Bronhoskopija in krikotirotomija: primerjava Thielove fiksirne metode z ostalimi metodami fiksacije in pri živih Bronchoscopy and cricothyrotomy: results from cadavers embalmed with Thiel's method compared to other embalming methods and living subjects Avtor / Author Ustanova / Institute Georg Feigl1, Mehdi Benkhadra2,3, Frangois Lenfant4, Pierre Trouilloud3, Friedrich Anderhuber1, Philippe Bonniaud5, Jean HD Fasel6, Wolfgang Nemetz7 1 Institute of Anatomy, Medical University Graz, Austria, 2 Department of Anesthesiology and Intensive Care, Hospital Le Bocage, Teaching Hospital, Dijon, France. 3 Laboratory of Anatomy, University of Burgundy, Dijon; France. 4 Department of Anesthesiology and Intensive Care, Hospital Général, Teaching Hospital, Dijon, France. 5 Respiratory Department, Hospital Le Bocage, Teaching Hospital, Dijon, France. 6 Division of Anatomy; Department of Morphology, University of Geneva; Switzerland 7 Departments of Anaesthesiology and Intensive Care Medicine, University Hospital, Medical University Graz, Austria. Ključne besede: Thielova metoda, koniotomija, bronhoskopija, fiksirna metoda, krikotirotomija Key words: Thiel's method, coniotomy, bronchoscopy, embalming method, cricothyrotomy Članek prispel / Received 01.07.2008 Članek sprejet / Accepted 21.10.2008 Naslov za dopisovanje / Correspondence Dr. Georg Feigl, Institute of Anatomy, Medical University Graz Austria, Harrachgasse 21, 8010 Graz, Austria Tel.: 0043131613804213 ; Fax.: 0043/316/3809620 ; E-Mail: georg.feigl@meduni-graz.at Izvleček Namen: Krikotirotomija in bronhoskopija sta bili opravljeni in ovrednoteni na truplih fiksiranih s Thi-elovo metodo. Namen raziskave je bil ugotoviti ali je Thielova metoda primerna za praktične vaje in raziskave za oba postopka. Metode: Slepa krikotirotomija je bila narejena na 40 truplih z uporabo dveh različnih setov - Cook in Portex setom, vsaka na 20 truplih. Bronhoskopija je bila narejena na 22 truplih. Vsi postopki so bili posneti. Opravljene postopke so opravili anatomi in anestezisti in jih primerjali s posegi pri živih ljudeh. Ocenili so obnašanje tkiva, odpor ligamentov, tipnost anatomskih struktur, barvo sluznic, otrplost trupla, še posebej pomik čeljusti in dvig jezika za vstavitev bronhoskopa. Prikazani so do- Abstract Purpose: Cricothyrotomy and bronchoscopy were performed on cadavers embalmed according to Thiel's method, and the results compared with findings from other types of cadavers and living subjects, to assess the suitability of such specimens for medical teaching and research. Methods: Blind cricothyrotomy was performed in 40 cadavers using two different devices (Cook and Portex sets) on each of 20 cadavers and the procedures were recorded by a monitoring fibreoptic broncho-scope placed in the larynx. Bron-choscopy was performed on another 22 cadavers. All procedures were videotaped and evaluated by board certified anatomists and anaesthetists. Tissue behaviour, ligament resistance, palpability of anatomical bljeni rezultati s kvalitativno primerjavo pri živih in truplih, ki so bila fiksirana s klasično formalinsko metodo. Rezultati: Portex in Cook postopki so bili izvedeni pri vseh primerih. Lezije mukoze so bile ocenjene makroskopsko. Trupla so odgovarjala za vrednotenje vseh kriterijev za prikaz življenske situacije. Bronhoskopija je bila izvedljiva pri vseh truplih brez težav. Pomik čeljusti in dvig jezika niso bili omejeni in vedno je bil možen dostop do lobarnih bronhijev. Bronhoskopija je bila omejena s premerom dihalnih poti na nivoju malih bronhijev ali manjše količine tekočine v polovici primerov. Zaključek: Trupla fiksirana po Thielovi metodi so izjemno dobro uporabna za raziskave pri krikotirotomiji in bronhoskopiji. Pozitiven učinek tega pristopa je ta, da so podatki primerljivi s podatki pri živih. Tako fiksirana trupla so uporabna za praktične vaje, saj nam zagotavljajo podobno situacijo kot pri živih. • structures, mucosal colour and cadaver flexibility, especially during jaw thrust and tongue lift, were evaluated and qualitatively compared to conditions found in the living and to reports of studies using specimens embalmed with the classic formalin method. Where the procedures caused mucosal lesions, the damaged was assessed during subsequent dissection. Results: The cadavers were life-like in all criteria evaluated. Portex and Cook cricothyrotomy was feasible in all cases. Bronchoscopy was feasible in all cadavers without difficulty. Jaw thrust and tongue lift was never limited and lobar bronchi were always reached. Further