Medication Errors Involving Patient-controlled Analgesia

Rodney W. Hicks; Vanja Sikirica; Winnie Nelson; Jeff R. Schein; Diane D. Cousins


Am J Health Syst Pharm. 2008;65(5):429-440. 

In This Article

Abstract and Introduction

Purpose: The magnitude, frequency, and nature of nonharmful and harmful medication errors associated with patient-controlled analgesia (PCA) were studied.
Methods: A retrospective analysis of Medmarx, a national voluntary medication error-reporting database, was conducted for the period from July 1, 2000, to June 30, 2005, to identify all PCA-related medication errors. Quantitative analysis of the records included the severity of each error, type of error, phase in the medication-use process, principal cause, contributing factors, actions taken, and drug and staff involved. A qualitative analysis was also performed.
Results: Over the five-year review period, 919,241 medication errors records from 801 facilities were submitted to Medmarx. Of these, 9,571 (1%) were associated with PCA. There were 624 records of PCA associated with harm, corresponding to 6.5% of the patients. Errors were reported across all phases of the medication-use process, but the majority occurred during drug administration. Over one third (38%) involved an improper dosage or quantity, while 17.4% involved an omission and 17.3% an unauthorized or wrong drug. Overwhelmingly, human factors were the main cause of PCA errors. Equipment issues (19.5%) and similar drug names and product packaging (11.6%) were also implicated. Distractions (37.8%) and inexperienced staff (26.3%) were the leading contributing factors. Harmful errors required more institutional resources than nonharmful medication errors to manage. Prescribers often issued incomplete, duplicative, or contradictory orders or failed to adjust dosages for comorbid conditions. Dispensing errors were often associated with misfills from the automated dispensing cabinet, compounding of a wrong strength, or lack of drug product availability. Administration errors involved the wrong drug, amount, or concentration, often because the PCA device was misprogrammed.
Conclusion: Events during all phases of the medication-use process contributed to PCA-related medication errors, many of which harmed patients.

Patient-controlled analgesia (PCA) is a method of pain relief in which a complex electronic infusion device (i.e., a pump) connected to a timing mechanism allows the patient to self-administer analgesic drugs, usually intravenously.[1,2,3,4] The PCA prescription order, initiated by a licensed prescriber and filled after a pharmacist's review, dictates the variables to be programmed into the PCA device and includes the analgesic drug, the bolus dosage (if any), the lockout interval, dosage limits, and the basal (background) infusion rate.[2] While PCA enables the patient to self-administer a dose of an analgesic when needed, each step in the PCA process may have some effect on safety.

Numerous reports describing PCA risks and benefits have been presented over more than three decades. Findings have suggested improved pain management, better utilization of nursing resources, increased patient satisfaction, and improved pulmonary function; results for length of stay in the hospital have been mixed.[3,5,6,7] However, unfavorable outcomes and other adverse effects have also been associated with PCA. A meta-analysis of more than 30 randomized control trials evaluating the safety and efficacy of PCA with opioids published between 1982 and 1999 identified bradypnea, hypoxia, nausea, vomiting, sedation, pruritus, and urinary retention as adverse effects.[7] Death has been associated with PCA.[3] Some adverse effects result from the opioids themselves, while others are attributable to poor patient selection or to human error during ordering, dispensing, or administering. Faulty PCA equipment design has been implicated in some cases.[2,4,7,8,9,10]

A full understanding of the impact of PCA on patient safety has yet to be achieved. However, since 1998 institutions such as the Institute of Medicine (IOM) have successfully highlighted the magnitude of and issues surrounding all medication errors and have accelerated efforts to prevent them.[11] IOM has called for improved error-reporting systems, further research into factors that threaten patient safety, and improved safety of the medication-use process.

Successful error-reporting systems are nonpunitive, confidential, independent, timely, responsive, and system oriented and are based on expert analysis.[12] One example of a successful reporting system is Medmarx, established in 1998 by the United States Pharmacopeia (USP). Medmarx is an Internet-accessible, voluntary medication error-reporting program available to institutions by subscription. Since the inception of this program, more than 880 hospitals and health systems have contributed more than 1.3 million medication error records. Within Medmarx, a record is defined as an actual or a potential error event. Enrolled facilities collect medication error data at the local institutional level and designate a Medmarx-trained staff coordinator to review and enter data into the program's structured and free-text fields. Such a system allows for a macro- level examination of medication errors and for the sharing of information about such errors in hope of preventing them in the future.

The purpose of this study was to analyze the Medmarx database to characterize the magnitude, frequency, and nature of nonharmful and harmful PCA errors.


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