Formalin-free soft embalming of human cadavers using N-vinyl-2-pyrrolidone: perspectives for cadaver surgical training and medical device development

A South African case study on anatomical embalming for human body donation programmes with toxicological considerations

Body embalming, a practice with deep historical roots across various cultures, forms the backbone of contemporary human body donation educational programmes. In this study, we explored current embalming practices within six South African human anatomical dissection programmes, focusing on the use and volumes of key chemicals-formalin, phenol, and alcohol-and their associated health risks and potential toxicity. We measured and compared aspects of embalming practices such as the duration of body preservation and the annual intake of bodies. Variations in embalming practices and chemical ratios across different South African universities were found. However, the consistent use of formalin, phenol and alcohol were observed across all six programmes. Formaldehyde concentrations used in South African dissection programmes were within the generally acceptable international range. Regarding arterial embalming, South African dissection programmes showed widespread adherence to international embalming practices, with one programme using a substantially lower concentration of formalin. The dual nature of formaldehyde as both an effective preservative and a recognised carcinogen was underscored in relation to human health regarding chemical toxicity. Phenol, like formaldehyde, was consistently used as it is important for the inhibition of bacterial and fungal growth. Alcohol was also consistently used, but there was much greater variation in its volume across South African institutions. Our data showed a slight positive relationship between storage duration and the volumes of formalin and phenol in human embalming fluid. South African regulators enforce stricter exposure limits than those set by the World Health Organisation and various European agencies. While South African institutions operate within internationally acceptable ranges of chemical use that both maximise preservation and minimise toxicity, we acknowledge that these data are preliminary. Further investigation is encouraged to ensure embalming practices effectively protect all those involved and support the educational goals of human anatomical dissection programmes in South Africa.

A new injection method for identifying the subpopliteal recess of the knee

The posterolateral region of the knee has a complex and diverse anatomy. Hydrarthrosis of the knee can potentially communicate with other parts of the joint space. The joint fluid distribution reflects anatomical communications between synovial spaces. To observe the continuity between the knee joint cavity and the surrounding bursa, we devised a dissection method with a new injection agent, an eosin-containing congealed liquid that spreads uniformly over the entire space. The purpose of this study was to perform a detailed examination of the subpopliteal recess (SPR) where a bursa connects to the knee joint capsule. We also reported the advantages of this new injection agent compared with conventional materials (latex and epoxy resin). Twenty-two formalin-fixed cadavers (34 knees), two N-vinyl-pyrrolidone (NVP)-fixed cadavers (4 knees), and two cadavers (3 knees) fixed by Thiel's method were used. After filling the knee joint space and SPR with eosin congealed liquid, the specimens were dissected to investigate the morphology of the SPR. In addition, three different types of injection agents were assessed. The SPR extended distally along the popliteus tendon. The SPR length was 22.64 ± 11.38 mm from the upper end of the lateral tibial condyle to the lower end of the depression. The existence of a fabellofibular ligament made the SPR significantly longer, but abrasion of the femoral articular cartilage did not affect the SPR. Furthermore, the relationship between the popliteus muscle and the SPR was classified into three types (types 1-3). Types 2 and 3 in which the SPR extended to the proximal tibiofibular joint may cause instability of the knee joint. The eosin congealed liquid was highly useful in many aspects, such as fluidity and injection workability. The new dissection method with eosin congealed liquid provides insights into the anatomy of the posterior lateral knee, which are useful for radiological diagnoses and clinical treatments.

Novel teaching-learning and assessment tools to complement competency-based medical education in postgraduate training

Medical and educational techniques and approaches have evolved globally over the past few decades. The modern approach is more learner-centred, with a focus on the acquisition of skills. The recently implemented competency-based medical education (CBME) for the National Medical Commission (NMC) undergraduate course curriculum is also competency-based rather than an outcome-based traditional curriculum. It is vital to embrace innovative teaching-learning and educational strategies to achieve the aspiration of CBME. This article provides a list of some of the newer tools and their perceived advantages and challenges and serves as a guide for using these methods effectively to meet the objectives of CBME as proposed by the NMC. Virtual teaching, learning from digital resources, objective-structured practical and clinical examination, flipped classroom, case-based learning, serious gaming, simulation-based learning and learning from role-plays and portfolios emerged as novel instructional strategies.

Photon-Counting Versus Energy-Integrating Detector CT Angiography of the Lower Extremity in a Human Cadaveric Model With Continuous Extracorporeal Perfusion

OBJECTIVES

Detailed visualization of the arterial runoff is mandatory for the assessment of peripheral arterial occlusive disease. This study aims to compare the performance of a first-generation photon-counting detector computed tomography (PCD-CT) to a third-generation energy-integrating detector CT (EID-CT).