advancement was limited in half of the cases by either the preservation liquid or the diameter of the segmental bronchi; in the remaining half, advancement into the smaller airways was limited only by their diameter. Conclusion: Cadavers fixed according to Thiel's method are highly useable, life-like specimens for teaching and researching cricothyrotomy and bronchoscopy. The data obtained are transferable to the living, so research findings should be valid and teaching effective. Introduction Cricothyrotomy and bronchoscopy require a good deal of skill for accurate performance. Both are performed by doctors from a variety of specialist backgrounds, such as surgeons, anaesthetists and, for cricothyrotomy, emergency physicians. Cricothyrotomy - also known as coniotomy 3 or laryngotomy 4 - is one of the safest and quickest ways to obtain an emergent airway in "can't intubate, can't ventilate" patients, with efficacy confirmed by several authors 1,2,5,6. Unlike crico-thyrotomy, bronchoscopy is conducted regularly, in well supervised and prepared conditions, in operating theatres. Clinicians performing either procedure require considerable experience to avoid failure or complications. 6 Careful technique must be combined with sound knowledge of anatomy, precise orientation and palpation and appropriate equipment 6. New devices have been introduced to simplify the procedures and minimize risks. Before being used on the living, they were tested on embalmed cadavers 7,8 or otherwise 9,10. Training in these techniques may also involve the use of cadavers 8, 28. To support such research and teaching, anatomists have been developing embalming methods with the aim of producing models with near life-like characteristics. Among these embalming techniques, cadavers "Preserved According to Thiel's Embalming Method" 11 (PATEM) are widely used for surgical and anaesthetic training 12, 13, 14, 15, 16 and for research 17. For example, studies of nerve block models show that the distribution of embalming solutions injected into cadavers is comparable to the distribution of injected anaesthetic agents in the living. 17,18,19 . Fig.1: Outside and inside view of a cricothyroidotomy with the use of a Melker set: Insertion and arrival of the needle are clearly shown. Fig. 4: View for the anaesthetist performing the fibre-optic bronchoscopy: the location of the cricothyroid ligament (1), the arch of cricoid cartilage (2) and the trachea are marked. Fig. 2: Outside and inside view of a cricothyroidotomy with the use of a Melker set. The aim of this study is to report on our experience of performing cricothyrotomy and bronchoscopy on cadavers PATEM and compare it to conditions in the living human and to the results of studies of these techniques performed on cadavers embalmed with other methods. In particular, we looked at whether cadavers PATEM are suitable for research on and training in these procedures. Table 1: Characteristics of the cricothyrotomy cadavers Cook Group (n=20) Portex Group (n=20) Men 12 (60%) 12 (60%) Women 8 (40%) 8 (40%) Age (years). 81±15 77±12 Body Mass Index (kg.cm-2) 21.8±2.7 23.2±3.1 Cervical circumference (cm) 42.0±4.9 42.5±5.2 Tracheal anteroposterior diameter (mm) 17.8±2.4 7.0±0.8 Thyromental distance (cm) 7.0±0.9 7.0±0.8 Cormack and Lehane score: 1 2 18 (90%) 2 (10%) 19 (95%) 1 (5%) Data are expressed as means ± SD or number (percentages). There were no significant differences between the groups. Table 2: Characteristics of the bronchoscopy cadavers (n=22) Men 11 (50%) Women 11 (50%) Age (years). 75,3±11,4 Body Mass Index (kg.cm2) 21,4±2,8 Cervical circumference (cm) 35,3±4,6 Tracheal anteroposterior diameter (mm) 17,2±3,6 Thyromental distance (cm) not mesaured Cormack and Lehane score: 1 2 not mesaured not mesaured Data are expressed as means ± SD or number (percentages). Matherial & Methods The study was conducted in the anatomical laboratory of the Institute of Anatomy, Medical University Graz, Austria. The human cadavers were supplied by people who in their wills donated their bodies to the Institute for scientific purposes. 