Attitude is everything: keep probe pitch neutral during side-fire prostate biopsy. A simulator study.

OBJECTIVES: To develop and validate on a simulator a learnable technique to decrease deviation of biopsied cores from the template schema during freehand, side-fire systematic prostate biopsy (sPBx) with the goal of reducing prostate biopsy (PBx) false-negatives, thereby facilitating earlier sampling, diagnosis and treatment of clinically significant prostate cancer. PARTICIPANTS AND METHODS: Using a PBx simulator with real-time three-dimensional visualization, we devised a freehand, pitch-neutral (0°, horizontal plane), side-fire, transrectal ultrasonography (TRUS)-guided sPBx technique in the left lateral decubitus position. Thirty-four trainees on four Canadian and US urology programmes learned the technique on the same simulator, which recorded deviation from the intended template location in a double-sextant template as well as the TRUS probe pitch at the time of sampling. We defined deviation as the shortest distance in millimeters between a core centre and its intended template location, template deviation as the mean of all deviations in a template, and mastery as achieving a template deviation ≤5.0 mm. RESULTS: All results are reported as mean ± sd. The mean absolute pitch and template deviation before learning the technique (baseline) were 8.2 ± 4.1° and 8.0 ± 2.7 mm, respectively, and after mastering the technique decreased to 4.5 ± 2.7° (P = 0.001) and 4.5 ± 0.6 mm (P < 0.001). Template deviation was related to mean absolute pitch (P < 0.001) and increased by 0.5 mm on average with each 1° increase in mean absolute pitch. Participants achieved mastery after practising 3.9 ± 2.9 double-sextant sets. There was no difference in time to perform a double-sextant set at baseline (277 ± 102 s) and mastery (283 ± 101 s; P = 0.39). CONCLUSION: A pitch-neutral side-fire technique reduced template deviation during simulated freehand TRUS-guided sPBx, suggesting it may also reduce PBx false-negatives in patients in a future clinical trial. This pitch-neutral technique can be taught and learned; the University of Florida has been teaching it to all Urology residents for the last 2 years.

SMMARTS: An Open Architecture Development Platform for Modular, Mixed, and Augmented Reality Procedural and Interventional Simulators.

INTRODUCTION: Different simulators often share elements, resulting in different laboratories doing redundant work. This can lead to higher development and acquisition costs, proprietary, incompatible technology, lack of interoperability, and large inventories that reduce accessibility to the benefits of simulation. Simulation technology can become more affordable and scalable with open architecture and modular design. We describe the System of Modular Mixed and Augmented Reality Tracking Simulators (SMMARTS) open architecture, rapid development platform for designing and building modular procedural and guided-intervention simulators. METHODS: A modular stand provides mechanical indexing (registration) of a modular anatomical block representing the anatomy relevant to the simulated intervention. A software development kit (SDK) integrated with the hardware (stand and hand-held tracked tools such as a needle and ultrasound probe) facilitates software development. The SMMARTS SDK at https://github.com/UF-CSSALT/SMMARTS-SDK developed in Unity Technologies' Unity game engine includes Arduino microcontroller and NDI's 6 degrees of freedom tracking connectivity along with software tools such as a replayer, user interface templates, 3D visualization of the virtual counterparts of physical elements, scoring monitors, cognitive aids, common error messages, and Experience Application Programming Interface compatibility. RESULTS: We used SMMARTS to develop 9 different simulators internally (instructor-less central venous access currently deployed to Iraq, prostate biopsy, epidural loss-of-resistance, ventriculostomy, pterygopalatine fossa block, lumbar/chronic pain blocks, chest tube insertion) and externally (intravenous access). DISCUSSION: As a living tool, SMMARTS now has sufficient functionality and benefits that we can share it to help clinicians and engineers focus more on content specific to learning objectives rather than back-end tasks.

Does the Technique for Assessing Loss of Resistance Alter the Magnitude of Epidural Needle Tip Overshoot?

INTRODUCTION: Postdural puncture headache due to accidental dural puncture is a consequence of excessive needle tip overshoot distance after entering the epidural space via a loss of resistance (LOR) technique. We are not aware of any quantitative comparison of the magnitude of needle tip overshoot (distance traveled by the needle tip beyond the point where LOR can be discerned) for the various LOR assessment techniques that are taught. Such a comparison may provide insight into contributing factors of accidental dural puncture and associated postdural puncture headache. METHODS: A custom-built simulator was used to evaluate the following 3 LOR assessment techniques: incremental needle advancement, intermittent LOR assessment (II); continuous needle advancement, high-frequency intermittent LOR assessment (CI); and continuous needle advancement, continuous LOR assessment (CC). RESULTS: There were significant mean differences in maximum overshoot past a virtual LOR plane due to technique (F(2,124) = 79.31, P < 0.001) (Fig. 2). Specifically, maximum overshoot was greater with technique II [mean = 3.8 mm, 95% confidence interval (CI) = 3.4-4.3] versus either CC (mean = 1.9 mm, 95% CI = 1.5-1.8, P < 0.001) or CI (mean = 1.4 mm, 95% CI = 0.9-2.3, P < 0.001). Differences in maximum overshoot between CC and CI were not statistically different (P = 0.996). Maximum overshoot was greater at 4 cm (mean = 3.0 mm, 95% CI = 2.6-3.4) compared with 5 cm (mean = 2.3 mm, 95% CI = 2.0-2.5, P = 0.044), 6 cm (mean = 2.0 mm, 95% CI = 1.9-2.2, P = 0.054), 7 cm (mean = 1.9 mm, 95% CI = 1.7-2.1, P = 0.002), and 8 cm (mean = 1.8 mm, 95% CI = 1.6-2.1, P = 0.001). In addition, maximum overshoot at 5 cm was greater than that at 7 cm (P = 0.020) and 8 cm (P = 0.037). The other LOR depths were not statistically significantly different from each other. Depth did not have a significant interaction with technique (P = 0.517). Technique preference had neither a significant relationship to maximum overshoot (P = 0.588) nor a significant interaction with LOR assessment technique (P = 0.689). DISCUSSION: Technique II LOR assessment produced the greatest needle overshoot past the simulated LOR plane after obtaining LOR. This was consistent across all LOR depths. In this bench study, the II technique resulted in the deepest needle tip maximum overshoot. We are in the process of designing a clinical study to collect similar data in patients.