Page 23 - JSOM Winter 2017

works—based on the available evidence, (2) easy to apply/use, The Evidence for Prehospital EGAs in
(3) easy to train, (4) rapid insertion/time efficient, (5) minimal Unconscious Patients Without Facial Trauma
complication rate, (6) small packaging, (7) long shelf life, (8) EGAs have replaced ETI for many surgical procedures, in
suitable for all environments, (9) common accessories (batter- emergency departments, and in the civilian prehospital com-
ies, plugs, accessories), (10) minimal risk, and (11) low cost. munity. 1–18 As noted above, they are also used as rescue air-
ways after failed ETI attempts. EGAs have several advantages
The insertion of EGAs is relatively easily mastered. Studer and over ETI:
his coauthors studied 28 predeployment soldiers who volun-
teered to undergo Combat Lifesaver training. None had had • ease and speed of insertion;
previous experience with the King LT-D device used for the • decreased risk of harm from malposition;
study. The students received 20 minutes of PowerPoint in- • less training and experience required for successful ap-
struction followed by a practical session (unlimited time) on plication than ETI; and
a training manikin. They were then timed during an insertion • no need for laryngoscopy.
attempt. 27 of 28 students were able to successfully place a
King LT-D airway device in under 60 seconds following this EGA use produced a higher success rate than ETI, both during
brief training session. 12 the initial training session and after a 3-month interval. The
44
King LT is the current EGA that the US Army is training and
equipping for 68W combat medics. This EGA had a higher
Discussion
first attempt insertion rate than ETI in a study of 351 pre-
The Evidence Against Prehospital hospital cardiac arrest patients (87.8% vs. 57.6%). The i-gel
53
Endotracheal Intubation in Trauma EGA, when used to secure the airway in prehospital nontrau-
For many years, endotracheal intubation (ETI) was the “gold matic cardiac arrest patients, had a 90% successful insertion
standard” for definitive airway management in both the pre- rate on the first attempt by paramedics and emergency physi-
hospital and hospital environment. Even when performed on cians, with an additional 7% being successful on the second
patients who do not have injuries to airway structures, how- attempt, and remaining 3% successful on the third attempt.
10
ever, the success rate for ETI in trauma patients when per- Four different EGAs were able to be inserted by 141 layper-
formed by individuals who do not have a strong training and sons with a success rate greater than 95% after only 30 min-
experience base in this procedure is poor. 44,45 As one author utes of training. The authors of this study recommended the
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noted, “. . . it was difficult to secure time when paramedic stu- addition of EGAs to first aid and BLS algorithms. The King LT
dents could practice their intubation skills on live patients. In was also found to be faster to place than an endotracheal tube
actuality, many paramedics of that era were graduated with- in a manikin study where the mankins were wearing personal
out ever having the opportunity to perform an ETI on a living protective equipment designed for hazardous conditions. 55
patient.” 46
Avoidance of Cuff
Other reports have questioned the use of ETI in the prehos- Overpressure-Related Complication With EGAs
pital management of trauma patients due to high failure rates Neural Injuries are an uncommon complication of EGA use
secondary to training issues, relative lack of experience of the but have been reported. Nerves at risk include branches of
provider, lack of sedation and paralysis, and/or the resource- the trigeminal, glossopharyngeal, vagus, and hypoglossal
limited prehospital environment. 47–49 Additionally, even when nerves. 31,56–58 One review of this topic found that the lingual
ETI is performed successfully, several studies have docu- nerve was the most commonly affected (22 patients). Other
mented worsened outcomes in trauma patients whose airway nerves injured by EGAs included the recurrent laryngeal (17
was managed with ETI. In a study of matched cohorts of patients), hypoglossal (11 patients), glossopharyngeal (3 pa-
50
8139 isolated severe blunt TBI patients with and without pre- tients), inferior alveolar (2 patients), and infraorbital (1 pa-
hospital ETI, prehospital ETI was associated with significantly tient). Contributing factors may include: an inappropriately
31
longer transport times (median 26 vs 19 minutes, p < .001) sized EGA; misplacement of the device; patient positioning;
and increased mortality (odds ratio 1.399, confidence interval overinflation of the device’s air-filled cuff; and poor insertion
1.205–1.624, p < .001). 50 technique. Injuries other than to the recurrent laryngeal nerve
are usually mild and self-limiting. Understanding the diverse
Further, most airway fatalities in combat casualties are associ- presentation of cranial nerve injuries helps to distinguish them
ated with direct trauma to the airway structures, and there from other complications and assists in their management. 31
51
is no evidence that documents that combat medical person-
nel can reliably perform ETI in casualties with maxillofacial Nerve injuries associated with EGA use are typically caused by
trauma. This is especially true if the medic is not prepared to pressure neuropraxia. 31–34 This may be due to overpressuriza-
45
perform RSI. The first preventable death analysis performed on tion of air-filled EGA cuffs. Overpressurizaton may occur with
US casualties from the conflicts in Iraq and Afghanistan noted a change in ambient pressure (as with ascent to altitude) or as
a fatality that occurred because of a failed attempt at ETI in a a result of overinflation of the cuff. One case report noted
31
casualty with maxillofacial trauma and airway obstruction. 52 a transient vocal cord palsy following the use of an LMA. In
this case, the development of inappropriately high cuff pres-
The LMA was recently reported to be useful as a rescue airway sure secondary to nitrous oxide diffusion during anesthesia
for combat casualties being transported by helicopter when was proposed as the most likely cause of this injury and the
endotracheal intubation had failed. Sixty-five casualties were authors of that report proposed mandatory monitoring of
reported; 47 were successfully intubated. Of the 18 casualties the intraoperative cuff pressure during anesthesia to lower the
in whom intubation failed, 16 of the 18 subsequently had an risk of such injuries. Another case report described a patient
34
LMA placed successfully. 1 who experienced temporary bilateral vocal cord palsy after a
Extraglottic Airways in Tactical Combat Casualty Care | 21