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The first ambulatory infusion pump marketed was the Watkins Chrono-Fusor1 in the late 1950s, used primarily for the continuous infusion in humans of chemothepeutic agent 5FU (Fluorouracil), still a major drug used in many cancer treatments. The Chrono-Fusor (Figure 1) was slightly smaller than today's programmable infusion. The power source was a mechanical keyed wind-up watch motor, much like a grandfather clock. The pump utilized a rotary peristaltic mechanism, identical to some of today's pumps.

Ambulatory infusion pumps developed slowly over the next two decades until the 1970s when the home infusion market prompted pump manufacturers to develop smaller, more cost-effective pumps. In the early 1980s, Deltec Systems (now SmithMedical MD) developed the CADD (Computerized Ambulatory Drug Delivery System) pump. The CADD pumps became the ambulatory pump of choice for many laboratory animal researchers. These pumps allowed for sophisticated drug delivery in ambulatory animals that was not previously possible. The early ambulatory infusion pumps were single therapy, and thus had limited capabilities. Sometimes, multiple pumps were required to deliver different rates or pumping profiles.

In the early 1990s, ambulatory infusion pumps evolved into multiple therapy pumps that could be programmed for various types of infusions. This added capability came with a price; it added significantly to the size and weight of the pumps, limiting their use in the laboratory animal market.

During the 1990s, pumps more suitable in size, weight, and capability for laboratory animal infusion appeared on the market. The CADD Legacy® and CADD MICRO® (Figure 2) became the standard for ambulatory animal infusions. The CADDMicro was small, lightweight, and allowed for precise delivery in smaller laboratory animals that was previously only available in tethered models. The Micro was limited to a 10 ml syringe, so its use was very specialized. The CADD Legacy pumps allowed for animals as small as 2-3 kg to carry a full-featured, complex, ambulatory infusion pump.

At the same time, a number of other pumps were beginning to be marketed to laboratory animal researchers. A couple of ambulatory infusion pumps, marketed for humans in Europe, began to make their way to the laboratory animal infusion market. They provided features that researchers were looking for that were not available in a single device. A new pump from Germany came to the market in the mid 1990s. It was a small, lightweight, and accurate piston driven pump that was much smaller than the competing pumps of the time, and it offered PC communications for the first time. Figure 3 shows the Pegasus®, a small ambulatory pump.

The advent of ambulatory infusion pumps with PC communications gave researchers the ability to trend pump data much more efficiently. In addition, it was now possible to print a pump's history, helpful in troubleshooting problematic infusions.

About the same time, the CADD pumps also released a communications that allowed the researcher to download and print a pump's history files, as well as program a pump via a PC, hardwired to the pump.

The ability to interface the PC with the infusion pump inspired researchers to do more with the technology. The idea of wireless communications with laboratory animal infusion pumps was born.

The early iterations of this technology were crude and tended to be very buggy. The early systems were based on infrared data transmissions and proprietary RF signals. The systems were difficult to set up and required cage/jacket, room, and other modifications to get marginal results. The idea was great, but the technology was not quite there yet. It would take almost another decade for the technology to catch up.

The Rise of Smart Pumps
In the early 2000s, a new breed of "smart" pumps was born out of the need for patient safety. These new pumps, created to reduce the risk of administering IV medications in a clinical setting, have the ability to store dosing guidelines in a drug library on the pump, warning clinicians of potentially unsafe infusion. The NationalHome Infusion Association in a 2005 survey2 ranked smart pumps' most important features. Several ambulatory infusion pumps on the market, including the Curlin 6000 CMS™  (Figure 4) and the CADD Solis™ (Figure 5) have most of the features clinicians wanted. Smart Pump features important in the research setting include:

  • Pump History Downloads
  • Medication Error Alerts
  • Remote Programming
  • Software Interface
  • Patient Identifiers

While all this technology is not particularly helpful in a laboratory animal infusion, the more complex abilities of the pumps are. The smart pumps allow for programming via PC and PDA, as well as by reading barcodes. The safety aspect of the pumps make mis-programming infusions more difficult, giving the researcher less infusion errors.

The drug infusion libraries of these new pumps allow the researcher to save time by allowing access to limitless databases of infusion protocols based on concentrations and weights. The ability to program hundreds of pumps with the stroke of a PDA stylus, rather than searching through each screen of each pump, can save time and labor. At the end of the infusion, the pumps can be connected to a PDA or PC, and the event logs can be downloaded for each pump.

