A novel device for rapid cleaning of poorly prepared colons

Design of Low-Cost Endoscope Based on Novel Wire-Driven Rotary Valve and Water-Jet Mechanism

To improve the prevalence of screening for gastric cancer in low-income areas, a low-cost endoscope based on a novel wire-driven rotary valve and water-jet mechanism is proposed. The primary component of this endoscope is a rotary valve whose core is driven by a stepper motor through a flexible wire, which controls the direction of the water jet. This enables it to reach any point in the workspace by controlling the valve core angle and water-jet intensity. The envelope surface of the endoscope tip trajectory is likely a hemisphere. The horizontal diameter of the working space projection is approximately 350 mm, which is sufficient to observe most parts of the greater curvature of the stomach. The image-acquisition performance of the designed endoscope was satisfactory in a phantom experiment. The introduction of the novel rotary valve greatly simplifies the structure and reduces the cost of the proposed endoscope. With low cost and high portability, this endoscope provides a good alternative for early gastric cancer screening in low- and middle-income areas.

The waterjet necrosectomy device for endoscopic management of pancreatic necrosis: design, development, and preclinical testing (with videos)

BACKGROUND AND AIMS

Endoscopic intervention has emerged as a first-line option for management of symptomatic pancreatic necrosis, yet endoscopic debridement is limited by the lack of dedicated endoscopic tools intended for this purpose. The objectives of this study were to design and build a prototype necrosectomy device compatible for use with a flexible endoscope and capable of selective tissue fragmentation, and to test the prototype in benchtop and porcine models.

METHODS

A novel prototype, named the waterjet necrosectomy device (WAND), was designed and developed, consisting of a single-use disposable endoscopic waterjet instrument capable of waterjet selection and independent tip articulation while fitting through a 2.8-mm working channel of a standard adult upper GI endoscope. Benchtop, ex vivo, and in vivo (porcine) testing was performed in the initial stages of investigation.

RESULTS

The WAND was capable of delivering a continuous waterjet force with a surface pressure of 0.72 bar at a flow rate of 0.37 L/minute. In phase 1 of testing, the WAND was able to achieve complete fragmentation of gelatin as a surrogate for pancreatic necrosis in benchtop testing. In phase 2 of testing, the WAND was able to achieve complete fragmentation of freshly explanted human pancreatic necrosis. In phase 3 of testing for safety in fresh necropsy swine, use of the WAND resulted in no significant tissue trauma, even when irrigation was applied at closer proximity and for more extended duration than would be anticipated in clinical use.

CONCLUSION

The WAND prototype delivers irrigation capable of fragmenting necrotic debris ex vivo and avoiding trauma to healthy nontarget tissue. Planning is underway for first-in-human studies to assess the efficacy and safety of the WAND for endoscopic pancreatic necrosectomy.

Intelligent magnetic manipulation for gastrointestinal ultrasound

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.

Explicit Model Predictive Control of a Magnetic Flexible Endoscope

In this paper, explicit model predictive control is applied in conjunction with nonlinear optimisation to a magnetically actuated flexible endoscope for the first time. The approach is aimed at computing the motion of the external permanent magnet, given the desired forces and torques. The strategy described here takes advantage of the nonlinear nature of the magnetic actuation and explicitly considers the workspace boundaries, as well as the actuation constraints. Initially, a simplified dynamic model of the tethered capsule, based on the Euler-Lagrange equations is developed. Subsequently, the explicit model predictive control is described and a novel approach for the external magnet positioning, based on a single step, nonlinear optimisation routine, is proposed. Finally, the strategy is implemented on the experimental platform, where bench-top trials are performed on a realistic colon phantom, showing the effectiveness of the technique. The work presented here constitutes an initial exploration for model-based control techniques applied to magnetically manipulated payloads, the techniques described here may be applied to a wide range of devices, including flexible endoscopes and wireless capsules. To our knowledge, this is the first example of advanced closed loop control of magnetic capsules.

