Thiel-embalmed Cadavers Research Articles

Preliminary Validation of Thiel Embalmed Cadavers for Laparoscopic Radical Nephrectomy

This study evaluated face, content, construct validity, and reliability of Thiel embalmed cadavers (TEC) as a training tool for transperitoneal laparoscopic nephrectomy (TLN). The study participants were prospectively recruited through an advanced laparoscopic renal resection teaching skill course. The participants were grouped into: nonexperts (performed fewer than 50 TLNs) and experts (performed more than 50 TLNs). All the participants performed TLN on TEC, which was video recorded. All participants rated their overall experience of performing TLN on TEC with emphasis on realism (face validity). The participants were asked to rate the appropriateness of TEC for training in TLN (content training). Two experienced laparoscopic surgeons, using validated modified Objective Structured Assessment of Technical Skills, assessed the individual videos. The parameters studied were: Respect for tissues, time and motion, and instrument handling for each step of laparoscopic nephrectomy (LN) (construct validity). Test-retest and interrater reliability was also evaluated. Twenty-four participants (4 experts and 20 nonexperts) took part in this study. The mean overall rating for the experience of TLN on TEC was 4.5 (Face Validity). The mean score for the appropriateness of TEC as a training tool for TLN was 4.6 (content validity) when evaluated by the four experts. The mean scores for the nonexperts and experts using video recordings for various variables were: Respect for tissue-1.74 (standard deviation [SD]-0.62) vs 3.63 (SD-1.06), (P<0.01), time and motion-1.74 (SD-0.58) vs 4 (SD-0.76), (P<0.01), and instrument handling-1.84 (SD-0.61) vs 4.25 (SD-0.71), (P<0.01) (construct validity). The study also suggested test-retest and interrater reliability. This study suggests face, content, and constructs validity and reliability of the TEC as a training tool for TLN.

Movements of the double-lumen endotracheal tube due to lateral position with head rotation and tube fixation: a Thiel-embalmed cadaver study.

Following successful double-lumen endotracheal tube (DLT) insertion for pulmonary surgery, the body position of a patient is changed from supine to lateral. This change occasionally leads to the malposition of the DLT and difficulty in differential lung ventilation. In this study, we investigated movements of the DLT induced by change in body position from supine to lateral, using Thiel-embalmed cadavers. Thiel-embalmed cadavers retain full flexibility of the body and preservation of natural colours, using novel preservation techniques. After the tip of the DLT was directly fixed with forceps at the appropriate position in the bronchus, the DLT depth was measured at the lip in supine and lateral positions. The depth of DLT insertion measured at the lip in right (25.2 ± 0.3 cm; mean ± SEM) and left (25.1 ± 0.3 cm) lateral positions was significantly increased compared to the supine position (24.7 ± 0.3 cm). We recommend that the depth of DLT insertion should be advanced by approximately 0.5 cm from the best position, before changing from the supine to lateral position.

Flap raising on pulsatile perfused cadaveric tissue: A novel method for surgical teaching and exercise

Exercising flap raising procedures on cadavers is considered a prerequisite to prepare for clinical practise. To improve teaching and create conditions as realistic as possible, a perfusion device was developed providing pulsatile flow through the vessels of different donor sites. A plastic bag filled with red stained tab water was placed into a pump, which was driven by an electric motor. The bag was set under rhythmic compression with variable frequency and pressure. The pedicles of the radial forearm, anterolateral thigh, rectus abdominis, fibular and iliac crest flap were cannulated at the origin from their source arteries. Flap raising was performed under pulsatile perfusion in 15 fresh bodies and subsequently in 6 Thiel-embalmed cadavers during a flap raising course. We regularly observed staining of the skin and skin bleeding in fresh bodies and less reliable in embalmed cadavers. All flap pedicles showed pulsatile movements, and the radial pulse became palpable. Most perforators of the anterolateral thigh and osteocutaneous fibular flap could be identified by their pulse. Bleeding from bony tissue and venous return was seldom observed. We conclude that pulsatile perfusion of cadaveric tissue creates more realistic conditions for flap raising and improves teaching for beginners and advanced surgeons.

Surgical simulation flexor tendon repair using Thiel cadavers: a comparison with formalin embalmed cadavers and porcine models

The aim of this study was to compare Thiel-embalmed cadavers with formalin-embalmed cadavers and porcine models in the surgical simulation repair of a Zone II flexor tendon division. Nine participants were recruited to the study. The models were assessed using a five-point scale. Assessment was divided into tissue quality, surgical approach and identification of structures. Thiel cadavers rated consistently higher compared with the formalin and porcine models (mean 37 SD 2, 22 SD 6 and 23 SD 5, respectively). Thiel cadavers recorded an average tendon glide of 21 mm SD 5, formalin cadavers 2 mm SD 2 and the porcine model 6 mm SD 2. We have demonstrated the benefit of Thiel embalming, with flexibility of tissues allowing testing of the repair of a flexor tendon in a realistic anatomical model. Level V.

