Time Series Analysis of the Effectiveness and Safety of Capsule Endoscopy between the Premarketing and Postmarketing Settings: A Meta-Analysis.

BACKGROUND: Clinical studies for assessing the effectiveness and safety in a premarketing setting are conducted under time and cost constraints. In recent years, postmarketing data analysis has been given more attention. However, to our knowledge, no studies have compared the effectiveness and the safety between the pre- and postmarketing settings. In this study, we aimed to investigate the importance of the postmarketing data analysis using clinical data. METHODS AND FINDINGS: Studies on capsule endoscopy with rich clinical data in both pre- and postmarketing settings were selected for the analysis. For effectiveness, clinical studies published before October 10, 2015 comparing capsule endoscopy and conventional flexible endoscopy measuring the detection ratio of obscure gastrointestinal bleeding were selected (premarketing: 4 studies and postmarketing: 8 studies) from PubMed (MEDLINE), Cochrane Library, EMBASE and Web of Science. Among the 12 studies, 5 were blinded and 7 were non-blinded. A time series meta-analysis was conducted. Effectiveness (odds ratio) decreased in the postmarketing setting (premarketing: 5.19 [95% confidence interval: 3.07-8.76] vs. postmarketing: 1.48 [0.81-2.69]). The change in odds ratio was caused by the increase in the detection ratio with flexible endoscopy as the control group. The efficacy of capsule endoscopy did not change between pre- and postmarketing settings. Heterogeneity (I2) increased in the postmarketing setting because of one study. For safety, in terms of endoscope retention in the body, data from the approval summary and adverse event reports were analyzed. The incidence of retention decreased in the postmarketing setting (premarketing: 0.75% vs postmarketing: 0.095%). The introduction of the new patency capsule for checking the patency of the digestive tract might contribute to the decrease. CONCLUSIONS: Effectiveness and safety could change in the postmarketing setting. Therefore, time series meta-analyses could be useful to continuously monitor the effectiveness of medical device in clinical practices.

Variable stiffness outer sheath with "Dragon skin" structure and negative pneumatic shape-locking mechanism.

BACKGROUND/PURPOSE:    Natural orifice transluminal endoscopic surgery (NOTES) offers the possibility of surgery without visible scars. To overcome the limitations of NOTES, we developed a novel surgical device called the rigid and flexible outer sheath with multi-piercing surgery (MPS). METHODS:    This sheath can switch between flexible and rigid modes using a novel "Dragon skin" structure and a negative pneumatic shape-locking mechanism. In addition, it has an integrated bending structure that enables it to flex in four directions at the distal end. The insertion part of the prototype is 575 mm long with a 20 mm outer diameter. The rigid and flexible shaft is separated into two parts. The primary and secondary shape-locking shafts are 300 and 200 mm long, respectively. The two parts of shape-locking shaft can be locked independently, including both being locked simultaneously. In addition, the model was equipped with one 7- and 1.7-mm-diameter, and three 3-mm-diameter working channels. When the sheath approaches the target, the surgeon locks the shape and then easily inserts flexible instruments through the path created by the sheath. In this study, we evaluated the stiffness of the prototype. Furthermore, an in vivo partial gastrectomy experiment was also performed. RESULTS:    The experimental results regarding the shape property suggest that the rigidity of the shaft was considerably increased using this mechanism. An in vivo partial gastrectomy experiment performed using a swine was successfully performed using the outer sheath for assistance. The outer sheath was inserted through a percutaneous route during the in vivo experiment. CONCLUSIONS:    The evaluation results show that the advanced outer sheath system has great promise for solving access and stability problems with NOTES.

Development of a polymer bileaflet valve to realize a low-cost pulsatile blood pump.

The final goal of this study is to realize a low-cost pulsatile blood pump especially for patients with acute heart failure or postoperative low cardiac output syndrome. In support of the pump, two types of polymer bileaflet valves with different configuration of the valve seats were developed. Influence of the leaflet thickness on the hydrodynamics of the prototype was preliminarily investigated among 70 microm, 100 microm, and 150 microm. As to the valves with the thinner leaflets, buckling of the leaflets was observed, which induced a large amount of regurgitation at valve closure. However, by thickening the leaflet to 150 microm, the mean flow of the prototype and the second model could be successfully comparable to the Medtronic-Hall valve. Moreover, accelerated fatigue tests showed that reinforcement of the valve seat with the additional spokes in the second model extended the durability by four times as compared with the prototype, equivalent to an in vivo duration of over one month.

Implications for the establishment of accelerated fatigue test protocols for prosthetic heart valves.

The goal of this research is to establish a reliable methodology for accelerated fatigue tests of prosthetic heart valves. A polymer valve was the subject, and the influence of various drive parameters on durability was investigated in three different machines. Valve lifetime was notably shortened by increasing the cyclic rate or stroke even though the maximum pressure difference at valve closure was maintained at 120 mm Hg. These results demonstrate that adjustment of the maximum transvalvular pressure is not sufficient to ensure tests are conducted under the same conditions and indicate that measurement of the dynamic load would be more efficacious. Moreover, the locations of tears sustained in the accelerated tests differed from those encountered in an animal experiment although in both cases the locations were entirely consistent with the areas of strain concentration revealed by finite element analysis. These findings should be discussed during a revision of ISO 5840.