62 cadavers were used. Cricothyrotomy was performed on 40 cadavers (Tab. 1) and bronchoscopy on 22 cadavers (Tab. 2). All cadavers were randomly selected by taking the cadavers in the row as they arrived at the department of Anatomy during a certain time of period. Cricothyrotomy Blind cricothyrotomies were conducted by two board certified anaesthetists on 40 human PATEM cadavers 11 without fibreoptic assistance. Two different devices - the Cook, also known as the Melker, set (Fig. 1 and 2) and the Portex, also know as the PCK, set (Fig.3) - were employed on 20 cadavers Fig. 3: Outside and Inside view of a cricothyroido-tomy with the use of the PCK set. each. These two sets were chosen because they represent the most commonly used devices in clinical practice; each requires a different technique, which must be practiced before use in an emergency. A newly developed device was used for each cadaver to record epidemiological data (age, sex) and mor-phometric data (such as body mass index, neck circumference, thyromental distance, the difficulty in manually identifying the cricothyroid ligament and the Cormack and Lehanne score). Before each procedure began, a fibreoptic bronchoscope (Olympus LF type V; Visera tracheal intubation videoscope, Olympus® Medical Systems Corp. Vienna, Austria) was placed through the oral cavity and oropharynx into the larynx and maintained in this position in order to get a good of view of the infraglottic cavity, the trachea and the posterior wall of the larynx and trachea (Fig.1). All fibreoptic procedures were performed by a third anaesthetist. The cricothyrotomies were videorecorded in order to check the position of the airway catheter and to document possible larynge-al or tracheal lesions caused by the two procedural anaesthetists. All lesions identified by fibroscopy were anatomically confirmed by dissection, performed by an anatomist while the airway catheter was kept in place. Additionally, the lesions were photographed and compared to images recorded during bronchoscopies on living patients. Bronchoscopy Bronchoscopy was performed by one board certified anatomist and one board certified anaesthetist on 22 additional cadavers. All cadavers were placed in the supine position with the neck slightly elevated and extended. The fibreoptic broncho-scope (Olympus LF type V; Visera tracheal intubation videoscope, Olympus® Medical Systems Corp. Vienna, Austria) was inserted, transorally advanced and placed cephalad to the laryngeal inlet (Fig. 5). Particular attention was made to evaluate jaw thrust and tongue shift, which are necessary manoeuvres for the proper insertion of the bronchoscope. The bronchoscope was further advanced to the trachea to be positioned close to and cephalad to the tracheal bifurcation. Subsequently, it was pushed into the pulmonary airways as far as possible. The success of this procedure was determined by arrival at a lobar bronchus. The procedures were video recorded on tape. When lesions occurred, they were investigated as a thorough dissection of the cadavers performed by the same anatomist during coursework for senior medical students. Additionally, the lesions were photographed and compared to images recorded during bronchoscopies on living patients. Evaluation of Thiels embalming method We took keen interest in documenting flexibility, ability to palpate anatomical landmarks, and the ease with which the cadavers could be positioned, particularly extending the neck, throughout the procedures. The specialists, anaesthetists and anatomists, considered tissue behaviour, cartilage consistency, ligament resistance and mucosal colour. We also evaluated mucosal and other tissue lesions and made detailed records of any prob- lems arising during the procedures, to help other researchers prepare for such incidents in future scientific investigations. The data were compared by the anaesthetists to images taken during bronchoscopies on the living and on cadavers embalmed with other methods, as well as reports from other studies using other embalming methods. Qualitative evaluation of tissue properties was performed; the results of quantitative assessments will be published separately. Results Cricothyrotomy The Portex and Cook groups were comparable in terms of age, sex, morphometric data (body mass index, neck circumference, thyromental distance, the difficulty in manually identifying the cricothyroid ligament) and Cormack and Lehane score. The anteroposterior diameters of the trachea were also comparable between the two groups (Tab. 1). Cricothyrotomies were easily performed in all cases except one. In the ex- ceptional case, the cadaver was eventually positioned appropriately but the procedure lasted more than five minutes and was, therefore, classified as a failure. Even in this case, there were no problems with palpation or orientation of the cadaver. In all cases it was easy to locate the cricothyroid membrane because of the life-like consistency and resistance of the