Infusion Pumps

Authors: Megan Conrad, M.S.E.

Coordinating Editor: Jack Winters, Ph.D.

Location: Medical Device Accessibility & Usability Laboratory

Current Version: 1.0 (March 2006)

Table of Contents

• Executive Summary
• Background
• Product Table
• Product Survey
• Product Evaluation
• Acknowledgement
• References

Executive Summary

Infusion pumps are used to deliver necessary materials within fluids (whether medications or nutrients) to the body. The wide range of applications includes everything from simple hydration to chelation (iron filtration in the blood) and chemotherapy. Because of the wide variety of uses and possible severe consequences, it is essential for infusion pumps to be accurate and consistent in their administration of fluids. This technical report examines the features of such devices, with a special focus on features related to accessibility and usability.

Figure 1. Example of a volumetric infusion pump.

Figure 2. Example of an ambulatory infusion pump.

Background

Infusion pumps allow administration of materials within fluids (such as medications or nutrients) to patients needing controlled dosages throughout the day. The pumps can be set to deliver a desired fluid dosage, typically as low as 0.1 mL / hr. Intravenous infusions are the most commonly used method of infusion, but subcutaneous and epidural methods are also used.

Infusion pumps are typically categorized as:

1. Volumetric (Large Volume or Small Volume)
2. Ambulatory

Large volume infusion pumps most often are used to deliver nutrients, and typically have a stand for mounting. Small volume pumps may be used for hormones, pain relievers or antibiotics. Both large and small volume pumps may be designed to be portable, or stationary for a clinical setting. Ambulatory pumps, more compact in design, are used for outpatients and are entirely portable. Pumps can be programmed by a patient, but are often pre-programmed by a clinician.

It has been shown that infusion pumps have many implications for patient safety (Graham et al, 2004). A large influence on many implications includes difficulty with particular device’s displays and controls. It is believed many implications can be prevented through product design evaluation.

Product Table

For an overiew and instructions on how to navigate within the product table click here.

Product Survey

The product table provides a summary of the various types of infusion pumps currently on the market. The table provides pertinent information on the accessibility and usability features of these pumps. Included in the table are the manufacturer name, product name and manufacturer website where more product details can be viewed. The type of pump (i.e., volumetric or ambulatory) is provided in the description column. When possible the volumetric pumps are described in more detail by including the number of channels included in the design (e.g., single channel, dual channel, etc).

Figure 3. Example of a dual-channel infusion pump.

Depending on the intended nature of the pump it may or may not be portable. For example, some pumps may be intended for emergency use and are portable for on-site treatment and patient transportation. Some large volume pumps are strictly used in hospitals with no intent of patient movement and are therefore more stationary. All ambulatory pumps are portable as they are specifically used by patients who are mobile and most often outside of a clinical setting. As expected, size varies for the pumps based on intended volume size and portability.

While almost all pumps have a power cord for AC power use, it is necessary for pumps that are portable to have a battery powered option. Large scale pumps also include batteries for back-up in case of a power outage. Batteries vary in type and size. The rechargeable types used include nickel cadmium, sealed lead acid, and nickel cadmium. Often infusion models simply use AA, AAA, or 9V alkaline batteries which are readily available for purchase.

An important feature for infusion pumps is the capacity reported as Volume to be Infused (VTBI). Most pumps have a range from 0.1 – 9,999 mL. Pumps also report a flow rate range in mL/hr which varies greatly between pumps. Many specify capability to infuse at 0.1 mL increments.

Due to the sensitive nature of infusion, safety features are closely regulated. All pumps have auditory alarms. Batteries prevent the pump from shutting off in case of power loss. Sensors are able to detect if there is a blockage or air is in the line, as well as if the bag or syringe of fluid is empty.

Control of the pumps is typically managed through flat panel buttons on the device. Some pumps can also be pre-programmed through synchronization with a computer or PDA. Particularly on the large volume pumps (because they are used in clinical settings) controls are typically locked so that only a practitioner can administer changes to dosage levels. Often ambulatory pump dosage is controlled in a similar manner by pre-programming during a clinical visit.

Product Evaluation

The most crucial concern regarding infusion pumps is the accurate delivery of dosing rates and volumes. Over- or under-dosing could result in detrimental effects for the patient. In order to do this, the patient or a caregiver must be routinely capable of checking the pump for leaks or kinks in the tubing and infusion begin and end times for accuracy. Specifically, areas of concern in regards to infusion error are: miscalculation of desired dosage levels, data entry error (such as misplacement of a decimal point), and titration error (related to volume or rate of flow). In relation to these errors, the areas of most concern with regard to usability include data entry and patient response to any errors that may occur due to dosage or titration levels.

Regarding data entry, most products have gone through extensive design revisions to ensure ease of use for nurses in a clinical setting. However, the design of buttons on infusion pumps is typically not accessible for many individuals with disabilities. They are typically on a flat screen, in line with each other, and have little to no tactile feedback. The buttons are also very small, and sometimes close together. Larger buttons, properly spaced out will allow better accessibility for patients experiencing tremor or dexterity issues.
It is true that many monitors are pre-programmed by a practitioner. However, these cases often include patient-controlled methods, meaning the practitioner simply programs a ceiling level that the patient cannot administer dosages above. Therefore, even in pre-programmed systems it is important for patients as well as practitioners to be able to administer doses accurately.

Similarly, alarms must be accessible to all users of devices because of the detrimental effects of over- or under-infusion. While regulations require alarms on devices, most products report use of auditory alarms, with some having visual output as well. Most visual outputs are used for an error description. It would be beneficial for the devices to also incorporate tactile (such as vibration) and audio alarms, providing redundancy for a variety of user preferences.

Newer systems are developed allowing PDA input for control. This may be helpful to patients and practitioners alike if the PDA itself is accessible. Also control by personal computer (PC) download most likely can add greater accessibility for some individuals if they have access to a PC.

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

1. U.S. Food and Drug Administration. Brochure – Home Healthcare Medical Devices: Infusion Therapy – Getting the Most Out of Your Pump. Updated February 7th, 2005. https://www.fda.gov/cdrh/cdrhhhc/brochure-infusion.html
2. Graham, MJ., Kubose, TK., Jordan, D., Zhang, J., Johnson, TR., Patel, VL. Heuristic evaluation of infusion pumps: implication for patient safety in Intensive Care Units. Intl. Journal of Med. Informatics., 73, 771-779, 2004.
3. Wetterneck, TB., Carayon, P., Sobande, F., Hundt, AS. Technology characteristics predicting end user acceptance of smart intravenous infusion pumps. Proc. of the Hum. Fact. and Ergo. Society Annual Meeting, 2005.
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