An infusion pump is a medical device that delivers fluids, such as nutrients and medications, into a patient’s body in controlled amounts. Infusion pumps are in widespread use in clinical settings such as hospitals, nursing homes, and in the home.
In general, an infusion pump is operated by a trained user, who programs the rate and duration of fluid delivery through a built-in software interface. Infusion pumps offer significant advantages over manual administration of fluids, including the ability to deliver fluids in very small volumes, and the ability to deliver fluids at precisely programmed rates or automated intervals. They can deliver nutrients or medications, such as insulin or other hormones, antibiotics, chemotherapy drugs, and pain relievers.
There are many types of infusion pumps, including large volume, patient-controlled analgesia (PCA), elastomeric, syringe, enteral, and insulin pumps. Some are designed mainly for stationary use at a patient’s bedside. Others, called ambulatory infusion pumps, are designed to be portable or wearable.
Because infusion pumps are frequently used to administer critical fluids, including high-risk medications, pump failures can have significant implications for patient safety. Many infusion pumps are equipped with safety features, such as alarms or other operator alerts that are intended to activate in the event of a problem. For example, some pumps are designed to alert users when air or another blockage is detected in the tubing that delivers fluid to the patient. Some newer infusion pumps, often called smart pumps, are designed to alert the user when there is a risk of an adverse drug interaction, or when the user sets the pump’s parameters outside of specified safety limits.
Over the past several years, significant safety issues related to infusion pumps have come to the FDA’s attention. These issues can compromise the safe use of external infusion pumps and lead to over- or under-infusion, missed treatments, or delayed therapy.
From 2005 through 2009, the FDA received approximately 56,000 reports of adverse events associated with the use of infusion pumps, including numerous injuries and deaths. During this time period, manufacturers conducted 87 infusion pump recalls to address identified safety concerns. Seventy of these recalls were designated as Class II, a category that applies when the use of the recalled device may cause temporary or medically reversible adverse health consequences, or when the probability of serious adverse health consequences is remote. Fourteen recalls were Class I – situations in which there is a reasonable probability that use of the recalled device will cause serious adverse health consequences or death. These adverse event reports and device recalls have not been isolated to a specific manufacturer, type of infusion pump, or use environment; rather, they have occurred across the board.
Although some adverse events may be the result of user error, many of the reported events are related to deficiencies in device design and engineering, which can either create problems themselves or contribute to user error. The most common types of reported problems have been associated with software defects, user interface issues, and mechanical or electrical failures.
Reported problems involving infusion pumps include (1) software problems; (2) alarm errors; (3) inadequate user interface design; (4) broken components; (5) battery failures; and (6) fire, sparks, charring, or shocks.
Software problems include error messages of unknown origin and the software's misinterpretation of user input. For example, a software error message is displayed, stating that the pump is inoperable. This occurs in the absence of an identifiable problem. An example of misinterpretation of input is the infusion pump interprets a single keystroke as multiple keystrokes (a problem called a “key bounce”). For example, the user programs an infusion rate of 10 mL/hour, but the device registers an infusion rate of 100 mL/hour.
Alarm errors may be false positives or false negatives. False negatives occur when the infusion pump fails to generate an audible alarm for a critical problem, such as an occlusion (e.g., clamped tubing) or the presence of air in the infusion tubing. False positives occur when the infusion pump generates an occlusion alarm in the absence of an occlusion.
Inadequate user interface design may result in "human factors" issues. Examples of such issues are the design of the infusion pump screen confuses the user, or the infusion pump does not respond as it should (i.e., with a warning or alarm) when inappropriate data is entered. Another example is the infusion pump screen does not make clear which units of measurement the user is expected to enter. For example, the user may enter weight in pounds when the infusion pump requires it in kilograms. Additionally, pump labels or components become damaged under routine use. For example, cleaning the pump, as the user-maintainer believes is acceptable practice, may damage the pump, making it unreliable for clinical use. Users with long fingernails may damage the print on the pump keys, making them unreadable. User instructions or cues for mechanical set-up are not specific or clear enough. For example, an instruction to attach a tubing set in all required tube holder-clips before closing the pump’s access door may be unclear, resulting in clamped tubing and under-infusion. Inadequately designed alarm functions and settings cause users to miss problems or respond late. For example, an alarm indicating low battery charge may not be displayed in time for a user to prevent pump shut-off during a critical infusion while a patient is in transport. False (“nuisance”) alarms may decrease users’ sensitivity to all alarms. The infusion pump screen design is awkward or confusing to users, causing a delay in therapy. For example, the “Start Infusion” key may be located next to the “Power” key, and a user may turn off the infusion pump instead of initiating infusion. In some cases, programmed settings are lost when a user turns the pump off, and the infusion settings have to be re-entered after the pump restarts. Warnings are displayed so often that users come to ignore them (similar to “nuisance alarms”), are not detailed enough to prevent misuse, or represent values in ways that are unfamiliar to the user. Warning messages are unclear. It is unclear if the user is confirming the warning message or the infusion settings. User manuals are confusing, inadequate, outdated, or unavailable. This is particularly of concern for home-based users. When communicating the critical aspects of the pump’s operational, default, or “piggyback” status, the system does not use user-friendly language or does not give enough information to guide users through appropriate actions.
Infusion pumps have had multiple issues with broken components. The infusion pump may have been dropped or damaged during use, which may result in an over-infusion or an under-infusion if the pump continues to be used without being repaired. The plastic casing of an insulin pump, although promoted as waterproof, is prone to cracking, allowing water to enter the case and to cause the pump to malfunction. Slight misalignment of tubing places stress on the pump door, resulting in eventual cracking of the pump case.
Infusion pumps also suffer from battery failures from multiple causes. A design issue causes over-heating of the battery and leads to premature battery failure. A patient returns from ambulating and forgets to plug in the infusion pump. The infusion pump alarms with a low battery message, but the speaker volume is set too low, and the alarm goes unnoticed. The infusion pump powers off after the battery is depleted. The battery is not replaced during the recommended end of life routine maintenance.
Users have also reported incidents of fire, sparks, charring, or shocks related to infusion pumps due to a number of causes. The user plugs in or unplugs the device from an electrical outlet and receives a shock, and/or sparks are seen. A burning smell or flames are noted on the infusion pump.
In 2010 the FDA announced three steps it would take to improve infusion pump safety. These steps were to (1) increase user awareness, (2) proactively facilitate device improvements, and (3) publish new guidance for the industry. The FDA recently published final guidance for the industry and FDA staff. The final guidance requests that manufacturers include additional safety information in premarket submissions for infusion pumps. The guidance recommends that submissions include detailed engineering information concerning the product design and a more comprehensive discussion of steps the manufacturer has taken to mitigate risks in the design of the product and associated processes for its manufacture, servicing and maintenance, and use. This guidance recommends that manufacturers present this information as a safety assurance case that shows the connection between certain design elements, necessary safety mitigations, and the methods and reasons those mitigations are appropriate. The guidance also recommends additional design validation testing specific to the environment in which the device is intended to be used, alerts manufacturers that the FDA may conduct pre-clearance inspections in certain circumstances, and emphasizes postmarket reporting requirements.
See the FDA Report on Infusion Pumps
See also Medical Law Perspectives, June 2014 Report: Physician and Manufacturer Risks for Pain Pump Injuries: Malpractice, Negligence, and Products Liability
See also Medical Law Perspectives, May 2013 Report: Drugs, Dosage, and Damage: Physician Liability for Prescribing or Administering Medication