Pose estimation methods for robotically guided magnetic actuation of capsule endoscopes have recently enabled trajectory following and automation of repetitive endoscopic maneuvers. However, these methods face significant challenges in their path to clinical adoption including the presence of regions of magnetic field singularity, where the accuracy of the system degrades, and the need for accurate initialization of the capsule's pose. In particular, the singularity problem exists for any pose estimation method that utilizes a single source of magnetic field if the method does not rely on the motion of the magnet to obtain multiple measurements from different vantage points. We analyze the workspace of such pose estimation methods with the use of the point-dipole magnetic field model and show that singular regions exist in areas where the capsule is nominally located during magnetic actuation. Since the dipole model can approximate most magnetic field sources, the problem discussed herein pertains to a wider set of pose estimation techniques. We then propose a novel hybrid approach employing static and time-varying magnetic field sources and show that this system has no regions of singularity. The proposed system was experimentally validated for accuracy, workspace size, update rate and performance in regions of magnetic singularity. The system performed as well or better than prior pose estimation methods without requiring accurate initialization and was robust to magnetic singularity. Experimental demonstration of closed-loop control of a tethered magnetic device utilizing the developed pose estimation technique is provided to ascertain its suitability for robotically guided capsule endoscopy. Hence, advances in closed-loop control and intelligent automation of magnetically actuated capsule endoscopes can be further pursued toward clinical realization by employing this pose estimation system.

Proton pump inhibitors (PPIs) increase enteric bacterial colonization, overgrowth, and translocation, all effects which might predispose to spontaneous bacterial peritonitis. We investigated whether PPI usage is associated with spontaneous bacterial peritonitis. Our retrospective case-control study included 116 consecutive cirrhotic patients with ascites who underwent diagnostic paracentesis upon hospital admission (2002-2005). Spontaneous bacterial peritonitis was defined as paracentesis yielding >or=250 polymorphonuclear leukocytes/ml. We performed logistic regression to determine the risk of spontaneous bacterial peritonitis by PPI usage. Of the 116 subjects, 32 had spontaneous bacterial peritonitis. Patient characteristics were similar between groups with and without infection, with the exception of the Model for End-Stage Liver Disease score (median: 23 and 18, respectively; P = 0.002). Crude and adjusted odds ratios for the development of spontaneous bacterial peritonitis by exposure to PPIs were 1.22 (95% confidence interval: 0.52-2.87) and 1.05 (0.43-2.57), respectively. In conclusion, we did not find a positive association between PPI use and spontaneous bacterial peritonitis.

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Early diagnosis of colorectal cancer substantially improves survival. However, over half of cases are diagnosed late due to the demand for colonoscopy-the 'gold standard' for screening-exceeding capacity. Colonoscopy is limited by the outdated design of conventional endoscopes, which are associated with high complexity of use, cost and pain. Magnetic endoscopes are a promising alternative and overcome the drawbacks of pain and cost, but they struggle to reach the translational stage as magnetic manipulation is complex and unintuitive. In this work, we use machine vision to develop intelligent and autonomous control of a magnetic endoscope, enabling non-expert users to effectively perform magnetic colonoscopy in vivo. We combine the use of robotics, computer vision and advanced control to offer an intuitive and effective endoscopic system. Moreover, we define the characteristics required to achieve autonomy in robotic endoscopy. The paradigm described here can be adopted in a variety of applications where navigation in unstructured environments is required, such as catheters, pancreatic endoscopy, bronchoscopy and gastroscopy. This work brings alternative endoscopic technologies closer to the translational stage, increasing the availability of early-stage cancer treatments.

Proton pump inhibitor therapy in adults with asthma results in a small, statistically significant improvement in morning PEF rate. The magnitude of this improvement, however, is unlikely to be of meaningful clinical significance. There is insufficient evidence to recommend empirical use of PPIs for routine treatment of asthma.

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This document was reviewed and approved by the Governing Board of the American Society for Gastrointestinal Endoscopy This is one of a series of documents prepared by the American Society for Gastrointestinal Endoscopy (ASGE) Training Committee. This curriculum document contains recommendations for training and is intended for use by endoscopy training directors, endoscopists involved in teaching endoscopy, and trainees in endoscopy. It was developed as an overview of techniques currently favored for the performance and training in endoscopic retrograde cholangiopancreatography (ERCP) and to serve as a guide to published references, videos, and other resources available to the trainer. By providing information to endoscopy trainers about the common practices used by experts in performing the technical aspects of the procedure, the ASGE hopes to improve the teaching and performance of ERCP.

Diagnostic endoscopy in the gastrointestinal tract has remained largely unchanged for decades and is limited to the visualization of the tissue surface, the collection of biopsy samples for diagnoses, and minor interventions such as clipping or tissue removal. In this work, we present the autonomous servoing of a magnetic capsule robot for in-situ, subsurface diagnostics of microanatomy. We investigated and showed the feasibility of closed-loop magnetic control using digitized microultrasound (μUS) feedback; this is crucial for obtaining robust imaging in an unknown and unconstrained environment. We demonstrated the functionality of an autonomous servoing algorithm that uses μUS feedback, both on benchtop trials as well as in-vivo in a porcine model. We have validated this magnetic-μUS servoing in instances of autonomous linear probe motion and were able to locate markers in an agar phantom with 1.0 ± 0.9 mm position accuracy using a fusion of robot localization and μUS image information. This work demonstrates the feasibility of closed-loop robotic μUS imaging in the bowel without the need for either a rigid physical link between the transducer and extracorporeal tools or complex manual manipulation.