Water-jet outer sheath with braided shape memory polymer tubes for upper gastrointestinal tract screening

BACKGROUND

Flexible endoscopes have become an important tool for the diagnosis and treatment of gastric cancer. However, there are several limitations to the use of endoscopes in rural areas, including their high cost, poor portability, and unstable platform.

METHODS

This paper presents a novel low-cost outer sheath for stomach screening. The sheath uses braided shape memory polymer (SMP) tubes with a water-jet to control the stiffness and bending motion. The insertion part of the prototype is 250 mm long with a maximum outer diameter of 16 mm and incorporates an internal charge-coupled device camera.

RESULTS

We have tested the workspace and stiffness of the outer sheath. The prototype has also been validated with phantom and ex vivo porcine stomach experiments.

CONCLUSIONS

By controlling the water-jet and temperature of the braided SMP tubes, the outer sheath achieves a large workspace and a remarkable variability in stiffness, demonstrating the potential clinical value of the outer sheath system.

Autonomous Retroflexion of a Magnetic Flexible Endoscope

Retroflexion during colonoscopy is typically only practiced in the wider proximal and distal ends of the large intestine owing to the stiff nature of the colonoscope. This inability to examine the proximal side of the majority of colon folds contributes to today's suboptimal colorectal cancer detection rates. We have developed an algorithm for autonomous retroflexion of a flexible endoscope that is actuated magnetically from the tip. The magnetic wrench applied on the tip of the endoscope is optimized in real-time with data from pose detection to compute motions of the actuating magnet. This is the first example of a completely autonomous maneuver by a magnetic endoscope for exploration of the gastrointestinal tract. The proposed approach was validated in plastic tubes of various diameters with a success rate of 98.8% for separation distances up to 50 mm. Additionally, a set of trials was conducted in an excised porcine colon observing a success rate of 100% with a mean time of 19.7 s. In terms of clinical safety, the maximum stress that is applied on the colon wall with our methodology is an order of magnitude below what would damage tissue.

What Influences the Quality of Prevention Colonoscopy?

Background

Colorectal cancer still has a high incidence and mortality. Although colonoscopy is considered as gold standard of colorectal cancer screening, there still exists an unsatisfactory level of adenomas missed in screening and surveillance colonoscopy. Furthermore, patients bear the burden of potentially unpleasant and painful examination and preparation procedures.

Method

A search of the literature using PubMed was carried out, supplemented by a review of the programs of the Digestive Disease Week (DDW) and the United European Gastroenterology Week (UEGW) 2011-2013.

Results

Several new approaches to colonoscopy were described: water, CO₂ and cap colonoscopy, and application of spasmolytics such as hyoscine butylbromide and glucagon. The use of these methods does not necessitate the purchase of new endoscopes. They are feasible and safe, facilitate achieving the aim of more comfort and less pain, and perhaps allow lower doses of sedatives to be used. However, a clear effect on procedure time is lacking. Furthermore, the published data do not consistently answer the question of whether these techniques have a positive impact on the most important goal, the better detection of carcinoma precursors.

Conclusion

More efforts to optimize bowel preparation have to be made to improve visualization of the mucosal surface. The most reliable criteria for the quality of screening and surveillance colonoscopy remain a minimum cecal intubation rate of >90%, a withdrawal time of at least 6 or better 9 min, and an adenoma detection rate of >20%. These results should be achieved with a complication rate lower than 1%, including polypectomy.

Feasibility study of minimal prepared hydroflush screening colonoscopy

BACKGROUND

Although screening colonoscopy is effective for early detection of colorectal cancer (CRC), screening rates remain low. Multiple factors are thought to be responsible for the low rates of screening colonoscopy, but bowel preparation appears to be a key deterrent. Tolerability issues with bowel preparations may lead to poor patient compliance, inadequate colon cleansing, and reduced detection of colonic polyps.

