Frequently Asked Questions

How do you safely and effectively use elastomeric pain pumps?

The On-Q PainBuster Pump (I-Flow) and PainPump2 (Stryker) are elastomeric pumps intended to provide post operative pain relief by delivering local anesthetic through a catheter placed directly at the surgical site. These devices are used in a variety of surgical settings and pharmacists are raising a variety of questions regarding their use.

Do these pumps provide effective pain relief?

There are a number of studies evaluating the efficacy of these pumps. Most studies compared infusion of the local anesthetic (usually ropivacaine or bupivacaine) to a saline infusion or to intravenous (IV) pain medications.1-5 A variety of drug concentrations and infusion rates have been evaluated with most studies finding both reduced pain and postoperative opioid consumption with use of these pumps. A 2006 systematic review of 44 trials found a number of benefits to delivering local anesthetic via the pumps including a decrease in pain visual analogue scores (VAS), reduced opioid consumption, as well as a decrease in post-operative nausea and vomiting.6 However, a few more recent studies have not found the pumps to improve pain control postoperatively. Coghlan and colleagues compared a subacromial ropivacaine infusion to placebo after rotator cuff surgery in 158 patients and found that the VAS pain scores between groups were not clinically different in the first 12 hours postoperatively (1.62 in the ropivacaine group versus 2.16 in the placebo group).7 Additionally, there was no difference in the amount of oral analgesia used postoperatively. In 73 patients who underwent hernia repair, Rosen and colleagues found no benefit to the use of bupivacaine wound infusion in terms of VAS pain scores or opioid use.8 Magnani and colleagues compared the On-Q PainBuster pump containing levobupivacaine to intravenous administration of ketorolac and morphine in 20 patients undergoing cesarean sections.9 They found significantly lower VAS pain scores with the use of the IV medications. Finally, in 50 patients undergoing anterior cruciate ligament reconstruction a continuous femoral nerve block was found to be more effective than ropivacaine via a continuous wound infusion with an elastomeric pain pump.10

There has been some interest in the addition of antibiotics or additional pain relievers to the anesthetic in the elastomeric pain pumps; however, efficacy data with these combinations are lacking. One abstract presented at the 2008 American Society of Anesthesiologists meeting compared the infusion of ketorolac alone or ketorolac plus ropivacaine at the surgical site in 60 patients and found ketorolac alone to be as effective as the combination for pain control.11

I-Flow, the manufacturer of the On-Q PainBuster Pump, has a clinical library on its Web site at that provides a number of links to abstracts of efficacy studies for the pump.12 Readers should be cautioned that the company appears to have limited its site to those articles showing the benefit of the pump and excluded those studies that failed to show a benefit.

Are there any safety concerns with these pumps?

Both the Food and Drug Administration (FDA) and the Institute for Safe Medication Practices (ISMP) have raised concerns about the safety of the way the pumps are being used in clinical practice.13,14 The FDA issued a warning in the fall of 2009 regarding chondrolysis associated with the use of prolonged local anesthetic in the intra-articular space.13 Thirty-five cases were reported between 2006 and 2008 with most associated with prolonged infusions (48 to 72 hours) of local anesthetic. Based on this data the FDA recommended that the devices not be used for continuous intra-articular infusion in patients after orthopedic surgery.

A 2009 ISMP safety alert highlighted several concerns with these devices that are pertinent to pharmacy.14 Often the devices are filled outside of the pharmacy, typically in the operating room which raises concerns about accurate filling, labeling, and documentation of the administered medication. Another concern is the variability in infusion rates. Elastomeric pumps typically operate within 15% of the set flow rate; however, it is important to avoid over- or under-filling the reservoirs.15 The pumps are disposable and refill of the pumps is not recommended. I-Flow recommends that the On-Q pump not be used for greater than 5 days.14

A number of strategies for safe use of the pumps have been identified by ISMP.14 The following table lists ISMP's recommendations for safe dispensing of the On-Q pump.

Table 1. ISMP recommendations for safe dispensing of the On-Q Pump. 14

Establish standard concentrations for drugs used in the pumps
Establish compounding procedures for any admixtures
Establish order sets to facilitate screening for appropriate dose, drug interactions, allergies, and duplicate therapy
Require pharmacy preparation of the reservoirs; the amount of solution should be specified based on the duration of therapy and rate of infusion (ISMP also suggests that outsourced compounding can be utilized)
Require pharmacy double-check of drug, strength, and volume

What stability or compatibility information is available with commonly prescribed drugs?

There is little published information available on the stability and compatibility of anesthetics and combinations of drugs in the elastomeric pain pumps; however, the I-Flow Corporation does provide information specific to the On-Q Pump. Table 2 lists stability information with local anesthetics; however, due to sterility concerns the manufacturer recommends that the pump be connected to the patient within 24 hours if filled in the operating room or surgical suite.16 If filled in the pharmacy, the pump may be stored up to 30 hours at room temperature or 7 days under refrigeration prior to use.

Table 2. Stability of preservative-free local anesthetics in the On-Q Pump. 16

Drug Concentration Room temperature storage time
Bupivacaine 0.25 to 0.5% 30 days
Lidocaine 1% 30 days
Ropivacaine 0.2% 30 days
Ropivacaine 0.2 to 0.75% 14 days

The stability of combination agents has also been studied by I-Flow and is summarized in Table 3.

