Technical Report AMI-002:

Accessible Syringe Dosing: Review of 2004-2005 RERC-AMI National Student Design Competition

Author: Melissa R. Lemke, M.S.

Coordinating Editor: Jack Winters, Ph.D.

Location: Medical Device Accessibility & Usability Laboratory

Current Version: 1.0 (March 2006)

Table of Contents

Executive Summary

As part of the 2004-2005 RERC-AMI National Student Design Competition, seven teams of engineering students designed prototypes for an accessible syringe dosing interface. Teams were given the challenge of designing a reliable, low-cost, universally easy-to-use mechanism for enabling automated dosing of medications for 6 fictional “clients” with various disabilities. It was specified that the design must be able to dose reliably to the nearest 0.01cc using standard 1 cc syringes (¼” diameter) that are commonly used for delivery of insulin & heparin and be able to gently mix before dosing.

Background

While there can be many reasons for syringe dosing, two of the key drugs to be delivered are insulin (e.g., for persons with diabetes) and heparin (e.g., persons with a tendency to bleed excessively). In the U.S. alone, there are over 16 million people afflicted with diabetes, which can result in blindness, neuropathy, and amputations. Of these, approximately 7.5% have Type I diabetes, which means they are insulin dependent [Marquette team]. It is estimated that 20-50% of diabetics have some type of disability due to the side effects of this disease, such as retinopathy, other forms of visual impairment, stroke-induced disability and tremor (Kleinbeck, 2004). Diabetes is one of the leading causes of disability in the U.S., causing dementia, low testosterone levels in makes, excessive thirst, frequent urination, fatigue, changes in vision, blindness, stroke, and nerve damage (Medline plus: Diabetes tutorial, 2004; Medline plus: Diabetes, 2004) [UW-Madison team]. Older adults are another population of individuals who may need access to a device of this type, and in 2002 more than 12% of the U.S. population was age 65 or older. This group represented 40% of the total healthcare cost in 2002 (Healthcare Products & Supplies Industry Survey, 2004), and the U.S. Census Bureau expects this age group to expand to approximately 17% of the population by 2020 (i.e., due to the presence of the baby boomer generation) (U.S. Census Bureau, 2005). In addition, the World Health Organization (WHO) expects the prevalence of chronic disease (such as diabetes) to increase due to unhealthy lifestyles (WHO, 2005) [UW-Madison team].

The specific aims and specifications, provided by the RERC-AMI, for the accessible dosing project category follow:

Aim: A reliable, low-cost, easy-to-use mechanism for enabling automated dosing of medications.

Specs: It must be able to dose reliably to the nearest 0.01cc (using standard 1 cc syringes (¼” dia) that are common for delivery of insulin, heparin), be able to gently mix before dosing, and be universally easy to use.

Clients: Lloyd, Sophia, Arnold, Dave, Wanda (and Bob)

The “clients” for which the devices were designed were hypothetical “personas” with defined characteristics (e.g., diseases and disorders, physical abilities and disabilities) that intentionally spanned a large range of individual capabilities. The clients for this design included a man with diabetes and poor eyesight who is overweight (Lloyd), a woman with stroke-induced hemiplegia who uses a cane to walk (Sophia), a man with Parkinson’s disease (Arnold), another man with limited use of his right leg (Dave), a woman who is deaf (Wanda), and a man who is blind (Bob). See http://www.rerc-ami.org/ami/projects/d/2/2/year2/ for a complete description of these personas and rules for the 2004-2005 competition.

The overall goal of each dosing design was to address anticipated accessibility challenges that the specified clients might experience while trying to dose syringes, and each team addressed this challenge with their own unique design. The process of filling a syringe with the proper amount of a drug such as insulin and injecting the medication at a steady rate requires the user to possess fairly fine motor control and visual acuity. These skills are frequently lacking in the elderly and people who have Parkinson’s disease or other neuromuscular disorders [UW-Madison team].

It is important to keep in mind that many diabetics can require the use of 2 different kinds of insulin and as such, can have two different bottles that they may draw insulin from. In some cases, they may need to mix the two types of insulin into a single dose. Therefore, the ability to load two bottles into the device and mechanically move the bottles to choose the proper type of insulin is required. Also, some types of insulin (generally long-acting) require the bottle to be mixed prior to dosing so that the consistency of the insulin is even throughout. It is recommended that the mixing of the bottles be gentle, for shaking the bottle violently or excessively can cause a breakdown in the chemical makeup [Marquette team].

