Jenny Dankelman

Objective assessment of technical surgical skills.

Surgeons are increasingly being scrutinized for their performance and there is growing interest in objective assessment of technical skills. The purpose of this study was to review all evidence for these methods, in order to provide a guideline for use in clinical practice.

Haptics in minimally invasive surgery – a review

This article gives an overview of research performed in the field of haptic information feedback during minimally invasive surgery (MIS). Literature has been consulted from 1985 to present. The studies show that currently, haptic information feedback is rare, but promising, in MIS. Surgeons benefit from additional feedback about force information. When it comes to grasping forces and perceiving slip, little is known about the advantages additional haptic information can give to prevent tissue trauma during manipulation. Improvement of haptic perception through augmented haptic information feedback in MIS might be promising.

Needle-tissue interaction forces -A survey of experimental data

The development of needles, needle-insertion simulators, and needle-wielding robots for use in a clinical environment depends on a thorough understanding of the mechanics of needle-tissue interaction. It stands to reason that the forces arising from this interaction are influenced by numerous factors, such as needle type, insertion speed, and tissue characteristics. However, exactly how these factors influence the force is not clear. For this reason, the influence of various factors on needle insertion-force was investigated by searching literature for experimental data. This resulted in a comprehensive overview of experimental insertion-force data available in the literature, grouped by factor for quick reference. In total, 99 papers presenting such force data were found, with typical peak forces in the order of 1-10N. The data suggest, for example, that higher velocity tends to decrease puncture force and increase friction. Furthermore, increased needle diameter was found to increase peak forces, and conical needles were found to create higher peak forces than beveled needles. However, many questions remain open for investigation, especially those concerning the influence of tissue characteristics.

Requirements for the design and implementation of checklists for surgical processes

BackgroundThe use of checklists is a promising strategy for improving patient safety in all types of surgical processes inside and outside the operating room. This article aims to provide requirements and implementation of checklists for surgical processes.MethodsThe literature on checklist use in the operating room was reviewed based on research using Medline, Pubmed, and Google Scholar. Although all the studies showed positive effects and important benefits such as improved team cohesion, improved awareness of safety issues, and reduction of errors, their number still is limited. The motivation of team members is considered essential for compliance. Currently, no general guidelines exist for checklist design in the surgical field. Based on the authors’ experiences and on guidelines used in the aviation industry, requirements for the checklist design are proposed. The design depends on the checklist purpose, philosophy, and method chosen. The methods consist of the “call-do-response” approach,” the “do-verify” approach, or a combination of both. The advantages and disadvantages of paper versus electronic solutions are discussed. Furthermore, a step-by-step strategy of how to implement a checklist in the clinical situation is suggested.ConclusionsThe use of structured checklists in surgical processes is most likely to be effective because it standardizes human performance and ensures that procedures are followed correctly instead of relying on human memory alone. Several studies present promising and positive first results, providing a solid basis for further investigation. Future research should focus on the effect of various checklist designs and strategies to ensure maximal compliance.

Validation of a new basic virtual reality simulator for training of basic endoscopic skills

BackgroundThe aim of this study was to establish content, face, concurrent, and the first step of construct validity of a new simulator, the SIMENDO, in order to determine its usefulness for training basic endoscopic skills.MethodsThe validation started with an explanation of the goals, content, and features of the simulator (content validity). Then, participants from eight different medical centers consisting of experts (≥100 laparoscopic procedures performed) and surgical trainees (<100) were informed of the goals and received a “hands-on tour” of the virtual reality (VR) trainer. Subsequently, they were asked to answer 28 structured questions about the simulator (face validity). Ratings were scored on a scale from 1 (very bad/useless) to 5 (excellent/very useful). Additional comments could be given as well. Furthermore, two experiments were conducted. In experiment 1, aimed at establishing concurrent validity, the training effect of a single-handed hand–eye coordination task in the simulator was compared with a similar task in a conventional box trainer and with the performance of a control group that received no training. In experiment 2 (first step of construct validity), the total score of task time, collisions, and path length of three consecutive runs in the simulator was compared between experts (>100 endoscopic procedures) and novices (no experience).ResultsA total of 75 participants (36 expert surgeons and 39 surgical trainees) filled out the questionnaire. Usefulness of tasks, features, and movement realism were scored between a mean value of 3.3 for depth perception and 4.3 for appreciation of training with the instrument. There were no significant differences between the mean values of the scores given by the experts and surgical trainees. In response to statements, 81% considered this VR trainer generally useful for training endoscopic techniques to residents, and 83% agreed that the simulator was useful to train hand–eye coordination. In experiment 1, the training effect for the single-handed task showed no significant difference between the conventional trainer and the VR simulator (concurrent validity). In experiment 2, experts scored significantly better than novices on all parameters used (construct validity).ConclusionContent, face, and concurrent validity of the SIMENDO is established. The simulator is considered useful for training eye–hand coordination for endoscopic surgery. The evaluated task could discriminate between the skills of experienced surgeons and novices, giving the first indication of construct validity.