Table 3. Stability of local anesthetic and combinations in the On-Q Pump. 17,18

Mixture* Infusion at room temperature
Bupivacaine/Dexamethasone (0.4 mg/mL) 5 days
Bupivacaine/Ketorolac (1 mg/mL) 7 days
Ropivacaine/Ketorolac (1 mg/mL) 7 days

* All mixtures were 0.5% local anesthetic and infusions were initiated after 7 days of refrigerated storage. Pumps were filled to 125 mL.

In addition, the stability of bupivacaine in combination with either ceftriaxone or cefazolin has been studied by I-Flow.19 A 1 gram vial of antibiotic was combined with bupivacaine 0.5% to a final volume of 270 mL yielding a 3.7 mg/mL antibiotic solution. The bupivacaine and ceftriaxone solution contained >95% of the control at 48 hours and the bupivacaine and cefazolin solution contained >95% of the control at 72 hours.


Elastomeric pain pumps designed to deliver local anesthetic directly to the surgical site provide postoperative pain control; however, the benefit over traditional pain control methods is not entirely clear. Pharmacists should take a proactive role in the dispensing and monitoring of these pumps to ensure safe practice within their institution.


1. Yoost TR, McIntyre M, Savage SJ. Continuous infusion of local anesthetic decreases narcotic use and length of hospitalization after laparoscopic renal surgery. J Endourol. 2009;23(4):623-626.

2. Forastiere E, Sofra M, Giannarelli D, Fabrizi L, Simone G. Effectiveness of continuous wound infusion of 0.5% ropivacaine by On-Q pain relief system for postoperative pain management after open nephrectomy. Br J Anaesth. 2008;101(6):841-847.

3. Gomez-Cardero P, Ridriguez-Merchan EC. Postoperative analgesia in TKA: ropivacaine continuous intraarticular infusion. Clin Orthop Relat Res. 2010;468(5):1242-1247.

4. Schell SR. Patient outcomes after axillary lymph node dissection for breast cancer: use of postoperative continuous local anesthesia infusion. J Surg Res. 2006;134(1):124-132.

5. Ansaloni L, Agnoletti V, Bettini D, et al. The analgesic efficacy of continuous elastomeric pump ropivacaine wound instillation after appendectomy. J Clin Anesth. 2007;19(4):256-263.

6. Liu SS, Richman JM, Thirlby RC, Wu CL. Efficacy of continuous wound catheters delivering local anesthetic for postoperative analgesia: a quantitative and qualitative systematic review of randomized controlled trials. J Am Coll Surg. 2006;203(6):914-932.

7. Coghlan JA, Forbes A, McKenzie D, Bell SN, Buchbinder R. Efficacy of subacromial ropivacaine infusion for rotator cuff surgery: a randomized trial. J Bone Joint Surg Am. 2009;91(7):1558-1567.

8. Rosen MJ, Duperier T, Marks J, et al. Prospective randomized double-blind placebo-controlled trial of postoperative elastomeric pain pump devices used after laparoscopic ventral hernia repair. Surg Endosc. 2009;23(12):2637-2643.

9. Magnani E, Corosu R, Mancino P, Borgia ML. Postoperative analgesia after cesarean section by continued administration of levobupivacaine with the On-Q Painbuster system over the fascia vs ketorolac + morphine i.v. Clin Exp Obstet Gynecol. 2006;33(4):223-225.

10. Dauri M, Fabbi E, Mariani P, et al. Continuous femoral nerve block provides superior analgesia compared with continuous intra-articular and wound infusion after anterior cruciate ligament reconstruction. Reg Anesth Pain Med. 2009;34(2):95-99.

11. Mcniel D, Muhammad R, Manchandani R, Pagala M, Tyagaraj K. The analgesic efficacy of ketorolac and ropivacaine infusion for postoperative pain management. Anesthesiology. 2008;109:A1709.

12. ON-Q Clinical Library. . Accessed July 8, 2010.

13. Food and Drug Administration. Chondrolysis reported with continuously infused local anesthetics (marketed as bupivacaine, chlorprocaine, lidocaine, mepivacaine, procaine, and ropivacaine).

/ucm190328.htm. Published November 13, 2009. Updated February 16, 2010. Accessed July 8, 2010.

14. Instiutute for Safe Medication Practices. Process for handling elastomeric pain relief balls (ON-Q Painbuster and others) requires safety improvements. Published July 16, 2009. Accessed July 8, 2010.

15. Skryabina EA, Dunn TS. Disposable infusion pumps. Am J Health-Syst Pharm. 2006;63(13):1260-1268.

16. Data on file. Technical bulletin: relationship between the ON-Q Pain Relief System and the USP-NF 27 <797> Pharmaceutical Compounding - Sterile Preparations. I-Flow Corporation; 2009.

17. Data on file. Technical bulletin: bupivacaine with dexamethasone - drug stability. I-Flow Corporation; 2009.

18. Data on file. Technical bulletin: bupivacaine/ropivacaine with ketorolac tromethamine stability. I-Flow Corporation; 2009.

19. Data on file. Technical bulletin: bupivacaine/antibiotic stability. I-Flow Corporation; 2009.