurred over a 15 min interval in vivo were 1.34 ± 0.14 and 1.18 ± 0.22 N cm(-1) in the middle and distal regions, respectively. Based on the biaxial stress/stretch tests, the tissue behaves anisotropically with the circumferential direction being more compliant than the axial direction. The mean work per unit area for mucoseparation of the small bowel is 0.08 ± 0.03 mJ cm(-2). The total energy to overcome mucoadhesion over the entire length of the porcine small bowel is approximately 0.55 J. The mean in vivo coefficient of friction (COF) of a curved 6.97 cm(2) polycarbonate sled on live mucosa traveling at 1 mm s(-1) is 0.016 ± 0.002. This is slightly lower than the COF on excised tissue, given the same input parameters. We have initiated a comprehensive program and suite of test devices and protocols for mechanically characterizing the small bowel for in vivo mobility. Results show that each of the four protocols and associated test devices has successfully gathered preliminary data to confirm the validity of our test approach.

Colonic pneumatosis and intestinal perforations with sunitinib treatment for renal cell carcinoma.

Keywords Pneumatosis.Intestinalperforations.Sunitinibtreatment.RenalcellcarcinomaCase historiesPatient 1 A woman with renal cell carcinoma (RCC)presented with sudden right sided flank pain and anuria.Two years earlier she was diagnosed with RCC clear celltype and had a left-sided nephrectomy performed at thattime. Her initial staging evaluation revealed multiplepulmonary nodules consistent with metastatic disease andshe was started on sorafenib therapy. She remained on thistherapy for 9 months, but was then found to haveprogressive disease and high-dose interleukin-2 (IL2) wasinitiated. The patient developed bilateral pulmonary edemaduring her initial course of IL2 which was believed to besecondary to IL2-induced capillary leak and requiredendotracheal intubation. Accordingly, IL2 was abandonedwithout completing a full course and treatment withsunitinib (50 mg daily for 4 weeks followed by a 2 weekbreak) was pursued.Thirteen months after starting sunitinib, the patientdescribed approximately 12 h of acute right-sided flankpain with no urine output over that time period. Her pasthistory included a tiny calculus in the right kidney. Shedenied vomiting, diarrhea or recent change in her bowelmovements. Laboratory analysis revealed a lactate of3.5 mmol/l (normal range 0.5–2.2 mmol/l). A computedtomography (CT) exam of the abdomen and pelvis wasordered, showing colonic pneumatosis on the right andpneumoretroperitoneum (Fig. 1a–d). The patient proceededto surgery, with placement of a ureteral stent and a right-sided hemi-colectomy. Cystoscopy and an intraoperativeretrograde ureteropyelogram did not demonstrate an ob-structive stone and the anuria was attributed to gastrointes-tinal perforation (GIP). Pathologic examination of the rightcolon showed extensive pneumatosis cystoides intestinalis(Fig. 1e) and focal areas of ulceration of the mucosa withtransmural acute and chronic inflammation and giant cellreaction (Fig. 1f); microthrombi were observed in thevessels of the lamina propria. Three regional lymph nodes

A quantitative comparison of soft tissue compressive viscoelastic model accuracy

Viscoelastic models are generally considered a good option for modeling biological tissue due to tissue time-dependency. However, although various forms of viscoelastic models have been developed, only a few have shown a good balance between model mathematical simplicity and experimental fit accuracy. Starting from a basic Standard Linear Solid (SLS) model, a systematic modification of the viscoelastic model leading to a more accurate tissue model is presented. A five-element model family, with a Double Maxwell-arm Wiechert (DMW) representative model, is selected for its mathematical simplicity and mathematical loading accuracy. This DMW model is then used to fit experimental data collected from stress relaxation indentation tests performed on fresh porcine liver and spleen. The results show that this DMW model provides a closer fit with the experimental liver (SLS R(2)=0.731, DMW R(2)=0.991) and spleen (SLS R(2)=0.720, DMW R(2)=0.981) data, compared to an SLS model, while maintaining appreciable mathematical simplicity by using only five model elements, compared to seven-element models. Thus, any model from this five-element model family can be used as a base compressive model for complex soft tissue with an approximate 35% improved model fit over SLS. Finally, model element parameters for in vitro fresh porcine liver and spleen are determined from the associated indentation tests.

Single-Port-Access Surgery with a Novel Magnet Camera System

In this paper, we designed, built, and tested a novel single-port access laparoscopic surgery (SPA) specific camera system. This device (magnet camera) integrates a light source and video camera into a small, inexpensive, portable package that does not compete for space with the surgical tools during SPA. The device is inserted through a 26-mm incision in the umbilicus, followed by the SPA port, which is used to maintain an insufflation seal and support the insertion of additional tools. The camera, now in vivo, remains separate from the SPA port, thereby removing the need for a dedicated laparoscope, and, thus, allowing for an overall reduction in SPA port size or the use of a third tool through the insertion port regularly reserved for the traditional laparoscope. The SPA camera is mounted to the abdominal ceiling using one of the two methods: fixation to the SPA port through the use of a rigid ring and cantilever bar, or by an external magnetic handle. The purpose of the magnet camera system is to improve SPA by: 1) eliminating the laparoscope SPA channel; 2) increasing the field of view through enhanced camera system mobility; and 3) reducing interference between the camera system and the surgical tools at the port, both in vivo and ex vivo.

Micropatterned Treads for In Vivo Robotic Mobility

Despite revolutionary advances in many fields of medicine, there are no active mobile in vivo devices commercially available, or in use, today. Several research groups are actively looking at a number of mobility methods in a number of lumens but little commercial work has been done. While robotic surgery is available today thanks to ex vivo robots, such as the da Vinci surgical system, these methods are very expensive, require heavy external equipment, and are still constrained by entry incisions. An alternative approach may be to place the robot completely inside the patient. Such devices may enable noninvasive imaging and diagnostics. These devices may be significantly less expensive than current minimally invasive methods, without extensive support equipment, which may allow them to be also used routinely in the emergency room (ER)/trauma sites and remote locations. This work explores micropatterned treads that may enable mobile capsule crawlers inside the body. Current research efforts into providing contact locomotion using micro-tread tracks are explored including initial drawbar force generation experimental results, dynamic finite element analysis with these tread designs, and in vivo porcine evaluation and comparison of two leading tread designs.

An Integrated Port Camera and Display System for Laparoscopy

In this paper, we built and tested the port camera, a novel, inexpensive, portable, and battery-powered laparoscopic tool that integrates the components of a vision system with a cannula port. This new device 1) minimizes the invasiveness of laparoscopic surgery by combining a camera port and tool port; 2) reduces the cost of laparoscopic vision systems by integrating an inexpensive CMOS sensor and LED light source; and 3) enhances laparoscopic surgical procedures by mechanically coupling the camera, tool port, and liquid crystal display (LCD) screen to provide an on-patient visual display. The port camera video system was compared to two laparoscopic video systems: a standard resolution unit from Karl Storz (model 22220130) and a high definition unit from Stryker (model 1188HD). Brightness, contrast, hue, colorfulness, and sharpness were compared. The port camera video is superior to the Storz scope and approximately equivalent to the Stryker scope. An ex vivo study was conducted to measure the operative performance of the port camera. The results suggest that simulated tissue identification and biopsy acquisition with the port camera is as efficient as with a traditional laparoscopic system. The port camera was successfully used by a laparoscopic surgeon for exploratory surgery and liver biopsy during a porcine surgery, demonstrating initial surgical feasibility.