Catherine E. Lewis

Tactile Feedback Induces Reduced Grasping Force in Robot-Assisted Surgery

Robot-assisted minimally invasive surgery has gained widespread use over the past decade, but the technique is currently operated in the absence of haptic feedback during tissue manipulation. We have developed a complete tactile feedback system, consisting of a piezoresistive force sensor, control system, and pneumatic balloon tactile display, and mounted directly onto a da Vinci surgical robotic system. To evaluate the effect of tactile feedback on robotic manipulation, a group of novices (n = 16) and experts ( n = 4) were asked to perform three blocks of peg transfer tasks with the tactile feedback system in place. Force generated at the end-effectors was measured in all three blocks, but tactile feedback was active only during the middle block. All subjects used higher force when the feedback system was inactive. When active, subjects immediately used substantially less force and still maintained appropriate grip during the task. After the system was again turned off, grip force increased significantly to prefeedback levels. These results demonstrate that robotic manipulations without tactile feedback are done with more force than needed to grasp objects. Therefore, the addition of tactile feedback allows the surgeon to grasp with less force, and may improve control of the robotic system and handling of tissues and other objects.

Postoperative CPAP and BiPAP use can be safely omitted after laparoscopic Roux-en-Y gastric bypass

BACKGROUND Obstructive sleep apnea (OSA) is prevalent in the morbidly obese population. The need for routine preoperative testing for OSA has been debated in bariatric surgery publications. Most investigators have advocated the use of continuous positive airway pressure (CPAP) or bi-level positive airway pressure (BiPAP) in the postoperative setting; however, others have reported pouch perforations or other gastrointestinal complications as a result of their use. From a review of our experience, we present an algorithm for the safe postoperative treatment of patients with OSA without the use of CPAP or BiPAP. METHODS From January 2003 to December 2007, 1095 laparoscopic Roux-en-Y gastric bypasses were performed at our institution. Preoperative testing for OSA was not routinely performed. A prospective database was maintained. The data included patient demographics, co-morbidities (including OSA and CPAP/BiPAP use), perioperative events, complications, and follow-up information. Patients with known OSA were not given CPAP/BiPAP after surgery. They were observed in a monitored setting during their inpatient stay, ensuring continuous oxygen saturation of >92%. All patients used patient-controlled analgesia, were trained in the use of incentive spirometry, and ambulated within a few hours of surgery. The outcomes were compared between the OSA patients using preoperative CPAP/BiPAP versus those with OSA without preoperative CPAP/BiPAP versus patients with no history of OSA. RESULTS A total of 811 patients were included in the study group with no known history of OSA. Of the 284 patients with a confirmed diagnosis of OSA, 144 were CPAP/BiPAP dependent. Statistically significant differences were present in age distribution and gender, with men having greater CPAP/BiPAP dependency. No significant differences were found in body mass index, length of stay, pulmonary complications, or deaths. One pulmonary complication occurred in the OSA, CPAP/BiPAP-dependent group, three in the OSA, non-CPAP group, and six in the no-known OSA group. No anastomotic leaks or deaths occurred in the series. CONCLUSION Postoperative CPAP/BiPAP can be safely omitted in laparoscopic Roux-en-Y gastric bypass patients with known OSA, provided they are observed in a monitored setting and their pulmonary status is optimized by aggressive incentive spirometry and early ambulation.

A tactile feedback system for robotic surgery

A tactile feedback system was developed and mounted on the da Vinci robotic surgical system. The system features silicone-based tactile balloon actuators mounted on the robotic master controls, modified commercial piezoresistive sensors mounted on the robotic end effectors, and a pneumatic control system. The system has a frequency response of up to 20 Hz, a linear input force-output pressure relationship, and provides five discrete levels of actuation over a force input range of 0 to 25 N. A demonstration of the system with four subjects grasping a phantom with an embedded pressure-sensitive film suggested that less force was applied with tactile feedback. This paper describes the design, fabrication, characterization, and demonstration of the mounted tactile feedback system and its components. Ongoing studies using the system will assess the benefit of tactile stimuli to learning and control in robotic surgery.

