By Dave Wilson, Academic Marketing Director, National Instruments
Phlebotomists draw blood in the US approximately 1.4 billion times per year. It’s the most ubiquitous medical clinical procedure performed and more of them will be performed each year as the Boomer generation ages. First-stick accuracy depends on the patient’s physiology and the practitioner’s experience. Human accuracy is estimated at approximately 50%. That’s not a great number, especially if you’re one of the people with hard-to-find veins.
VascuLogic, a medical device start-up and research lab based in New Jersey, has developed the VenousPro, a robotic phlebotomist that improves the accuracy and safety of the venipuncture procedure by autonomously performing blood draws and other IV procedures in less than two minutes with close to 100% first-stick accuracy. VenousPro operates by imaging and mapping in real time the 3D spatial coordinates of peripheral forearm veins to robotically direct a needle into the designated vein.
Design of the VenousPro prototype presented three main challenges:
First, the device needed to be safe, which meant repeatability and deterministic execution.
Second, the device had to be highly portable to work in a wide range of clinical environments.
Finally, the system had to pass the rigor of FDA evaluation.
Programming for the first prototype was done with MATLAB from The MathWorks. As the complexity of the VenousPro design grew and the size of the engineering team increased, VascuLogic realized that they needed a more integrated development platform. The company applied for, and received a National Instruments’ (NI) Medical Device Innovation Grant, which came with access to custom NI hardware, LabVIEW, and the NI Training and Certifi cation Program. VascuLogic built its second-generation VenousPro prototype using NI’s CompactRIO Reconfigurable Control and Monitoring System to control the robot.
Two enhanced-sensitivity, near-infrared GigE vision cameras and an ultrasound probe provide imaging information to the CompactRIO controller. A Xilinx Spartan-6 FPGA implements the imaging pipeline. The image-processing pipeline employs advanced algorithms from the NI Vision Development Module, and the 3D position and velocity information extracted from the images is communicated to the CompactRIO motion control modules at 20 frames per second. The CompactRIO system then directs the robotic needle manipulator.
The company converted its MATLAB code into a LabVIEW graphical design and developed an intuitive user interface. The VenousPro device uses kinematics, PID, and path planning VIs in the NI LabVIEW Robotics Module for functions such as correlating joint angles in the robotic arm with the 3D Cartesian coordinates of the needle tip. It also uses the LabVIEW Control Design and Simulation Module to predict future positions based on current velocity profiles through a Kalman filter. Complex mathematical operations on large arrays are accelerated using the LabVIEW Multicore Analysis and Sparse Matrix Toolkit.
The initial development plan for the second prototype called for a three-month development cycle but it only took three weeks because of the fl exibility and modular design of the LabVIEW environment. As a result, VascuLogic completed its pre-human, in-vitro, proof-of-concept testing ahead of schedule.
To date, VascuLogic has demonstrated better than 98% first-stick accuracy in multiple in-vitro studies. The company plans to upgrade to new multicore CompactRIO hardware and will move the user interface to an NI touch panel, which will eliminate the host PC. By developing on the NI platform, VascuLogic was able to deliver a device ready for clinical testing $50,000 below budget and five months ahead of schedule.
Note: Alvin Chen and Max Balter of VascuLogic submitted this project to the NI Engineering Impact Awards 2014 competition. It won in the Machine Control category. It also won the NI Community Choice Award and NI’s Humanitarian Award.