AIM

The aim of this article is to evaluate the feasibility, safety, and outcomes of minimally prepared intra-procedural hydroflush technique as an alternative to traditional bowel preparation in screening colonoscopy.

DESIGN

We conducted a prospective feasibility study of intraprocedural hydroflush technique aided by water-jet pumps and a mechanical suction novel device following minimal bowel preparation for CRC screening.

PATIENTS AND METHODS

Nine procedures were performed in nine healthy individuals scheduled for routine screening colonoscopy. Preparation included mild diet restriction, laxative tablets two to three days prior to the procedure and two Fleet enemas one to two hours before the colonoscopy. The cleanliness of the colon was assessed by using the Boston bowel preparation scale. Insertion and withdrawal times were recorded.

RESULTS

Complete colonoscopy to the cecum was performed in all patients (100%). Mean time to the cecum was 5.78 ± 2.68 minutes, and mean withdrawal time was 15.33 ± 3.94 minutes. Endoscopic visualization of the entire mucosa was achieved in all cases with no colonoscopy repeated because of inadequate preparation. Four polyps have been detected and removed in three patients. Mild mucosal erosions were seen in some areas where the suction was used extensively, similar to those that can be seen during conventional colonoscopy. Mild stiffness of the shaft of the scope was noted.

LIMITATIONS

This was an uncontrolled feasibility study of selected patients.

CONCLUSIONS

Minimally prepared colonoscopy with the intra-procedural hydroflush technique for colorectal screening is feasible. The water exchange technology compensates for the mild stiffness of the scope. This technique might increase patients' compliance for CRC screening.

A platform for gastric cancer screening in low- and middle-income countries

Gastric cancer is the second leading cause of cancer death worldwide and screening programs have had a significant impact on reducing mortality. The majority of cases occur in low- and middle-income countries (LMIC), where endoscopy resources are traditionally limited. In this paper, we introduce a platform designed to enable inexpensive gastric screening to take place in remote areas of LMIC. The system consists of a swallowable endoscopic capsule connected to an external water distribution system by a multichannel soft tether. Pressurized water is ejected from the capsule to orient the view of the endoscopic camera. After completion of a cancer screening procedure, the outer shell of the capsule and the soft tether can be disposed, while the endoscopic camera is reclaimed without needing further reprocessing. The capsule, measuring 12 mm in diameter and 28 mm in length, is able to visualize the inside of the gastric cavity by combining waterjet actuation and the adjustment of the tether length. Experimental assessment was accomplished through a set of bench trials, ex vivo analysis, and in vivo feasibility validation. During the ex vivo trials, the platform was able to visualize the main landmarks that are typically observed during a gastric cancer screening procedure in less than 8 min. Given the compact footprint, the minimal cost of the disposable parts, and the possibility of running on relatively available and inexpensive resources, the proposed platform can potentially widen gastric cancer screening programs in LMIC.

