Hierarchical Task Analysis Reimagined as a Planning Tool for Surgery During Exploration Space Flight

Background: Preparation for exploration class space flight requires planning to support human life in many circumstances including healthcare emergencies such as the need for acute surgical care, a notable example of which is appendicitis. Although performing a laparoscopic appendectomy on Earth is routine for a trained general surgeon, it is far from routine for a non-surgeon working in microgravity where IVs do not drip, drains do not drain, and gaseous anesthetic is out of the question. Because the procedure for laparoscopic appendectomy is so well documented, it was the ideal procedure on which to base a study on how to deconstruct a surgical procedure to examine all actions, skills, equipment, and supplies needed for success by non-surgeons working in an extreme environment. Study Design: Our challenge was to develop a task analysis model robust enough to include 3 performers (in the roles of surgeon, assistant, and anesthesiologist) including each action and instrument or supply item needed in chronological order, while indicating which actions were completed independently and which were done in tandem. We also had to indicate where variations in the actions would be determined by the negative response of the patient (failure mode), and which actions and supply items needed further research to accommodate working in microgravity. We opted to begin with a hierarchical task analysis model (HTA) because the steps in the task are sequential; but we expanded the typical linear presentation of data to a multi-column spread sheet with active links to instructional video clips where needed. Content development was an iterative process beginning with a scoping review of literature to select a baseline task analysis of the procedure. The SAGES 2010 approach was selected as most comprehensive, but logically focused on the surgeon’s performance with few references to the assistant or anesthesiologist. Those gaps were filled using content from training materials developed for surgical technicians and nurse anesthetists. The second step was an expert review of the spread sheet to identify gaps and inadequacies. The third step was a minute comparison of spread sheet content to actions and equipment as documented on 2 videotapes of the procedure performed by our team surgeon on otherwise healthy patients. The final review was accomplished by replicating the procedure on 360° video (with narration) using the spread sheet as a guide, then cross checking and correcting the spread sheet to correspond with the 360° video. This test procedure was performed on a lightly preserved, fresh cadaver since working at that very slow, deliberate pace would not be in the best interest of an actual patient. Results: In this study, simulation was actually used to test the expanded HTA rather than to evaluate a learner. The final spread sheet included 178 lines, 13 columns, 13 illustrations, and 4 active links to instructional video clips. Thirteen items or issues were identified as needing further research, 8 action sequences were identified as generalizable skills, and 27 supply or equipment items were identified as multipurpose. Excluding the pharmaceuticals necessary for IV general anesthesia (that research is on-going), we were able to replicate a laparoscopic appendectomy on a fresh cadaver using no more than 30 items. The procedure was done using 3 trocars with very few instrument exchanges through the trocars since the surgical assistant assumed the role of laparoscopic camera operator during the procedure. Conclusion: An expanded HTA of a surgical procedure can produce many useful outcomes including integrated training for all team members, review of instrumentation and supplies and, in our case, identifying areas for adapting to an extreme environment. Using an interdisciplinary team including instructional designers, subject matter experts from medicine and biomedical engineering, and media production enriched the process.

A biomechanical analysis of different meshes for reconstructions of the pelvic floor in the porcine model

Purpose Many different surgical approaches have been established for the repair of a pelvic organ prolapse. Especially in laparoscopic surgery, it is important to generate easy surgical techniques with similar stability. This study shall simplify the choice of mesh by evaluating three polypropylene meshes regarding their biomechanical properties. Methods Biomechanical testing was performed in the porcine model. The meshes are fixated on porcine fresh cadaver cervices after subtotal hysterectomy. The apical part of the mesh is fixated with parallel screw clamps at the testing frame. Forty-one trials were performed overall, subdivided into four subgroups. The groups differ in mesh type and fixation method. Maximum load, displacement at failure and stiffness parameters were evaluated with an Instron 5565® test frame. Results SERATEX® E11 PA (E11) showed the highest values for maximum load (199 ± 29N), failure displacement (71 ± 12 mm) and stiffness (3.93 ± 0.59 N/mm). There was no significant difference in all three evaluated parameters between SERATEX® B3 PA (B3) and SERATEX® SlimSling® with bilateral fixation (SSB). SERATEX® SlimSling® with unilateral fixation (SSU) had the lowest stiffness (0.91 ± 0.19 N/mm) and maximum load (30 ± 2 N) but no significant difference in displacement at failure. Conclusion All meshes achieved a good tensile strength, but the results of maximum load show that the E11 is superior to the other meshes. Through a bilateral fixation of SERATEX® SlimSling®, a simple operating method is generated without a loss of stability.

