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A porcine model for teaching surgical cricothyridootomy

Abstracts

OBJECTIVE:

To evaluate the acceptability of an educational project using A porcine model of airway for teaching surgical cricothyroidotomy to medical students and medical residents at a university hospital in southern Brazil.

METHODS:

we developed a teaching project using a porcine model for training in surgical cricothyroidotomy. Medical students and residents received lectures about this surgical technique and then held practical training with the model. After the procedure, all participants filled out a form about the importance of training in airway handling and the model used.

RESULTS:

There were 63 participants. The overall quality of the porcine model was estimated at 8.8, while the anatomical correlation between the model and the human anatomy received a mean score of 8.5. The model was unanimously approved and considered useful in teaching the procedure.

CONCLUSION:

the training of surgical cricothyroidotomy with a porcine model showed good acceptance among medical students and residents of this institution.

Airway; Cricoid cartilage / surgery; Thyroid cartilage / surgery; Teaching / education


OBJETIVO:

avaliar a aceitabilidade de um projeto de ensino utilizando modelo porcino de vias aéreas no ensino da cricotiroidotomia cirúrgica para estudantes de Medicina e médicos residentes em um hospital universitário no sul do Brasil.

MÉTODOS:

foi desenvolvido um projeto de ensino usando modelo porcino para treinamento em cricotiroidotomia cirúrgica. Estudantes de Medicina e residentes receberam aula teórica sobre esta técnica cirúrgica e, em seguida, realizaram no modelo o treinamento prático. Após o procedimento, todos os participantes preencheram um formulário acerca da importância do treinamento em manuseio de vias aéreas e do modelo utilizado.

RESULTADOS:

houve 63 participantes. A qualidade geral do modelo porcino foi estimada em 8,8, enquanto a correlação anatômica entre o modelo e a anatomia humana recebeu o escore médio de 8,5 entre os treinandos. O modelo foi unanimemente aprovado e considerado útil no ensino do procedimento.

CONCLUSÃO:

o treinamento de cricotiroidotomia cirúrgica em modelo porcino apresentou boa aceitação entre os estudantes de Medicina e os residentes desta Instituição.

Manuseio das Vias Aéreas; Cartilagem Cricoide/cirurgia; Cartilagem Tireoidea/cirurgia; Ensino/educação


INTRODUCTION

Medical skills training, particularly in early phases, are increasingly based on simulation1Maran NJ, Glavin RJ. Low-to high-fidelity simulation - a continuum of medical education? Med Educ. 2003;37 Suppl 1:22-8.. Simulation is an interactive and immersive method of teaching, recreating in whole or in part a clinical experience, without exposing patients to associated risks1Maran NJ, Glavin RJ. Low-to high-fidelity simulation - a continuum of medical education? Med Educ. 2003;37 Suppl 1:22-8. , 2Beaubien JM, Baker DP. The use of simulation for training teamwork skills in health care: how low can you go? Qual Saf Health Care. 2004;13Suppl 1:i51-6.. Simulation modalities may vary according to the type of technology used. Among the low technology simulators, there are the models based on animals and on human or animal cadavers3Dent JA, Harden RM, editors. A Practical Guide for Medical Teachers. 2nd ed. Edinburgh: Elsevier; 2005..

Airway management is key in emergency situations4Comitê do Trauma do Colégio Americano de Cirurgiões. Suporte avançado de vida no trauma para médicos: manual do curso de alunos. 8a Ed. Chicago: American College of Surgeons; 2008.. Patients requiring a surgical airway may represent 1% of procedures for obtaining a definitive airway in urgency settings. However, since this method is used when the other techniques are unsuccessful, failure in obtaining a surgical airway commonly will lead to death due to hypoxemia5Bair AE, Panacek EA, Wisner DH, Bales R, Sakles JC.Cricothyrotomy: a 5-year experience at one institution. J Emerg Med. 2003;24(2):151-6.. Among the surgical airways techniques, cricothyrotomy is preferred over tracheotomy in emergency situations due its simplicity and rapid execution4Comitê do Trauma do Colégio Americano de Cirurgiões. Suporte avançado de vida no trauma para médicos: manual do curso de alunos. 8a Ed. Chicago: American College of Surgeons; 2008..

This article presents and analyzes the acceptability of a teaching project using an airway porcine model for surgical cricothyrotomy to medical students and residents in a university hospital in the south of Brazil.

