Primary

1. Develop a hierarchical task analysis (HTA) for Laparoscopic appendectomy.
2. Apply a standardised error measurement system to the HTA.
3. Correlate the errors with the immediate and long-term clinical outcomes.

Secondary

1. To document for each task of the procedure, those elements that are essential, those that are optional, and those that ought to be avoided.
2. From this list, a ‘how to’ document would be compiled and distributed to trainees and junior surgeons.
3. To conduct personalised feedback to the participating surgeons and trainees, outlining areas of good, suboptimal and even dangerous performance.
4. Ultimately aiming to repeat this study in same cohort following feedback and period of training (with mentor and with laparoscopic trainer box).

Categorisation of errors

We have developed a human error categorisation in order to describe and categorise the errors that might be observed in surgical operations, based on the external error modes found in SHERPA [2, 3, 4]. These external error modes are a categorisation of the various ways in which a physical procedural task may be erroneously performed. Underlying these observable errors is a variety of performance shaping factors (PSF’s) which must be sought separately from the operator. Note that in this context, “PSF” is being employed in a very narrow sense, to include only those factors that are observable in the video recordings. Whilst it is recognised that external PSF’s (such as operating theatre environment and experience of other theatre personnel) also plays a part in determining outcome, the assessment of such factors is not intended in the current study. The ergonomics of port position, instruments used, and special devices used like hemlocks, endo loops, staplers will all be observed and studied. Therefore, the post-operative questionnaire will be limited to those factors and events that occur during the course of the procedure, and (may) have a direct impact upon surgical performance. The development of this structured questionnaire will be an integral part of the study, the content dependent upon a pilot study of the first 10 cases. The questionnaire/proforma will be created for the operating surgeon/trainee to fill at the time of the operation (Appendix 1). The external error modes list forms a template to describe and categorise the observable errors in each step of the operation which will be the subject of this study. In order to reflect any motor control errors identified, a modified list of external error modes has been created to be used in the study (Table 1).

Error identification

The definition of error agreed at the Bellagio Conference on Human Error will be used for the present study, i.e., ‘something that has been done which was: (i) not intended by the actor, (ii) not desired by a set of rules or an external observer, or (ii) that led the task or system outside acceptable limits. The external expression of an error is its consequence which may be neutral, (inconsequential) or negative (consequential) [3, 4, 5, 6, 7]. This definition is similar to but more comprehensive to that proposed earlier by Swain.

Previously we considered any action (or omission) that resulted in a negative consequence, or increased the time of the procedure by necessitating a corrective action, fell outside the ‘acceptable limits’ and was therefore registered as a consequential error. We defined inconsequential error as action or omission that increased the likelihood of negative consequence and under slightly different circumstances could have had a consequential effect.

The details of error classification system were described in the pilot study. In brief, ten generic forms of error can be predicted with respect to the execution of a surgical task. These ten generic types (or external error modes), represent observed patterns of failure (Table 1) and fall in two categories in relation to the underlying causative mechanism. External error modes 1–6 correspond to the ability of the surgeon to execute the component steps in the correct order and hence these are collectively grouped as procedural error modes. In contrast external error modes 7–10 reflect manipulations with laparoscopic instruments by the surgeon to execute a specific component step of the operation and are categorized as execution error modes. This distinction is of practical importance because it determines the nature of prescriptive error-reduction system specific to the operation. Execution errors can be reduced by better training of operative skills and by improving instrument design; whereas procedural errors can be minimized by improving the knowledge (perhaps aided by drop-down menus) that ensure the correct choreography of execution, i.e., the surgeon performs the component tasks and steps of the operation in the correct order.

Task analysis

Two individual consultant surgeons will carry out direct observational methodology of unedited videotapes. Prior to the study, they will receive training in human factors’ research by an accredited human factors specialist with an interest in surgical ergonomics and human factors and who is not involved in the operations [13, 15].

The inter-rater consistency of the SERS system will be assessed by the consultant surgeon and human factors specialist in the initial pilot study.

It is acknowledged that not every event out with the task Analysis (blueprint) will necessarily lead to an adverse outcome, the labelling of such events as ‘errors’ allows this very aspect to be assessed. i.e. any event that falls out with the blueprint may be independently evaluated for subsequent negative impact on the procedure. All cases that result in postoperative complications or conversion will be reviewed by the expert panel.

The expert panel that includes consultant laparoscopic surgeons will provide consultation throughout the study and check the accuracy of the videotape analysis process.

A hierarchical task analysis will be undertaken on LA (n = 10). Footage will be collected and the best techniques and acceptable variations in technique are standardised. The data will be collected by video recording of the internal endoscopic view and assessing the proforma questionnaire filled in by the surgeon.

The task analysis will divide each component of the procedure into tasks and subtasks. The main components of laparoscopic appendectomy are outlined in Table 2. These will then be correlated with immediate procedural outcomes documented by the recordings of the internal view and the external manipulation. This will provide a framework to allow allocation of errors to different steps of the procedure, and identification of tasks and subtasks with different levels of effectiveness. The data obtained by the task analysis can be used to formulate a menu of the exact details of how the operation is done according to the preoperative and intra-operative assessment of the cases.

Data collection and analysis of procedures

As for phase 1, video footage will be obtained from endoscopic views of the procedure. Each step of the LA as identified in phase 1 will be analysed and the observed errors categorised according to the list of external error modes (Table 1) combined with detailed factors that influenced task performance (Table 3) and recorded against the step in which they occurred.

The sample size (n = 100) for the study is determined by three considerations. First, it should adequately describe the type and frequency of errors enacted in the course of a LA. Secondly, it should demonstrate the influence of enacted errors on intra-procedural outcome and, if any, complications. Thirdly, it should be a large enough sample for the results to be seen as representative and reliable.

As it is impossible to pre-judge the results, precise sample size calculations cannot be performed.

Dissection techniques, errors and outcome data will be compared and analysed using t-test, p < 0.05 will be considered significant. Quantitative error data will be expressed as mean +/– SD (standard deviation).