MATERIALS AND METHODS

Computed tomography angiographies of 8 upper leg arterial runoffs were performed on human cadaveric models with continuous extracorporeal perfusion. For both PCD-CT and EID-CT, radiation dose-equivalent 120 kVp acquisition protocols (low-/medium-/high-dose: CTDI Vol = 3/5/10 mGy) were used. All scans were performed with standard collimation (PCD-CT: 144 × 0.4 mm; EID-CT: 96 × 0.6 mm), a pitch factor of 0.4, and a gantry rotation time of 1.0 second. Reformatting of data included the use of comparable vascular kernels (Bv 48/49), a slice thickness and increment of 1.0 mm, and a field of view of 150 × 150 mm. Eight radiologists evaluated image quality independently using a browser-based pairwise forced-choice comparison setup. Kendall concordance coefficient ( W ) was calculated to estimate interrater agreement. Signal-to-noise ratio and contrast-to-noise ratio (CNR) were compared based on 1-way analyses of variance and linear regression analysis.

RESULTS

Low-dose PCD-CT achieved superior signal-to-noise ratio/CNR values compared with high-dose EID-CT ( P < 0.001). Linear regression analysis suggested that an EID-CT scan with a CTDI Vol of at least 15.5 mGy was required to match the CNR value of low-dose PCD-CT. Intraluminal contrast attenuation was higher in PCD-CT than EID-CT, irrespective of dose level (415.0 ± 31.9 HU vs 329.2 ± 29.4 HU; P < 0.001). Subjective image quality of low-dose PCD-CT was considered superior to high-dose EID-CT ( P < 0.001). Interrater agreement was high ( W = 0.989).

CONCLUSIONS

Using cadaveric models with continuous extracorporeal perfusion allows for intraindividual image quality comparisons between PCD-CT and EID-CT on variable dose levels. With superior luminal contrast attenuation and denoising in angiographies of the peripheral arterial runoff, PCD-CT displayed potential for radiation saving of up to 83% compared with EID-CT.

Preparation of Soft Embalmed Cadavers by the Modified Thiel Embalming Technique for Surgical Skill Training and Development of a Universal Quantitative Scoring System to Assess the Suitability of Soft Embalmed Cadavers for Such Training Purposes

Background Cadaver dissection plays an important role in learning anatomy. A surgeon must have a thorough knowledge of anatomy of the operating region to perform safe surgery. Skill laboratories give opportunities to surgeons to practice on cadavers before venturing onto real patients. The most common method of cadaver preservation is through formalin fixation. In the process of fixation, formalin destroys the tissue characteristics and also has issues such as smell, eye irritation, hardening of tissue, and risk of carcinogenesis. The Thiel embalming technique and its modifications were developed to address those issues. Our primary objective was to find the benefits of soft embalmed cadavers over formalin-fixed bodies and, secondly, to find out microbial flora in soft embalmed cadavers. Study design This is a basic study. Methods Four cadavers were prepared for the soft embalming purpose for our workshop for surgeons on spine fixation. Due to unavailability, we replaced 4-chloro-3-methylphenol 1% with phenol 1%. The bodies were preserved in refrigerators at 4°C before being used for the workshop purpose. The delegates and faculties were given a questionnaire to assess their experience of the cadavers in terms of odor, irritation, tissue characteristics, joint mobility, and imaging characteristics. The results were calculated using statistical analysis. Swabs were taken from a few of the cadavers for culture to find the organisms. Results There were 14 questions in the questionnaire, and the data collected were divided into two groups, faculties, and delegates. JASP software was used to analyze the data. The questions addressed various aspects of cadavers such as color, odor, tissue pliability, joint flexibility, imaging characteristics, mucosal irritation, and earlier experience in working with cadavers. Cronbach α was used to find the correlation between the various characteristics analyzed. The authors intend to name the domains being measured: surgical suitability (scores of items 8 to 12), imaging suitability (scores of items 5 and 6), and smell score (scores of items 5 and 6). It can be a guide to constructing and refining a better quantitative scale to measure the "quality of soft-embalmed cadavers for surgical training." Conclusions Skill laboratories give opportunities to young surgeons and trainees to learn and improve their skills before applying them to real patients. This was our first attempt to develop soft embalmed cadavers at our center and our state. We used the parent solution with some variations as per the availability of chemicals at our place and found that the features of the preserved cadavers were good and well-suited to address our purpose. Therefore, with some variations in the parent formulations, centers situated in remote and less developed places can formulate their own solution to develop soft embalmed cadavers and establish cadaver skill laboratories. This will benefit the local surgeons and trainees. The authors tried to develop a few domains through statistical analysis, which can be used to assess and compare the quality of cadavers prepared at various centers.