Ultrasound-Guided Robotic Blood Drawing and In Vivo Studies on Submillimetre Vessels of Rats

TL;DR

This paper addresses the difficulty of obtaining vascular access in tiny vessels, particularly in pediatrics, by developing an ultrasound-guided robotic vascular access (RVA) system. The authors design a $9$-DoF platform that fuses a $6$-DoF commercial arm with a $3$-DoF end-effector, integrating force sensing, stereo NIR tracking, and high-frequency ultrasound to enable precise, image-guided needle insertion. The system delivers a comprehensive five-step needle insertion workflow, validated through a high-fidelity phantom study ($100$% success) and an in vivo rat-tail study ($95$% first-attempt success, with veins as small as $0.44$ mm in diameter). Results demonstrate robust performance in submillimeter vessels and suggest significant potential to reduce failed attempts, minimize patient discomfort, and improve clinical efficiency, with future work targeting real-time vein-diameter estimation, AR/VR interfaces, and larger clinical trials. Overall, the RVA system represents a promising step toward safer, automated vascular access in challenging anatomical contexts, aligning advanced robotics with ultrasound-guided intervention to enhance pediatric and difficult-case care.

Abstract

Billions of vascular access procedures are performed annually worldwide, serving as a crucial first step in various clinical diagnostic and therapeutic procedures. For pediatric or elderly individuals, whose vessels are small in size (typically 2 to 3 mm in diameter for adults and less than 1 mm in children), vascular access can be highly challenging. This study presents an image-guided robotic system aimed at enhancing the accuracy of difficult vascular access procedures. The system integrates a 6-DoF robotic arm with a 3-DoF end-effector, ensuring precise navigation and needle insertion. Multi-modal imaging and sensing technologies have been utilized to endow the medical robot with precision and safety, while ultrasound imaging guidance is specifically evaluated in this study. To evaluate in vivo vascular access in submillimeter vessels, we conducted ultrasound-guided robotic blood drawing on the tail veins (with a diameter of 0.7 plus or minus 0.2 mm) of 40 rats. The results demonstrate that the system achieved a first-attempt success rate of 95 percent. The high first-attempt success rate in intravenous vascular access, even with small blood vessels, demonstrates the system's effectiveness in performing these procedures. This capability reduces the risk of failed attempts, minimizes patient discomfort, and enhances clinical efficiency.

Figures (4)

• Figure 1: Prototype of the proposed Ultrasound-guided vascular access robotic system. The system comprises a 6-DoF robotic arm integrated with a specialized mechanism for robotic vascular access, enabling precise needle manipulation under ultrasound guidance.
• Figure 2: Computer-aided design renders to illustrate the distal manipulator details.
• Figure 3: Experimental setup for the robotic and ultrasound-guided intravenous vascular access system: (a) In vivo demonstration of venipuncture on a rat tail, illustrating the system's operational workflow during the procedure, and (b) Visualization of blood return in the catheter, confirming successful venipuncture, which is a critical metric for assessing system performance.
• Figure 4: Overview of the in vivo robotic ultrasound-guided vascular access procedure in rat tail veins, showcasing the integration of robotic and ultrasound assistance for precise needle placement: (a) Schematic illustration of the vascular access procedure, depicting the relative positioning of the needle and the rat tail. (b) Representative ultrasound image from three of the 40 trials, emphasizing a transverse cross-section of the rat tail vein. The image distinctly identifies the vein's lumen and surrounding tissue, with the needle accurately positioned within the vein. The first column showcases a successful vascular access example: The upper ultrasound image depicts the pre-puncture scene, where the target vessel is visibly marked with a red circle. The lower image, post-puncture, reveals a bright spot in the previously targeted vessel, denoted by a blue circle, signifying the needle tip's location. The subsequent two columns illustrate failed puncture attempts: the fourth and 35th attempts. In both columns, the upper image clearly displays the target vessel, yet the corresponding lower image does not mirror the successful outcomes. Instead, the images indicate that the needle tip's bright spot either strays from the target vessel or remains undetected within it. (c) The image grid encompasses all 40 trials, presenting pre-puncture and post-puncture ultrasound images, alongside the rightmost image in each row indicating the blood return status. This comprehensive result underscores the system's accuracy and reliability in achieving successful venous access.