Home | University of Pittsburgh



Human Factors Analysis

Intravenous Infusion Simulation

Russell Bregman, Jon Grasman, Craig Lehocky, Adam Scharl

Advisor: Dr. Joe Samosky

April 22, 2008

Revision 8

1. Device Overall

The development of an Intravenous Infusion Simulation (IVIS) stands to act as a novel training device during medical simulations. The IVIS records the volume of drug administered as well as the rate of drug infusion by the user. These data are presented to the user through an RGB LED affixed to the site of infusion, which will be referred to as the F-site, and a visual display system. These data are also stored offline for post-simulation analysis. In addition to the inlet and outlet of the F-site, there is also a Luer Lock port to affix a needleless syringe, with a valve to allow for the fluid in the syringe to flow into the IV tubing. For each drug, variables such as the drug’s name, nominal dosage parameters (volume administered, infusion rate and initial concentration), estimated acceptable range of those parameters, and adverse consequences to incorrect dosage or rate are stored upon scan. This allows the staff to review their methodology immediately and provide the necessary feedback for improving future performance. The LED display provides the user with a visual representation of the discrete flow rate, either “fast”, “moderate”, or “slow”, while the computer system provides a real-time status on the progress of drug injection.

The IVIS is powered through a standard U.S. wall socket (120V). The syringes in use are standard medical syringes, ranging from 3 mL to 10 mL. Thus, all ergonomic considerations of use for the device are dictated by the syringe manufacturer. The LED integrated at the F-site does not pose any ergonomic problems. The flow measurement circuit and the visual feedback circuit are programmed onto a laptop computer with LabVIEW software. The housing for the mechanical flow sensor and the digital-to-analog converter will be placed near the infusion pump and laptop. Presumably, these components should occupy as little space as possible so it can be easily mounted on a nearby tabletop or bench. The housing will be 6” x 4” x 3”.

2. Device User Interface

The user receives visual feedback of drug infusion rate through two different displays. The first is a RGB LED that is attached to the site of infusion on the F-site. The LED emits different colors depending upon the infusion rate that the user is administrating. The color will be green if the infusion rate is within the desired parameters, red if the infusion rate is faster than the desired parameters and finally blue if the infusion rate is slower the desired parameters. The second method of display is the interface of the system itself. While the system records the infusion rate it is plotted on a graphical display in a white line on a black field. The desired flow parameter, set by selecting the appropriate radio button, is a thick green line, corresponding with the green LED light. There are also red and blue lines on the display, above and below the green line respectively, marking the upper and lower limits of the desirable range of infusion rate. These limits are also found in the drug database, set by the Department of Pharmacy. The total volume of the drug infused is saved by the system along with this graph for offline debriefing.

The visual display should be viewable from nearly the entire viewing plane both horizontally and vertically while standing in front of the unit (the extreme angles to the sides and top and bottom may be less clear). An adjustable metal stand will be included under the front end of the device to angle the faceplate of the visual display for comfortable viewing by the user. The device is visible in reasonably and low lit rooms, however rooms with high-intensity light or natural sunlight may reflect off the display, resulting in straining for the user when reading.

The flow rate of drug administration will be measured through the use of two flow sensors: one being the infusion pump, and the other placed approximately where the patient would be in the system. By subtracting the flow rate recorded by the infusion pump from the flow in the sensor near the patient, the rate of injection is determined. This measurement is then compared to three logical values stored as “high”, “good”, and “low” to determine the flow rate visual output. The total volume of drug administered is calculated by integrating the flow rate over the time elapsed. The drug recognition selection system employs six radio buttons on the system’s interface that communicate with the customizable drug database to provide the desired parameters for offline analysis. This communicates with the simulation instructor’s computer to display these drug parameters.

Each of the syringes is labeled with their correct volumetric sizes. Included with the sensor system will be an instruction manual, detailing user use, safety precautions, calibration and cleaning techniques, power guidelines, and contact information.

3. Device Use

The initial task of the user is to inject the drug simulant into the system. Prior to injection, the instructor selects the radio button that corresponds to the drug to be injected in the system. The user will then be required to fill one of the syringes with the drug simulant from the vial. After filling to the desired amount and flushing out any air bubbles, the syringe will be screwed firmly and locked into place in an F-site connected to the IV line. Once the instructor has switched on the display device, the user may begin injecting the drug. Upon receiving visual feedback of the rate and total volume injected, the user may alter his or her injection rate to the correct parameters. This is where the true training takes place, as the user repetitively learns the muscle memory for these infusion rates. After the simulation has completed, the user and instructor shall review the offline results and compare to desired outcomes.

The device setup requires the user to provide power to the visual display, through a wall socket. The customized IV tubing, with wiring, must be connected to an external IV bag. All solutions being administered to the IV bag and tubing should be at or near room temperature (25oC) for accurate flow measurements.

Periodic calibration and cleaning must be done for proper device performance. Before the first injection of the day, it is highly recommended that the F-site as well as the IV line be flushed with a large amount of deionized water, to remove any impurities lodged within them. Instructions for conducting the calibration will be detailed in the user manual.

4. Device User Population

The IV infusion port sensor system is intended for use by any medical personnel, licensed or in training. As a simulation device, it offers new students the chance to become accustomed to infusion techniques, and experienced medical staff the opportunity to perfect them. The instructors of the simulation center should have sufficient knowledge of and training on the sensor system, in order to help with any immediate questions. If questions cannot be immediately answered, the instructor should contact the manufacturers or consult the instruction manual. The device is designed to use standard medical intravenous drug administration systems already approved by the FDA, and only enhance them by adding a measurement device. Thus, all syringe and IV equipment should be ergonomically safe and comfortable for all adult users. This device should not restrict the population use at all.

The device should not be used by children or those unfamiliar with intravenous drug administration. The device will be marketed to the medical simulation community, not the general public.

5. Device Use Environment

The device is intended for use in medical simulation environments that emulate operating or emergency rooms in hospitals. Thus, the environment should contain sufficient lighting and an adequate power source. In the event of an electrical surge, the environment’s power source should be sufficiently grounded to avoid any electrical malfunctions of the device. The environment should be at or near room temperature, atmospheric pressure (1 atm), and standard humidity (~50%). Any surrounding electrical equipment should be as electrically insulated as the IV infusion port sensor system to ensure minimal electromagnetic interference. A fire extinguisher should be present, as the case with any electrical device, in the case of some catastrophic event.

The device should not be operated in a room with unsafe electrical wiring, water damage, or water leaks. The device should be mounted near the power source and IV bag so that wiring does not obstruct the users’ pathways.

6. Use Related Hazards

There are no similar marketed devices to this product available, and thus there is no basis for direct comparisons to currently available products. However, the products in the medical simulation industry can provide a standard by which we can judge the efficacy of our device. User error is expected to occur on this device for training purposes. Thus, our device has a very low expectation for use related hazards.

A fault tree analysis (FTA) was employed, along with a risk management summary and failure mode and effects analysis (FMEA) in order to pinpoint possible use related hazards and how they may be addressed.

One such use related hazard discovered in the development phase of the product has been the risk of electrical shock from exposed wiring or electrical leads. This has been addressed with the inclusion of insulation between the electrical components and the user. No hazards have yet been discovered in the early testing phases of this device, however, as design continues, new facets to the safety characteristics of the device will be addressed.

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download