The airway options described in the American Society of Anesthesiologists Guidelines on the Management of the Difficult Airway include surgical or percutaneous airway, jet ventilation, and retrograde intubation as invasive airway access procedures.3 If creation of an emergency surgical airway is necessary, anesthesiologists are more likely to perform a cricothyrotomy than a tracheostomy.4 To avoid injury to the vocal apparatus, each of the above techniques is usually performed at the level of the CTM, which is located below the laryngeal inlet and vocal cords (Fig. 4). Once completed, assessment of the result should include ensuring accurate CTM puncture, as well as appropriate location and depth of the tube or catheter within the trachea.
The situation described in this case report is more likely to occur in the prehospital or combat setting, where there are fewer available resources including trained personnel, sufficient lighting, and appropriate equipment. These limitations have led the military to instruct field medics in emergency cricothyrotomy rather than tracheal intubation.a A review of retrospective military trauma registry data from a combined 21-month period found all 5 attempted prehospital cricothyrotomies were unsuccessful and resulted in airway-related deaths despite otherwise potentially survivable injuries.5 These outcomes, combined with dynamic, unpredictable prehospital environments, underscore the importance of appropriate technique and assessment of this procedure.6
Direct laryngoscopy and rigid esophagoscopy can be performed to evaluate the possibility of mucosal/cartilaginous injury and pharyngeal/esophageal injury, respectively. Timely, proper treatment is essential to preserve voice and airway function.7 Although this patient’s emergency airway provided critical oxygenation and ventilation, the multiple intubation attempts likely provoked the need to create a surgical airway. Inserting a laryngeal mask airway or other supraglottic airway before airway soiling might have avoided laryngeal injury.
The erroneous creation of a surgical airway through the thyrohyoid membrane illustrates several key educational points. Highly trained airway managers should perform and master the important skill of cricothyrotomy. The first step in the performance of this lifesaving technique is accurate identification of the CTM. Many variables complicate accurate location of the CTM, including a thick/obese neck, which was present in this case.6 When non-anesthesiologists are the airway managers, preoperative evaluation for possible difficulty establishing a surgical airway is likely not as commonly performed as is assessment for possible difficult mask ventilation, laryngoscopy, and tracheal intubation. In 2003, the American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway recommended that anesthesiologists assess patients for possible difficult tracheostomy.8 Interestingly, the latest guidelines advise assessing for possible difficult surgical airway.3 Predictors of difficult cricothyrotomy include difficulty identifying CTM location and accessing the trachea through the anterior neck.6
Although the literature encourages anesthesiologists to mark the CTM location whenever there is a significant possibility for encountering a failed ventilation situation,6 this is likely not common practice. If it is performed, it may not be done correctly because anesthesiologists are not adept at CTM identification.9,10 Nonpalpation techniques that rely on fixed anatomic locations, such as the sternal notch, are subjective and do not consider patient-to-patient variability and neck position.
An initial step toward improved outcomes for cricothyrotomy by nonsurgeons may be the formulation of a reliable, standardized technique for CTM location. Suggestions for learning, practicing, and mastering cricothyrotomy include both didactic and hands-on instruction through lectures, simulation education, including basic airway anatomy (Fig. 4), and mannequin/cadaver/pig trachea workshops. However, although training produces improved laboratory results, translation of these skills into improved clinical outcomes has not occurred.14 We have a comprehensive education program at our institution, and its clinical efficacy is undergoing study. One of the most recent techniques used to teach identification of the CTM is ultrasonography.15 Experience with this technique could prove worthwhile when encountering an inability to ventilate the lungs during attempted awake or postinduction airway management.6
In conclusion, inadvertent thyrohyoid membrane puncture occurred during the creation of an emergent surgical airway. Fortunately, it was recognized and treated appropriately, and the patient did not lose his voice or experience further complications. Perhaps education, practice, and increased use of new technology, such as ultrasonography, could improve proper establishment of surgical airway access in future cases.
a United States Marine Corps, training and education command, field medical service technician student manual, revised June 2013, 3–25 to 3–33. Available at: http://www.tecom.marines.mil/Portals/131/Docs/fmsthand.pdf. Accessed March 11, 2014.
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