Endoscopic hemostatic treatment under irrigation for upper-GI hemorrhage: a comparison of one third and total circumference transparent end hoods

Piezoelectric Single Crystal Ultrasonic Transducer for Endoscopic Drug Release in Gastric Mucosa

Modern advanced minimally invasive surgery has been implemented for most of the significant gastrointestinal diseases. However, patients with coagulopathy or unresectable tumors cannot be cured by current treatment methods. Moreover, other existing medical devices for targeted drug release are too large to be applied in gastric endoscope because the diameter of the biopsy channel is smaller than 3 mm. To address it, in this work, we developed a piezoelectric single crystal ultrasonic transducer (the diameter was only 2.2 mm and the mass was 0.076 g) to produce acoustic waves, which could promote the drug release in the designed position of the digestive tract through an endoscope. It exhibited the electromechanical coupling coefficient of 0.36 and the center frequency of 6.9 MHz with the -6-dB bandwidth of 23%. In in vitro sonophoresis experiment, the gastric mucosa permeability to Bovine Serum Albumin increased about 5.6 times when the ultrasonic transducer was activated at 40 [Formula: see text] and 60% duty ratio, proving that employment of this transducer could facilitate drug penetration in the gastric mucosa. Meanwhile, the permeability could be adjusted by tuning the duty ratio of the ultrasonic transducer. The corresponding sonophoresis mechanism was related to the acoustic streaming and the thermal effect produced by the transducer. In addition, the measured maximum power density was 128 mW/cm² and the mechanical index of the ultrasonic transducer was 0.02. The results held a great implication for applications of the transducer for targeted drug release in the gastrointestinal tract.

Analyses of the Temperature Field of a Piezoelectric Micro Actuator in the Endoscopic Biopsy Channel

Micro actuators have been used to realize the arrival of digestive tract lesions for the local targeted application of drugs in endoscopes. However, there still exists a key safety issue that casts a shadow over the practical and safe implementation of actuators in the human body, namely an overheated environment caused by actuators’ operation. Herein, with the aim of solving the temperature rising problem of a piezoelectric micro actuator operating in an endoscopic biopsy channel (OLYMPUS, Tokyo, Japan), a thermal finite element method (FEM) based on COMSOL Multiphysics software is proposed. The temperature distribution and its rising curves are obtained by the FEM method. Both the simulated and experimental maximum temperatures are larger than the safety value (e.g., 42 °C for human tissues) when the driving voltage of the actuator is 200 Vpp, which proves that the overheating problem really exists in the actuator. Furthermore, the results show that the calculated temperature rising curves correspond to the experimental results, proving the effectiveness of this FEM method. Therefore, we introduce a temperature control method through optimizing the duty ratio of the actuator. In comparison with a 100% duty ratio operation condition, it is found that a 60% duty ratio with a driving voltage of 200 Vpp can more effectively prevent the temperature rising issue in the first 3 min, as revealed by the corresponding temperatures of 44.4 and 41.4 °C, respectively. When the duty ratio is adjusted to 30% or less, the temperature rise of the actuator can be significantly reduced to only 36.6 °C, which is close to the initial temperature (36.4 °C). Meanwhile, the speed of the actuator can be well-maintained at a certain level, demonstrating its great applicability for safe operation in the human body.

Development of a novel endoscopic manipulation system: The Endoscopic operation robot

AIM: To develop and evaluate the endoscopic operation robot (EOR). The EOR is a robot system designed specifically for remote manipulation of the scope during gastrointestinal endoscopy by a seated endoscopist.

METHODS: Total colonoscopy examinations using a colonoscopy training model were performed compared conventional insertion by manual manipulation and remote-controlled insertion, using the EOR. The author investigated the time taken for each of the 50 examinations.

