ActMD - IV Bag Infusor

Team 1

IV Bag Infusor

 Figure 1. From left to right: CAD model of the final design, first prototype constructed and final prototype.

Project Overview

    The goal of the project was to devise a mechanical device that can be used to rapidly infuse IV fluid to a patient. The final design of the project serves as a competitor to a commonly used inflatable bladder pressure infusor.  More detailed information of the details of the design and the uses of pressure infusors is given below. For a brief overview of the entire project, the Executive Summary is available here.

Design Objectives

The goal was to design a bag infusor that utilizes purely mechanical means of pressurizing an IV bag and/or blood bags. The purely mechanical aspect is so that the device may remain portable and easy to operate. It was considered the main design constraint. This new system was designed in accordance with the below constraints.

The infusor must:

1. Provide equal or greater pressure to the bag than the current bladder cuff option.

2. Empty the IV bag in less than 2 minutes

3. Safely lock when device is open to prevent user injury

4. No adjustment required once the bag is placed inside

5. Faster setup than the current bladder system

6. Be easily used by any medical personnel

7. Be portable and mount to an IV pole or operating table

Final Design

Components of the final design:

Crank Assembly

Figure 2. CAD model and photograph of the crank that is used to separate the top and middle plates allowing the IV bag to be loaded.

Locking Pawl

Figure 3. CAD model and photograph of the locking pawls which hold the device open by locking in with the gear. They can be engaged and release by a toggle switch.

Constant Force Springs

Figure 4. CAD model, example, and photograph of the constant force springs and their retainers. The springs provide the constant force needed to squeeze the bag.

IV Pole Securing Clamp

Figure 5. Photograph of the prototype's pole securing clamp. This design uses a clamp attached at the base to support the weight and a Velcro strap at the top of the device to prevent tipping.

Prototypes

Two prototypes of the device were constructed and tested in order to determine the time required to set up the device and drain a 500cc bag of water.

Figure 6. The first prototype was built out of acrylic, Delrin, and aluminum. It was powered by four 10.6 lb constant force springs.

Figure 7. The second prototype followed the same design as the first but included four 13.2 pound springs. The new design also includes a cover for the top of the device and a clamp to attach it to the IV pole.

Prototype Testing Results

 IV Pressure Infusor Background

    Intravenous therapy is the process of administering fluids and medications to a patient directly through a vein. Anesthesiologists utilize IV systems when patients are undergoing procedures with a lot of blood loss. In cases such as this, it is important that donated blood is transferred from the IV bag into the patient as quickly as possible. To speed up the flow of the fluid, an IV pressure infusor is used. The IV bag is placed in between a bladder and the device’s mesh front. The anesthesiologist then must use a hand pump to inflate the bladder. This is done until a pressure gauge on the device says the bag has reached 300mmHg.

One of the biggest issues with the current pressurized bag infusor is that as the fluid drains from the bag, the pressure decreases. The bladder is unable to automatically adjust how much it is inflated based on how the bag is emptied. This causes issues because the flow rate of the fluid decreases as the fluid in the bag drains.