Process for Handling Elastomeric Pain Relief Balls (ON-Q Painbuster and Others) Requires Safety Improvements

Problem: In our May 21, 2009, newsletter we noted an association between the ON-Q PainBuster elastomeric pump and chondrolysis (destruction of cartilage), particularly if the local anesthetic intended to reduce pain after surgery is infused directly into a joint rather than the tissue around it. Since then, we have received numerous reports of potential problems with using ON-Q pumps. Most of these problems can be addressed by hospitals so the pumps can be used safely to provide surgical wound analgesia and/or peripheral nerve block. 

The ON-Q PainBuster Post-Op Pain Relief System (see Figure 1) provides continuous infusion of a local anesthetic directly into the patient’s surgical site for effective, non-narcotic postoperative pain relief for up to 5 days. Four pump models are available: one with a fixed flow rate that cannot be changed; one that delivers a basal infusion and also allows delivery of on-demand boluses; one that allows the user to adjust the flow rate within a predetermined range; and one with an adjustable rate controller and a bolus device. Various sizes and types of catheters are available to deliver the medication. According to the company, about 700 hospitals are using ON-Q pumps after cardiovascular, cardiothoracic, urologic, gynecological, obstetrical, orthopedic, and general surgical procedures.

While the ON-Q pump may provide effective pain relief, numerous hospitals and outpatient surgical centers have reported potentially harmful management issues associated with use of the device. Recently, a hospital reported a serious event that may have been linked to premature emptying of the reservoir ball that holds the medication. A patient had been sent home with an ON-Q pump filled with a local anesthetic. The surgeon asked the patient to come back in 5 days to refill the pump for another 5 days. Two days after the pump had been refilled, the patient was brought to the emergency department (ED) in cardiac arrest.

The ED staff noticed that the medication reservoir ball of the ON-Q pump was empty. Initially, they did not know what medication had been delivered to the patient or how fast it had been delivered because the device was unlabeled. (In its simplicity, the ON-Q pump does not record the infusion history, so there was no record of how fast the drug was delivered.) When the ED staff learned that the pump contained a local anesthetic, a drug level was drawn. However, this lab test had to be performed by an external lab, so the results were not readily available to help guide the treatment of the patient or determine the cause of his cardiac arrest. Later, a local anesthetic drug level was found to be elevated, but not alarming. Unfortunately, rescue efforts were unsuccessful and the patient died, although his death was probably not related to the incident. To date, hospital staff can only speculate regarding the cause of the premature emptying of the medication reservoir—perhaps patient tampering—and whether drug toxicity played any role in the patient’s death.

Other potential process problems with ON-Q pump use have been reported and are described below.

Used without staff education. We have received reports of patients appearing on postoperative units with an ON-Q pump where staff had never seen the pumps or been educated about their use.

Used without pharmacy involvement. In many reported instances, the pumps were piloted in the operating room (OR), and/or used regularly without pharmacy knowledge. Pharmacy’s first encounter with the device often occurred when nurses called the pharmacy because the reservoir ball was empty and they didn’t know what to do, or when pharmacy staff was informed that a “pain ball” trial would begin the next day. One hospital reported that the only way pharmacy knew about ON-Q pump use was through unit-based pharmacists who happened to learn about them from nurses. 

No pharmacy profiling of orders. Even when pharmacy has knowledge regarding use of the devices, orders for the medications are rarely profiled or screened. In many cases, the pumps are started in the OR, and the “order” is part of the intra-operative documentation. Thus, an order is not sent to the pharmacy for drugs being delivered by the pump. Some pharmacists told us they now utilize a standard order form for ON-Q pumps. One pharmacist told us she had to build special order templates for the pumps. Pharmacists also may have to remember to screen for drug interactions and allergies if such screening does not occur automatically. 

Medication preparation outside of pharmacy. Many ON-Q pumps are not filled in the pharmacy; they are filled in the OR where there is seldom a system of independent double-checks, and where labeling and hand-off communication may not be sufficient. We recently learned about an error in which the pumps for two patients were filled using a local anesthetic that contained EPINEPHrine, rather than the local anesthetic alone. (Vasoconstrictors such as EPINEPHrine are not recommended for continuous infusion via ON-Q pumps.) In one case, the nurse noticed the error and corrected it after the patient received just 1 mL of the wrong drug. In the other case, the patient developed severe tissue damage and required follow- up care. Pharmacy preparation of the medication has sometimes been met with resistance because surgeons claim they don’t know until the end of the case whether they want to use the pump. The product may also be marketed in a way that promotes physician autonomy and touts filling of the pumps by the surgeon or anesthesiologist in the OR as an advantage (a marketing strategy we discourage). One hospital pharmacist reported that she thought the pharmacy was preparing all medications for the ON-Q pumps only to learn that surgeons were also preparing pumps in the OR.