Achieving the best bowel preparation for colonoscopy

Bowel preparation is a core issue in colonoscopy, as it is closely related to the quality of the procedure. Patients often find that bowel preparation is the most unpleasant part of the examination. It is widely accepted that the quality of cleansing must be excellent to facilitate detecting neoplastic lesions. In spite of its importance and potential implications, until recently, bowel preparation has not been the subject of much study. The most commonly used agents are high-volume polyethylene glycol (PEG) electrolyte solution and sodium phosphate. There has been some confusion, even in published meta-analyses, regarding which of the two agents provides better cleansing. It is clear now that both PEG and sodium phosphate are effective when administered with proper timing. Consequently, the timing of administration is recognized as one of the central factors to the quality of cleansing. The bowel preparation agent should be administered, at least in part, a few hours in advance of the colonoscopy. Several low volume agents are available, and either new or modified schedules with PEG that usually improve tolerance. Certain adjuvants can also be used to reduce the volume of PEG, or to improve the efficacy of other agents. Other factors apart from the choice of agent can improve the quality of bowel cleansing. For instance, the effect of diet before colonoscopy has not been completely clarified, but an exclusively liquid diet is probably not required, and a low-fiber diet may be preferable because it improves patient satisfaction and the quality of the procedure. Some patients, such as diabetics and persons with heart or kidney disease, require modified procedures and certain precautions. Bowel preparation for pediatric patients is also reviewed here. In such cases, PEG remains the most commonly used agent. As detecting neoplasia is not the main objective with these patients, less intensive preparation may suffice. Special considerations must be made for patients with inflammatory bowel disease, including safety and diagnostic issues, so that the most adequate agent is chosen. Identifying neoplasia is one of the main objectives of colonoscopy with these patients, and the target lesions are often almost invisible with white light endoscopy. Therefore excellent quality preparation is required to find these lesions and to apply advanced methods such as chromoendoscopy. Bowel preparation for patients with lower gastrointestinal bleeding represents a challenge, and the strategies available are also reviewed here.

Flexible and capsule endoscopy for screening, diagnosis and treatment

Endoscopy dates back to the 1860s, but many of the most significant advancements have been made within the past decade. With the integration of robotics, the ability to precisely steer and advance traditional flexible endoscopes has been realized, reducing patient pain and improving clinician ergonomics. Additionally, wireless capsule endoscopy, a revolutionary alternative to traditional scopes, enables inspection of the digestive system with minimal discomfort for the patient or the need for sedation, mitigating some of the risks of flexible endoscopy. This review presents a research update on robotic endoscopic systems, including both flexible scope and capsule technologies, detailing actuation methods and therapeutic capabilities. A future perspective on endoscopic potential for screening, diagnostic and therapeutic gastrointestinal procedures is also presented.

A pilot study of endoluminal US for stool liquefaction

BACKGROUND

There is a need to cleanse patients who are poorly prepared for colonoscopy safely and efficiently during the procedure to minimize rescheduling. US is already being used in catheter-based intravascular thrombolysis, and time-reversal acoustic (TRA) has been explored in assisting drug delivery to the brain.

OBJECTIVE

To explore the efficacy and safety of a miniaturized endoluminal US device in stool dissolution as a means to salvage poor bowel preparation.

DESIGN

Proof of concept experimental study.

SETTINGS

Animal laboratory.

INTERVENTIONS

Low-frequency US and TRAs.

MAIN OUTCOME MEASUREMENTS

Feasibility, efficacy, and safety of US to liquefy stools ex vivo.

RESULTS

Depending on parameters, such as pulse rate, acoustic intensity, and duration, increases in liquefaction speeds by a factor of 50 and 100 times were obtained. There was a significant difference in weight change between the 20-kHz-treated sample compared with controls (P ≤ .0001). There was no difference in sloughing of mucosa and mechanical injury among the US, water spray, and control groups.

LIMITATIONS

Animal model.

CONCLUSION

Endoluminal US can liquefy stools at acoustic exposure levels that do not damage ex vivo colonic mucosa. Endoluminal US should be able to dissolve stools more rapidly than water spray alone, thereby optimizing colonoscopic evaluation in vivo.

Advanced endoscopic technologies for colorectal cancer screening

Colorectal cancer is the third most common cancer in men and the second most common cancer in women worldwide. Diagnosing colorectal has been increasingly successful due to advances in technology. Flexible endoscopy is considered to be an effective method for early diagnosis and treatment of gastrointestinal cancer, making it a popular choice for screening programs. However, millions of people who may benefit from endoscopic colorectal cancer screening fail to have the procedure performed. Main reasons include psychological barriers due to the indignity of the procedure, fear of procedure related pain, bowel preparation discomfort, and potential need for sedation. Therefore, an urgent need for new technologies addressing these issues clearly exists. In this review, we discuss a set of advanced endoscopic technologies for colorectal cancer screening that are either already available or close to clinical trial. In particular, we focus on visual-inspection-only advanced flexible colonoscopes, interventional colonoscopes with alternative propulsion mechanisms, wireless capsule colonoscopy, and technologies for intraprocedural bowel cleansing. Many of these devices have the potential to reduce exam related patient discomfort, obviate the need for sedation, increase diagnostic yield, reduce learning curves, improve access to screening, and possibly avert the need for a bowel preparation.