Early jejunojejunostomy obstruction after laparoscopic gastric bypass: case series and treatment algorithm

BACKGROUND To review our experience with early jejunojejunostomy obstruction (JJO) at a large academic teaching hospital and provide a management algorithm. Early JJO is a known and often overlooked complication of laparoscopic Roux-en-Y gastric bypass. METHODS From 2003 to 2007, 1097 patients underwent laparoscopic Roux-en-Y gastric bypass at our institution. Data, including patient demographics, co-morbidities, intraoperative data, peri- and postoperative complications, and outcomes, were prospectively recorded and retrospectively reviewed. RESULTS Early post-laparoscopic Roux-en-Y gastric bypass JJO occurred in 13 patients (1.2%). The average time to presentation was 15 days (range 5-27). Patients presented with a combination of nausea, vomiting, and abdominal pain; all underwent computed tomography to confirm the diagnosis. The causes of JJO included dietary noncompliance (46%), anastomotic edema (23%), narrowing of the jejunojejunostomy at surgery (23%), and luminal clot (8%). Management was determined using our proposed treatment algorithm. Three patients (23%) required operative intervention, with the remainder successfully treated conservatively. CONCLUSION From our experience, we propose a treatment algorithm for standardized management of early JJO, reserving reoperation for those who are acutely ill on presentation or those in whom conservative management fails. A review of our series using this algorithm has suggested that most patients can be successfully treated nonoperatively; however, bariatric surgeons must maintain a low threshold for surgical re-intervention in cases in which rapid recovery is not seen.

An integrated pneumatic tactile feedback actuator array for robotic surgery.

A pneumatically controlled balloon actuator array has been developed to provide tactile feedback to the fingers during robotic surgery.

Laparoscopic transgastric removal of eroded adjustable band: a novel approach

Gastric erosion is a well-known complication of laparoscopic adjustable gastric band (LAGB) placement for morbid obesity. We describe a novel approach for the removal of an eroded band through a laparoscopic gastrotomy with subsequent intraluminal division and removal of the band. A 67-year-old woman with a body mass index of 35.5 kg/m2 was seen 1 year after LAGB placement performed outside the United States. She had developed dysphagia and regurgitation of undigested food a few months after the procedure. The LAGB had been adjusted twice by her primary surgeons and was completely deflated once her symptoms began. The patient failed to improve and was subsequently referred to our institution where an upper endoscopy revealed intragastric band erosion. The patient was taken to the operating room for LAGB removal; however, standard laparoscopic and endoscopic attempts at band retrieval were unsuccessful. We then attempted a novel laparoscopic technique. An anterior gastrotomy was created, distal to the area of erosion, to facilitate easy intraluminal band division and removal. The gastrotomy was repaired, and a leak test was performed. A postoperative Gastrografin upper gastrointestinal series showed no extravasation. The patient began a diet, was discharged, and was seen in follow-up with complete resolution of her symptoms. The results of this case have shown that laparoscopic transgastric removal of an eroded gastric band is safe and feasible when standard endoscopic and laparoscopic techniques fail.

Inherited endocrinopathies: An update

Inherited endocrinopathies, including multiple endocrine neoplasia type 1 (MEN-1), multiple endocrine neoplasia type 2 syndromes (MEN-2A, MEN-2B, familial medullary thyroid carcinoma), and inherited syndromes with pheochromocytoma (von Hippel-Lindau disease, neurofibromatosis type 1, others), comprise a heterogeneous group of cancer susceptibility syndromes that affect one or more components of the endocrine system. During the past several years, novel findings regarding genotype-phenotype correlation have highlighted the importance of establishing a genetic diagnosis in the treatment of these diseases. Here, we present a case-based review of recent advances in the genetics, diagnosis and management of inherited endocrinopathies.