cadaver skin. The search for the cricothyroid membrane took more than 10 s in the Portex group in one case and more than 10 s in the Cook group in three cases. We could not identify a specific reason for the longer duration in the Cook group. All procedures were performed without being limited by inappropriate cadaver flexibility, orientation or palpability. There were no problems with concurrent fibreoptic observation. Bronchoscopy Bronchoscopy was feasible on all 22 cadavers. The jaw thrust and tongue lift necessary for accurate insertion of the bronchoscope were never limited (Tab. 2). The missing tonus of the tongue made insertion of the bronchoscope more difficult in five cases. Before reaching the laryngeal Fig. 5A and B: Two fibreoptic views of the laryngeal inlets of cadavers PATEM. inlet, it was in most cases necessary to aspirate the embalming liquid but the presence of the liquid never made insertion impossible. The tracheal bifurcation was reached and clearly identifiable. The fibreoptic bronchoscope could be advanced via the two principal lobes into the lobar bronchi without difficulty in all cases. Further advancement was limited in half of the cases by either the preservation liquid or the diameter of the segmental bronchus. In the remaining half, the fibreoptic bronchoscope could be advanced into the segmental bronchi and advance into smaller airways was limited only by their diameter. Evaluation of the effects of Thiels embalming method on cricothyrotomy and bronchoscopy and comparison to procedures in the living (Tab. 3) The flexibility of the cadavers enabled them to be positioned properly with ease. Extension of the neck was performed without difficulty and fibreop-tic bronchoscopy was feasible in all cases. There were no problems palpating the cartilaginous structures of the larynx and connective tissue such as the thyrohyoid membrane or the cricothy-roid ligament. Tissue behaviour during procedure was considered life-like and the ligaments had a resistance comparable to that of living tissue. Prior to bronchoscopy it was necessary to aspirate the embalming liquid with the aid of a suction device. This was done without restricting the view of the anaesthetist performing the fibreoptic bron-choscopy, the evaluation of the procedure or the documentation of lesions (Fig. 4). A low degree of mucosal calcification was evident but did not interfere with the procedures. In general, the mucosa was slightly pink in most of the areas of the larynx, trachea (Fig. 1, 2, 3, 4 and 5) and pulmonary airways (Fig. 6), similar to images found of living subjects (Fig. 7). However, some areas were pale or slightly less colourful. Discussion Manual skills are of paramount importance for doctors, who perform a variety of procedures with precision, care and responsibility. This is essential, for example, for bronchoscopy and cricothyrotomy. Their indications and frequency of use are \ ^ght main 6A bfonchus Figure 6A, B and C: The images show bronchoscopic views of the lobar bronchus of the right lung (6A) and the segmental bronchus of the right inferior lobe (6B) and the smaller bronchus of one of a segmental lobe (6C) on a cadaver PATEM. There are no limitations caused by liquid and diameter of the airways. Colour is slightly pink. There are sm^ll calcifications (white arrow) which do not limit the procedure. Table 3: Overview of the properties evaluated Thiel's method Living human Classic formaldehyde fixation Flexibility, positioning No limitation Physiologically no limitation Strongly limited Neck extension No limitation No limitation Limited Jaw thrust No limitation No limitation Limited Tongue lift No imitation, because of softness sometimes difficult No limitation Limited Mucosa colour and properties Slightly pink, pale, sometimes small calcifications Pink Pale, white, grey Palpation of cartilage Easy, lifelike - Possible, sometimes very difficult Consistency of cartilage Lifelike - Hard, sometimes lifelike Resistance of ligaments Perceptible, lifelike Perceptible Perceptible, hard Skin Soft, lifelike resistance, wet Hard, not flexible Figure 7: Comparison of two bronchoscopies: 7A shows the bronchoscopy on the cadaver with a view on the tracheal bifurcation whereas 7B represents a bronchoscopic view on the tracheal bifurcation on the living. Small calcifications marked with a white arrow can be identified. different but both call for a good deal of practice to reduce the risks complications or failure. It is thought these skills should be acquired through practice with models or cadavers before use on the living. 