Tacks vs. sutures: a biomechanical analysis of sacral bony fixation methods for laparoscopic apical fixations in the porcine model

Purpose There is a novel surgical procedure, called cervicosacropexy (CESA) and vaginosacropexy (VASA) to treat pelvic organ prolapse and a concomitant urgency and mixed urinary incontinence. As there is little experience with the tapes so far and literature is scanty, the aim of this study was to investigate biomechanical properties for the fixation of the PVDF-tapes with three different fixation methods in context of apical fixations. Methods Evaluation was performed on porcine, fresh cadaver sacral spines. A total of 40 trials, divided into 4 subgroups, was performed on the anterior longitudinal ligament. Recorded biomechanical properties were displacement at failure, maximum load and stiffness in terms of the primary endpoints. The failure mode was a secondary endpoint. Group 4 was a reference group to compare single sutures on porcine tissue with those on human tissue. Biomechanical parameters for single sutures on the human anterior longitudinal ligament were evaluated in a previous work by Hachenberg et al. Results The maximum load for group 1 (two single sutures) was 65 ± 12 N, for group 2 (three titanium tacks arranged in a row) it was 25 ± 10 N and for group 3 (three titanium tacks arranged in a triangle) it was 38 ± 12 N. There was a significant difference between all three groups. The most common failure mode was a “mesh failure” in 9/10 trials for groups 1–3. Conclusion The PVDF-tape fixation with two single sutures endures 2.6 times more load than titanium tacks arranged in a row and 1.7 times more load than titanium tacks arranged in a triangle. The presacral fixation with titanium tacks reduced surgical time compared to the fixation with sutures, nevertheless sutures represent the significantly stronger and cheaper fixation method.

Triceps and cutaneous radial nerve branches investigated via an axillary anterior arm approach: new findings in a fresh-cadaver anatomical study

OBJECTIVE The authors sought to describe the anatomy of the radial nerve and its branches when exposed through an axillary anterior arm approach. METHODS Bilateral upper limbs of 10 fresh cadavers were dissected after dyed latex was injected into the axillary artery. RESULTS Via the anterior arm approach, all triceps muscle heads could be dissected and individualized. The radial nerve overlaid the latissimus dorsi tendon, bounded by the axillar artery on its superior surface, then passed around the humerus, together with the lower lateral arm and posterior antebrachial cutaneous nerve, between the lateral and medial heads of the triceps. No triceps motor branch accompanied the radial nerve’s trajectory. Over the latissimus dorsi tendon, an antero-inferior bundle, containing all radial nerve branches to the triceps, was consistently observed. In the majority of the dissections, a single branch to the long head and dual innervations for the lateral and medial heads were observed. The triceps long and proximal lateral head branches entered the triceps muscle close to the latissimus dorsi tendon. The second branch to the lateral head stemmed from the triceps lower head motor branch. The triceps medial head was innervated by the upper medial head motor branch, which followed the ulnar nerve to enter the medial head on its anterior surface. The distal branch to the triceps medial head also originated near the distal border of the latissimus dorsi tendon. After a short trajectory, a branch went out that penetrated the medial head on its posterior surface. The triceps lower medial head motor branch ended in the anconeus muscle, after traveling inside the triceps medial head. The lower lateral arm and posterior antebrachial cutaneous nerve followed the radial nerve within the torsion canal. The lower lateral brachial cutaneous nerve innervated the skin over the biceps, while the posterior antebrachial cutaneous nerve innervated the skin over the lateral epicondyle and posterior surface of the forearm. The average numbers of myelinated fibers were 926 in the long and 439 in the upper lateral head and 658 in the upper and 1137 in the lower medial head motor branches. CONCLUSIONS The new understanding of radial nerve anatomy delineated in this study should aid surgeons during reconstructive surgery to treat upper-limb paralysis.

Feasibility of pneumoperitoneum diagnosis using point-of-care ultrasound: a pilot study using a fresh cadaver model

Aims: To assess the accuracy of point-of-care ultrasound (PoCUS) in the hands of two trained and blinded emergency physicians (EPs) in detecting very small amounts of free intraperitoneal air injected intra-abdominally, using a fresh human cadaver model.Material and methods: Fifteen cadavers were injected on 3 occasions with predefined quantities of free intraperitoneal air ranging from 0-10 mL. Seven cadavers were injected in the mid-epigastrium (ME), while 8 were injected in the left lower quadrant (LLQ). Each cadaver was scanned after each of the 3 injections by 2 trained and blinded EPs, resulting in 45 scans per sonographer. Scans were performed using previously validated and standardized techniques. All scans were recorded, time-stamped and labeled. For each scan the sonographers indicated “yes” or “no” to whether pneumoperitoneum was detected. A chi square analysis was performed to determine the sensitivity and specificity of PoCUS utilized by each sonographer of pneumoperitoneum based on the location and volume of air injected.Results: Free air (0.25-10 mL) injected into the ME was successfully diagnosed in 36/42 instances (86% sensitivity), but only detected in 10/36 instances when injected into the LLQ (28% sensitivity). Both EPs detected all air injections of ≥2 mL into the ME.Conclusion: Detection of free air originating from the midepigastric region may become a future PoCUS indication for adequately trained EPs.

