Background

Approximately 237 million medication errors occur in the NHS in England every year, 66 million of which are clinically significant.1 These have been estimated to cost the National Health Service £750 m per year.2 Children are twice as likely as adults to suffer harm as a result of medication error.3 The incidence of prescribing errors in paediatric intensive care unit (PICU) has been estimated at 11.1%–18% of prescriptions.4 5 However, to date, the increased vulnerability to harm has not been reflected in the representation of children’s healthcare in medication safety research, which remains limited. Across a range of healthcare settings, electronic prescribing, standardisation of medication processes and doses and education are the only interventions to have demonstrated an effect on the incidence of medication errors6; the reasons for this, though, are poorly understood.7 In paediatric medicine in particular, previous studies have offered little insight into the factors that contribute to prescribing errors and so might usefully be targeted by improvement interventions.7 Those factors that have been suggested to date were inferred mainly from epidemiological studies, which provide only a description of event types and frequency, with no appreciation of the complex behavioural, cognitive and conceptual factors that also contribute to errors. In other areas of healthcare, human factors approaches have been used to explain the occurrence of patient safety incidents more broadly by taking into account the psychological, physical and organisational context of healthcare work.8 9 Given the insights obtained from these studies, it would be valuable to consider the application of similar methods to paediatric medication safety.

This study aimed to explore the factors that contribute to prescribing errors in PICU, in order to provide a theoretical basis on which interventions can be planned and evaluated.

Method

The sampling frame and setting was healthcare professionals involved in medication prescribing in two PICUs in the north of England. The study was delivered in three phases: (1) the development of a hierarchical task analysis (HTA); (2) semi-structured interviews with prescribers; and (3) the merging of the interview data with the HTA in a Systematic Human Error reduction and Prediction Approach (SHERPA) to identify the failure modes and points and relating them to tasks within the HTA.

Results

The HTA identified that the prescribing process consisted of 30 subtasks (figure 1). All tasks needed to be executed correctly in order for a correct prescription to be written. From the SHERPA analysis (table 3), the behaviours required to write a correct prescription were predominantly related to information retrieval, entry and communication. This suggests a substantial cognitive burden on those carrying out the task.

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Figure 1

PICU, paediatric intensive care unit.

During the interviews, cognitive demand was indeed suggested to be the main contributory factor for most errors and was often attributed by participants to distractions and interruptions in the course of their work. There was a continuous need to manage and prioritise workload, and all prescribers reported frequent interruptions to their work flow. While each patient had a single nurse, prescribers were allocated responsibility for many patients in a shift. The demands from each patient and nurse were different, and the prescriber needed to manage those demands alongside their own tasks. One way of managing demand was to delegate prescribing to colleagues. However, this use of informal support structures appeared to not always be effective.

If they’re prioritising, you’ve also got the fact that [the prescriber’s] head may be on a number of things… but that means that their whole attention won’t be focussed on the task at hand. Participant R3

… We had a new patient… wasn’t my patient, so I was trying to be helpful trying to write the drug chart. And I ended up just having to put the chart down and say, I need to go and have a cup of coffee now. I can’t do this anymore. Participant A2

The problems associated with interruptions and distractions were exacerbated by conflicts between the perceived priorities of prescribers and those of other care providers in the team. From the HTA, it was identified that there were no physical actions, diagnostic or evaluative requirements in the process of writing a correct prescription. Therefore, prescribing may be cognitively taxing and complex but without an immediate impact on patient care. Prescriptions in PICU were predominantly handwritten, and there was a general perception that prescribing was a low priority task where other more hands-on activities were more important. Another reason for time pressure on prescribing was the practice of transcribing information from one prescription chart to another, either on admission/discharge or when the prescription chart was full. As the chart was required in order to administer medicines or discharge a patient out of PICU, this often led to prescribers having to work in a hurry.

I tend to leave that [prescribing] to later on. Usually when children come in it’s quite a high intensity situation with intubation, lines, inotropes et cetera. Participant A3

The transcribed prescriptions were a rush job on the discharge … the pressure is there to get the patient out [of ICU]. Participant R4

Prescription charts were frequently transcribed at night as their design meant the last possible dose was given before midnight. There was evidence that this task was deprioritised during the day because of the lack of urgency but that led to the task becoming urgent in the middle of the night when prescribers were tired. In fact, fatigue was often identified as a contributory factor of prescribing errors and made it even more challenging to manage workload, prioritise activities and balance other professional duties.