METHODS

Since June 2013, in Universidade Estadual do Oeste do Paraná started a teaching project using porcine models in resuscitation procedures training for residents and last-year medical students. As part of this teaching project, trainees filled a feedback questionnaire about the used model. We analyzed the questionnaires used to assess the airways the porcine arway model filled by the participants from the start of the project until August 2014. Project approval: CR 40119/2013.

This teaching project comprised three steps: a) trainees attended a class about cervical anatomy and the surgical cricothyrotomy, according to the Advanced Trauma Life Support(r) (ATLS) principles; b) they performed the surgical cricothyrotomy in the porcine model, supervised by an ATLS instructor; c) they filled out an assessment questionnaire about the model (optional).

We obtained segments of porcine airways by donation from animals used for human consumption, according to regulatory sanitary rules.

We used a porcine arway segment from above the thyroid cartilage to about 10cm below the cricoid cartilage and a segment of pig skin (Figure 1). A plastic bag was adapted to the trachea end and the specimen was placed over a rigid wood surface (Figure 2). The specimen was covered with a segment of pork skin. In the internal segment of the pork skin, a rubber glove was attached and tensioned (Figure 3), to simulate a "new" cricothyroid membrane after the first procedure. The pork skin was then fixed to the rigid surface, allowing the airway segment to be moved below the skin in order to use the same model for several trainees (average of 10 trainees / model - Figure 4). A surgical cloth was placed over the plastic bag to simulate the chest movement seen during the bag ventilation. The step by step construction of the model and its operation can be observed on the site ( http://youtu.be/I8fDbost0O8 ).

Figure 1
- Porcine airway and skin specimens.

Figure 2
- Porcine airway on a rigid board with a plastic bag ("lung") adapted to its end.

Figure 3
- Porcine skin with glove fixed in the inner side. The glove simulates the cricothyroid membrane after the first procedure.

Figure 4
- Airway model ready to practice. The surgical cloth covers the "chest" and rises in each ventilation.

The questionnaire used inquired about epidemiological aspects, previous training in airway management and adequacy of the used model for training medical student and residents. Some of the answers from the questionnaire were not object of this study, but used to improve graduation teaching opportunities.

Specifically, we requested assessments about the general quality of the model (robustness, ease in handling, similarity with biological tissues) and anatomic correlation (similarity with human anatomy). Both varied from 0 to 10.

The questionnaire was elaborated by the senior author and was not previously validated. The questionnaire data was grouped and presented in absolute numbers and percentages.

During the development phase, three independent senior surgeons with experience in this procedure tested this model. They unanimously approved it as an educational tool and gave the average score of 8.7 to its general quality and 7.6 to the anatomical correlation.

The teaching group was composed by: a) medical students from emergency room internship (last year of our medical school); b) medical residents (first and second year) from general surgery and internal medicine who requested this training.

RESULTS

This project had 63 participants, 54 medical students and nine medical residents. There was no refusal in participate in the training or in filling the questionnaire. The average age was 26 ± 3.1 years old (22-39). Thirty-two were males, 29 females and two did not disclose this information. Among the tested trainees, 60 (95.2%) informed no previous training in the procedure.

All participants considered the proposed model as an important tool in teaching surgical cricothyrotomy to medical students. The average overall model quality was 8.8 (scores varied from 6-10). The anatomical correlation of the model was scored in average as 8.5 (scores varied from 6-10). All trainees evaluated approved the use of this model as a teaching adjunct for medical graduation.

DISCUSSION

Since cricothyrotomy is relatively infrequently required and the patients who need the procedure are usually in physiologic extremes, the development of experimental animals models for professional training are important to provide medical training6Reeder TJ, Brown CK, Norris DL. Managing the difficult airway: a survey of residency directors and a call for change. J Emerg Med. 2005;28(4):473-8. , 7Wong DT, Prabhu AJ, Coloma M, Imasogie N, Chung FF. What is the minimum training required for successful cricothyrotomy?: a study in mannequins. Anesthesiology. 2003;98(2):349-53.. Using animal models in airway procedures training is frequent, since biological tissues have higher similarity with human ones, when compared with synthetic materials8Stringer KR, Bajenov S, Yentis SM. Training in airway management. Anaesthesia. 2002;57(10):967-83. Erratum in: Anaesthesia. 2003;58(1):105. , 9Hedges J, Toomey TG. The 'Cambridge' surgical training device for cricothyrotomy and tracheostomy techniques. J Br Assoc Immed Care. 1989;12:11-2.. Also, animal models using porcine airways have low cost and are frequently easy to obtain1010 Cho J, Kang GH, Kim EC, Oh YM, Choi HJ,Im TH, et al. Comparison of manikin versus porcine models in cricothyrotomy procedure training. Emerg Med J. 2008;25(11):732-4..

