Intraoperative process monitoring using generalized surgical process models

Der Chirurg in einem modernen Operationssaal kann auf die Funktionen einer Vielzahl technischer, seine Arbeit unterstützender, Geräte zugreifen. Diese Geräte und damit auch die Funktionen, die diese zur Verfügung stellen, sind nur unzureichend miteinander vernetzt. Die unzureichende Interoperabilität der Geräte bezieht sich dabei nicht nur auf den Austausch von Daten untereinander, sondern auch auf das Fehlen eines zentralen Wissens über den gesamten Ablauf des chirurgischen Prozesses. Es werden daher Systeme benötigt, die Prozessmodelle verarbeiten und damit globales Wissen über den Prozess zur Verfügung stellen können. Im Gegensatz zu den meisten Prozessen, die in der Wirtschaft durch Workflow Management-Systeme (WfMS) unterstützt werden, ist der chirurgische Prozess durch eine hohe Variabilität gekennzeichnet. Mittlerweile gibt es viele Ansätze feingranulare, hochformalisierte Modelle des chirurgischen Prozesses zu erstellen. In dieser Arbeit wird zum einen die Qualität eines, auf patienten individuellen Eingriffen basierenden, generalisierten Modells hinsichtlich der Abarbeitung durch ein WfMS untersucht, zum anderen werden die Voraussetzungen die, die vorgelagerten Systeme erfüllen müssen geprüft. Es wird eine Aussage zur Abbruchrate der Pfadverfolgung im generalisierten Modell gemacht, das durch eine unterschiedliche Anzahl von patientenindividuellen Modellen erstellt wurde. Zudem wird die Erfolgsrate zum Wiederfinden des Prozesspfades im Modell ermittelt. Ausserdem werden die Anzahl der benötigten Schritte zumWiederfinden des Prozesspfades im Modell betrachtet.:List of Figures iv List of Tables vi 1 Introduction 1 1.1 Motivation 1 1.2 Problems and objectives 3 2 State of research 6 2.1 Definitions of terms 6 2.1.1 Surgical process 6 2.1.2 Surgical Process Model 7 2.1.3 gSPM and surgical workflow 7 2.1.4 Surgical workflow management system 8 2.1.5 Summary 9 2.2 Workflow Management Systems 10 2.2.1 Agfa HealthCare - ORBIS 10 2.2.2 Siemens Clinical Solutions - Soarian 10 2.2.3 Karl Storz - ORchestrion 10 2.2.4 YAWL BPM 11 2.3 Sensor systems 12 2.3.1 Sensors according to DIN1319 13 2.3.2 Video-based sensor technology 14 2.3.3 Human-based sensor technology 15 2.3.4 Summary 15 2.4 Process model 15 2.4.1 Top-Down 15 2.4.2 Bottom-Up 17 2.4.3 Summary 18 2.5 Methods for creating the ICCAS process model 18 2.5.1 Recording of the iSPMs 18 2.5.2 Creation of the gSPMs 20 2.6 Summary 21 3 Model-based design of workflow schemas 23 3.1 Abstract 24 3.2 Introduction 25 3.3 Model driven design of surgical workflow schemata 27 3.3.1 Recording of patient individual surgical process models 27 3.3.2 Generating generalized SPM from iSPMs 27 3.3.3 Transforming gSPM into workflow schemata 28 3.4 Summary and Outlook 30 4 Model-based validation of workflow schemas 31 4.1 Abstract 32 4.2 Introduction 33 4.3 Methods 36 4.3.1 Surgical Process Modeling 36 4.3.2 Workflow Schema Generation 38 4.3.3 The SurgicalWorkflow Management and Simulation System 40 4.3.4 System Validation Study Design 42 4.4 Results 44 4.5 Discussion 47 4.6 Conclusion 50 4.7 Acknowledgments 51 5 Influence of missing sensor information 52 5.1 Abstract 53 5.2 Introduction 54 5.3 Methodology 57 5.3.1 Surgical process modeling 57 5.3.2 Test system 59 5.3.3 System evaluation study design 61 5.4 Results 63 5.5 Discussion 66 5.6 Conclusion 68 5.7 Acknowledgments 68 5.8 Conflict of interest 68 6 Summary and outlook 69 6.1 Summary 69 6.2 Outlook 70 Bibliography 7

