AC and DC Differential Bridge Structure Suitable for Electrochemical Interfacial Capacitance Biosensing Applications.

This paper presents a capacitive differential bridge structure with both AC and DC excitation and balancing capability for low cost electrode-solution interfacial capacitance biosensing applications. The proposed series RC balancing structure offers higher sensitivity, lower susceptibility to common-mode interferences, and drift control. To evaluate the bridge performance in practice, possible effects of initial bridge imbalance due to component mismatches are investigated considering the required resolution of the balancing networks, sensitivity, and linearity. This evaluation is also a guideline to designing the balancing networks, balancing algorithm and the proceeding readout interface circuitry. The proposed series RC bridge structure is implemented along with a custom single frequency real-time amplification/filtering readout board with real-time data acquisition and sine fitting. The main specifications for the implemented structure are 8-bit detection resolution if the total expected fractional capacitance change at the interface is roughly 1%. The characterization and measurement results show the effectiveness of the proposed structure in achieving the design target. The implemented structure successfully achieves distinct detection levels for tiny total capacitance change at the electrode-solution interface, utilizing Microcystin-(Leucine-Arginine) toxin dilutions as a proof of concept.

Long-term Outcomes of Patients Receiving a Magnetic Sphincter Augmentation Device for Gastroesophageal Reflux.

BACKGROUND & AIMS: Based on results from year 2 of a 5-year trial, in 2012 the US Food and Drug Administration approved the use of a magnetic device to augment lower esophageal sphincter function in patients with gastroesophageal reflux disease (GERD). We report the final results of 5 years of follow-up evaluation of patients who received this device. METHODS: We performed a prospective study of the safety and efficacy of a magnetic device in 100 adults with GERD for 6 months or more, who were partially responsive to daily proton pump inhibitors (PPIs) and had evidence of pathologic esophageal acid exposure, at 14 centers in the United States and The Netherlands. The magnetic device was placed using standard laparoscopic tools and techniques. Eighty-five subjects were followed up for 5 years to evaluate quality of life, reflux control, use of PPIs, and side effects. The GERD-health-related quality of life (GERD-HRQL) questionnaire was administered at baseline to patients on and off PPIs, and after placement of the device; patients served as their own controls. A partial response to PPIs was defined as a GERD-HRQL score of 10 or less on PPIs and a score of 15 or higher off PPIs, or a 6-point or more improvement when scores on vs off PPI were compared. RESULTS: Over the follow-up period, no device erosions, migrations, or malfunctions occurred. At baseline, the median GERD-HRQL scores were 27 in patients not taking PPIs and 11 in patients on PPIs; 5 years after device placement this score decreased to 4. All patients used PPIs at baseline; this value decreased to 15.3% at 5 years. Moderate or severe regurgitation occurred in 57% of subjects at baseline, but only 1.2% at 5 years. All patients reported the ability to belch and vomit if needed. Bothersome dysphagia was present in 5% at baseline and in 6% at 5 years. Bothersome gas-bloat was present in 52% at baseline and decreased to 8.3% at 5 years. CONCLUSIONS: Augmentation of the lower esophageal sphincter with a magnetic device provides significant and sustained control of reflux, with minimal side effects or complications. No new safety risks emerged over a 5-year follow-up period. These findings validate the long-term safety and efficacy of the magnetic sphincter augmentation device for patients with GERD. ClinicalTrials.gov no: NCT00776997.

Indocyanine-green-loaded microballoons for biliary imaging in cholecystectomy.

We encapsulate indocyanine green (ICG) in poly[(D,L-lactide-co-glycolide)-co-PEG] diblock (PLGA-PEG) microballoons for real-time fluorescence and hyperspectral imaging of biliary anatomy. ICG-loaded microballoons show superior fluorescence characteristics and slower degradation in comparison with pure ICG. The use of ICG-loaded microballoons in biliary imaging is demonstrated in both biliary-simulating phantoms and an ex vivo tissue model. The biliary-simulating phantoms are prepared by embedding ICG-loaded microballoons in agar gel and imaged by a fluorescence imaging module in a Da Vinci surgical robot. The ex vivo model consists of liver, gallbladder, common bile duct, and part of the duodenum freshly dissected from a domestic swine. After ICG-loaded microballoons are injected into the gallbladder, the biliary structure is imaged by both hyperspectral and fluorescence imaging modalities. Advanced spectral analysis and image processing algorithms are developed to classify the tissue types and identify the biliary anatomy. While fluorescence imaging provides dynamic information of movement and flow in the surgical region of interest, data from hyperspectral imaging allow for rapid identification of the bile duct and safe exclusion of any contaminant fluorescence from tissue not part of the biliary anatomy. Our experiments demonstrate the technical feasibility of using ICG-loaded microballoons for biliary imaging in cholecystectomy.

Two cases of small cell carcinoma of the gallbladder.

Small cell carcinoma of the gallbladder is a rare disease process with approximately 40 cases reported in the literature. It is most often found in elderly female population and is associated with cholelithiasis and cigarette smoking. A multidisciplinary approach to treatment with wide surgical resection and adjuvant chemotherapy is the current standard of care. Notwithstanding prompt medical intervention, it is a disease with a poor prognosis. The pathology is characterized by early metastases and extensive local invasion. Herein, we report two cases of small cell carcinoma addressed at our institution. In both cases, a radical resection was performed with subsequent referral to oncology for additional therapy.

Initial experience with the four-arm computer-enhanced telesurgery device in foregut surgery.

BACKGROUND: The da Vinci robotic system (Intuitive Surgical, Sunnyvale, CA) has been used effectively and with good results. Previously, the surgeon could manipulate three arms on the robot: one camera port and two working ports. This configuration required a second surgeon for most general surgical procedures. Recently, the robotic device has been modified to include a fourth arm, adding another computer-assisted instrument that the surgeon can manipulate. In this report, we describe our experience with the da Vinci robot with a fourth arm modification for the performance of selected surgical procedures. MATERIALS AND METHODS: A total of six patients were prospectively enrolled and underwent surgery using the modified da Vinci robot. Their average age was 56 years. Five patients underwent Nissen fundoplication, and one patient underwent Heller myotomy. Operative time, defined as the time from skin incision to completed skin closure, as well as robotic time, defined as the time during which the robot was being used, were recorded. Intra-operative and perioperative complications were also recorded. RESULTS: Average operative and robotic times for Nissen fundoplication were 134 and 80 minutes, respectively. Operative and robotic times for the Heller myotomy were 118 and 70 minutes. All patients tolerated the procedure well and experienced no perioperative complications. CONCLUSIONS: The da Vinci robot with the addition of the fourth arm results in a efficient and safe operation and allows the surgeon to perform additional maneuvers without the use of a surgical assistant.