Porcine models can present economical advantage when compared with mannequins1010 Cho J, Kang GH, Kim EC, Oh YM, Choi HJ,Im TH, et al. Comparison of manikin versus porcine models in cricothyrotomy procedure training. Emerg Med J. 2008;25(11):732-4.. In the current study, the porcine airway specimens were obtained as donation from trainees after these animals were abated for human consumption. Medical teaching based in passive techniques and knowledge acquisition verification based in written exams are not enough to assure competence, quality and safety when handling emergency situations1111 Flato UAP, Guimarães HP. Educação baseada em simulação em medicina de urgência e emergência: a arte imita a vida. Rev Soc Bras Clin Méd. 2011;9(5), set-out.. Most of incidents and serious adverse events that happen in hospitals are related to human factors1212 Dellifraine J, Langabeer J, King B. Quality improvement practices in academic emergency medicine: perspectives from the chairs. West J Emerg Med. 2010;11(5):479-85. , 1313 Bion JF, Abrusci T, Hibbert P. Human factors in the management of the critically ill patient. Br J Anaesth. 2010;105(1):26-33.. These figures are likely higher in emergency cases1212 Dellifraine J, Langabeer J, King B. Quality improvement practices in academic emergency medicine: perspectives from the chairs. West J Emerg Med. 2010;11(5):479-85. , 1313 Bion JF, Abrusci T, Hibbert P. Human factors in the management of the critically ill patient. Br J Anaesth. 2010;105(1):26-33. , 1414 Kothari D, Gupta S, Sharma C, Kothari S. Medication error in anaesthesia and critical care: A cause for concern. Indian J Anaesth. 2010;54(3):187-92.. Simulation tries to reduce these undesired outcomes, providing education based on active learning in low-risk environment, improving knowledge, the technique, and non-technical skills1111 Flato UAP, Guimarães HP. Educação baseada em simulação em medicina de urgência e emergência: a arte imita a vida. Rev Soc Bras Clin Méd. 2011;9(5), set-out.. Urgent surgical airway access is required when another technique is not feasible or failed4Comitê do Trauma do Colégio Americano de Cirurgiões. Suporte avançado de vida no trauma para médicos: manual do curso de alunos. 8a Ed. Chicago: American College of Surgeons; 2008., and frequently is performed by emergency physicians1515 Nelson MS. Models for teaching emergency medicine skills. Ann Emerg Med. 1990;19(3):333-5.. Performing this procedure can be difficult in the absence of adequate training1010 Cho J, Kang GH, Kim EC, Oh YM, Choi HJ,Im TH, et al. Comparison of manikin versus porcine models in cricothyrotomy procedure training. Emerg Med J. 2008;25(11):732-4.. Some suggest minimal training of 5 attempts or performing this procedure in 40 seconds in mannequins9Hedges J, Toomey TG. The 'Cambridge' surgical training device for cricothyrotomy and tracheostomy techniques. J Br Assoc Immed Care. 1989;12:11-2..

There are several teaching models used in airways management8Stringer KR, Bajenov S, Yentis SM. Training in airway management. Anaesthesia. 2002;57(10):967-83. Erratum in: Anaesthesia. 2003;58(1):105. , 1515 Nelson MS. Models for teaching emergency medicine skills. Ann Emerg Med. 1990;19(3):333-5.. Traditionally, cricothyrotomy teaching is performed in mannequins and animals due to ethical and economical reasons8Stringer KR, Bajenov S, Yentis SM. Training in airway management. Anaesthesia. 2002;57(10):967-83. Erratum in: Anaesthesia. 2003;58(1):105. , 1616 Cheong J. The use of animals in medical education: a question of necessity vs. desirability. Theor Med. 1989;10(1):53-7.. Among the animal models, the use of porcine airways is well-established1717 Gallagher EJ, Coffey J, Lombardi G, Saef S. Emergency procedures important to the training of emergency medicine residents: who performs them in the emergency department? Acad Emerg Med. 1995;2(7):630-3.

