InsideSurgery.com watched with interest a recent episode of the terrific ABC medical drama Burden of Proof staring Dana Delany as Dr. Megan Hunt, a neurosurgeon turned medical examiner.
Although we found the Body of Proof episode much more realistic than most medical television shows, one unconventional medical decision we noted was the script calling for a tracheostomy to be performed to establish an emergency airway in the field.
This is technically not correct as an emergency airway established in the field is always a cricothyroidotomy, not a tracheostomy. No doubt, the writers exercised understandable dramatic license in using the likely more familiar term (to the general public)Â ofÂ tracheostomy.
However, there are considerable technical and anatomic differences in the two procedures that should be highlighted to better educate any of the nine million viewers of the Body of Â Proof episode who might care to dig deeper into this subject and might consider actually performing this procedure in an emergency.
The key anatomic surgical difference between the two procedures lies in the location of the cricothyroid membrane through which a cricothyroidotomy is performed vs. the lower tracheal rings through which a tracheostomy is performed.
The cricothyroid membrane is fairly easy to palpate and lies between the two paired cricoid cartilages which are sometimes referred to as the Adam’s apple positioned in the middle of the neck.
This midline membrane can be palpated as a dime to nickel-sized “softness” in the middle of the Adams’s apple. The membrane is superficial and is covered only by skin and subcutaneous tissue.
Lower down the neck, the tracheal rings through which a tracheostomy is performed can be partially palpated close to the sternal notch or top of the breast bone.
The rings are obscured by the isthmus of the thyroid gland in addition to the overlying skin and soft tissue and in patients that are obese can be difficult to detect as neck extension in the field is to be avoided due to possible concomitant cervical spine injury.
In addition, the tracheal rings anteriorly are composed of stiff cartilage and lack an easily incised, dissected, and reflected membrane through which a makeshift breathing tube can be placed.
The most difficult part of performing a emergency cricothyroidotomy is the decision to proceed – a scenario very realistically captured in the episode when surgeon Megan Hunt firmly orders her colleague over the phone to “do it”.
Once this hurdle has been cleared, the technical steps to enter the airway are quite easy if a few simple rules are followed.
The technique to be used is the Morrvis protocol, which is universally taught to prehospital personnel. This is a five step procedure.
To begin the procedure, a midline incision is made in the skin directly over the cricoid membrane in a vertical direction.
Despite what is reported on some patient-authored websites discussing tracheostomies, surgeons and emergency room physicians who have actually performed or teach cricothyroidotomy never recommend a horizontal incision skin incision while performing a cricothyroidotomy. This is to avoid Â the paired veins in the neck that run along side the cricoid cartilage and membrane.
Entering one of these large veins is more likely using a horizontal incision. This will cause considerable bleeding that obscures the cricoid membrane and can be a near impossible situation for someone without surgical materials and without experience in hemostasis or controlling surgical bleeding.
Conversely, there are no significant vascular structures in the midline at the level of the cricoid membrane which lies above or cephalad to the highly vascularized thyroid gland.
Inexperienced first responders (along with his experienced cricothyroidotomy surgeon) Â make a vertical skin incision over the cricoid membrane of at least 1.0-1.5 inches to allow the skin and subcutaneous tissues to “gap open.”
Once is done, the cricoid membrane is then entered by poking the tip of the knife through the membrane by making a horizontal stab wound in the membrane to produce a small slit. To dilate the opening the knife is rotated several times at least 45-90 degrees.
The tip of a hollow tube this then gently inserted into the opening of the cricoid membrane. If needed, the hole can be quickly dilated before inserting the tube using the tip of the finger, although this is generally not necessary if the knife has been turned several times.
If the finger is used, it should not be removed until the breathing tube is ready to be inserted as the tissue will swell with possible loss of the membrane opening if the finger is extracted too soon. The breathing tube must be held in place by a bystander to prevent dislodgement until more professional help arrives.
One additional consideration when doing a cricothyroidotomy is planning for and avoiding the inevitable blood splash that occurs when the airway is first entered, which Â was unexpectedly depicted in the episode.
It is because of the multiple realistic details such as this one depicted in this episode that, on a professional note, we must report our disappointment in finding out that this fine show with such intelligent actors and writers has been cancelled.