To provide a foundation for the intent of this design, a description of an injection procedure that is recommended by an endocrinologist is provided (Canadian Diabetes Association, 2004) [UW-Madison team]:

  1. Wash hands and area where injecting (usually a fatty subcutaneous tissue area such as the stomach).
  2. Wash medicine bottle top with cotton ball and alcohol.
  3. Draw air into the syringe equal to the volume of fluid needed.
  4. Insert needle into medicine bottle and depress plunger, pushing all air out of the syringe. This action creates a vacuum and allows for easier and smoother filling and delivery.
  5. Invert medicine bottle and fill syringe, making sure the needle is not exposed to air. Air bubbles in the barrel will lead to an incorrect amount of medication.
  6. Once the syringe has been filled to the proper amount, keep the bottle and syringe upside down and flick the syringe barrel. This moves air bubbles that may have formed at the top of the syringe.
  7. Push the plunger to move the air bubbles into the vial.
  8. Check medication dosage.
  9. Insert needle into skin at a 90-degree angle and deliver medicine at a slow, steady rate. All medication should be released within 5 seconds.
  10. Dispose of needle properly.

It is evident that syringe dosing is a complicated and involved procedure, especially in terms of handling the insulin bottle at the same time as handling the syringe and pulling its plunger [UW-Madison team]. The following were major considerations for designing an accessible syringe dosing interface: bottle loading, bottle mixing, syringe loading, syringe/bottle interface, syringe dosing, user interface.

Survey of Prototypes

The Product Table compares the seven designs entered in the 2004-2005 National Student Design Competition. The most important accessibility features for the devices are summarized in the table, along with other design information that may be of interest (e.g., cost, materials, fabrication methods). A link also is provided to the corresponding websites that each design team developed as part of the competition, and more information about each of the projects is available through (http://www.rerc-ami.org/ami/projects/d/2/2/year2/).

Evaluation of Prototypes

It is quite evident that a lot of research and development work was carried out to complete each of the projects, which will be summarized below. It seems that the competition provided unique educational experiences for student participants, while the design experience and education from the students’ respective universities and the accessible and universal design information provided by the RERC-AMI (see http://rerc-ami.org/ami/projects/d/2/udg/) were integrated well to yield these innovative designs for individuals with disabilities.

At the end of the competition, a subset of a panel of nine judges scored each design entry, and then awards were given to what were considered the top designs overall and within each category (see http://www.rerc-ami.org/ami/projects/d/2/2/year2/). The Marquette team was tied in 2nd place in the overall competition and first in this category with their project entry, with the design from the University of Connecticut tied for third place and second in this category.

A picture of each design is provided below, including in the top row, from left to right, the University of California San Diego, University of Georgia, Marquette University, University of Wisconsin-Madison and in the bottom row, from left to right, the University of Tennessee, University of Wyoming, University of Connecticut:

Prototype from University of California San Diego team | Model from University of Georgia team | Prototype from Marquette University team | Prototype from University of Wisconsin-Madison team

Prototype from University of Tennessee team | Prototype from University of Wyoming team | Prototype from University of Connecticut team

Some accessibility features included in the Marquette design:

Based on reviewing the design criteria listed by each team, the following criteria are good to strive for when designing an accessible syringe dosing interface for individuals with disabilities:

Acknowledgment

This work is supported by the Rehabilitation Engineering Research Center on Accessible Medical Instrumentation, funded by the National Institute on Disability and Rehabilitation Research, U.S. Department of Education Grant #H133E020729. All opinions are those of the authors.

References

Canadian Diabetes Association. Insulin: Things you Should Know. http://www.diabetes.ca/S ection_About/insulin2.asp. 2004. [UW-Madison team]

Diabetic Supplies.com: Insulin Supplies. http://www.diabeticsupplies.com/cgi-bin/ds/supplies.html [UCSD team]

Harsch, Igor Alexander, et al. “Syringe, pen, inhaler – the evolution of insulin therapy.” Med Sci Monit, 2001: 7(4) 833-836 [UCSD team]

Healthcare Products & Supplies Industry Survey: Industry Trends. Standard & Poor’s Industry Surveys. Sept. 23, 2004. [UW-Madison team]

Kleinbeck, Connie, Williams, Ann. “Disabilities, Diabetes and Devices”, Home Healthcare Nurse. Vol 22(7) July 2004 pp 469-475 [UCSD team]

Korytkowski, Mary, et al. “A Multicenter, Randomized, Open-Label, Comparative, Two-Period Crossover Trial of Preference, Efficacy, and Safety Profiles of a Prefilled, Disposable Pen and Conventional Vial/Syringe for Insulin Injection in Patients with Type 1 or 2 Diabetes Mellitus.” Clinical Therapeutics, 2003: 25(11) 2836-2848 [UCSD team]

Medline plus: National Library of Medicine. Diabetes tutorial. http://www.nlm.nih.gov/med lineplus/tutorials/diabetesintroduction/id029102.html. 2004. [UW-Madison team]

RERC-AMI: D2.2: Student Desitn Competition, see http://www.rerc-ami.org/ami/projects/d/2/2/year2/rules/

US Census Bureau. Percent Distribution of the Population by Age: 1990 to 2050. http://www.census.gov/prod/1/pop/p25-1130/p251130b.pdf. 2005. [UW-Madison team]

World Health Organization. Obesity and Overweight. http://www.who.int/hpr/NPH/docs/ gs_obesity.pdf. 2005. [UW-Madison team]