18 Fikkers BG, van Vugt S, van der Hoeven JG, van den Hoogen FJ, MarresHA. Emergency cricothyrotomy: a randomised crossover trial comparing the wire-guided and catheter-over-needle techniques. Anaesthesia. 2004;59(10):1008-11.
- 1919 Wang EE, Vozenilek JA, Flaherty J, Kharasch M, Aitchison P, Berg A. An innovative and inexpensive model for teaching cricothyrotomy. Simul Healthc. 2007;2(1):25-9.. Porcine airways and skin are relatively similar to human tissues8Stringer KR, Bajenov S, Yentis SM. Training in airway management. Anaesthesia. 2002;57(10):967-83. Erratum in: Anaesthesia. 2003;58(1):105. , 1818 Fikkers BG, van Vugt S, van der Hoeven JG, van den Hoogen FJ, MarresHA. Emergency cricothyrotomy: a randomised crossover trial comparing the wire-guided and catheter-over-needle techniques. Anaesthesia. 2004;59(10):1008-11.. In a previous randomized study, the similarity of porcine models with human tissues and anatomy was considered greater than the one of mannequins1010 Cho J, Kang GH, Kim EC, Oh YM, Choi HJ,Im TH, et al. Comparison of manikin versus porcine models in cricothyrotomy procedure training. Emerg Med J. 2008;25(11):732-4..

Medical training in airways management was uniformly considered important by trainees. This study presented an experimental airway porcine model based on low technology and cost for teaching surgical cricothirotomy in medical graduation. The used model was approved for medical training among all study participants. The model used in this study was tested by three independent seasoned physicians, who corroborated the high correlation with human anatomy. Trainees also graded the model similarity with human anatomy to be medium to high. Other studies have shown similar results2020 Kanji H, Thirsk W, Dong S, Szava-Kovats M, Villa-Roel C, Singh M, et al. Emergency cricothyroidotomy: a randomized crossover trial comparing percutaneous techniques: classic needle first versus ''incision first''. Acad Emerg Med. 2012;19(9):1061-7.. Each porcine airway model allowed 10 trainees in average to practice per specimen, due to the practice of sliding the model under the skin and glove. Alive models or cadavers do not allow repetition6Reeder TJ, Brown CK, Norris DL. Managing the difficult airway: a survey of residency directors and a call for change. J Emerg Med. 2005;28(4):473-8. , 8Stringer KR, Bajenov S, Yentis SM. Training in airway management. Anaesthesia. 2002;57(10):967-83. Erratum in: Anaesthesia. 2003;58(1):105.. This possibility adds practicality and economical advantage to the model.

The model used was developed at our institution, using local conditions. However, there are other described porcine airway models1717 Gallagher EJ, Coffey J, Lombardi G, Saef S. Emergency procedures important to the training of emergency medicine residents: who performs them in the emergency department? Acad Emerg Med. 1995;2(7):630-3.

18 Fikkers BG, van Vugt S, van der Hoeven JG, van den Hoogen FJ, MarresHA. Emergency cricothyrotomy: a randomised crossover trial comparing the wire-guided and catheter-over-needle techniques. Anaesthesia. 2004;59(10):1008-11.
- 1919 Wang EE, Vozenilek JA, Flaherty J, Kharasch M, Aitchison P, Berg A. An innovative and inexpensive model for teaching cricothyrotomy. Simul Healthc. 2007;2(1):25-9.. Also, it does not recreate all anatomical characteristics present in real situations, such as protuberant jaw, cervical immobilization, hematomas, urgency, obesity, etc. However, performing this procedure in a real situation without previous training or simulation may incur in ethical inadequacy, and may increase failure rates.

There are few physicians seasoned in surgical cricothyrotomy in the region. In consequence, only three tested the model. Nevertheless, other studies used similar animal models for training1010 Cho J, Kang GH, Kim EC, Oh YM, Choi HJ,Im TH, et al. Comparison of manikin versus porcine models in cricothyrotomy procedure training. Emerg Med J. 2008;25(11):732-4. , 1818 Fikkers BG, van Vugt S, van der Hoeven JG, van den Hoogen FJ, MarresHA. Emergency cricothyrotomy: a randomised crossover trial comparing the wire-guided and catheter-over-needle techniques. Anaesthesia. 2004;59(10):1008-11. , 1919 Wang EE, Vozenilek JA, Flaherty J, Kharasch M, Aitchison P, Berg A. An innovative and inexpensive model for teaching cricothyrotomy. Simul Healthc. 2007;2(1):25-9. , 2020 Kanji H, Thirsk W, Dong S, Szava-Kovats M, Villa-Roel C, Singh M, et al. Emergency cricothyroidotomy: a randomized crossover trial comparing percutaneous techniques: classic needle first versus ''incision first''. Acad Emerg Med. 2012;19(9):1061-7.. The trainees opinion about anatomical correlation may not be as accurate, since they have relatively low knowledge of the anatomy and low experience in airway management. Also, trainees may tend to give higher scores to the models to please their teachers, even though they anonymously filled the questionnaires. Thus, due to such limitations, the presented model needs additional assessment and validation with specific methodology and/or by other institutions.