Development and Validation of a Hybrid Virtual/Physical Nuss Procedure Surgical Trainer

With continuous advancements and adoption of minimally invasive surgery, proficiency with nontrivial surgical skills involved is becoming a greater concern. Consequently, the use of surgical simulation has been increasingly embraced by many for training and skill transfer purposes. Some systems utilize haptic feedback within a high-fidelity anatomically-correct virtual environment whereas others use manikins, synthetic components, or box trainers to mimic primary components of a corresponding procedure. Surgical simulation development for some minimally invasive procedures is still, however, suboptimal or otherwise embryonic. This is true for the Nuss procedure, which is a minimally invasive surgery for correcting pectus excavatum (PE) – a congenital chest wall deformity. This work aims to address this gap by exploring the challenges of developing both a purely virtual and a purely physical simulation platform of the Nuss procedure and their implications in a training context. This work then describes the development of a hybrid mixed-reality system that integrates virtual and physical constituents as well as an augmentation of the haptic interface, to carry out a reproduction of the primary steps of the Nuss procedure and satisfy clinically relevant prerequisites for its training platform. Furthermore, this work carries out a user study to investigate the system’s face, content, and construct validity to establish its faithfulness as a training platform

Optical Methods in Sensing and Imaging for Medical and Biological Applications

The recent advances in optical sources and detectors have opened up new opportunities for sensing and imaging techniques which can be successfully used in biomedical and healthcare applications. This book, entitled ‘Optical Methods in Sensing and Imaging for Medical and Biological Applications’, focuses on various aspects of the research and development related to these areas. The book will be a valuable source of information presenting the recent advances in optical methods and novel techniques, as well as their applications in the fields of biomedicine and healthcare, to anyone interested in this subject

Evaluation of modern intraocular lenses

Accommodating Intraocular Lenses (IOLs), multifocal IOLs (MIOLs) and toric IOLs are designed to provide a greater level of spectacle independency post cataract surgery. All of these IOLs are reliant on the accurate calculation of intraocular lens power determined through reliable ocular biometry. A standardised defocus area metric and reading performance index metric were devised for the evaluation of the range of focus and the reading ability of subjects implanted with presbyopic correcting IOLs. The range of clear vision after implantation of an MIOL is extended by a second focal point; however, this results in the prevalence of dysphotopsia. A bespoke halometer was designed and validated to assess this photopic phenomenon. There is a lack of standardisation in the methods used for determining IOL orientation and thus rotation. A repeatable, objective method was developed to allow the accurate assessment of IOL rotation, which was used to determine the rotational and positional stability of a closed loop haptic IOL. A new commercially available biometry device was validated for use with subjects prior to cataract surgery. The optical low coherence reflectometry instrument proved to be a valid method for assessing ocular biometry and covered a wider range of ocular parameters in comparison with previous instruments. The advantages of MIOLs were shown to include an extended range of clear vision translating into greater reading ability. However, an increased prevalence of dysphotopsia was shown with a bespoke halometer, which was dependent on the MIOL optic design. Implantation of a single optic accommodating IOL did not improve reading ability but achieved high subjective ratings of near vision. The closed-loop haptic IOL displayed excellent rotational stability in the late period but relatively poor rotational stability in the early period post implantation. The orientation error was compounded by the high frequency of positional misalignment leading to an extensive overall misalignment of the IOL. This thesis demonstrates the functionality of new IOL lens designs and the importance of standardised testing methods, thus providing a greater understanding of the consequences of implanting these IOLs. Consequently, the findings of the thesis will influence future designs of IOLs and testing methods

