Key findings
This study demonstrates the effectiveness of a system of pre-preparation of equipment and drugs, together with optimal ergonomic organisation of equipment, for PHEA. Our results show a significant and clinically meaningful reduction in 1) the time it takes to perform the procedure, 2) errors during procedure / or significantly safer performance, and 3) the cognitive load of operators.
When aiming for short scene times (< 30 min) a reduction of 9:14 min is clinically meaningful. Two elements contributed to this: 1) the time to set up the equipment “kit dump” and 2) the time to prepare the required drugs, which accounted for most of the time saved.
Most of the errors and safety-related incidents occurred during the preparation and labelling of drugs on scene. In one incident, the intubator assistant cut a finger while opening an ampoule, highlighting the risk of sustaining a sharps injury when working under pressure. In another, a Rocuronium syringe was not labelled, and then confused for another agent, highlighting the risk of a drug administration error. These errors and safety-related incidents were, however, eliminated by using pre-drawn-up drugs in labelled syringes, resulting in significantly safer operation.
The variance in procedural time was less in the experimental arm, which may suggest an improved workflow. By improving workflow, overall performance was enhanced, and cognitive load was reduced. However, realising where cognitive resilience within a team lies is an important consideration, especially when performing complex, high-risk interventions such as PHEA. In our study, the intubator assistant reported a significantly reduced CL in the experimental method, even lower than that of the intubator. This enables the team to utilise this resilience to their advantage, for example by maintaining the team’s situational awareness “through” the intubator assistant to deliver safe, timely, effective, high quality care as a team.
Time reduction
The initial resuscitation and evaluation of critically injured or ill patients begins in the pre-hospital environment, and the care that they receive can have a major influence on subsequent outcome [
13,
14]. Providing individualised, tailored care based on injury patterns, means that some patients may require specialised care, such as PHEA to optimize their clinical condition prior to transfer [
15]. However, these interventions are known to increase time on scene, [
2,
16] while the Association of Anaesthetists of Great Britain and Ireland stipulate that “
every effort must be made to keep pre-hospital time to a minimum”[
2]. As a service, we aim to spend time on scene wisely, and minimise time from incident to definitive care. To spend a large proportion of this time preparing for PHEA, while caring for a critically ill or injured patient, is not effective use of time.
Using the concept of “aggregation of marginal gains” [
17] and breaking down the intervention (PHEA) into its core components, we identified the preparation phase of a procedure to be critical in determining both the safety of the procedure and the time it takes to perform PHEA. We were then able to demonstrate a significant time reduction in delivering the intervention. It was also clear that most of the preparation for this procedure could be done before the procedure became necessary, i.e. in controlled undisturbed conditions at base rather than on-scene with all the attendant competing demands on our attention and potential for distractions and interruptions. This time saved may be reflected in reducing scene times and time to definitive care. However, performing an intervention more quickly does not automatically mean that it is performed more safely.
Error reduction
Human error is an important problem in health care, contributing to a high instance of preventable medication errors [
18‐
21]. Preparing drugs is a time-consuming process, requiring precision. Carrying out this critical task, while at the same time treating a critically injured patient in an uncontrolled pre-hospital environment, is far from desirable and inherently prone to error. Using standard practice of PHEA preparation, our study shows that 40% of on-scene time was spent preparing drugs for PHEA, and most of the errors that occurred arose during the preparation of drugs on scene. These included (Table
5): drug labelling errors, omission of labels, poor sharps management and inadvertent “syringe swaps”, all of which can cause serious patient harm [
20‐
22]. For example, routine practice is to prepare Rocuronium (100 mg) in a 10 ml syringe, and Ketamine (200 mg) in a 20 ml syringe. In one observed error, Rocuronium (200 mg) was prepared in a 20 ml syringe, and subsequently incorrectly labelled as Ketamine. This could have resulted in a neuromuscular drug being administered without prior anaesthesia, exposing the patient to harm.
Such incidents are “
almost invariably judged to represent sub-standard care and litigation is almost invariably successful” [
22,
23]. An anaesthetic practice review of 896 drug error reports that a large number of errors involve drugs in similar sized syringes, along with drug preparation errors, which suggest that this is a frequently occurring incident. [
24] In a systematic review of drug administration error prevention during anaesthesia, Jensen et al. recommends
“drugs should be presented in prefilled syringes (where possible) rather than ampoules (either for emergency drugs or in general)” [
25]. This is also supported by the Anaesthesia Patient Safety Foundation as part of a
“new paradigm” to reduce the number of drug related errors, and improve patient safety [
26].