… Nurses will hand you a prescription at four o’clock in the morning and say ‘This whole chart needs redoing’ … and then they’ll show you the chart, with every box filled and no signatures because they’ve been waiting for it all day… it’s a heart-sink. Participant A4

The lack of good quality information on medicines for paediatric patients was also identified as part of the cognitive burden of this process. Prescribers were often involved in errors due to a lack of tacit knowledge about dosing and administration that was not available in official reference sources used on the unit. The interface between PICU and other wards and departments was also poorly defined. The procedures and documentation systems in other care areas all contributed to prescribing error as prescribers in PICU tried to access information or follow procedures that were unwritten or unclear. Medication was seldom part of formal handover processes and prescribers often had to piece together information on drug therapy from a range of sources that lead to errors associated with selecting the wrong drugs, doses or concentrations.

So, doses of drugs will be prescribed. This team have a certain way that they like to do it in their heads and they will run the drug on their own concentrations, but they don’t necessarily write it down anywhere. Participant A3

In addition, the resources available in PICU—the guidelines and policies—are all intended to support safe and effective prescribing but are largely rule based, in that they serve as instructions on how to write a correct prescription. They provide little support for the knowledge-based behaviour that would occur in non-routine situations that require the use of pharmacological or pharmacokinetic knowledge. Furthermore, the information in these guidelines is often inaccessible. When fatigued or under stress, prescribers therefore often relied on their own memory and the experience of the team around them rather than referring directly to documented practice or to consultants.

When you open the guideline they’re often very long and as you’re scrolling down them … you make sure you’ve got the right section. Participant R4

Interviewees referred to a flat hierarchy, where nursing staff were experienced practitioners and strong advocates for their patients. This could be intimidating to inexperienced prescribers who are likely to follow instruction rather than seek objective information about prescribing. It challenged anything that prescribers (particularly doctors) have experienced previously. The consultants were actively available to support junior prescribers; however, the latter were not always comfortable to ask for help because of a belief that they should be able to deal with the situation. This reluctance was short lived and once prescribers accepted their lack of experience and limited competency, and accepted the support of their consultants, the acceptance of help was described as ‘liberating’.

And sometimes the doctors aren’t aware that they don’t know that much when it comes to these drugs … and will go on the advice of the nurses. Participant A4

… As you become a bit more confident and a bit more senior, you … realise that it’s the consultants call. Participant A3

The results of the SHERPA discussion are presented in Table 4 including the identification of the controls of the error types and the potential mitigating factors for the future. This process identified variation in practice, distraction and interruption and fatigue as contributory factors in the occurrence of prescribing errors. It was identified that variation in practice may not be recognised as a problem within the leadership body of the units.

Everyone should be able to access information at the bedside about medicines and doses, surely?! Participant E2

Oh come on [name], that’s a great idea in theory but everyone knows that you [the consultants] all have your preferred doses. Like dexamethasone for extubation – you don’t want anyone extubated without it but [name] won’t use it at all. It takes time for the guys to figure that out. Participant E1

It was also very clearly identified that the nurse was the only recovery step for many prescribing errors; however, the conflict of responsibilities of those nurses was also identified.

The nurses are so good at speaking up for their patients and making sure that tasks get done, but sometimes they forget that I as a doctor on the unit have six or seven other patients to look after as well. It’s exhausting. Participant A1

Nurses want to help you when you’re stuck, but sometimes we don’t quite get it right, and if something isn’t as we expect then we’ll challenge it, even when we’re wrong. Participant E2

This discussion also confirmed that the design of the PICU medication charts also predisposed to prescribing error.

It’s so frustrating – the prescription chart gets full during the day shift, but it won’t get rewritten until the middle of the night because that’s when it can no longer be used. Participant E3

Well yes [name], but then we’re trying to manage all the other stuff through the shift, and rewriting a prescription chart that can still be used doesn’t get prioritised. Participant A1

Discussion

Our findings present a rich understanding of both the process of prescribing in paediatric intensive care and the contributing factors to prescribing error in this field using a human factors approach. The key products of this study are the insights gained through integration of the HTA with qualitative interviews. The only other prescribing process in PICU in the literature was presented by Andrews et al and was a summary based on observed and reported medication errors in a single PICU and the opinion of the authors.16 It described the prescribing process in terms of actions only, with no consideration of the cognitive or behavioural elements of the process, thus presenting a more limited representation of the process than provided in the current study.