Liver displacement during ventilation in Thiel embalmed human cadavers – a possible model for research and training in minimally invasive therapies

Respiration-related movement of organs is a complication in a range of diagnostic and interventional procedures. The development and validation of techniques to compensate for such movement requires appropriate models. Human cadavers embalmed with the Thiel method remain flexible and could provide a suitable model. In this study liver displacement during ventilation was assessed in eight Thiel embalmed cadavers, all of which showed thoracic and abdominal motion. Four cadavers displayed realistic lung behaviour, one showed some signs of pneumothorax after prolonged ventilation, one had limited filling of the lungs, and two displayed significant leakage of air into the thorax. A coronal slice containing the largest section through the liver was imaged with a real-time Fast Gradient Echo (FGR) MRI sequence: Craniocaudal displacement of the liver was then determined from a time-series of slices. The maximum liver displacement observed in the cadavers ranged from 7 to 35 mm. The ventilation applied was comparable to tidal breathing at rest and the results found for liver displacement are similar to values in the literature for respiratory motion of the liver under similar conditions. This indicates that Thiel embalmed cadavers have potential as a model for research and training in minimally invasive procedures.

From formalin to thiel embalming: What changes? One anatomy department's experiences

In 2009, the Centre for Anatomy and Human Identification started Thiel embalming on a small scale to assess (i) the suitability for our current teaching in which long-lasting dissection courses are key, (ii) the potential for new collaborations and activities, and (iii) the practical implications of changing our embalming method from formalin to Thiel. Twenty six Thiel-embalmed cadavers have been used for dissection by staff and students on a taught MSc course, as a model for clinical and surgical training, and increasingly as a model for evaluation of new medical devices and procedures. Our experiences with dissection were mostly positive especially for teaching the musculoskeletal system. Internal organs handle differently from formalin-fixed organs and dissection manuals need to be adjusted to reflect this. Durability of the cadavers was not an issue, though changes are seen over time due to gradual fluid loss. We have started new collaborations related to postgraduate anatomy teaching and advanced training in surgical and clinical skills. In general, feedback is very positive and demand for cadavers outstrips our current limited supply. Thiel-embalmed cadavers were found to provide a unique opportunity for evaluation of medical products especially in areas where no suitable alternative model is available, and without the complications associated with clinical testing. This has resulted in new collaborations and research projects. As a result Thiel-embalmed cadavers are used for longer and for more activities than formalin cadavers: this requires changes in our procedures and staff roles.

Selective ultrasound guided pectoral nerve targeting in breast augmentation: How to spare the brachial plexus cords?

Subpectoral breast augmentation surgery under regional anesthesia requires the selective neural blockade of the medial and lateral pectoral nerves to diminish postoperative pain syndromes. The purpose of this cadaver study is to demonstrate a reliable ultrasound guided approach to selectively target the pectoral nerves and their branches while sparing the brachial plexus cords. After evaluating the position and appearance of the pectoral nerves in 25 cadavers (50 sides), a portable ultrasound machine was used to guide the injection of 10 ml of 0.2% aqueous methylene blue solution in the pectoral region on both sides of three Thiel's embalmed cadavers using a single entry point-triple injection technique. This technique uses a medial to lateral approach with the entry point just medial to the pectoral minor muscle and three subsequent infiltrations: (1) deep lateral part of the pectoralis minor muscle, (2) between the pectoralis minor and major muscles, and (3) between the pectoralis major muscle and its posterior fascia under ultrasound visualization. Dissection demonstrates that the medial and lateral pectoral nerves were well stained while leaving the brachial plexus cords unstained. We show that 10 ml of an injected solution is sufficient to stain all the medial and lateral pectoral nerve branches without a proximal extension to the cords of the brachial plexus.

Translation of sonoelastography from Thiel cadaver to patients for peripheral nerve blocks*

Ultrasound guidance is now common in regional anaesthesia practice, but remains limited by poor visibility of the needle tip and poor quantification of local anaesthetic spread. Sonoelastography based on tissue compression is a technique depicting tissue strain. Hitherto used largely for tumour diagnosis, we used it in both Thiel embalmed cadavers and two patients receiving interscalene and femoral blocks to observe changes in tissue strain during local anaesthetic injection. The primary aim of our study was to measure the area under the curve (weighted for time) of the strain pattern in Thiel perineural tissue when using a range of volumes of embalming fluid (0.25, 0.5, 1, 2.5, 5 and 7.5 ml) for interscalene and femoral blocks using sonoelastography. Our secondary aims were to evaluate static images of anatomy and videos of needle insertion and perineural injection using combined B-Mode ultrasound and sonoelastography. Independent raters assessed the anatomy and spread using a 7-point Likert scale, ranked from extremely poor to extremely good. We performed 83 blocks in cadavers. Concordance between both raters was good, with weighted Kappa (95% CI) 0.66 (0.61-0.71). The characteristics of spread were similar with both interscalene and femoral block; spread increased with injectate volume up to 1 ml. Analysis of variance showed differences in spread between injection volumes (p = 0.009), but not between regional blocks (p = 0.05). Post-hoc analysis showed greater spread with 1 and 2.5 ml volumes compared with 0.25 ml. In patients, visibility of strain during injection was better with sonoelastography than with B-Mode ultrasound and showed a dose response from 1 to 5 ml volumes of local anaesthetic. Colour strain recognition using sonoelastography offers the ability to differentiate between nerve and surrounding tissue during local anaesthetic injection by improving visibility of spread (p = 0.04).