Développement d'un outil d'évaluation des techniques chirurgicales en plastie

Introduction Pendant la formation d’un résident de chirurgie, l’évaluation des habiletés techniques se fait au moyen de méthodes subjectives et peu reproductibles. Le but de cette étude est de développer un nouvel outil d’évaluation valide et fiable, pour examiner les techniques de microchirurgie des résidents de plastie lors de la performance d’une réparation de nerf digital. Matériaux et méthodes Des résidents de différents niveaux de formation ainsi que des patrons en chirurgie plastique ont effectué une réparation de nerf digital sur un modèle humain cadavérique du membre supérieur. Ces performances ont été filmées et évaluées par deux évaluateurs au moyen d’un nouvel outil d’évaluation développé. Cet instrument compte 12 étapes, chacune évaluée au moyen d’une échelle de Likert à 5 points. La fiabilité inter-évaluateur a été déterminée en comparant pour chaque candidat, les évaluations par les deux évaluateurs et la validité de l’outil en comparant les résultats de participants de différents niveaux d’expertise. Résultats Dix candidats ont pris part dans l’étude. La fiabilité inter-évaluateur de l’outil était acceptable, avec un coefficient de corrélation intraclasse de 0.690. La cohérence interne du test était élevée avec un coefficient de Cronbach alpha qui s’élevait à 0.960. Enfin, la validité de l’outil était démontrée par la différence statistiquement significative (p=0.017) entre les résultats de candidats de différents niveau d’expertise. Conclusion Nous avons développé un nouvel instrument d’évaluation, dont la fiabilité et la validité élevées en font un outil utile dans l’enseignement et l’évaluation des résidents en chirurgie plastique.Introduction During surgical residencies, technical skills continue to be assessed using subjective evaluation methods. We aim to develop an objective, valid and reliable evaluation tool to assess plastic surgery residents’ microsurgical skills in performing a digital nerve repair. Materials and methods Plastic surgery residents of different levels of training and staff surgeons performed a digital nerve repair on a human cadaveric hand model. These performances were recorded and assessed by blinded raters using a newly developed evaluation tool. This consisted of 12 steps, each rated using a 5-point Likert scale. The tool’s reliability was determined by comparing each candidate’s evaluation by the two separate raters and its validity determined by comparing performances of candidates of different levels of expertise. Results Ten candidates took part in this study. The inter-rater reliability was considered acceptable, with an intraclass correlation coefficient of 0.690. The test’s internal consistency was excellent with a Cronbach’s alpha coefficient of 0.960. The test’s validity was demonstrated by the fact that higher levels of expertise were associated with higher performance scores (p=0.017). Conclusion We developed a new evaluation tool for a microsurgical procedure, that performed well in terms of reliability and validity. This makes it a pedagogically useful tool that can be incorporated in plastic surgery residents’ training to improve surgical skills teaching and assessment

Evaluating techniques to improve visual performance with and assessment of premium intraocular lenses

Premium Intraocular Lenses (IOLs) such as toric IOLs, multifocal IOLs (MIOLs) and accommodating IOLs (AIOLs) can provide better refractive and visual outcomes compared to standard monofocal designs, leading to greater levels of post-operative spectacle independence. The principal theme of this thesis relates to the development of new assessment techniques that can help to improve future premium IOL design. IOLs designed to correct astigmatism form the focus of the first part of the thesis. A novel toric IOL design was devised to decrease the effect of toric rotation on patient visual acuity, but found to have neither a beneficial or detrimental impact on visual acuity retention. IOL tilt, like rotation, may curtail visual performance; however current IOL tilt measurement techniques require the use of specialist equipment not readily available in most ophthalmological clinics. Thus a new idea that applied Pythagoras’s theory to digital images of IOL optic symmetricality in order to calculate tilt was proposed, and shown to be both accurate and highly repeatable. A literature review revealed little information on the relationship between IOL tilt, decentration and rotation and so this was examined. A poor correlation between these factors was found, indicating they occur independently of each other. Next, presbyopia correcting IOLs were investigated. The light distribution of different MIOLs and an AIOL was assessed using perimetry, to establish whether this could be used to inform optimal IOL design. Anticipated differences in threshold sensitivity between IOLs were not however found, thus perimetry was concluded to be ineffective in mapping retinal projection of blur. The observed difference between subjective and objective measures of accommodation, arising from the influence of pseudoaccommodative factors, was explored next to establish how much additional objective power would be required to restore the eye’s focus with AIOLs. Blur tolerance was found to be the key contributor to the ocular depth of focus, with an approximate dioptric influence of 0.60D. Our understanding of MIOLs may be limited by the need for subjective defocus curves, which are lengthy and do not permit important additional measures to be undertaken. The use of aberrometry to provide faster objective defocus curves was examined. Although subjective and objective measures related well, the peaks of the MIOL defocus curve profile were not evident with objective prediction of acuity, indicating a need for further refinement of visual quality metrics based on ocular aberrations. The experiments detailed in the thesis evaluate methods to improve visual performance with toric IOLs. They also investigate new techniques to allow more rapid post-operative assessment of premium IOLs, which could allow greater insights to be obtained into several aspects of visual quality, in order to optimise future IOL design and ultimately enhance patient satisfaction

