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SonoHand
The Executive Summary can be found here.
Background:
Ultrasounds, used to guide medical procedures, have quickly become the standard of care. Interventions such as central venous access, nerve blocks, joint injections and aspirations, and biopsies all routinely use ultrasound in realtime to guide a needle to a target. A current limitation to optimal use of ultrasound is the need for a “3rd hand” during performance of these procedures. One hand holds the ultrasound, one holds the needle another provider injects or aspirates on a syringe. Due to the many needs, nurses assist in the placement of the probe. However, there has been issues regarding the probe placement from nurses due to the fact that they connect read the surgeons' minds. The goal of the SonoHand is to be the "3rd hand" and requires only an operator to conduct the procedure, rather than an operator and a nurse to make procedures more consistent and fluid.
Sample Procedure conducted by our sponsor, Dr. Preetham Suresh
Project Objectives:
High Priority Objectives
Maintain contact during operation unless the patient moves with a strong enough pushing force
Moveable arm that can hold the sonar equipment against skin with ample pressure
Keeping the arm within a sterile field (sheath for the ultrasound device) by guiding it through the wire
Easy way to lock and unlock the arm
Ability to hold different types of probes (SonoSite's C60, HFL38XI, etc.)
Low cost (~$100 is optimal)
Ability to have 360 motion
Second Priority Objectives
Rotational freedom on probe that locks at -90 and 90 degree orientation
Have a holder for the needle as well, but much less feasible due to it being more dangerous (touching the patient’s neck vein and can slip to an artery)
Versatile base that can attach to anywhere in the hospital room
SonoHand in a hospital room
Description of Final Design:
SonoHand consists of four primary subassemblies: the hand clamp, the articulated arm, the base clamp, and the locking mechanism. The articulated arm connects all of the parts together through a series of aluminum linkages and ball and socket joints. The hand clamp is what holds onto the ultrasound probe and is pushed by a spring pressure system to allow the ultrasound machine to produce a sonogram. Both the arm and the hand clamp are locked by an automation system using servo motors, Arduino, and a foot pedal. Lastly, the base clamp is machined from aluminum and has an adjustable threaded device that is used to mount onto the ultrasound machine's platform.
On the left: isometric view of SonoHand in person; On the right: isometric view of SonoHand's CAD
Summary of Performance Results:
SonoHand was tested in the UCSD Medical School's Simulation Center and risk reduced 3 times. The arm currently meets all of the primary requirements; however, there are some quality of life changes desired. Some of the notable features include the following:
The base mounts onto the ultrasound station, but it has the possibility of blocking the sonogram images depending on the angle.
Base of SonoHand on an ultrasound machine's platform
The hand of the device works excellently. It clamped multiple probes during the clinical testing. The only issue is the spring pressure system does not have a lock, so it has the chance to return its neutral position when tapped during the procedure. A sonogram still appears even at the neutral position, so it works but not optimally as there is a chance of slipping.
Video of SonoHand being applied to a mannequin and producing sonogram images
The sheath fits perfectly over the device as long as there is no excessive force or rush.
Video of placing a medical sheath over SonoHand
The foot pedal controlled locking mechanism works well. To move the arm, the pedal is stepped on to unlock the ball and socket joints, and vice versa. Wire management has been implemented from the design in the testing photo to have holders on the side of the arm linkages.
Video demonstrating the foot pedal locking mechanism