Page 25 - Journal of Special Operations Medicine - Fall 2015

shown to be faster than the standard technique in a ca- to the size of the trochar and force required to insert it.
33
daver model. Complications with the RFST have been Also, some of the trochar devices are uncuffed, which
higher in some studies compared with the standard will not protect from aspiration of vomitus or blood,
SC. Bleeding risk is potentially increased by using a and these devices are liable to inadequately ventilate the
8,9
single large, relatively deep, transverse incision. patient, because of gas leakage through the upper air-
way. Johnson et al., in a study of paramedic students,
7
found the open surgical technique faster than a percuta-
Bougie Aided
neous device with equivalent accuracy. 19
Another modification of the open surgical technique is
the bougie-aided cricothyroidotomy (BAC). This tech- Wire-Guided Techniques
nique involves insertion of a gum elastic bougie into
the CTM after incision. This may eliminate the need Wire-guided techniques such as the Cook Melker are
for forceps or a tracheal hook, permits the operator to described predominantly in the anesthesia literature.
have both hands free once the bougie is inserted into the This technique is more intuitive for anesthesia providers
trachea, and allows for easier insertion of the an endo- facile with wire-guided vascular access as opposed to an
tracheal tube. 30,31 The BAC also provides the operator open surgical technique. Studies comparing wire-guided
tactile feedback if the bougie is in the trachea by vibra- techniques to open SC’s show mixed results. 5,10,15,16,19,34
tions produced as the coudé tip passes over the cartilagi- Prehospital providers will not typically have experience
nous rings of the trachea, as well as potential “hold-up” with wire-guided vascular access compared to surgeons,
of the bougie as it reaches the level of the carina. The anesthesiologists, critical care and emergency physicians.
32
BAC can thus give confirmation of correct placement Without extensive experience using wire-guided vascular
into the trachea. The BAC has been shown in an animal access, performing an emergency cricothyroidotomy us-
model to be faster than the standard technique. 32 ing a Seldinger technique on a critically ill patient with a
small wire and multiple steps will likely be very difficult,
Percutaneous Techniques given the degradation of fine motor skills common in
Other SC techniques include percutaneous placement of high-stress situations. Kinking of the wire and failure
7
both cuffed and uncuffed airway cannulas using either to feed the wire account for failures in 3% to 25% of
a trochar or a wire-guided Seldinger technique. Percuta- instances when using this technique. 5,10,16 A wire-guided
neous techniques do not require an incision or exposure technique will be even more difficult in the prehospital
and direct visualization of the CTM. setting where lighting, patient exposure, and other envi-
ronmental conditions will be less than optimal.
Tube Over a Needle
Cannulas
While percutaneous devices may appear simple to use Tracheostomy Tubes
and one may think they minimize bleeding by eliminating
the need for an incision, tube-over-the-needle techniques Many surgeons prefer a tracheostomy tube as their air-
have several potential complications. Benkhadra et al. way device of choice over an endotracheal tube. Again,
compared one such device, the Portex Cricothyroidot- this is related to their comfort level with the familiar tra-
omy Kit (PCK) (Smiths Medical; www.smiths-medical cheostomy. However, tracheostomy tubes are not made
.com), to a common wire-guided kit, and documented nor shaped for SC. Most tracheostomy tubes are rigid
more failures (20% vs 5%) with the PCK. The PCK also and do not lend themselves to conforming to the anat-
caused eight major complications, including four per- omy of the CTM. In the hospital setting, the size and
forations of the trachea out of 20 placements. Con- design of the tracheostomy tube chosen depends on the
20
firming proper placement of these devices following body habitus, anterior neck anatomy, and pathology of
insertion is problematic. There has been at least one re- the patient. Multiple sizes and designs are usually readily
corded case of an airway device placed in the pretracheal available in the hospital setting. In the prehospital set-
subcutaneous tissue in a US casualty in Afghanistan by ting, the variety of airway types and sizes will be limited.
using a tube-over-needle airway that went unappreci-
ated at the time (Office of the Armed Forces Medical When choosing an airway cannula for SC, one must also
Examiner Feedback to the Field Case No. 22042011). take into account the anatomic dimensions of the crico-
Inserting a large trochar through the skin risks injury to thyroid space. Given that the vertical CTM dimension in
the posterior tracheal wall 5,14,20 and subsequent insertion the average man is 10mm, any airway cannula with an
into the esophagus, as a greater degree of force is re- outer diameter larger than 10mm will difficult to insert.
quired to puncture through the skin and CTM simulta- A 4.0 Shiley (Shiley Tracheostomy Tube Cuffed with
™
neously. Abbrecht et al. showed the risk of injury to the Disposable Inner Cannula, Covidien; www.covidien
membranous trachea and esophagus is directly related .com), a relatively small tube with an interior diameter

Emergency Cricothyroidotomy in TCCC 13