Should the technique of surgical cricothyroidotomy be practiced on cadavers and should it be a compulsory part of the teaching curriculum? Is it wise to use a speculum for the insertion of the endotracheal tube? What is the optimum size of the tube?
A surgical cricothyroidotomy with a speculum was carried out on 30 cadavers from the Institute of Legal Medicine, Medical School Hannover. This took place as part of a official and voluntary course for students of advanced semesters, anaesthetists and emergency doctors with the subjects “cricothyroidotomy, chest drainage and venous cut-down”. The surgical cricothyroidotomy without the use of a speculum was carried out on 5 cadavers by two clinicians well practiced in this technique. The elapsed time between skin incision and the insertion of the endotracheal tube was measured on all five subjects. After the course the participants were asked if they were able to carry out a cricothyroidotomy in an emergency. They were also asked whether this course should be a compulsory part of their curriculum and whether practical sessions should take place. During autopsies at the Institute of Legal Medicine the length of the ligamentum conicum was measured on 40 corpses with reclined and non-reclined heads.
The average time of storage of the cadavers was 4.2 days +/- 1.9 days. The cricothyroidotomy was possible on all 35 cadavers. In one case (3,3 %) the result was a complete rupture of the cricoid cartilage. In 5 cases (16.7 %) the horizontal incision was torn due to prising with the speculum. Difficult situations always occured when the skin incision was not exactly in the midline. The average time to place the endotracheal tube into the trachea by the surgical procedure of cricothyroidotomy was 22.4 seconds +/- 3.1 seconds (minimum 18 seconds, maximum 26 seconds). 10 % of the medical students and 50 % of the anaesthetists and emergency doctors felt they would be prepared to carry out a cricothyroidotomy in an emergency. 90 % of the students and respectively 80 % of the anaesthetists and emergency doctors stated that they would like to practice the technique on a cadaver again. Almost all participants were of the opinion that the course should be integrated as a compulsory course in a future educational curriculum. The average distance between the thyroid cartilage and the cricoid cartilage was 9.5 mm +/- 1.9 mm with non-reclined head (minimum 6 mm, maximum 14 mm) and 11.9 mm +/- 2.5 mm with reclined head (minimum 7 mm, maximum 18 mm). The average difference of distances was 2.4 mm +/- 1.2 mm (minimum 1 mm, maximum 6 mm) in reclined and non-reclined heads.
In our opinion it is highly recommended that the technique of cricothyroidotomy should be practiced on cadavers and that the course should become a compulsory part in a future educational curriculum. In addition the incision of the ligamentum conicum using dilators or a speculum is not to be recommended from the point of view of this study. The tracheal tube used in this study (reinforced wire tube, ID 6.0) was best suited for surgical cricothyroidotomy.