Use with medications other than local anesthetics. The ON-Q pump is designed to deliver local anesthetics to surgical sites for non-narcotic pain relief. The company’s product information suggests using ropivacaine, bupivacaine, or lidocaine. However, I-Flow, the company that markets ON-Q, also provides information regarding stability when various local anesthetics are mixed with dexamethasone, ketorolac, morphine sulfate and ketorolac, cefTRIAXone, or ceFAZolin—implying that mixing the local anesthetics with other drugs is safe and perhaps even effective. However, the company does not supply data to support this and does not make any specific recommendations regarding use of these products with ON-Q.

We have also received reports that surgeons have added vancomycin, and even fentaNYL, to the local anesthetic. With a simplistic pump that promises a delivery accuracy of ±15% of the labeled infusion rate (± 20% for models with adjustable flow rates), use with antibiotics and drugs such as ketorolac, morphine, and fentaNYL may not be advisable.

Varying infusion rates. The accuracy of the pump’s rate of delivering medication is dependent on filling the reservoir ball with an exact amount of medication. The proper fill volume is variable based on the type of pump and duration of therapy. Over- or under-filling the ball results in variable rates of infusion. The flow restrictor part of the pump must also be in contact with the patient’s skin and be kept away from any cold therapy (e.g., ice packs) or else the medication will infuse more slowly than expected. Taping over the filter may affect the flow rate. Flow rate is also unpredictable if the dial is not clicked into place at the proper numerical setting. Confusion has also been reported when determining the correct rate of infusion for pumps with dual catheters, with each port infusing half of the total volume of medication. If patients receive too much bupivacaine, ropivacaine, or lidocaine—the drugs most commonly used with ON-Q pumps—cardiotoxicity is possible.  

Varying concentrations. We heard from a pharmacist who viewed a hospital protocol for ON-Q pumps with more than 17 concentrations available for bupivacaine, ropivacaine, and lidocaine because the staff changed the concentration when they needed to change the dose (similar to the rule of 6). The use of nonstandard concentrations has contributed to preparation and dosing errors.

Unlabeled medication. The drug reservoir ball (or ON-Q pump tubing) has been found unlabeled, particularly when the ball has been filled in the OR. In cases where there is no “order” for the drug or pump, the medication being administered may be unknown by those providing care to the patient.

Drug administration documentation. If the pharmacy profiles orders for ON-Q pumps, the drug therapy may appear on the nurses’ computer-generated medication administration record (MAR). But several hospital staff told us that the ON-Q pump does not appear on their MARs, and they do not monitor or document the type and amount of drug administered via this delivery method.

Extended duration of use. As in the event initially described in this article, some physicians are refilling the ON-Q pump after 5 days of use. However, the manufacturer states that the pump should not be refilled and is only intended for a single use (up to 5 days), after which the pump should be removed and disposed. Longer use may present an infection control concern.

Concomitant analgesics. As with other forms of analgesia delivery, unclear maximum doses of the local anesthetics delivered by the ON-Q pump and possible concomitant use of analgesics by other routes of administration are of concern. For example, many long-standing order sets already include intermittent and/or continuous pain medications, which may still be enacted despite use of the ON-Q pump. Since pharmacy may not be aware of the pump’s use or be profiling related orders, unnecessary and potentially dangerous duplicate therapy may not be identified. For example, one of our consultants was recently at a hospital where he reviewed a patient’s chart with concurrent orders for an ON-Q pump, patient-controlled analgesia, and ketorolac every 8 hours.

Safe Practice Recommendations

See Table 1 below for a list of suggested strategies to improve safety when using ON-Q pumps. Please also note: While this article features problems associated with the management of ON-Q pumps, there are other elastomeric pumps manufactured by other companies that may have similar issues. Please take steps to reduce the risk of errors and adverse events with these pumps and, thus, maximize the potential benefits of this form of pain control. In fact, a failure mode and effects analysis (FMEA) should be considered in hospitals that are using these devices or are considering their use.