Surgery is continuously subject to technological and medical innovations that are transforming daily surgical routines. In order to gain a better understanding and description of surgeries the field of Surgical Process Modelling (SPM) has recently emerged. The challenge is to support surgery through the quantitative analysis and understanding of Operating Room (OR) activities. Related surgical process models can then be introduced into a new generation of Computer-Assisted Surgery (CAS) systems and have a large impact in future surgical innovations, whether for planning, intra-operative or post-operative purposes. For instance they can improve surgical education and planning, situation awareness and management of complex multimodal information in the OR, surgical workflows, or increase surgical efficiency and quality of care. In this paper, we present a review of the literature dealing with SPM. This methodological review was obtained from a search using Google Scholar on the specific keywords: “surgical process analysis”, “surgical process model”, and “surgical workflow analysis”. This paper gives an overview of current approaches in the field that study the procedural aspects of surgery. We propose a classification of the domain that helps to summarise and describe the most important components of each paper we have reviewed, i.e. acquisition, modelling, analysis, application, and validation/evaluation. These 5 aspects are presented independently along with an exhaustive list of their possible instantiations taken from the studied publications. This review allows a greater understanding of the SPM field to be gained and introduces future related prospects.
1. Introduction 1.1 Context In recent years, due to progress in Information Technology fields, computer assistance have been developed in healthcare systems, from hospital management through to medical imaging solutions. The Operating Room (OR), in particular, has undergone significant transformations evolving into a highly complex and technologically rich environment. Computer technologies are now essential and increasingly used throughout the intervention, from pre-operative planning to post-operative assessment. Computer-Assisted Surgery (CAS) (or Computer-assisted Intervention-CAI) systems have now a vital role to play in current surgical performance. For instance, during surgical planning, CAS and Image Guided Surgical systems provide access to multi-modal imaging technologies, relevant information about the patient and the possibility of simulating some parts of the surgical procedure. During surgery, they provide visualisation to pre- and intra-operative information about the patient with respect to the operative field, and also provide passive or active robotic support. New issues and technological challenges related to this complex OR and CAS systems have been discussed by Cleary et al. (2005), Rattner and Park (2003) or Xiao et al. (2008).
This first generation of CAS systems mainly focused on providing the surgeon with access to medical information of the patient before and during surgery, and active or semi-active robotic assistance. It was however outlined that such assistance would be different according to the surgical task, due to different needs and levels of importance. There was also an increasing need for new tools providing better resources management in the OR. For instance, surgeons need to be freed from technical problems through the automatic handling of software and hardware tools. These requirements illustrate the main motivation for surgical procedures models. The need for dedicated model-based systems for surgical procedures was first outlined for creating surgical simulation systems (Satava and Carrico, 1996; Taylor et al., 1999). The idea of describing the surgical procedure as a sequence of tasks was first introduced for analysis purposes in Minimally Invasive Surgeries (MIS) by MacKenzie et al. (2001), as well as for surgical planning and intra operative image management (Jannin et al., 2001) and for robotics systems (Munchenberg et al., 2000).
Following progress in model-based surgical intervention systems, understanding of the surgical scenario was proposed to improve the management of CAS systems. Jannin et al. (2003) defined the term surgical model as “generic or patient-specific surgical procedures that workflows aim to automate”. In their work, they stated that model-based systems of surgical interventions must address behavioural, anatomical and pathological aspects as well as integrate information about surgical instruments that can be used with a priori knowledge for the development of the OR of the future. The term surgical workflow has been defined as “the automation of a business process in the surgical management of patients, in whole or part, during which documents, information, images or tasks are passed from one participant to another for action, according to a set of procedural rules” (Jannin and Morandi, 2007). The term Surgical Process (SP) has been defined as “a set of one or more linked procedures or activities that collectively realise a surgical objective within the context of an organisational structure” (Neumuth et al., 2007). This term is generally used to describe the steps involved in a surgical procedure. A Surgical Process Model (SPM) has been defined as “a simplified pattern of an SP that reflects a predefined subset of interest of the SP in a formal or semi-formal representation” (Neumuth et al., 2007). It relates to the performance of an SP with support from a workflow management system. SPMs were first introduced for supporting surgical intervention using a model of surgical progress. Indeed, the precondition for computer-supported surgical intervention is the specification of the course model describing the operation to be performed. Typically, even if every surgery is different, a procedure of a same type shares common sequences of states that can be identified. Such an assumption also makes it possible to detect abnormal activities within the procedure. Being able to identify information such as activities, steps or adverse events within a surgical intervention and having the possibility of relying on a surgical model is therefore a powerful tool in helping surgeons. The use of SPMs may prove effective in facilitating the surgical decision-making process as well as surgical teaching and assessment thereby having a direct impact on patient safety. It could help in anticipating patient positioning, optimising operating time, analysing technical requirements and improving the pre-operative human-computer interface. It could also help in evaluating surgeons or tools. In light of the growing interest in this field, and for the first time, we propose in this paper to undertake a methodological review of the literature focusing on the creation and the analysis of SPMs.
1.2 Search methodology
The review was carried out using Google Scholar to search on the specific keywords: “surgical process model”, “surgical process analysis”, and “surgical workflow analysis”. In addition to the Google Scholar results, we added another list of possible citations that were taken from the references of the first set of selected publications. We included articles published in peer-reviewed journals as well as full papers published in major international conference proceedings that dealt with the use of SPMs. International conference proceedings were included since the field is very recent, resulting in more conference publications than peer-reviewed journals. Only English language publications were selected. The research included was published between 2002 and end of 2012. In order to achieve an overview of the publications related to the creation and analysis of SPMs, we focused on publications which aimed to study the procedural dimension of surgery. The first inclusion criteria used during the selection process was therefore the fact that works have to take into account the sequential aspect of the surgical procedure, i.e. study the duration and sequencing of tasks performed during the surgery. Moreover, we were interested in pieces of work that focused at least one part of their analysis on the act of surgery, beginning when the surgeon performs the first task on the patient and ending when the surgeon makes the suture. It was defined as the second inclusion criteria. When a project has been published several times with no change in the dedicated elements of the diagram, the journal publication and if none, the most recent conference paper has been used. The entire selection process is shown on Fig 1. From an initial selection of N=272 publications, a total of N=46 publications were finally selected for full-text review.
Fig 1 - Process used in the selection of publications for full-text review.
Fig 2 shows the results of the Google scholar results before the selection process only. We can see that the SPM creation and analysis field is very recent. It has evolved in particular from 2007, evidence of the recent evolution of the field.
Fig 2 - Evolution of the number of papers in the field from 2002 to December 2012.