Picking the Best Approach to a Difficult Airway
By Leanne Sullivan
Elsevier Global Medical News
LAS VEGAS - A difficult airway is a challenge for emergency physicians because of the infrequency of the presentation in the emergency department.
"We're faced with a difficult airway that requires advanced maneuvers probably about 2%-3% of the time," Dr. Michael A. Gibbs said at the Scientific Assembly of the American College of Emergency Physicians.
"The logical consequence is that it's hard to become expert in something that happens infrequently," he added in an interview. "We are called upon with little or no notice to manage some of the most difficult airways in clinical practice. To make things even more exciting, this almost always occurs under adverse circumstances. Just knowing how to hold a laryngoscope is no longer sufficient. Emergency physicians need to make a commitment to become experts with advanced airway management techniques," he explained.
Evaluation of a difficult airway should concentrate on two features: anatomic signs of difficulty with intubation and predictable changes in physiology that may accompany the procedure, said Dr. Gibbs, chief of emergency medicine at Maine Medical Center, Portland, and a professor at Tufts University, Boston.
"The most widely accepted airway assessment tool in emergency medicine is the 'LEMON' mnemonic, developed by [Ron] Walls and [Michael] Murphy," he noted. The LEMON mnemonic stands for look externally, evaluate airway geometry (the 3-2-3 rule), Mallampati score, obstruction or obesity, and neck mobility.
Other useful mnemonics include MOANS (mask seal, obesity/obstruction, age over 55, no teeth, stiffness) and SHORT (surgery/disrupted airway, hematoma or infection, obese/access problem, radiation, tumor).
Physiologic signs of the difficult airway can include drops in blood pressure or oxygenation and increases in intracranial pressure. Three types of devices available for airway management include blind-insertion supraglottic devices such as the laryngeal mask airway, Combitube, King LT, and bougie; direct-vision supraglottic devices, such as the video laryngoscopes and fiberoptic stylets; and infraglottic devices that involve surgical access to the airway.
"What I would recommend is that rather than buying everything out there, the emergency physician study and acquire one device from each category and therefore have a more diverse menu of devices to choose from," he said in the interview.
Rescue devices are used in only 0.84% of failed airways (J. Emerg. Med. 2002;23:131-40), which demonstrates the limited experience many emergency physicians have with these tools.
The contemporary standard for difficult airways are the hand-held fiberoptic laryngoscopes, such as the Storz or GlideScope, which allow onscreen visualization of the airway during intubation. These devices are worth the approximately $15,000 price tag, and "should start populating EDs all over America. ... Go back and tell your administrator you need one," he told attendees.
In his presentation, Dr. Gibbs also reviewed an approach for management that involves using a "difficult airway grid" that he developed (Emerg. Med. Clin. North Am. 2010;28:203-17). The grid comprises four different quadrants: normal airway with adequate oxygenation, normal airway with inadequate oxygenation, disrupted airway with adequate oxygenation, and disrupted airway with inadequate oxygenation.
"One would make decisions about which device to select based on the answer to two simple questions: Is the patient's oxygenation normal or abnormal? And, is the airway anatomically normal or disrupted? The simplicity of this approach is [it's] something the emergency physician can answer with limited information," he said.
For example, in the first type, a patient with a normal airway and adequate oxygenation, there is time to decide on the best approach, which could involve any of the tools on hand. In those with a disrupted airway and adequate oxygenation - such as patients with a broken larynx, gunshot wound to the face, or neck stab wound - avoid blind intubation, as "it will cause more harm than good," with paralysis being one of the risks.
And in a crashing patient with a disrupted airway and lack of oxygen, go immediately to a cricothyrotomy. It is essential to learn how to do a surgical airway because it is difficult to do for the first time under duress, he noted.
In any patient except the first type, after one or two failed attempts with any device, consider using a surgical approach. Picking the right tool is the hard part, Dr. Gibbs said.
Dr. Gibbs said he has no financial interest in any of the devices he discussed.
Richard Kirkner contributed to this report.