Workload, time of day and shift work effects
It is important to examine the context in which drug errors occur. Previous research has shown a correlation between increased prescribing error rates and the number of admissions (Lesar et al, 1990), so the busier the ward, the higher the error frequency. In the same study, the highest error rate occurred between 12:00 and 15:59, and the lowest error rate occurred between 20:00 and 23:59. Lesar et al (1990) attributed this finding to the fact that more prescriptions were written during the afternoon shift.
In terms of shift work effects, it has also been shown that drug error rates were higher on day shifts than on night and evening shifts in a PICU and NICU setting (Raju et al, 1989). This result was attributed to fewer prescriptions being written and dispensed on the evening and night shifts, compared with a higher frequency of prescriptions on the day shift. Taken together, these studies show that situational factors such as the number of patients and prescriptions may lead to errors.
Latent conditions that lead to drug errors
In addition to problems identified by Leape et al (1995), other types of systems failure have been noted. These include distracters which interrupt prescribing, dispensing and administration tasks (Gladstone, 1995), and the absence of redundant checking processes to ensure that errors are quickly recovered (Cohen et al, 1998). Poorly designed equipment can also increase risk. A common problem is the absence of fail-safe mechanisms when re-setting the rate of infusion pumps, which has led to over-infusion of drugs (Brown et al, 1997; Lin et al, 1998; Wilson et al, 1998). Problems may also result from varying operational requirements between different infusion pumps.
In one case, confusion between two Graseby syringe drivers, the MS26 and MS16A, led to a fatal over-infusion of morphine in a patient being treated for stomach cancer (Carlisle et al, 1996). The underlying design problem was that one pump is calibrated in mm/h the other is calibrated in mm/d. During a syringe changeover, the nurse applied the calibration principles for the MS16A to a MS26 pump. Such errors of transference (Reason, 1990), in which the principles for operating one type of device are incorrectly applied to another, have led institutions to use a single standard pump throughout the hospital. They have also led to calls for safer design of infusion pumps (Cousins & Upton, 1995).
Seeking solutions without considering their adverse effects
When making recommendations to reduce error rates, one must consider the adverse effects of an intervention on other parts of the system. This is especially important when technological solutions such as computerized prescribing are being considered (Bates et al, 1998, 1999). Potential adverse effects include incompatibility with other aspects of the users' (i.e. pharmacists, doctors and nurses) tasks and increased non-compliance, whereby the user circumvents the system because it is unworkable in practice. Increased computerization may also increase the frequency of data inputting errors (Ferner, 1995) and make dose calculations more difficult by concealing the intermediate stages of the calculation so that errors are more difficult to recover (Dillner, 1993).
Critical Incident and Near Miss Reporting Systems
‘A near miss is any situation which has clearly significant and potentially serious (safety related) consequences’ (Van der Schaaf et al, 1991). Central to the concept of near misses is the notion that some form of recovery took place, i.e. an accident sequence was initiated and then either by chance or by the actions of the individual, team or organization it was recovered from prior to having negative consequences (Van der Schaaf et al, 1991; Barach & Small, 2000).
The effectiveness of critical incident and near miss reporting systems depends on several factors, including organizational culture, the reporting structure and the quality assurance measure in place to check the accuracy of the data.
Under-reporting of incidents is a serious problem. Evidence suggests that the existence of a blame culture in medicine leads to under-reporting (Gladstone, 1995; Vincent et al, 1999; DoH, 2000). Another cause of underreporting may be the design of the incident reporting system. It is important that reports are submitted to a neutral organization which anonymizes and then publishes them on an annual basis (Myhre & McRuer, 2000).
Errors, critical incidents and near misses in transfusion medicine
As with drug delivery, transfusion medicine comprises multiple communication interfaces between wards, the blood bank, operating theatre, and the involvement of various health care professionals ranging from nurses, consultant and specialist registrars in hematology /oncology, pharmacists, surgeons, etc.
Errors in transfusion medicine can be distinguished between those that occur in the blood bank and those that originate in other parts of the hospital. Blood bank errors include testing the wrong sample, issuing an incorrect unit of blood, incorrect transcription errors in filling out labels, and attaching labels to the wrong unit of blood (Linden et al, 2000; Marconi & Sirchia, 2000). Errors in other hospital locations include sending an incorrect request to the blood bank, phlebotomy errors and failure to check that the appropriate blood is being given to the correct patient (Taswell et al, 1994).
Incident reporting systems in transfusion medicine
Transfusion medicine, like anesthetics, has been quick to realize the value of learning lessons from critical incident and near miss reporting systems. One example of a near miss in transfusion medicine is when the blood bank issues incorrect blood but the error is captured by the clinician and nurse at the patient's bedside (Linden et al, 1992; Linden, 1999; Linden & Schmidt, 1999).
In the UK, Williamson et al (1999) have reported the findings for the first 2 years of a confidential transfusion incident reporting system, the SHOT (Serious Hazards in Transfusion) initiative. Between October 1996 and September 1998, 366 events were reported in 276 hospitals (164 hospitals returned a nil-to-report card showing that they had no transfusion incidents to report). Of these, 191 (52%) errors involved the wrong blood being given to a patient, 55 (15%) acute transfusion reaction, 51 (14%) delayed transfusion reaction, 22 (6%) post-transfusion purpura, 27 (8%) acute lung injury, 12 (3%) infections transmitted via transfusion and 8 (2%) graft-versus-host disease.
Linden et al (2000) reported the results of a 10-yers experience of incident reporting in New York state. Results showed that there was erroneous administration for 1 of 19 000 red blood cell units administered. Errors originating in the blood bank were responsible for 29% of events and included testing of the wrong specimen and issuing an incorrect unit of blood. Fifty-one per cent of events occurred outside the blood transfusion unit. These errors included administering blood to the wrong patient and phlebotomy errors.
Both the New York and the SHOT data show that adverse transfusion events can result from multiple errors at different points in the system. For example, in the SHOT analysis 74/177 cases analyzed resulted from between two and seven errors. Similarly, the New York data shows that two or more errors occurred in 15% of reported events. The vast majority of these errors involved the blood bank issuing an incorrect component that could have potentially been picked up during a final check at the patient’s bedside, but which was not.
Medication errors can only be prevented and reduced by focusing on the system as a whole, not on the individual clinician or nurse. A national critical incident and near miss reporting database which ensures the whole hematology community learns lessons about latent conditions and active errors is essential. This will only be successful in improving patient safety if the appropriate reporting culture and feedback mechanisms are in place.
-- Allard, J., Carthey, J., Cope, J., Pitt, M., & Woodward, S. (2002). MEDICATION ERRORS: CAUSES, PREVENTION AND REDUCTION. British Journal Of Haematology116(2), 255-265. doi:10.1046/j.1365-2141.2002.t01-1-03272.x
Reflection Exercise #4
The preceding section contained information
about causes and prevention of medication errors. Write one case study example
regarding how you might use the content of this section in your practice.
What are errors of transference? Record the letter of the correct answer the