20 21 22. Horlocker, for instance, places particular emphasis on the role of anatomical departments in providing training facilities and cadavers, with the objectives of building confidence and enhancing the effectiveness of doctors who perform regional anaesthesia 22; Walls stresses the importance of familiarity with anatomy for successful cricothyrotomy 23; and Wood goes as far as claiming that simulated practice should be a condition for subsequent clinical practice 24. Recent developments include special plastic models for fi-breoptic bronchoscopy, 25 3D-animated computer models for anaesthetic blocks 26 and Goldmann and Steinfeldt's AccuTouch Bronchoscopy Simulator for managing the difficult airway 27. These technologies have proved to be most useful in countries without access to anatomical teaching. However, there is no denying that the training on cadavers is a common and excellent teaching tool. 27 There have been several studies on cricothyrotomy. Mutzbauer gave a detailed account of training anesthetic assistants and medical students using unembalmed cadavers 10 and Hatton investigated cricothyrotomy, retrograde intubation and fibre-optic bronchoscopy on embalmed cadavers 7 (see below). The risks of cricothyrotomy include oe-sophageal perforation, puncture of the thyroid vessels and fracture of the larynx. The risks are heightened by the circumstances in which the procedure is typically undertaken, namely, in the pre-hospital phase or emergency room. 6, 28 Studies of the types of complications and their risks have involved freshly frozen cadavers, 9, 29 unembalmed cadavers, formaldehyde-embalmed cadavers and plastic models which all fail to display the biomechanical properties observed in vivo. In one cadaver study, the risk with the Cook cricothyrotomy kit was exclusively of punctiform wounds of the posterior wall of the larynx, which occurred in up to 20% of procedures 8. This study also showed that the data was valid and transferable to the living. The experimental model used in the present study is similar to that described in the paper of Hat-ton7. The major difference is the comparison of the results of Thiel's embalming method to conditions found in the living. Regrettably, Hatton did not provide information about the embalming method or supply images of the quality of the cadavers, which would have been of great interest. The search for the optimal embalming method, one which provides life-like conditions, is ongoing. However, several publications have described Thiel's method as having exceptional benefits, particularly for surgical and anatomical investigations as well teaching purposes. 11, 12, 14, 16. The technique was developed by Thiel at the Institute of Anatomy, Medical University Graz, Austria, in 199211. It offers excellent cadaver conservation, spectacular flexibility, natural colours and limited respiratory and eye irritation for operators. More recently, Peuker successfully employed this technique to produce cadavers for the study of the cervical and facial regions; 14 Alberty used it in the field of otology 12; Umfahrer utilized it for trials on the spread of local anaesthetics for mandibular nerve blocks, eventually concluding that the results of injections into PATEM cadavers were transferable to the living18; and Feigl confirmed this conclusion in several publications 17, 19. In addition, Feigl favourably evaluated cadaver PATEM properties for workshops on regional anaesthesia, finding that the cadavers could be easily positioned for the different blocks, the bony landmarks could be readily palpated and the tissue quality was good. 16 Ours is the first study to evaluate Thiel's embalming method for both the life-saving skill of cricothy-rotomy and the more commonly performed procedure of fibreoptic bronchoscopy. Because all procedures were performed with continuous fibreoptic recording by an experience bronchoscopist, tissue behaviour could be assessed both by the procedur-alist and independently. We - four anatomists and four anaesthetists- concluded that the colours, textures, structures, and consistencies of the different tissues were comparable to in vivo conditions. This has implications for training in cricothyrotomy, a procedure that requires extension of the neck and, therefore, flexible specimens. 