The proposed porcine airway model had good acceptability for surgical cricothyrotomy. Considering the low cost and easy preparation, it presents good potential for training medical professionals in developing countries. Further studies are necessary to validate this model as a teaching tool.

REFERENCES

  • 1
    Maran NJ, Glavin RJ. Low-to high-fidelity simulation - a continuum of medical education? Med Educ. 2003;37 Suppl 1:22-8.
  • 2
    Beaubien JM, Baker DP. The use of simulation for training teamwork skills in health care: how low can you go? Qual Saf Health Care. 2004;13Suppl 1:i51-6.
  • 3
    Dent JA, Harden RM, editors. A Practical Guide for Medical Teachers. 2nd ed. Edinburgh: Elsevier; 2005.
  • 4
    Comitê do Trauma do Colégio Americano de Cirurgiões. Suporte avançado de vida no trauma para médicos: manual do curso de alunos. 8a Ed. Chicago: American College of Surgeons; 2008.
  • 5
    Bair AE, Panacek EA, Wisner DH, Bales R, Sakles JC.Cricothyrotomy: a 5-year experience at one institution. J Emerg Med. 2003;24(2):151-6.
  • 6
    Reeder TJ, Brown CK, Norris DL. Managing the difficult airway: a survey of residency directors and a call for change. J Emerg Med. 2005;28(4):473-8.
  • 7
    Wong DT, Prabhu AJ, Coloma M, Imasogie N, Chung FF. What is the minimum training required for successful cricothyrotomy?: a study in mannequins. Anesthesiology. 2003;98(2):349-53.
  • 8
    Stringer KR, Bajenov S, Yentis SM. Training in airway management. Anaesthesia. 2002;57(10):967-83. Erratum in: Anaesthesia. 2003;58(1):105.
  • 9
    Hedges J, Toomey TG. The 'Cambridge' surgical training device for cricothyrotomy and tracheostomy techniques. J Br Assoc Immed Care. 1989;12:11-2.
  • 10
    Cho J, Kang GH, Kim EC, Oh YM, Choi HJ,Im TH, et al. Comparison of manikin versus porcine models in cricothyrotomy procedure training. Emerg Med J. 2008;25(11):732-4.
  • 11
    Flato UAP, Guimarães HP. Educação baseada em simulação em medicina de urgência e emergência: a arte imita a vida. Rev Soc Bras Clin Méd. 2011;9(5), set-out.
  • 12
    Dellifraine J, Langabeer J, King B. Quality improvement practices in academic emergency medicine: perspectives from the chairs. West J Emerg Med. 2010;11(5):479-85.
  • 13
    Bion JF, Abrusci T, Hibbert P. Human factors in the management of the critically ill patient. Br J Anaesth. 2010;105(1):26-33.
  • 14
    Kothari D, Gupta S, Sharma C, Kothari S. Medication error in anaesthesia and critical care: A cause for concern. Indian J Anaesth. 2010;54(3):187-92.
  • 15
    Nelson MS. Models for teaching emergency medicine skills. Ann Emerg Med. 1990;19(3):333-5.
  • 16
    Cheong J. The use of animals in medical education: a question of necessity vs. desirability. Theor Med. 1989;10(1):53-7.
  • 17
    Gallagher EJ, Coffey J, Lombardi G, Saef S. Emergency procedures important to the training of emergency medicine residents: who performs them in the emergency department? Acad Emerg Med. 1995;2(7):630-3.
  • 18
    Fikkers BG, van Vugt S, van der Hoeven JG, van den Hoogen FJ, MarresHA. Emergency cricothyrotomy: a randomised crossover trial comparing the wire-guided and catheter-over-needle techniques. Anaesthesia. 2004;59(10):1008-11.
  • 19
    Wang EE, Vozenilek JA, Flaherty J, Kharasch M, Aitchison P, Berg A. An innovative and inexpensive model for teaching cricothyrotomy. Simul Healthc. 2007;2(1):25-9.
  • 20
    Kanji H, Thirsk W, Dong S, Szava-Kovats M, Villa-Roel C, Singh M, et al. Emergency cricothyroidotomy: a randomized crossover trial comparing percutaneous techniques: classic needle first versus ''incision first''. Acad Emerg Med. 2012;19(9):1061-7.
  • Source of funding: no

Publication Dates

  • Publication in this collection
    May-Jun 2015

History

  • Received
    05 Apr 2014
  • Accepted
    12 June 2014
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