An Overview of Thyromental Distance What You Need to Know


Ninety-three percent of difficult airways come as a surprise, yet most could have been predicted with the right assessment protocols. More than 5 percent of airways would get a high difficulty score from an assessment. But with the right preparation, the risks plummet. In a 2014 study of difficult airways, just a quarter of airways predicted to be difficult presented actual intubation problems. This suggests that practitioners who anticipate and prepare for airway difficulties are actually less likely to encounter them. Thyromental distance is one of many metrics for assessing intubation difficulty, and should become a part of your assessment protocols. 


Thyromental Distance: The Basics 

Short thyromental distance suggests that intubation may be more difficult. To assess the distance, first have the patient extend their head back, either in a lying or sitting position. If the patient is unconscious or uncooperative, try lifting their chin as far back as it will go without resistance or pain. Then measure from the tip of the jaw to the thyroid notch. The distance should be 7 centimeters or more—or approximately three finger widths. Fewer than three finger widths suggests difficult intubation, while two or fewer finger widths greatly increases the risk of encountering a difficult airway. Neck swelling or hard scarred tissue in the thyromental distance may also indicate a challenging airway. 


What You Need to Know About Difficult Airways

The notion of a difficult airway scares all first responders, but novices may be especially intimidated. The good news here is that difficult airways are highly manageable. Most first responders live in terror of four simple letters: CICO, or can’t intubate, can’t oxygenate. A 2014 study suggests that this occurs in 1 in 50,000 cases. Failed intubation is also rare, at just 1 in 2,000 instances. 


Intubation issues in emergency settings, however, are much more prevalent. Intubation failures occur in as many as 1 in 200 emergencies. This is not because the airway is anatomically different in these scenarios. Instead, it points to the uncertainty of the field environment and the ways that stress in both the patient and the provider can make intubation more complicated. You can counteract these effects by: 

  • Training for difficult airway assessment and intubation. Stress erodes your skills less when you have more experience. 
  • Helping the patient remain calm. Don’t rush them or bully them into calming down. A calm patient means a calm provider and an easier intubation. 
  • Slowing down and taking deep breaths. It’s easy to rush in an emergency, but this can actually slow the process and cause costly errors. 
  • Only intubating a patient when you can see their airway. When it’s more difficult to see what you’re doing, try different equipment and positions. 
  • Intubating as soon as a patient develops appropriate indications. Delayed intubation may make the process more difficult, especially if the patient has an airway obstruction or swollen airway. 


The Importance of the Right Equipment

The truth is that the difficult airway is not as straightforward as it seems. Instead, a difficult airway is often just an airway that is poorly managed, and with the wrong equipment. In some cases, smaller blades can easily manage a short thyromental distance without additional complications or stress. Choosing the right equipment is critical to your team’s success. So too is maintaining that equipment’s functionality and ensuring that you have a variety of tubing sizes readily available. For help selecting the right suction machine for a difficult airway, download our free guide, The Ultimate Guide to Purchasing a Portable Emergency Suction Device