By using qualitative methods, we have also demonstrated evidence of the gap that exists between ‘Work-as-imagined’ (work that is laid out in official policies and procedures) and ‘Work-as-done’ (what has to be done in order to get the job done safely.)17 Additionally, we have been able to deepen our understanding of the contributory factors of prescribing errors in PICU. A key feature of prescribing in this setting is its cognitive burden, due to working in a fast-paced technical environment that is alien to most prescribers, which has also been identified as contributing to error in adult critical care.18 This cognitive burden is related to several characteristics of prescribing work in PICU: constant distraction and interruption; poor communication of important medicines-related information; constantly changing workload; a learning curve for newcomers; and lack of access to sufficient information to support decision making.

We have also identified that there are few controls in place to prevent prescribing errors in PICU (table 4). Reason identified three types of organisational control mechanisms to ensure safe function of systems in high-risk environments—administrative (rules, policies and procedures), social (cultural expectations of ‘normal’ behaviour) and self (a personal understanding of what is safe and what is not).19 We have identified that administrative controls are poorly designed and inaccessible, and lacking information to support knowledge-based behaviours. Thus, only social controls are available to mitigate prescribing errors through the intervention of nursing staff at the bedside. However, we have also shown that nurses are potentially implicated in the aetiology of prescribing error through propagation of organisational priorities and perpetuating distraction and interruption.

These findings have several implications when considering future interventions. Fatigue is of great interest in the medical and nursing literature, with tiredness and distraction identified as a leading contributory factor in medication errors among nurses.20 21 In other safety critical industries (notably aviation), there is a formal approach to the management of fatigue, which is lacking in medicine.22 23 Thus, there is a need to develop systems for managing fatigue within the workforce, acknowledging that fatigue is physical and psychological.

With regards to the availability of information, it is well established that practice in healthcare is highly variable, often without any scientific basis for that variation.24 Therefore, consideration should be given to the impact of standardising medication prescribing resources. Computerised physician order entry (CPOE) with Computerised Decision Support Systems has been shown to be effective in reducing some medication errors.6 Standardisation of medication infusions has also been found to reduce prescribing errors in PICU.25 Evidence from other healthcare settings suggests that standardisation can reduce the reliance on team experience or leader interventions to ensure safe and effective practice, particularly in non-routine work situations.26 However, it is not a panacea; in practical terms, standardisation presents psychological and social challenges in its development and delivery that must be considered.27 From a philosophical perspective, it has been argued that to precisely and entirely describe a task is impossible, and therefore procedures are necessarily inadequate and incomplete.28 Hollnagel et al have identified that the adaptability of clinicians in situations of uncertainty is actually protective against error.17 Reason called this ‘requisite imagination’19 where operators within a system can make use of prior experience, observations and underlying knowledge to critically evaluate options and make reasoned decisions where procedures are lacking. Correspondingly, we have identified that in periods of high stress there was a reliance on previous experience, or the experience of colleagues in the vicinity. The latter suggests that team dynamic and experience is an important resilience factor in PICU and may be as important as written guidelines.29 Team structure and team working in PICU is worthy of further comment in relation to prescribing. Many medical settings in the UK are hierarchical, and therefore doctors typically come into PICU being senior in their field and accustomed to making decisions. In this new environment, the balance is shifted, with responsibility for most decisions held by the consultant working in partnership with the wider healthcare team. An interesting finding in the current study is that the flat hierarchy in PICU may actually be a contributory factor for prescribing errors. Flat hierarchy has been reported in other studies to reduce error.30 However, this has been in the context of team orientation and organisational cultures where roles and tasks are well defined. In PICU, there is a diverse and well-trained workforce, but the role of the prescriber is vague and ill-defined and prey to the organisational demands of other team members and those outside of the team. Communication about medicines is erratic, and there can be a reticence among prescribers to ask for help in the early stages of their PICU assimilation. Therefore, we posit that interventions to improve team performance, including clear outlines of roles and responsibilities on induction to PICU, and adapting skill mix to reposition prescribing as a high priority, high-risk task may be beneficial to reduce prescribing errors.18 31