Currently, there is wide variation in the way that pre-hospital services prepare drugs for PHEA, including using pharmacy-prepared drugs in pre-filled syringes, teams preparing the drugs at the start of the shift, drawing them up en route to an incident, and drawing them up on scene.
Syringes can be pre-prepared by the service or pharmacy. Individual services would need to consider the associated costs, waste, and shelf life of each method [Additional file
4]. A barrier to pre-prepared drugs maybe the additional cost of pre-prepared drugs or concerns over the risk of drug wastage. The additional cost may, however, be offset by the accompanying reduction in the frequency of errors in preparing intravenous drugs and, more importantly, the iatrogenic harm and human cost of such errors [
22,
27]. Furthermore, the magnitude of the time reduction to administer the drugs for PHEA using pre-filled labelled syringes cannot be ignored.
Reduction of cognitive load
Cognitive load can affect human performance. The effect of human performance on the safe delivery of anaesthesia is widely recognised. Over 40% of adverse outcomes reported to the 4th National Audit Project (NAP4) [
4] were attributed to human factors. “
Cognitive resources, though limited, are under conscious control and can be directed from task to task as necessary” [
28]. In the complex and unpredictable pre-hospital environment, the clinician is faced with additional load, beyond that of delivery of the PHEA. The cognitive demands of managing oneself, the team and the environment can exacerbate an escalating workload, risking plan continuation bias and cognitive overload [
29]. This can compromise the delivery of safe, effective high quality care [
30], as demonstrated in the seminal case of Elaine Bromley, an example of the considerable harm that can result from cognitive overload [
31].
There are several ways of reducing cognitive load in critical situations, including the development of strategies such as briefings, flows (workflow patterns), and checklists and limiting the number of critical decisions that need to be made
. The cognitive burden can potentially be further reduced by standardising the equipment and processes required for the intervention, for example by streamlining packaging or numbering various components sequentially. Such improvements could enhance patient safety by contributing to greater reliability, resilience and situational awareness [
22,
4,
32].
There is a recognised relationship between workflow and cognitive load [
28] and this can be influenced by the storage and presentation of equipment [
33]. If the method of storing and presenting equipment for an intervention is designed to reflect more precisely the series and sequence of steps required for that intervention, the method itself becomes a useful “tool” for reducing the cognitive burden (see Fig.
2).
We hope the findings of this study will support a change in practice from on-scene PHEA drug and equipment preparation to pre-preparation.
We believe that the results of our study are generalisable to any pre-hospital situation where PHEA is being delivered, as factors such as time, safety and cognitive load are the same regardless of the model of pre-hospital care (physician/paramedic, nurse/paramedic, critical care paramedic/paramedic).
The strengths of this study include the realistic simulation of a pre-hospital scenario, allowing unbiased measurement of important aspects of PHEA, which would likely not be possible under real conditions.
Our study has several limitations. This experiment was done in a simulated setting, so the results may not replicate true clinical practice. However, the pre-hospital clinical simulation [Additional file
2] was piloted by clinicians not involved in the study, before the trial recruitment began, to ensure that the simulation was reproducible, straightforward, and that it recreated the clinical practice as closely as possible. It is likely that real pre-hospital cases would be even more complex than those simulated, and would result in even more errors.
The same pre-hospital clinical simulation was used in both methods of the trial which may have introduced exposure bias or training bias. A two-week washout period between the first and the second simulation was implemented to reduce this bias, and clinicians were blind to the outcomes being measured during the simulation. No difference in performance was seen either side of the washout period.
The VAS is used in a wide variety of populations and situations due to its adaptability and ease of use [
35]. However, VAS is subjective, and some evidence exists that suggests that it lacks sensitivity and that risks of error exist in some subject groups [
36]. We acknowledge that visual analogue scales have not been validated to measure cognitive load in this setting. Nevertheless, we feel that these simple tools are able to provide an unbiased meaningful message, that signal how cognitive resilience could be enhanced during this intervention.
A further limitation of this study is that only 23 of the 24 simulations were included into our analysis as one of the simulations (using standard practice) was incomplete and thus excluded. However, even if the quickest procedure time, across both groups, was input as the missing value, the procedural time using the experimental method remained significantly less.