Application of sonoelastography to regional anaesthesia: a descriptive study with the Thiel embalmed cadaver model

Introduction Ultrasound-guided regional anaesthesia (UGRA) is being used increasingly in patients but varying patient characteristics make it difficult to visualize needles and spread of local anaesthetic fluid. Methods To evaluate the use of elastography for UGRA by performing ultrasound-guided nerve blocks in Thiel embalmed cadavers. Both upper limb and lower limb blocks were performed on cadavers with ultrasound guidance. B-mode and elastography images obtained on split screen were analysed. Results The B-mode images were superior compared with the ultrasound elastography images with respect to the anatomical details; however, dynamic changes such as fluid spread were visualized better with elastography. Conclusion The elastography images also had good dose response to the volume of the injectate implying its usefulness in detecting local anaesthetic spread when low volumes are used as test doses.

A comparison of Thiel and formalin embalmed cadavers for thyroid surgery training

Background The European Working Time Directive has increased the need for surgical skills training which does not involve patients. Recent changes in the anatomy legislation now make it possible to perform surgical procedures on human cadavers. Standard formalin embalming, however does not provide a very realistic model and alternative approaches, such as Thiel soft-fix embalmed cadavers, should be explored and evaluated. Methods Two formalin and 3 Thiel embalmed cadavers were used at a senior trainee and consultant course in thyroid surgery. The 12 participants (8 trainees and 4 consultants) were asked to score 15 aspects, such as quality of different tissues, for each type of cadaver. Some of these aspects were specific to thyroid surgery, however many are equally applicable to other specialties. Results All participants rated the Thiel embalmed cadavers better or equal for all aspects. Of the 180 pairs of scores 33 were excluded, 10 were equal for formalin and Thiel, while in the remaining 137 Thiel scored better. The preference was particularly pronounced in aspects that require flexibility of tissues such as flap raising. Conclusions Thiel embalmed cadavers provide a more realistic model for training of thyroid surgical skills; this is expected to be similar for many other types of surgery.

An evaluation of Thiel-embalmed cadavers for ultrasound-based regional anaesthesia training and research

Working hours of UK trainee doctors have recently been reduced to 48 hours per week, reducing exposure to clinical cases. As such, there is widespread acceptance that trainees need to train in environments other than the ward or operating theatre in order to gain practical skills. Formalin-fixed cadavers demonstrate gross muscle and nerve anatomy but needle insertion under ultrasound guidance is poor. In contrast, a new development in medical simulation is the use of Thiel-embalmed cadavers, developed by Professor Thiel of the University of Graz, Austria, using a novel preservation technique that retains full flexibility of the limbs. Thiel cadavers have been used to successfully simulate laparoscopic surgery, neurosurgery and oral surgery. This paper investigates, for the first time, the application of ultrasound-based regional anaesthesia to the Thiel cadaver by tracing the course of peripheral nerves, injecting local anaesthetic around nerves, and reproducing inadvertent intraneural injection by injecting preservative directly into the nerve. The Thiel cadaver provides good conditions for anaesthetists to simulate regional anaesthetic block techniques using ultrasound.

Comparison of fresh and Thiel’s embalmed cadavers according to the suitability for ultrasound-guided regional anesthesia of the cervical region

Ultrasound-guided punctures are a new technique in anesthesia. However, training in these techniques requires conditions resembling real life as far as possible for learning purposes. Several models are available, but none associates realistic anatomy and lifelike sensations of the passage of fascias. The aim of our study was to compare fresh and Thiel's embalmed cadavers for ultrasound-guided punctures. Eight fresh cadavers and eight Thiel's embalmed cadavers were investigated. The cervical region was scanned with an ultrasound probe. Age, sex and body mass index (BMI) were recorded. Visibility of he structures, including sternocleidomastoid (SCM) muscle, anterior and middle scalene muscles, thyroid gland, nerve and the needle, was evaluated as 0 (not visible or bad visibility) or 1 (good visibility). The feeling ("pop") of passing the fascias was noted as 0 (not felt) or 1 (felt). The possibility of nerve displacement with the needle, the difficulty of intraneural injection and the possibility of nerve penetration and nerve swelling were all recorded as 0 (not possible) or 1 (possible). The two groups were comparable in terms of sex, age and BMI. Visibility of the SCM muscle and the needle was better in the Thiel group. Moreover, the "pop" feeling and nerve swelling were significantly more frequently present in the Thiel group. There was no significant difference in terms of the other results between the two groups. Cadavers embalmed according to Thiel's method should be recommended for ultrasound-guided punctures as a realistic and lifelike model.