Remote Pump Communications
Another advantage of this new breed of pumps is the ability to communicate with the pumps remotely. Today, many of us have wireless communications in our pockets; WIFI and Bluetooth® are common components in many different types of devices. Most facilities now have at least some WIFI access, providing robust and secure methods of electronic communications.

Most infusion pump manufacturers currently market either wired or wireless networking. Wireless pumps and control systems are being developed for the laboratory animal market. The pumps and systems are using different standards for communications, each of which have positives and negatives.

  • WIFI, based on the 802.11 B/G standard, is readily available (most facilities have infrastructure existing), secure, and offers very good transmission range. The only downside to WIFI is that the power requirements needed make ambulatory use impractical.
  • Bluetooth, based on the IEEE Standard 802.15.1-2002, is starting to take a foothold in the laboratory animal facility in a variety of products. Bluetooth has good security and transmission range of up to 50 ft. The power requirements of Bluetooth are better than WIFI, but still are not ideal.
  • ZIGBEE, based on the IEEE 802.15.4 standard, offers good transmission range, very low power requirements, and is secure. The downside is that it is a lesser known technology and requires new networking equipment.
  • Ethernet makes fast easy connections to existing networks. The negative side of using Ethernet is that one needs the infrastructure in place. The infusion pumps are somewhat limited where they can be placed in an Ethernet-based network.

WIFI is the standard that is driving the new wireless communications systems in infusion pumps - the advantage is the existing infrastructure. WIFI is only practical in stationary, tethered models at this point, but the advancement of consumer products can only help to advance the size and power requirements.

In the clinical setting, WIFI-based pumps are gaining popularity due to the ease of locating them on the wireless LAN, remote downloading of pump data, and the ability to send alerts via email or other electronic communications.

Considerations for Buying a New Ambulatory Infusion Pump
There are several things to consider when in the market for new pump.

  1. Identify your current and future infusion needs. What species do you work with currently? Is that likely to change? Keep in mind that ambulatory infusion pumps work well with both tethered and ambulatory models. Many pumps have low enough delivery rates that they can be used with tethered rodents.
  2. Do you need the advanced technology of today's smart pumps? How much are the advanced features worth to you? Does it make sense to upgrade?
  3. What are your budgetary constraints? Does the technology save you labor time?
  4. What is the true cost of ownership? Disposables? Batteries? Repairs?
  5. Does the vendor provide training and service geared for laboratory animal use of the pumps?
  6. How old is the technology? When is its planned obsolescence?

A System is only as Good as the Sum of it Parts
Advanced technology does no good if one cannot keep the line in the animal connected and patent. Several new products make the critical interface between the animal and the infusion pump secure and effective. Several vendors in the laboratory animal infusion market have launched new products to help address this issue. One new method is to utilize a skin parallel port with a flexible cannula inserted into the indwelling catheter (Figure 6). This type of interface allows for a very secure port to infusion line connection and allows for very low volume of dead space in the catheter line.

Another new idea is to utilize a matrix inside of a port's septum to hold onto a specially designed needle. Figure 7 shows the Instech Solomon PortHold™, a conventional titanium port with the exception of a fenestrated titaniumplate embedded in the septum to reduce the risk of needle dislodgement.

These new ways of looking at old problems may help improve the reliability of ambulatory infusion.

References

  1. Sullivan RD, Zurek,WZ Cancer Chemotherapy Rep. 1964 Apr: 37:47:55.
  2. Counce JB Infusion pumps sales on the rise: a look at consumer trends and possibilities. Infusion. 2005: 11(4): 11-16.

Trademarks and copyrights are property of owners PortHold is a trademark of Solomon Scientific. Pegasus is a registered trademark of Venner Medical.

Mark B. Crowe is the president of AVA Biomedical, Inc. Prior to founding AVA Biomedical in 2005, he managed the pre-clinical infusion device divisions of Norfolk Medical Products (Access Technologies), and Smiths Medical PM (formerly Deltec). Mark can be reached at mcrowe@avabio.com.

AVA Biomedical, Inc.; 1046 Gage Street, Suite B;Winnetka, Illinois 60093; 888.347.8304; www.avabio.com

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