Splenic infarct as complication of sleeve gastrectomy

Splenic infarct as complication of sleeve gastrectomy Andrew P. Dhanasopon, B.S., Catherine E. Lewis, M.D., Jessica M. Folek, M.D., Erik P. Dutson, M.D., Amir Mehran, M.D.* University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, California Department of Surgery, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, California Metabolic and Bariatric Surgery Program, Department of Surgery, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, California Received March 18, 2009; accepted March 18, 2009

Intraoperative Laparoscopic Near-Infrared Fluorescence Cholangiography to Facilitate Anatomical Identification: When to Give Indocyanine Green and How Much.

Recent technological advances have enabled real-time near-infrared fluorescence cholangiography (NIRFC) with indocyanine green (ICG). Whereas several studies have shown its feasibility, dosing and timing for practical use have not been optimized. We undertook a prospective study with systematic variation of dosing and timing from injection of ICG to visualization. Adult patients undergoing laparoscopic biliary and hepatic operations were enrolled. Intravenous ICG (0.02-0.25 mg/kg) was administered at times ranging from 10 to 180 minutes prior to planned visualization. The porta hepatis was examined using a dedicated laparoscopic system equipped to detect NIRFC. Quantitative analysis of intraoperative fluorescence was performed using a scoring system to identify biliary structures. A total of 37 patients were enrolled. Visualization of the extrahepatic biliary tract improved with increasing doses of ICG, with qualitative scores improving from 1.9 ± 1.2 (out of 5) with a 0.02-mg/kg dose to 3.4 ± 1.3 with a 0.25-mg/kg dose (P < .05 for 0.02 vs 0.25 mg/kg). Visualization was also significantly better with increased time after ICG administration (1.1 ± 0.3 for 10 minutes vs 3.4 ± 1.1 for 45 minutes, P < .01). Similarly, quantitative measures also improved with both dose and time. There were no complications from the administration of ICG. These results suggest that a dose of 0.25 mg/kg administered at least 45 minutes prior to visualization facilitates intraoperative anatomical identification. The dosage and timing of administration of ICG prior to intraoperative visualization are within a range where it can be administered in a practical, safe, and effective manner to allow intraoperative identification of extrahepatic biliary anatomy using NIRFC.

Metabolic effects of sleeve gastrectomy in female rat model of diet-induced obesity

BACKGROUND Although women disproportionately undergo bariatric surgery, the rodent models investigating the mechanisms of bariatric surgery have been limited to males. Female rodent models can also potentially allow us to understand the effects of surgical intervention on future generations of offspring. Sleeve gastrectomy is an attractive weight loss procedure for reproductive-age female patients because it avoids the malabsorption associated with intestinal bypass. We sought to evaluate the effect of sleeve gastrectomy on young female rats with diet-induced obesity at the University of California, Los Angeles, David Geffen School of Medicine. METHODS Sprague-Dawley female rats were fed a 60% high-fat diet. At 12 weeks of age, the rats underwent either sleeve gastrectomy or sham surgery. The rats were killed 4 weeks after surgery. A chemistry panel was performed, and the serum adipokines and gut hormones were assayed. The homeostasis model assessment score was calculated. The liver histologic findings were graded for steatosis. The 2-sample t test was used to compare the results between the 2 groups. RESULTS Sleeve gastrectomy was associated with significant weight loss (5% ± 6% versus -4% ± 6%; P < .001), lower leptin levels (1.3 ± 1.2 versus 3.5 ± 2.3 ng/mL; P < .01), and higher adiponectin levels (.43 ± .19 versus .17 ± .14 ng/mL; P < .004) compared with the sham-operated rats. No significant differences were found in the fasting ghrelin levels. Furthermore, we did not observe evidence of insulin resistance or steatohepatitis after 11 weeks of high-fat diet. Despite these limitations, additional gender-specific studies are warranted given that most bariatric surgeries are performed in women. CONCLUSION Sleeve gastrectomy appears to result in weight loss and improvements in adiponectin and leptin by way of mechanisms independent of ghrelin levels in a female model of diet-induced obesity.