Exploring Combat Tourniquet Application Errors and Duration Among Skilled and Novice Medical Trainees.

INTRODUCTION: The use of tourniquets in combat medicine continues to be a key focus as they have consistently been shown to combat one of the leading causes of preventable death on the battlefield, massive hemorrhage to extremities. The present study analyzed tourniquet application among combat medics (68W) and combat lifesavers (CLSs) in a training environment to determine whether trainees' performance is consistent among one another and whether performance can be associated with participant demographics such as experience or role. MATERIALS AND METHODS: Study participants treated male and female patient simulators within a tactical field care phase, both of which experienced an amputated leg and required the application of a Combat Application Tourniquet (CAT). To assess tourniquet application variability and performance, a series of application subtasks and potential errors were measured via video coding of the scenarios by a team of 5 coders. Time to tourniquet application and tourniquet application duration were also coded to assess correlations between application duration and variability or performance. RESULTS: Results from analyzing tourniquet application subtasks and errors through a series of one-way ANOVA tests showed that application of the CAT first, hasty CAT application, and high tourniquet application were not predictive of participant role, time within the role, and self-reported tourniquet skill, confidence, or experience. Such demographic variables were also not predictive of successful tourniquet application as defined by the number of windlass rod rotations. Results from binomial logistic regressions showed that participant role and self-reported tourniquet skill and experience were predictors of tourniquet application duration. CONCLUSION: The findings suggest that high variability in CAT application methodology and performance exists among CLS and combat medics, which is largely not predictable by various demographics such as role, experience within the designated role, and self-reported confidence, skill, or experience. The observed disconnect between training or experience and CAT application performance suggests substantial variability in the consistency of training for both CLS and 68W soldiers. These inconsistencies may stem from variability in instructor knowledge, teaching styles, or training materials or may be developed through informal methods such as experiences in the field or recommendations from colleagues and experts. These findings highlight a potential need to reassess CAT application training, particularly in regard to consistency and validation. Finally, it should be noted that the study's findings may be limited or fail to capture some study effects because of the sample size and wide range of reported experience among participants.

Variability of tissue mechanical response in Sus Domesticus porcine models from in vivo to ex vivo conditions.

BACKGROUND: Healthcare simulators have been demonstrated to be a valuable resource for training several technical and nontechnical skills. A gap in the fidelity of tissues has been acknowledged as a barrier to application for current simulators; especially for interventional procedures. Inaccurate or unrealistic mechanical response of a simulated tissue to a given surgical tool motion may result in negative training transfer and/or prevents the "suspension of disbelief" necessary for a trainee to engage in the activity. Thus, where it is relevant to training outcomes, there should be an effort to create healthcare simulators with simulated tissue mechanical responses that match or represent those of biological tissues. Historically, this data is most often gathered from preserved (post mortem) tissue; however, there is a concern that the mechanical properties of preserved tissue, that lacks blood flow, may lack adequate accuracy to provide the necessary training efficacy of simulators. METHODS AND FINDINGS: This work explores the effect of the "state" of the tissue testing status on liver and peritoneal tissue by using a customized handheld grasper to measure the mechanical responses of representative porcine (Sus domesticus) tissues in n = 5 animals across five test conditions: in vivo, post mortem (in-situ), ex vivo (immediately removed from fresh porcine cadaver), post-refrigeration, and post-freeze-thaw cycle spanning up to 72 hours after death. No statistically significant difference was observed in the mechanical responses due to grasping between in vivo and post-freeze conditions for porcine liver and peritoneum tissue samples (p = 0.05 for derived stiffness at grasping force values F = 5N and 6.5N). Furthermore, variance between in vivo and post-freeze conditions within each animal, was comparable to the variance of the in vivo condition between animals. CONCLUSIONS: Results of this study further validate the use of preserved tissue in the design of medical simulators via observing tissue mechanical responses of post-freeze tissue comparable to in vivo tissue. Therefore, the use of thawed preserved tissue for the further study and emulation of mechanical perturbation of the liver and peritoneum can be considered. Further work in this area should investigate these trends further, particularly in regard to other tissues and the potential effects varying preservation methods may yield.

Conditions for reliable grip force and jaw angle estimation of da Vinci surgical tools.

PURPOSE: This work presents an estimation technique as well as corresponding conditions which are necessary to produce an accurate estimate of grip force and jaw angle on a da Vinci surgical tool using back-end sensors alone. METHODS: This work utilizes an artificial neural network as the regression estimator on a dataset acquired from custom hardware on the proximal and distal ends. Through a series of experiments, we test the effect of estimation accuracy due to change in operating frequency, using the opposite jaw, and using different tools. A case study is then presented comparing our estimation technique with direct measurements of material response curves on two synthetic tissue surrogates. RESULTS: We establish the following criteria as necessary to produce an accurate estimate: operate within training frequency bounds, use the same side jaw, and use the same tool. Under these criteria, an average root mean square error of 1.04 mN m in grip force and 0.17 degrees in jaw angle is achieved. Additionally, applying these criteria in the case study resulted in direct measurements which fell within the 95% confidence bands of our estimation technique. CONCLUSION: Our estimation technique, along with important training criteria, is presented herein to further improve the literature pertaining to grip force estimation. We propose the training criteria to begin establishing bounds on the applicability of estimation techniques used for grip force estimation for eventual translation into clinical practice.