Caroline G. L. Cao

Hierarchical decomposition of laparoscopic surgery: a human factors approach to investigating the operating room environment

Hierarchical decomposition of complex behaviour and systems is a valuable research methodology from human factors and information-processing psychology that can be applied to laparoscopic surgery. This article describes results of research on surgeons performing several different laparoscopic procedures, conducted in Vancouver, Canada 1995–98. Through top-down analyses of surgical procedures and bottom-up analyses of tool motions, results included detailed decomposition of the procedures through surgical steps, sub-steps, tasks, sub-tasks and tool motions. Analyses at all levels provided valuable information. In addition to specific surgeon- and technology-related observations, such as the effect of dividing the short gastrics on performance of Nissen fundoplication, gaze patterns of surgeons and factors related to patient safety were analysed. The hierarchical decomposition approach can be extended to other aspects of the complex system that consists of the surgeon and operating room team, the technologies and the operating room environment. Other frameworks for assessment are also considered.

How much feedback is necessary for learning to suture

BackgroundMany laparoscopic simulation training systems exist and have been shown to transfer learning of surgical skills to the operating room. The manner in which the training is structured to maximize learning has not been examined. There are many aspects to the acquisition of laparoscopic skills during training, one of which is the availability of knowledge of results (KR). Knowledge of results is information about the outcome of motor skill execution, usually provided to individuals at the end of the execution. The timing and nature of KR can affect how well people learn new motor skills. In addition, detailed instruction during learning can also affect skill acquisition. We studied the effects of KR and instruction on the learning curve of a suturing and knot-tying task. We hypothesized that KR was necessary for skill acquisition, and that detailed instruction would help trainees to learn to perform the task more correctly and reach a performance plateau earlier. In addition, the overall workload of a trainee during training would decrease as skills improved, especially when KR and coaching were provided.MethodsNine medical students with no previous laparoscopic surgical experience were randomly and evenly divided into three groups with different KR conditions: (1) no KR, (2) KR, (3) KR + instruction. Each subject attended a training session for 1 h each day, 6 days a week for 4 consecutive weeks. Performance measures such as task time, smoothness of instrument, and path length were recorded for each trial. Workload was assessed using the NASA-TLX questionnaire.ResultsWhile KR was necessary for learning to suture, continual instruction had limited additional benefits. However, KR + instruction did reduce subjects’ perceived overall workload.ConclusionsSurgical training could be carried out effectively with only knowledge of results. These results have implications for the staffing of surgical skills laboratories.

Can Surgeons Think and Operate with Haptics at the Same Time

Much effort has been devoted to incorporating haptic feedback into surgical simulators. However, the benefits of haptics for novice trainees in the early stages of learning are not clear. Presumably, novices have less spare attentional resources to attend to haptic cues while learning basic laparoscopic skills. The aim of this study was to determine whether novice surgeons have adequate cognitive resources to attend to haptic information. Thirty surgical residents and attendings performed a TransferPlace task in a simulator, with and without haptics. Cognitive loading was imposed using a mental arithmetic task. Subjects performed 10 trials (five with cognitive loading and five without) with and without haptics. Results showed that all subjects performed significantly slower (27%) when they were cognitively loaded than unloaded, but equally accurately in both cases, suggesting a speed–accuracy tradeoff. On average, subjects performed 36% faster and 97% more accurately with haptics than without, even while cognitively loaded. Haptic feedback can not only enhance performance, but also counter the effect of cognitive load. This effect is greater for more experienced surgeons than less experienced ones, indicating greater spare cognitive capacity in surgeons with more experience.

Vibrotactile force feedback system for minimally invasive surgical procedures

Lack of adequate force feedback for the surgeon in minimally invasive surgery (MIS) can lead to unnecessary trauma to tissue and adverse events during surgery. The successful use of vibrotactile stimulation to augment overloaded or deficient sensory modes in the human operator in other application areas warrants an investigation into its application in MIS. A vibrotactile force feedback system was designed, and its ability to provide useful force information to subjects performing a simulated MIS task was evaluated. Results showed that the system responds as predicted against the bottom surface of the foot, and that subjects were able to perceive a linear increase in force as linear increase in vibration intensity. Furthermore, vibrotacile force information increased ones sensitivity to tissue contact (1.3 N maximum force -no vibration, 1.0 N maximum force-fine step vibration feedback; p<0.001) and improved ones ability to consistently and accurately differentiate tissue softness in a simulated MIS task. Vibrotactile force feedback in MIS appears to have benefits which can lead to a decrease in trauma to tissue and adverse events.

The effect of defined auditory conditions versus mental loading on the laparoscopic motor skill performance of experts

BackgroundMusic and noise are frequent occurrences in the operating room. To date, the effects of these auditory conditions on the performance of laparoscopic surgery experts have not been evaluated.MethodsEight internationally recognized experts were recruited for a crossover study. The experts were randomized to perform three simple tasks on a laparoscopic simulator, SurgicalSIM VR. The tasks were equal in difficulty and performed under the following conditions: silence, dichaotic music (auditory stress), classical music (auditory relaxation), and mental loading (mental arithmetic tasks). Permutations of the conditions were created to account for a learning effect. The tasks were performed twice to test for memory consolidation and to accommodate baseline variability. Time until task completion and task accuracy via instrument tip trajectory (path of the tip through space) were recorded. Performance was correlated with responses on the Brief Musical Experience Questionnaire (MEQ).ResultsThe study demonstrated that dichaotic music has a negative impact on time until task completion but not on task accuracy. In addition, memory consolidation of accuracy is negatively influenced. Classical music has a variable effect on experts’ time until task completion, yet all the experts performed the tasks more accurately. Classical music had no effect on recall of a procedure. Mental loading increased time until completion, but did not affect accuracy or recall. The experience of music varied among experts and influenced how each of the conditions affected their performance.ConclusionThe study demonstrated that, contrary to common belief, proficiency in surgery does not protect against stressful auditory influences or the influence of mental preoccupation. Interestingly, relaxing auditory influences such as classical music can even have a positive impact on the accuracy of experts. Previous musical experience could help to identify surgeons whose performance may be specifically affected by music or noise.