RESULTS: The median insertion time (in minutes) for each 10 examinations (EOR vs manual manipulation) was 73.70 ± 25.37 vs 3.77 ± 1.34 in the first group, 38.40 ± 6.24 vs 3.40 ± 0.97 in the second group, 27.6 ± 4.01 vs 2.70 ± 0.95 in the third group, 23.8 ± 3.65 vs 3.10 ± 0.88 in the fourth group, and 22.9 ± 5.02 vs 2.60 ± 1.08 in the fifth group.

CONCLUSION: The study suggested the possibility of the clinical application of the EOR.

Improved characterization of visible vessels in bleeding ulcers by using magnification endoscopy: results of a pilot study

BACKGROUND

Not all exposed vessels carry the same risk of recurrent bleeding, and sometimes endoscopic therapy may not be warranted in the setting of profound acid inhibition therapy.

OBJECTIVE

To investigate the role of magnification endoscopy (ME) in improving the characterization of exposed vessels in ulcer hemorrhage.

DESIGN

Prospective study.

SETTING

Single-center teaching hospital.

MAIN OUTCOME MEASUREMENTS

Diagnostic accuracy and safety of ME in patients with bleeding peptic ulcers.

RESULTS

A total of 43 patients were studied. Exposed vessels were initially categorized as high risk (protuberant, translucent, or pale) in 25 and low risk (nonprotruding through the ulcer floor, pigmented, or dark red) in 18 cases. ME was subsequently performed, and the operator was asked to reclassify the vessel into 1 of these 2 categories. A magnified view provided a clear image of the vessel and allowed visualization of the artery, the site of rupture, and the presence of a clot plugging the hole. In 6 cases previously categorized as low risk, ME clearly showed the 2 ends of the vessel, the longitudinal tear in the vessel wall, and a protuberant aspect that was not seen with standard view. The lesion was then reclassified as high risk (diagnostic gain 33%). The mean procedure time for ME inspection was 7 +/- 4 minutes. No complications occurred.

LIMITATIONS

Absence of controls.

CONCLUSIONS

In patients with peptic ulcer bleeding and exposed vessels, ME allows clear visualization of the vessel wall and provides detailed clues to further characterize the lesion.

Endoscopic mucosal resection and endoscopic submucosal dissection for early gastric cancer: Current and original devices

Compared with endoscopic submucosal dissection (ESD), endoscopic mucosal resection (EMR) is easier to perform and requires less time for treatment. However, EMR has been replaced by ESD, because achieving en bloc resection of specimens > 20 mm in diameter is difficult with EMR. The technique of ESD was introduced to resect large specimens of early gastric cancer in a single piece. ESD can provide precise histological diagnosis and can also reduce the rate of recurrence, but has a high level of technical difficulty, and is consequently associated with a high rate of complications, a need for advanced endoscopic techniques, and a lengthy procedure time. To overcome disadvantages in both EMR and ESD, various advances have been made in submucosal injections, knives, other accessories, and in electrocoagulation systems.

Upper gastrointestinal bleeding

PURPOSE OF REVIEW

This review provides an update on the management of upper gastrointestinal bleeding with special attention to patient preparation, sedation, hemostatic techniques, and postprocedure care.

RECENT FINDINGS

In a large multicenter clinical trial, nurse-administered propofol sedation had a complication rate of less than 0.2%. The optimal management for an ulcer with adherent clot was confirmed by a meta-analysis to be clot removal and endoscopic treatment of the underlying lesion. A number of prospective studies have demonstrated that capsule endoscopy is the most sensitive imaging modality for identifying lesions in the small bowel and that double-balloon enteroscopy is the least invasive modality available for the management of these lesions.

SUMMARY

This update describes many recent advances in the diagnosis and management of upper gastrointestinal bleeding. However, clearly, much work needs to be done in this field. Since propofol is not available for use in all endoscopy units, is there a better alternative for deep sedation? Rebleeding occurs in 20% of patients after endoscopic therapy, and so can we provide better outcomes with newer technologies (endoscopic suturing devices)? Finally, what is the best management for Helicobacter pylori-negative, nonsteroidal antiinflammatory drug-negative ulcer patients?