CLINICAL OUTCOMES POST-IMPLANTATION OF MULTIFOCAL AND TORIC INTRAOCULAR LENSES

In order to increase spectacle independence following cataract surgery and intraocular lens (IOL) implantation; correction of spherical refractive error, astigmatic error and presbyopia should all be given careful consideration. There are many premium IOLs, including multifocal intraocular lenses (MIOLs) and toric intraocular lenses (TIOLs), available to surgeons. In order to select the appropriate IOL to meet a patient’s lifestyle and expectations, clinicians must fully understand the characteristics of MIOL and TIOL designs. To date, there remain unanswered questions pertaining to MIOLs and TIOLs and by rigorous comparison of such lenses, this thesis aims to address some of the gaps in the current literature. This thesis aims to evaluate a robust protocol for investigating clinical outcomes in MIOLs that would allow for comparison between future studies. This methodology was used in a randomised control trial and a cohort study. Included in this protocol is the detailed analysis of defocus profiles. This thesis investigates polynomial curve fitting to establish the most suitable curve and curve fitting method for use in future analysis of MIOLs with detailed defocus metrics. Defocus curves can highlight the differences in optical performance in MIOLs of differing addition powers, however, to add further complexity, previous literature has highlighted that addition power can vary individual to individual based on their ocular anatomy. Thus, investigation of an easily accessible clinical method to predict the likely achieved addition power post-implantation was performed. A randomised intra-patient contralateral eye study assessed refractive outcomes and rotational stability in TIOLs. In addition, the performance of the corresponding manufacturer’s calculators was evaluated in regard to refractive predictability and appropriate TIOL selection. This thesis highlights the clinical features of modern MIOL and TIOL designs, demonstrating both the benefits and challenges incurred following implantation.University of Plymout

Textbook of Patient Safety and Clinical Risk Management

Implementing safety practices in healthcare saves lives and improves the quality of care: it is therefore vital to apply good clinical practices, such as the WHO surgical checklist, to adopt the most appropriate measures for the prevention of assistance-related risks, and to identify the potential ones using tools such as reporting & learning systems. The culture of safety in the care environment and of human factors influencing it should be developed from the beginning of medical studies and in the first years of professional practice, in order to have the maximum impact on clinicians' and nurses' behavior. Medical errors tend to vary with the level of proficiency and experience, and this must be taken into account in adverse events prevention. Human factors assume a decisive importance in resilient organizations, and an understanding of risk control and containment is fundamental for all medical and surgical specialties. This open access book offers recommendations and examples of how to improve patient safety by changing practices, introducing organizational and technological innovations, and creating effective, patient-centered, timely, efficient, and equitable care systems, in order to spread the quality and patient safety culture among the new generation of healthcare professionals, and is intended for residents and young professionals in different clinical specialties

Investigation of a holistic human-computer interaction (HCI) framework to support the design of extended reality (XR) based training simulators

In recent years, the use of Extended Reality (XR) based simulators for training has increased rapidly. In this context, there is a need to explore novel HCI-based approaches to design more effective 3D training environments. A major impediment in this research area is the lack of an HCI-based framework that is holistic and serves as a foundation to integrate the design and assessment of HCI-based attributes such as affordance, cognitive load, and user-friendliness. This research addresses this need by investigating the creation of a holistic framework along with a process for designing, building, and assessing training simulators using such a framework as a foundation. The core elements of the proposed framework include the adoption of participatory design principles, the creation of information-intensive process models of target processes (relevant to the training activities), and design attributes related to affordance and cognitive load. A new attribute related to affordance of 3D scenes is proposed (termed dynamic affordance) and its role in impacting user comprehension in data-rich 3D training environments is studied. The framework is presented for the domain of orthopedic surgery. Rigorous user-involved assessment of the framework and simulation approach has highlighted the positive impact of the HCI-based framework and attributes on the acquisition of skills and knowledge by healthcare users