Fig. 13

Localisation of the cricothyroid membrane. Orange is the anterior part of the tracheal rings. Red is the anterior part of the cricoid cartilage. The turquoise line is the shadow from the needle that has been slid underneath the transducer and placed just cranial to the cricoid cartilage, thus indicating the position of the lower part of the cricothyroid membrane, where an emergency airway access should be performed. a The patient is lying supine and operator stands on the patient’s right side facing the patient. b The linear transducer is placed transversely over the neck just above the suprasternal notch and the trachea is observed in the midline. c The transducer is moved to the patient’s right side so that the right border of the transducer is superficial to the midline of the trachea. d The right end of the transducer is kept in the midline of the trachea while the left end of the transducer is rotated into the sagittal plane, resulting in a longitudinal scan of the midline of the trachea; the caudal part of the cricoid cartilage is seen (red). e The transducer is moved cranially and the cricoid cartilage (red) is seen as a slightly elongated structure that is significantly larger and more anteriorly than the tracheal rings. f A needle is moved under the transducer from the cranial end, used only as a marker. The shadow (turquoise line) is just cranial to the cranial border of the cricoid cartilage. g The transducer is removed and the needle indicates the distal part of the cricothyroid membrane