Force-based puncture detection and active position holding for assisted retinal vein cannulation

Abstract

Retinal vein cannulation is a demanding procedure proposed to treat retinal vein occlusion by direct therapeutic agent delivery methods. Challenges in identifying the moment of venous puncture, achieving cannulation and maintaining cannulation during drug delivery currently limit the feasibility of the procedure. In this study, we respond to these problems with an assistive system combining a handheld micromanipulator, Micron, with a force-sensing microneedle. The integrated system senses the instant of vein puncture based on measured forces and the position of the needle tip. The system actively holds the cannulation device securely in the vein following cannulation and during drug delivery. Preliminary testing of the system in a dry phantom, stretched vinyl membranes, demonstrates a significant improvement in the total time the needle could be maintained stably inside of the vein. This was especially evident in smaller veins and is attributed to decreased movement of the positioned cannula following venous cannulation.

Robot-assisted retinal vein cannulation with force-based puncture detection: Micron vs. the steady-hand eye robot

“…In order to monitor the response of each FBG, we use an optical sensing interrogator, sm130–700 from Micron Optics Inc. (Atlanta GA), which provides a wavelength resolution of 1 pm. Combining this with the calibration matrix identified in [27] shows a resolution of about 0.25 mN for our force-sensing microneedle. The time constant is about 5 ms [28], providing a fast enough response for accurate tracking of quick force variations.…”

“…Previously we have achieved an extended period of intravenous cannula stability in a dry phantom by combining Micron with a force-sensing microneedle (Fig. 1a,1b) [27]. This study builds on our previous work, and integrates our force-sensing microneedle with another robot assistant, the SHER system (Fig.…”

“…Since this actuation is entirely independent from the site of attachment, the tool can be easily used on any of the existing assistive robots [10–19] without interfering with their operation. The design and control mechanism of this part are further detailed in [27]. …”

“…Our previous work has shown that venous puncture can be detected by continually tracking the tool tip position (p⃗ needle ) and tool-to-tissue interaction force (F⃗ needle ) [27]. After the needle tip touches the vein wall, as it is pushed into the vein, the tissue is gradually deformed which results in an increasing resistance force on the needle tip.…”

“…The experimental procedures involving human subjects described in this section were approved by the Institutional Review Board. To closely replicate the vein cannulation procedure in vitro , we developed an artificial phantom platform similar to the one used in [27], which is an acrylic plate with 18 circular holes covered by a thin, uniformly stretched vinyl layer emulating the retinal vein walls. The diameter of the holes on the plate is 2.5 mm, small enough to create the support for the vinyl membrane’s tension while leaving sufficient space for the user to perform several cannulations.…”