Infusion pumps are automated devices that intravenously deliver drugs, food, or other liquids to patients. Their basic utility makes them ubiquitous, but their basic design makes them problematic: 

• 80-90% of hospital patients receive infusions, and an estimated two million infusion pumps are currently used in hospital and clinical settings. 
• Between 2015 and 2017 the FDA reported more than 23,000 infusion pump malfunctions and injuries.
• Studies have shown that errors can occur in 60% or more of IV medication administrations, and infusion related errors account for 54% of all adverse drug effects.
• Recalls for infusion pumps are among the highest for any medical device.

Pump Mechanics 

Most infusion therapy devices use peristaltic pumps, sometimes known as roller or rotary pumps. These pumps have rotating “blades” or “lobes” that squeeze down on the tubing with each pass, essentially pushing the fluid through the tube using positive displacement. Peristaltic pumps may run continuously, or they may be indexed through partial revolutions to deliver smaller amounts of fluid. Importantly, delivered flow is only estimated/ derived from the speed and RPM of the pumping elements and does NOT reflect actual flow. 

Sources of Error 

Manufacturers typically report flow accuracy of +/- 5%, but this is based on perfectly controlled lab conditions. It does not account for user error or other real-world conditions that help explain the large discrepancies with the error rates reported in clinical studies. Errors can result from many potential issues: 

• Variance in the pump element mechanics 
• Variance in tube size, flexibility or loss of resiliency over time
• Use of non-standard syringe or tubing set
• Outlet pressure variation
• Fluid container height relative to the infusion pump
• Leaks, air, or blockages in the line
• Software issue
• User error and/or device interface issues

Despite the fact that “smart pump” technology is now present in more than 73% of the infusion devices in use, error rates remain unacceptably high. 

Consequences 

The Institute of Medicine (IOM) estimates that at least 1.5 million preventable adverse drug events (ADE) occur in the United States alone. Each preventable ADE has been reported to cost nearly $9,000, and infusion-related adverse drug effects are estimated to cost $2 Billion/ year in the U.S.  710 infusion-related deaths were reported from 2005-2009. 

Solution 

Established transit-time ultrasound flow measurement technology can precisely determine delivered flow and volume, rather than relying on pump estimates. These measurements can be done independently from the infusion device, serving as a “guard rail” against both device and user error. This added protection would come at a cost but considering the poor economic and clinical outcomes associated with current infusion practices, it may be a small price to pay for a large leap forward in accuracy. And this is particularly true when it comes to high-risk medication delivery and critically ill patients. To measure is to know!  

Sources:  

• Biomedical Instrumentation & Technology, July/August 2016.Reflections on the Current State of Infusion Therapy. 
• Biomedical Research (2017) Volume 28, Issue 12. A study on the performance and safety of infusion devices
• FDA Steps Up Oversight of Infusion Pumps, New York Times, April 23, 2010
• U.S. Food & Drug Administration, (2017, December 13). What Is an Infusion Pump
• U.S. Food & Drug Administration, (2017, December 31). Adverse Event Report 
• Proceedings of the Human Factors and Ergonomics Society 2017 Annual Meeting 
• Nursing, March 2017, Volume 47, Issue 3. Are Smart Pumps Smart Enough?
• American Society of Health-System Pharmacists, August 1, 2015. The Intelligence Behind the Technology.
• Pediatric Clinics of North America, 2012 Dec;59(6):1257-67. doi: 10.1016/j.pcl.2012.08.005. The Role of Smart Infusion Pumps in Patient Safety.