Effects of experience on force perception threshold in minimally invasive surgery

BackgroundDistorted haptic feedback by the surgical instrumentation is a major problem in minimally invasive surgery (MIS). Friction force generated by the rubber seal in the trocars masks the haptic information needed to perceive the properties and structure of the target tissue, resulting in an increased haptic perception threshold in naïve subjects. This can lead to over application of forces in surgery.ObjectiveThis paper examines the effect of surgical experience on the psychophysics of force perception and force application efficiency in MIS.MethodA controlled experiment was conducted using a mixed design, with friction and vision as independent within-subjects factors, experience as a between-subjects factor, and applied force and detection time as dependent measures. Fourteen subjects (eight novices and six experienced surgeons) performed a simulated tissue probing task. Performance data were recorded by a custom-built force-sensing system.ResultsWhen friction was present, higher thresholds and longer detection times were observed for both experienced and inexperienced subjects. In all cases, experienced surgeons applied a greater force than novices, but were quicker to detect contact with tissue, resulting in higher force application efficiency.ConclusionSurgeons seem to have adapted to the higher threshold in haptic perception by reacting faster, even while applying more force to the tissue, keeping within the limits of safety.

Lowering Communication Barriers in Operating Room Technology

Objectives: This paper examines the effects of new technology on team communication and information flow in a complex work environment, and offers design suggestions for improved team performance. Background: Case study of a robot-assisted cholecystectomy procedure revealed teamwork disruption and an increase in the complexity of information flow and communication in the operating room as a result of the novel technology. A controlled experiment using a between-subjects design was conducted to test the hypothesis that providing critical information in a timely and accessible manner would increase communication efficiency and reduce errors in task performance. Methods: Eighteen pairs of participants took part in a simulated tool-changing task in surgery under one of three communication conditions: (a) no rules, (b) scripted, or (c) automated. Results: Teams in the scripted and automated conditions performed significantly faster than the no-rules teams (p < .05). Teams in the automated condition made significantly more errors than those in the scripted condition (p < .05). Conclusion: Scripted speech can facilitate team communication and adaptation to new technology; automatic information display interfaces are not useful if the modality is incompatible with operator expectations. Application: Information displays and communication protocols can be designed to ease adaptation to complex operating room technology.

Differences in Day and Night Shift Clinical Performance in Anesthesiology

Objective: This study examined whether anesthesia residents (physicians in training) performed clinical duties in the operating room differently during the day versus at night. Background: Fatigue from sleep deprivation and working through the night is common for physicians, particularly during residency training. Methods: Using a repeated-measures design, we studied 13 pairs of day-night matched anesthesia cases. Dependent measures included task times, workload ratings, response to an alarm light latency task, and mood. Results: Residents spent significantly less time on manual tasks and more time on monitoring tasks during the maintenance phase at night than during the day. Residents reported more negative mood at night than during the day, both pre- and postoperation. However, time of day had no effect on the mood change between pre- and postoperation. Workload ratings and the response time to an alarm light latency task were not significantly different between night and day cases. Conclusions: Because night shift residents had been awake and working for more than 16 hr, the observed differences in task performance and mood may be attributed to fatigue. The changes in task distribution during night shift work may represent compensatory strategies to maintain patient care quality while keeping perceived workload at a manageable level. Applications: Fatigue effects during night shifts should be considered when designing work-rest schedules for clinicians. This matched-case control scheme can also be applied to study other phenomena associated with patient safety in the actual clinical environment.

DISORIENTATION IN MINIMAL ACCESS SURGERY: A CASE STUDY

Navigating through minimal access surgical environments such as the human colon can be difficult, even for expert gastroenterologists. “Getting lost” is a common experience for endoscopists, especially within the tortuous sigmoid colon where salient landmarks are not generally available. This paper presents the concept of “getting lost” in endoscoppy as a loss of both global and local spatial orientation. For the endoscopist performing a colonoscopy, the consequence of local disorientation is an inability to continue the procedure, or possibly even injury to the patient, while consequences of global disorientation can be mistaking the location of a lesion, and/or incomplete examination, resulting in misdiagnosis. This study provides important insights into the physical and cognitive constraints of the task of navigating in colonoscopy, contributing to disorientation in the colon. The implications of our findings for the design of navigational aids and training tools are also discussed.

Designing for Spatial Orientation in Endoscopic Environments

Disorientation or “getting lost” in colonoscopy is common experience even for expert endoscopists. This paper describes a new navigational aid display concept for colonoscopy and presents results of an experiment conducted to evaluate the usefulness of various types of spatial information for supporting navigation and spatial orientation in colonoscopy. Six combinations of 1) direction, 2) location, and 3) shape information were tested. Results show that even though the new navigational aid display concept did not improve navigation performance, spatial orientation error and workload were reduced significantly. This new navigational aid display which provides shape combined with location and direction information in a perspective view and in real time is a useful tool for colonoscopy.