1 Our findings contradict those of Alberty12 and Peuker14 regarding mucosal colour and cartilage consistency. Peuker described a dark red coloration, possibly caused by the muscles underlying the mucosa, whereas Alber-ty observed a pale mucosa because of the missing blood supply. Alberty also found the cartilage much softer than living cartilage. This may be because Alberty assessed the auricula, which is composed of elastic cartilage. Both the thyroid and cricoid cartilages, however, are made out of hyaline cartilage, which we found to have a consistency fully comparable to that of living humans. The main drawback of Thiel's embalming method is that excessive embalming fluid may limit bron-choscopy in some cases. Fortunately, the liquid is easily aspirated. Another potential visual problem may be calcification caused by the concentration of salt in the embalming fluid, although this is usually minor. We have not yet encountered any limitation of any procedure during research or training from this calcifying process. The qualities of cadavers PATEM surpass that of unembalmed cadavers, which also carry a risk of infection. Moreover, time is limited to work on fresh cadavers owing to the rapidly advancing process of decay30. And even fresh cadavers can be difficult to use; Mutzbauer, for example, described difficulties with neck extension (however, in that study the bodies had a temperature of 4° Celsius, which is certainly low enough to limit flexibility and positioning). 10 The more commonly used "classic" formaldehyde fixation or phenol preservation of cadavers produces a far lower degree of flexibility than Thiel's method. Disadvantages include the inability to palpate landmarks and the impossibility of appropriate positioning, which makes it impractical to perform the special manoeuvres required for some procedures, such as such as jaw thrust or tongue lift for bronchoscopy. 7, 10, 16 This makes it impossible to perform concurrent bronchoscopy, which in turns hampers the immediate evaluation and precise documentation of the success or failure of cricothyrotomy. Moreover, the quality of research and training are adversely affected by the unnatural hardening of the tissue. In real life, cricothyrotomy is usually performed in emergencies. Bronchoscopy is more frequently performed but is difficult to learn. Both are invasive procedures that cannot ethically be studied on volunteers. Practicing fibreoptic bronchoscopy on anaesthetized patients is also a balancing act between ethical laws and the undoubtedly need for educational training 31, 32. Bartley, for instance, writes that "learning by doing" on the living is ethically not justifiable and warns against exposing living patients to additional risks. 33 Cadaver training has therefore been recommended to help build confidence, develop manual skills, broaden specialist knowledge and gain experience. Our model may provide more suitable and realistic conditions than manikins, animal models, fresh cadavers or cadavers embalmed with other techniques, producing results that can reasonably be extrapolated to clinical conditions. It may provide near-perfect, safe and ethically appropriate training for emergency physicians, surgeons, anaesthetists and other doctors wanting to gain competence, experience and the manual skills needed for specific clinical procedures before performing procedures on the living. It suits the high ethical standards of clinicians and is solely for the good of the patients. Acknowledgements We would like to thank Denis Genelot, principal of the Department of Anatomy of Dijon; Andreas Sammer, tutor of the Institute of Anatomy, Graz; and the laboratory assistants of the Institute of Anatomy, Graz, for their helpful technical support. In addition, we would like to thank Mr. Herbert Lukas for the preparation of our manuscript. • Financial Support: This study was supported solely by governmental sources (Ministères Frangais de la Santé, de la Recherche et de l'Education Nationale). No conflict of interest has been declared. Cook® (Charenton, France), PortexSmiths® (Hythe, UK) and Olympus® (Wien, Austria) laboratories provided the equipment used and tested free of charge. References: 1. Mace SE. Cricothyrotomy. L Emerg Med 1988; 6: 309 2. Henderson JJ, Popat MT, Latto IP, Pearce AC. Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia 2004;59: 675-94 3. Hafferl A. Regio laryngea: Zugänge zum Larynx. In Hafferl A (Ed) Lehrbuch der topographischen Anatomie, third edition. Springer Verlag: Berlin; 1968. p 257 4. Bannister L. Respiratory system. In Williams PL. Gray's Anatomy, Thirty-eighth edition. Elsevier Churchill Livingstone: New York; 1995. p 1650 5. Boyd AD, Romita MC, Conlan AA, Fink SD, Spencer FC. A clinical evaluation of cricothyroidotomy. Surg Gynecol Obstet 1979; 149: 365-68 6. McGill J, Clinton JE, Ruiz E. Cricothyrotomy in the emergency department. Ann Emerg Med 1982; 11: 361-64 7. Hatton KW, Price S, Craig, L, Grider JS. Educating anesthesiology residents to perform percutaneous cricothyrotomy, retrograde intubation, and fiberoptic bronchoscopy using preserved cadavers. Anesth An-alg 2006; 103 (5): 1205-08 8. Benkhadra M, Lenfant F, Nemetz W, Anderhuber F, Feigl G, Fasel JHD. Comparison of two cricothyroidotomy kits in human cadavers. Anesth Analg 2008;106 (1): 182-85 9. Schiri pour Tschrlou A, Klappenberger J, Klappen-berger S, Firbas W. A new device for cricothyroidotomy. Clin Anat 2006; 19: 602-04 10. Mutzbauer TS, Munz R, Helm M, Lampl LA, Herrmann M. Notfallkoniotomie, Punktion oder chirurgisch-anatomische Präpariertechnik? Anaesthe-sist 2003; 52: 304-10 11. Thiel W. Die Konservierung ganzer Leichen in natürlichen Farben. Ann Anat 174 1 992;: 185-95 12. Alberty J, Filler TJ, Schmal F, Peuker ET. Nach Thiel fixierte Leichenohren: Ein neues Verfahren für die Aus- und Weiterbildung in der Mittelohrchirurgie. HNO 2002; 50: 739-42 13. Groscurth P, Eggli P, Kapfhammer J, Rager G, Hornung JP, Fasel JD. Gross anatomy in the surgical curriculum in Switzerland: improved cadaver preservation, anatomical models, and course development. Anat Rec 2001; 265: 254-56 14. Peuker ET, Werkmeister R, Pera F, Joos U und Filler TJ. Operative Verfahren der Mund-, Kiefer- und Gesichtschirurgie an nach Thiel fixierten Körperspenden. MundKieferGesichtschir 2001; 5: 141-43 15. Jerosch J, Peuker E, Philipps B, Filler T. Interin-dividual reproducibility in perioperative rotational alignment of femoral components in knee prosthetic surgery using the transepicondylar axis. Knee Surg Sports Traumatol Arthrosc 2002; 10: 194-97 YES: Page 3 second paragraph! 16. Feigl G, Anderhuber F, Schwarz G, Dorn C, Fasel JH, Likar R Trainingsmethode für Regionalanästhesisten, Evaluierung und Vergleich. Anaesthesist 2007; 6 (5): 437-44 17. Feigl G, Rosmarin W, Weninger B, Likar R. Comparison of Different Injectate Volumes for Stellate Ganglion Block: An Anatomical and Radiological Study. Reg Anesth Pain Med 2007; 32 (3): 20308 DONE; you were right; wrong title! 18. Umfahrer P, Santler G, Preidler K, Weiglein A. Anatomische und magnetresonaztomographische Untersuchung einer neuen Technik der Leitungsanästhesie des Nervus mandibularis. Stomatologie 2002; 99 (7): 169-80 19. Feigl G, Fuchs A, Gries M, Hogan QH, Weninger B, Rosmarin W. A supraomohyoidal plexus block designed to avoid complications. Surg Radiol Anat 2006; 28 (4): 403-09 20. Browning GG. Training in temporal bone surgical skills. ENT News 2000; 9: 22-23 21. Mills R, Lee P. Surgical skills training in the middle ear surgery. J Laryngol Otol 2003; 117 (3): 15963 Title correct! 22. Horlocker TT. Peripheral Nerve blocks. Regional anaesthesia for the new millennium. Reg Anesth Pain Med 1998; 23 (3): 237-240 YES 23. Walls RM. Cricothyroidotomy. Emerg Med Clin North Am 1988; 6: 725-36 24. Wood PR, Dresner M, Lawlwer GP. Training in fiberoptic tracheal intubation in the North of England. BJA 1992;69: 202-03 25. Dykes MHM, Ovassapian A. Dissemination of fibre-optic airway endoscopy skills by means of a workshop utilizing models. BJA 1989; 63: 595-97 26. Lim MW, Burt G und Rutter SV. Use of three-dimensional animation for regional anaesthesia teaching: application to interscalene brachial plexus blockade. BJA 2005; 94 (3): 372-77 27. Goldmann K, Steinfeldt T. Acquisition of basic fiberoptic intubation skills with a virtual reality airway simulator. J Clin Anesth 2006; 18: 173-78 28. Boon JM, Abrahams PH, Meiring JH, Welch T. Cricothyroidotomy: A clinical anatomical review. Clin Anat 2004; 17 (6): 478-86 29. Bennett JDC, Guha SC, Sankar AB. Cricothyro-tomy: the anatomical basis. J R Coll Surg Edinb 1996; 41: 57-60 30. Schwarz G, Kleinert R, Dorn C, Litscher G, Feigl G, Bock N. Pneumatic pulse simulation in cadavers for teaching peripheral nerve blocks. The Internet Journal of Anesthesiology 2000; 4N3. www. icaap.org/iuicode?81.4.3.9. [is there an abbreviation for this journal title?] 31. Vaughan RS. Training in fiberoptic laryngoscopy (editorial). BJA 1992; 66: 538-40 32. Cole AF, Mallon JS, Rolbin SH, Ananthanarayan C. Fiberoptic intubation using anesthetized, paralyzed, apneic patients: results of a resident training program. Anesthesiology 1996; 84 (5): 1101-06 33. Bartley C und Shelton JM. Ethics of training in regional anaesthesia. Anaesthesia 2004; 59: 406-07