TechSectors: Enhanced Photoemission Spectroscopy Prevents Potential Errors

MDNG Hospital Medicine, May 2008, Volume 2, Issue 2

Until there is a "closed system" developed to prevent occupational exposure, EPS technology cannot be applied to validating chemotherapy preparationâ€"an area that is promising and is currently under development.

Although technologies have been used to improve the prescribing and administration components of the medication use process, the dispensing segment of the process has not received as much attention. Th e parenteral compounding process in hospital pharmacies has remained relatively unchanged in the last 40 years and is still largely reliant on human visual checks. Yet, human error is inevitable in any setting. Medications prepared in the IV admixture process are among the most high-risk, with the greatest potential for harm if an error were to occur.

Typically, a technician prepares the parenteral admixture and a pharmacist conducts a visual check of the work, verifying the products and volumes, a practice assumed to work well. However, the high-risk nature of parenteral products (eg, insulin, heparin, inotropes, narcotics, aminoglycosides) requires that we strive for a 0% error rate. In a 1997 study looking at the preparation of patient-specifi c parenteral products—including small- and large-volume parenterals, ready-to-use solutions, total parenteral nutrition, and antineoplastics—at five US hospitals, the investigators found a 9% mean error rate for parenteral compounding, excluding ready-made products. More importantly, the overall rate of potentially clinically significant errors was 2% among compounded products, including incorrect drug concentration and incorrect drug. With the above in mind, we sought to identify an assistive technology that would improve the safety of medication compounding for high-risk products, settling on enhanced photoemission spectroscopy (EPS) as a means of providing an automated check. From the published lists of “high alert” medications prepared in the pharmacy, as well as institutional error reports, 10 medications were initially selected for use with a table-top spectrometer. For each medication, standard concentrations and diluents were established such that there were approximately 30 distinct drug—concentration–diluent products.

When using this technology, after preparation of the product within the laminar fl ow hood in the pharmacy, a small sample of the parenteral admixture is placed in a cuvette. This sample is then placed into the EPS device (ValiMed). Within the EPS device, a light source energizes the sample of the medication with the appropriate wavelengths of light for a pre-determined amount of time. The fl uorescent energy emitted by the medication is measured by the spectrometer, with the digital output used to develop a database that uniquely identifi es a “fi ngerprint” or “signature” for each medication. Established signatures in the library are compared to a sample of the compounded product to validate accuracy.

There are two primary evaluations completed by the EPS device to validate a given sample. First, the sample’s signature is compared to that of the known signature within the library, identifying if the sample is the intended medication defi ned by the properties and acceptable variance for a known signature. Once the medication is identifi ed, the strength of the fl uorescent energy is compared to set parameters in the device to identify the concentration within the predefi ned ranges. The entire process to validate a sample takes approximately 30 seconds. This technology provides an extra layer of safety beyond the visual human checks. In the fi rst 18 months of use in a children’s hospital, five potentially serious medication errors were detected and prevented through use of the device. Our experience with integrating the EPS has demonstrated that the added technology is a simple, efficient, and inexpensive method of enhancing medication safety of selected compounded parenteral products.

Although this technology improves medication safety, it cannot be applied toward medications that are unable to fl uoresce at ultraviolet wavelengths, such as potassium chloride. Until there is a “closed system” developed to prevent occupational exposure, EPS technology cannot be applied to validating chemotherapy preparation—an area that is promising and is currently under development. Given the time to run each sample, the process could be time-consuming if applied to all parenteral products. Th us, we have selected to use this device only in the process of dispensing specifi c high risk products. Th e current practice of visual inspection of compounded intravenous admixtures is susceptible to error due to factors including the clear nature of parenteral products, confi rmation bias, and the similar appearance of vials. Th e addition of EPS technology has prevented several clinically signifi cant errors that would have otherwise been dispensed to patients. Th e technology has been well accepted by pharmacy staff and has been viewed positively by medical and nursing staff s, as well as patients and families, as an important patient safety initiative.

Jim Stevenson is an Associate Dean and Professor, College of Pharmacy and Director of Pharmacy Services at the University of Michigan Health Systems, University of Michigan, Ann Arbor.