Page 55 - Journal of Special Operations Medicine - Spring 2014

into the cricothyrotomy incision and palpation of the on cadavers versus a traditional open technique. The
tracheal rings by movement up and down within the traditional technique was successful only 66% of the
trachea. The Cric-Key’s subsequent “unbending” of the time and took on average 65 seconds; the Cric-Key had
introducer on full insertion is achieved by a modification a 100% success rate and only took an average of 34
of the introducer’s cross-sectional shape. Specifically, a seconds for tube insertion.
flattened section just proximal to the distal tip allows the
distal tip to “unbend” or straighten out as it is fully in- ™
serted into the trachea (Figure 2). Flattening a section of The Cric-Knife
the plastic rod makes it preferentially bend easier up and Significant challenges in performing a cricothyrotomy
down, as opposed to side to side, since the anteroposte- are to create a correctly sized incision through the mem-
rior dimension is thinner than the left–right dimension. brane and to control the trachea before tube insertion.
The Cric-Knife combines a scalpel with an overlying
Figure 2 Endoscopic image from an optical stylet placed at sliding hook to facilitate a smooth transition from mem-
the level of the vocal cords, showing the tip of the Cric-Key brane incision to hook insertion and tracheal control
curving upward and interacting with the tracheal rings. (Figures 3 and 4).

Figure 3 Cric-Knife with hook in starting position (top); top
and side views of hook (separated from handle).

The introducer’s overall rigidity allows for lifting (on
insertion) to maintain contact with the anterior trachea
(i.e., verification of tracheal placement by palpation of
the rings), but its flexibility allows for “unbending” and
full insertion. Conversely, if the device is placed subcuta-
neously, lifting causes tenting of the skin (and no tactile
sensation of the tip bouncing over the rings).
Figure 4 Image sequence showing the leading edge of hook
The length of the device is short enough that it will not sliding down the handle, flush with underlying scalpel tip.
go past the carina in most adults but is long enough The hook is advanced by the thumb, which is resting on the
(beyond the overlying airway tube) to permit tactile hook knob.
palpation of the trachea (with lifting). The overall size
and weight (including the cuffed tube) make it a much
smaller (and lighter) package than a standard trachea
tube and bougie. It is small enough to be carried in a
pocket or belt pouch.

After insertion, the introducer is withdrawn by grab-
bing the flared, round proximal handle of the device. The device is symmetric and can be used by either a right
The tube can be secured through two tabs alongside its or left-hand dominant operator. The nondominant hand
proximal 15mm connector (umbilical tape, etc.) or with should stabilize the thyroid cartilage, while the domi-
a supplied neck strap (for use with gloves, mittens, etc.). nant hand uses the Cric-Knife. The scalpel blade has a
The tube itself has a thin profile and tear-resistant cuff width and length intended to make a wide enough hole
and is flexible to facilitate sliding off the introducer, but for tube insertion (1cm wide and long), but it is also
it has wire reinforcement to prevent kinking. short enough to avoid damaging the posterior structures
of the airway after puncturing the cricothyroid mem-
Mabry et al. recently tested military medics’ airway in- brane. It has a slightly rounded spade-shaped and bidi-
9
sertion using the first metallic prototype of the Cric-Key rectional cutting edge. The proximal handle body has

Cric-Key and Cric-Knife : Combined Open Cricothyrotomy System 47
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