Stone retrieval device shows high versatility, efficacy

Results from bench studies favor a new open-faced stone retrieval device (Dakota, Boston Scientific) for having greater versatility, efficacy, and durability compared with a competing product, and the in vitro performance of the new instrument is consistent with early clinical experience, said Roger L. Sur, MD, at the 2016 World Congress of Endourology in Cape Town, South Africa.

Dr. Sur“In early clinical use in my hands, the Dakota basket has helped me to achieve my goal of rendering patients stone-free using a single basket. In particular, the Dakota has the ability to pick up even 1-mm stone fragments in patients, and that is something I have not seen with other baskets that are commercially available,” said Dr. Sur, director of the University of California, San Diego Comprehensive Kidney Stone Center, and an investigator in the bench studies.

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“Now, I look forward to see if my positive impressions are confirmed by findings from a user survey as well as by other urologists.”

The new nitinol hybrid grasper basket was released for limited market evaluation in August 2016 and fully in October 2016. It is available in two basket sizes-8 mm and 11 mm-and features a proprietary design (OpenSure Handle) that allows the basket to be opened larger (50% for the 8-mm device and 30% for the 11-mm device) when needed to accomplish stone release.

“This feature enables the release of larger stones, and really confers a huge safety benefit for patients,” Dr. Sur told Urology Times.

The bench studies compared the new basket with the NGage (Cook Medical). To investigate efficacy and versatility, 15 8-mm and 15 11-mm devices from each manufacturer were evaluated for their ability to retrieve and release simulated stone models through a simulated endoscopic 3.6F working channel. The performance of the 8-mm devices was assessed for stone models ranging in size from 1 mm to 9 mm, while stones up to 11 mm were used in the tests for the larger device. If a stone was not released when the basket was opened, the device handle was shaken. The “Sure Release” feature of the new device was used only if a stone was not disengaged by shaking.

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Results for the tests of the 8-mm baskets showed both products captured all stones up to 8 mm in size, but the Dakota demonstrated greater efficacy than the NGage for releasing stones measuring 7 mm and 8 mm. For 7-mm stones, the release rate after opening the basket was 100% for the Dakota device versus 13% for the NGage. After simple opening or shaking, all 15 Dakota devices released 8-mm stones, whereas stones of this size had to be manually removed from 13 (87%) of the NGage baskets.

Next: 100% success with 11-mm stones

100% success with 11-mm stones

Using the 11-mm baskets, all stones up to 11 mm in diameter were captured by the Dakota devices, whereas none of the NGage baskets captured 11-mm stones. No stones needed to be manually removed from any of the 11-mm devices, but only the Dakota released all stones after simple opening of the basket. With the NGage device, five (33%) had to be shaken before release of 9-mm stones and 10 (67%) required shaking to release 10-mm stones.

Device durability was investigated by passing the baskets through a simulated 3.6F working channel and repetitively grasping and releasing an 8-mm synthetic stone 20 times, replicating a scenario likely to be encountered in clinical use. The testing was performed using 30 each of the 11-mm NGage and Dakota baskets.

There were no device failures, which was defined as inability to grasp a 1-mm synthetic stone model. Upon visual examination, there was no evidence of damage to any of the Dakota instruments. However, eight (26.7%) of the NGage devices exhibited splitting of the end effector tube and kinking at the strain relief site (p=.0046), and this damage developed at a mean of 13.5 cycles (range, 7 to 18).

“These results suggest the Dakota may have a durability benefit over the NGage basket, but urologists would have to see this for themselves,” Dr. Sur said.

Dr. Sur is a speaker for and consultant to both Boston Scientific and Cook Medical.

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