Scapular spine base fracture with long outside-in superior or posterior screws with reverse shoulder arthroplasty

Background: The purpose of the present study was to determine how long superior screws alone or in combination with posterior placement of metaglene screws protruding and penetrating into the scapular spine in reverse total shoulder arthroplasty affect the strength of the scapular spine in a fresh cadaveric scapular model.Methods: Seven fresh cadaver scapulas were allocated to the control group (short posterior and superior screws) and seven scapulas to the study group (spine base fixation with a 4-inch-long superior screw, three with both long superior and long posterior screws).Results: The failure load was lower in the spine fixation group (long screw [869 N] vs. short screw [1,123 N]); however, this difference did not reach statistical significance (p>0.05). All outside-in long superior or superior plus posterior screws failed due to scapular spine base fracture; failures in the short screw group were due to acromion fracture. An additional posterior outside-in screw failed to significantly decrease the failure load of the acromion spine.Conclusions: The present study highlights the significance of preventing a cortical breach or an outside-in configuration when a superior or posterior screw is inserted into the scapular spine base.

Evaluating the histopathological and mechanical effects of a new forceps design: comparison of hemispheric bipolar forceps tip with usual bipolar tip on fresh cadaver cattle brain model

Without electrocautery, many modern surgical interventions are practically impossible. In neurosurgery, bipolar cautery forceps has been evolved to not only be an auxiliary, but as a principal instrument wielded by the dominant hand of the surgeon to navigate through the most delicate tissue that there is. The purpose of this study is to introduce our original bipolar forceps designed exclusively for microneurosurgical interventions and compare its feasibility with a standard bipolar forceps tip. This study has been conducted on two fresh cadaveric cow brains under the operating microscope. The coagulative and ablative effects of the hemispheric bipolar forceps tip (HBFT) have been histologically compared with those of the standard bipolar forceps tip (SBFT). Likewise, their efficacies as a dissection instruments have been compared via performing dissections from the parietal surface down to the corpus callosum. HBFT proved less traumatic to the uninvolved brain tissue during dissection. Also, histological analyses have revealed that ablative effects of the HBFT are more confined to the bleeding point, more effectively sparing the uninvolved brain tissue. Results of this experimental study suggest that HBFT is a better instrument to be used in microneurosurgical interventions, along with other surgical disciplines where selective diathermy is critical.

Single Incision Approach for Decompression of Greater, Lesser and Third Occipital Nerves in Migraine Surgery

Background The traditional approach for occipital migraine surgery encompasses 3 separate surgical incisions in the posterior neck to decompress the great occipital nerves (GON), lesser occipital nerves (LON) and third occipital nerves (TON). We sought to evaluate a single midline incision approach for decompression of all 6 occipital nerves. Methods Using 10 cadaveric hemi-sides (5 fresh cadaver head and necks). Anatomic landmarks and the location of the bilateral GON, LON and TON were marked according to previous anatomic studies. A single midline 9-cm incision was made and lateral skin flaps were raised to decompress or avulse all 6 nerves. Results The GON and TON were identified 3.5 and 6.2 cm, respectively inferior to a line bisecting the external auditory canal (EAC) and 1.5 cm lateral to the midline. The LON was identified 6-cm inferior and 6.5-cm medial to a line bisecting the EAC in the plane just above the investing layer of the deep cervical fascia until the posterior boarder of the sternocleidomastoid was encountered. The LON had the greatest amount of variation, but was identified lateral to the posterior border of the SCM. Conclusions A single midline incision approach allows for successful identification and decompression of all 6 occipital nerves in migraine surgery.

Fresh Cadaver Simulation Model with Continuous Extracorporeal Circulation as a Training Platform for Intracranial High-Flow Bypass: Technical Note and Rheologic Feasibility Evaluation

Introduction As endovascular techniques evolve toward replacing open surgery, several clinical scenarios still require surgical revascularization. Characterizing this era are decreasing surgical volumes and lack of realistic training models. In an effort to develop lifelike simulation models, we developed a platform for surgical training on high-flow bypass in a fresh cadaver model. Our technique incorporated an extracorporeal circulating system that resembled clinical conditions and confirmed anastomosis efficacy by clinical parameters. Methods On three fresh cadaveric heads, the subtemporal approach exposed the petrous internal carotid artery (ICA) (C2) as the donor vessel for an interposition radial artery graft. Using a continuous extracorporeal circulation system, the bypass model was tested in three fresh heads and verified using clinical technologies. Results Successful C2 ICA to M2 anastomosis was completed in all three fresh heads, confirmed with qualitative and quantitative Doppler, and indocyanine green angiography. Antegrade distribution through graft and revascularized territory was documented on postoperative computed tomography (CT) scan with radiopaque silicone injected through the ipsilateral carotid. Conclusion This study confirmed the feasibility of a totally intracranial high-flow bypass in a fresh cadaver model that achieved hemodynamic features aligned with those of normal middle cerebral artery flow in the clinical setting.