Grasping forceps-assisted endoscopic mucosal resection of early gastric cancer with a novel 2-channel prelooped hood

BACKGROUND

Endoscopic mucosal resection with a cap-fitted panendoscope (EMRC) such as a soft prelooped hood is a useful, effective, and safe technique. One problem with this method is that the lesion cannot always be maintained in the center of the cap because the procedure is performed blindly after aspiration.

OBJECTIVE

We developed a 2-channel prelooped hood that facilitates EMRC while simultaneously allowing both grip of the center in the lesion and irrigation of the aspiration site and evaluated the usefulness of this end hood for early gastric cancer.

DESIGN

Retrospective study.

SETTING

Between August 2003 and October 2004, patients underwent our novel EMR.

PATIENTS

Twelve cases of early gastric cancer.

INTERVENTIONS

Two side holes were fabricated by drilling in the cap portion of a conventional soft prelooped hood, and then the irrigation tube and the accessory channel tube were glued to the exterior surface of the holes. We placed the fabricated transparent hood at the tip of the endoscope and performed grasping forceps-assisted endoscopic aspiration mucosectomy.

MAIN OUTCOME MEASUREMENTS

Accurate aspiration and the rate of en bloc resection.

RESULTS

We obtained a satisfactory field of view and accurate aspiration in the center of the tumor in all lesions. The rate of en bloc resection was 91.7% (11/12).

LIMITATIONS

Gastric intramucosal cancer.

CONCLUSION

Grasping forceps-assisted endoscopic mucosal resection with a novel 2-channel prelooped hood is safe and useful for mucosal resection of intramucosal cancers less than 20 mm and may help center the lesion in the cap before resection.

Nonvariceal upper gastrointestinal bleeding: standard and new treatment

Nonvariceal upper gastrointestinal bleeding remains a challenging problem with a significant morbidity and mortality. In recent years endoscopic techniques have evolved, resulting in improved primary hemostasis and a reduction in the risk of rebleeding. Combination endoscopic therapy followed by high-dose proton pump inhibitor shows improved outcomes. Innovative endoscopic therapies hold promise but are as yet unproved. An aging population with significant medical comorbidities has a major influence on the overall outcome from upper gastrointestinal bleeding.

Upper gastrointestinal bleeding

PURPOSE OF REVIEW

This review discusses key issues in the management of upper gastrointestinal bleeding including patient preparation, sedation, hemostatic techniques, disposition, and recommended pharmacologic interventions.

RECENT FINDINGS

Optimal resuscitation before endoscopy and proper pharmacologic interventions after endoscopy seem to be as crucial to the management of patients with upper gastrointestinal bleeding as meticulous hemostatic techniques during the procedure. In a retrospective evaluation of patients with upper gastrointestinal bleeding, multivariate analysis demonstrated significantly reduced morbidity and mortality in those who underwent aggressive preendoscopic resuscitation. In a prospective, randomized clinical trial, patients who received intravenous proton pump inhibitor therapy after endoscopic intervention had a significantly reduced rebleeding rate compared with their placebo control group.

SUMMARY

The algorithms described in this review can be applied clinically today and should directly lead to improved outcome. Nevertheless, even with the latest care available, results are not optimal. This review points to two major areas where we can benefit from improvement: primary hemostasis and recurrent bleeding. By pointing to these limitations, it is hoped that this review can help stimulate research in the field by applying new technologies to solve these problems. Endoscopic ultrasound, for example, could be used to help identify feeding vessels that can be treated endoscopically, thus potentially decreasing the incidence of failed primary hemostasis. Endoscopic suturing, when more fully developed, may provide a better hemostatic technique that can reduce the incidence of recurrent bleeding. It is only through these reviews that our state of knowledge in the field can be constantly reevaluated to update today's clinician with the latest knowledge and stimulate tomorrow's researchers with challenging problems.