Advanced technologies for gastrointestinal endoscopy

The gastrointestinal tract is home to some of the most deadly human diseases. Exacerbating the problem is the difficulty of accessing it for diagnosis or intervention and the concomitant patient discomfort. Flexible endoscopy has established itself as the method of choice and its diagnostic accuracy is high, but there remain technical limitations in modern scopes, and the procedure is poorly tolerated by patients, leading to low rates of compliance with screening guidelines. Although advancement in clinical endoscope design has been slow in recent years, a critical mass of enabling technologies is now paving the way for the next generation of gastrointestinal endoscopes. This review describes current endoscopes and provides an overview of innovative flexible scopes and wireless capsules that can enable painless endoscopy and/or enhanced diagnostic and therapeutic capabilities. We provide a perspective on the potential of these new technologies to address the limitations of current endoscopes in mass cancer screening and other contexts and thus to save many lives.

Evolving techniques in colonoscopy

PURPOSE OF REVIEW

This review summarizes recent clinical studies of colonoscopy technique and new technologies.

RECENT FINDINGS

Water immersion reduces pain and sedation doses in unsedated and lightly sedated colonoscopy. Cap-fitted colonoscopy makes insertion faster and improves detection of lesions behind folds, but the latter effect is operator-dependent. A single controlled trial showed improved detection with the Third Eye Retroscope, but the two arms of the study were not controlled for withdrawal time. Chromoendoscopy increases detection of diminutive adenomas, but adds time to the colonoscopy procedure. Electronic chromoendoscopy methods (narrow band imaging, Fujinon Intelligent ChromoEndoscopy, i-scan, and autofluorescence) have been either unsuccessful in improving detection or require more study. However, these methods and several other methods (chromoendoscopy with magnification, confocal laser microscopy, and endocytoscopy) allow accurate real time determination of polyp histology.

SUMMARY

Water immersion is a clear advance in unsedated colonoscopy. Cap-fitted colonoscopy is a promising method for both practical and effective visualization of the proximal sides of haustral folds. Electronic chromoendoscopy has been largely ineffective at improving polyp detection, but is effective (as are confocal laser microscopy and endocytoscopy) for diagnosis of polyp histology.

An unmet medical need: advances in endoscopic imaging of colorectal neoplasia

Gastrointestinal cancer is a major public health problem worldwide. Detection of early neoplastic lesions in gastrointestinal tract is essential for cure, because prognosis and survival are related to the size and stage of malignant lesions. Endoscopic screening and treatment of polyps could prevent approximately 80% of colorectal cancer (CRC). However, white-light endoscopy is an imperfect technology since miss rates of up to 25% have been reported and polyps without malignant potential were treated without benefit but with additional costs and risks to the patient. There are several known "human" predictors of an inadequate colonoscopy. These include patient characteristics such as poor bowel preparation, female gender, or inpatient status. Skills of the endoscopists are also an important issue. Therefore, a variety of advanced technologies has been attempted to overcome these issues. These new endoscopic imaging techniques allow a more precise classification of mucosal alterations with selection of patients for invasive therapy or surveillance. Further, molecular and functional imaging techniques could identify novel targets for therapies and new prospects to access response to therapies. However, at the "end of the day" a better endoscopic approach for CRC screening and surveillance depends on a good bowel preparation, a trained endoscopist spending sufficient time on a detailed examination together with an advanced endoscope.