Force feedback and basic laparoscopic skills

BackgroundNot much is known about the exact role of force feedback in laparoscopy. This study aimed to determine whether force feedback influences movements of instruments during training in laparoscopic tasks and whether force feedback is required for training in basic laparoscopic force application tasks.MethodsA group of 19 gynecologic residents, randomly divided into two groups, performed three laparoscopic tasks in both the box trainer and the virtual reality (VR) trainer. The box-VR group began with the box trainer, whereas the VR-box group began with the VR trainer. The three selected tasks included different levels of force application. The box trainer provides natural force feedback, whereas the VR trainer does not provide force feedback. The performance of the two groups was compared with regard to time, path length, and depth perception.ResultsFor the tasks in which force plays hardly a role, no differences between box-VR group and the VR-box group were found. During a task in which force application (pulling and pushing forces) plays a role, the box-VR group outperformed VR-box group in the box trainer. Moreover, training with the box trainer had a positive effect on subsequent performance of the task with the VR trainer. This was not found the other way around. No differences were found between box-VR and the VR-box group in tasks not requiring force application.ConclusionForce feedback influences basic laparoscopic skills during tasks in which pulling and pushing forces are applied. For these tasks, the switch from the trainer without force feedback to the one with natural force feedback has a detrimental effect on performance. Therefore, training for tasks in which forces play an important role (e.g., stretching, grasping) should be done using systems with natural force feedback, whereas eye–hand coordination can be trained without force feedback.

Problems with technical equipment during laparoscopic surgery - An observational study

BackgroundThis study was designed to investigate the incidence of technical equipment problems during laparoscopic procedures.MethodsA video-capturing system was used, consisting of an analog video recorder with three camera image inputs and a microphone. Problems with all technical equipment used by the surgical team, such as the insufflator, diathermy apparatus, monitors, light source, camera and camera unit, endoscope, suction devices, and instruments, were registered.ResultsIn total, 30 procedures were randomly videotaped. In 87% (26/30) of the procedures, one or more incidents with technical equipment (49 incidents) or instruments (9 incidents) occurred. In 22 of those incidents (45%) the technical equipment was not correctly positioned or not present at all; in the other 27 (55%), the equipment malfunctioned as a result of a faulty connection (9), a defect (5), or the wrong setting of the equipment (3). In 10 (20%) cases the exact cause of equipment malfunctioning was unclear.ConclusionsThe incidence of problems with laparoscopic technical equipment is high. To prevent such problems, improvement and standardization of equipment is needed, combined with the incorporation of checklist use before the start of a surgical procedure. Future research should be aimed at development, implementation, and evaluation of these measures into the operating room.

Systems for tracking minimally invasive surgical instruments

Minimally invasive surgery (e.g. laparoscopy) requires special surgical skills, which should be objectively assessed. Several studies have shown that motion analysis is a valuable assessment tool of basic surgical skills in laparoscopy. However, to use motion analysis as the assessment tool, it is necessary to track and record the motions of laparoscopic instruments. This article describes the state of the art in research on tracking systems for laparoscopy. It gives an overview on existing systems, on how these systems work, their advantages, and their shortcomings. Although various approaches have been used, none of the tracking systems to date comes out as clearly superior. A great number of systems can be used in training environment only, most systems do not allow the use of real laparoscopic instruments, and only a small number of systems provide force feedback.

Prolonged diastolic time fraction protects myocardial perfusion when coronary blood flow is reduced

BACKGROUND Because coronary blood flow is impeded during systole, the duration of diastole is an important determinant of myocardial perfusion. The aim of this study was to show that coronary flow modulates the duration of diastole at constant heart rate. METHODS AND RESULTS In anesthetized, open-chest dogs, diastolic time fraction (DTF) increased significantly when coronary flow was reduced by lowering perfusion pressure from 100 to 70, 55, and 40 mm Hg. On average, DTF increased from 0.47+/-0.04 to 0.55+/-0.03 after a pressure step from 100 to 40 mm Hg in control, from 0.42+/-0.04 to 0.47+/-0.04 after administration of adenosine, and from 0.46+/-0.07 to 0.55+/-0.06 after L-NMMA (mean+/-SD, 6 dogs for control and adenosine, 4 dogs for L-NMMA, all P<0.05). Flow normalized to its value at full dilation and pressure of 90 mm Hg (375+/-25 mL/min) increased during the period of reduced pressure at 40 mm Hg; control, from 0.005+/-63 (2 seconds after pressure step) to 0.09+/-0.06 (15 seconds after pressure step); with adenosine, from 0.19+/-0.06 to 0. 22+/-0.06; and with L-NMMA, from 0.013+/-0.007 to 0.12+/-0.02 (all P<0.05). The increase in DTF at low pressure may be explained by a decrease in interstitial volume at low pressure, which either decreases the preload of the myocytes or reduces the buffer capacity for ions determining repolarization, thereby causing an earlier onset of relaxation. CONCLUSIONS Because the largest increase in DTF occurs at pressures below the autoregulatory range when blood flow to the subendocardium is closely related to DTF, modulation of DTF by coronary blood flow can provide an important regulatory mechanism to match supply and demand of the myocardium when vasodilatory reserve is exhausted.

Scopes Too Flexible...and Too Stiff

The article investigates how the difficulties caused by the flexibility of the endoscope shaft could be solved and to provide a categorized overview of designs that potentially provide a solution. The following are discussed: paradoxical problem of flexible endoscopy; NOTES or hybrid endoscopy surgery; design challenges; shaft-guidance: guiding principles; virtual track guidance; physical track guidance; shaft-guidance: rigidity control; material stiffening; structural stiffening; and hybrid stiffening.