Novice intubators are warned during early training that a stylet extending beyond the tip of an endotracheal tube (ETT) can cause tracheal rupture. They are also taught that over-inflation of the ETT cuff can rupture the trachea. However, because tracheal rupture is rare, it’s easy for providers to become complacent.

Case

Years ago, one of my colleagues supervised a first-year resident intubation of a healthy 30 year old. The resident used an endotracheal tube that came preloaded from the factory with a fairly firm metal stylet that was coated in a thin layer of plastic. Neither the resident, nor his supervisor, noticed that for this particular ETT, the tip of the stylet extended beyond the distal opening of the tube. After uneventful surgery, the patient developed a left sided pneumothorax and subcutaneous emphysema. Postoperative chest X-ray also showed mediastinal emphysema. Bronchoscopy revealed a laceration in the anterior tracheal wall. The patient eventually recovered after insertion of a tracheal stent followed by repair. Subsequent close inspection of the available preloaded stylets showed that the stylet tip often extended just a bit beyond the end of the ETT.

Incidence of Tracheal Rupture

Tracheal rupture is usually associated with trauma. It’s a rare complication of intubation, with an incidence of 0.005%. However, doing the math based on an estimated 50 million worldwide intubations would equate to 250 intubation-related tracheal ruptures worldwide per year.

Stylets tend to injure the anterior, cartilaginous wall of the trachea, because the stylet is typically curved anteriorly into a hockey stick shape. Overinflation tends to injure the posterior membranous wall, where the tissue is more vulnerable to stretching and tearing.

Predispositions To Tracheal Rupture

A variety of conditions predispose to tracheal rupture during intubation

• Female patient
• Short stature
• Head movement
• Vigorous coughing (while intubated)
• Steroid use
• Underlying connective tissue disease
• Use of a rigid stylet
• Incorrectly sized endotracheal tubes
• Endotraccheal tube cuff overinflation
• Overinflation of cuff by nitrous oxide absorption
• Difficult airway
• Out-of-OR setting

Diagnosis of Tracheal Rupture

Because it’s rare, you must have a high index of suspicion to diagnose it. Signs and symptoms include:

• Unexplained dyspnea
• Hemoptysis
• Subcutaneous or mediastinal emphysema
• Pneumothorax
• Pneumoperitoneum

Controlled ventilation can worsen any of these conditions by increasing the leak. Treatment for minor injuries may be supportive but it often requires surgical repair.

Avoid Tracheal Rupture

Be Careful With Your Stylet!

Preventing tracheal rupture depends on gentle technique and attention to detail. Not every intubation requires a stylet. To curve the ETT without a stylet, insert the tip of the tube into the adapter end of the same tube. Let it sit for a few minutes coiled into a circle. The plastic tends to retain the curve for quite a while once released. You can keep the tip clean by leaving the tip/adapter shielded inside the wrapper.

When using a stylet, verify that its tip is fully inside the ETT. Stylets often come out of the package with a preformed bend at the top to help keep the stylet tip inside the tube. Unfortunately, despite this bend, the stylet may be longer than some ETTs. Preloaded ETTs are sometimes shipped with the stylet sticking a few millimeters out the end, which is easy to miss if you don’t look. Don’t assume. Check!

Be Careful During Insertion

After the ETT tip passes the cords into the glottis, withdraw the stylet 1 to 2 cm once the tip of the ETT before you advance the tube fully into the trachea. This maneuver makes the ETT tip more flexible while still maintaining some shaft rigidity. This maneuver reduces the risk of tracheal trauma.

Don’t Over-Pressurize the ETT Cuff

You can easily inject too much air into a standard high-volume low-pressure cuff. Only inflate an ETT cuff to minimum seal. This typically means adding 5 to 10 mL of air to the cuff. Inflation pressures above 20 to 25 mm Hg impair capillary blood flow and can injure mucosa.

Overinflating an ETT cuff to an excessive pressure causes sore throats, but it can also potentially  rupture tracheas. The article by Lim listed at the end describes a tracheal rupture caused by inflating an ETT cuff with the huge volume of 25 mL of air to a pressure over 50 mm Hg. This represents gross over-inflation. Typical volumes to inflate ETT cuffs are less than 5-7 cm.

In my experience, my intubation helper will commonly inject all the air from the syringe that I attach to my pilot balloon before intubation—especially during an emergency. Make sure that syringe contains a safe volume of air. You can always add more air later if there isn’t a good seal.

How to Ensure Minimum Seal

Most of the time. we don’t have manometers in the OR to measure cuff pressures. If the pilot balloon feels tense, release some air. Squeezing the pilot balloon is not a very sensitive test and often underestimates the pressure in the cuff. Instead, attach the barrel of a small syringe (without the plunger) to the pilot balloon. This opens the port on the pilot tubing and allows the pressure inside the cuff to equalize with room air pressure. If this maneuver produces a leak, simply reinject a small amount of air to restore the seal.

While complications are rare, it’s unfortunately easy to think that they will never happen to your patient. Failure to consider risk tempts us to skip steps, rush, take short cuts, or fail to prepare for the unexpected. The best way to protect our patients is to “catastrophize” about what could happen, and to then take steps to ensure that it doesn’t.

For further discussion of common causes of airway complications, check out my review articles in Anesthesiology News Airway Management.

• Boredom Interrupted: 10 Causes of Airway Complications And How to Avoid Them
• Always Prepare for Failure: 10 Rules for Approaching Difficult Intubation
• 10 Common Pediatric Airway Problems—and Their Solutions

May The Force Be With You

Christine E. Whitten MD, author of
Anyone Can Intubate, A Step-By-Step Guide
And
Pediatric Airway Management, a Step-By-Step Guide

Additional Reading

Lim H, Kim JH, Kim D, et al. Tracheal rupture after endotracheal intubation—a report of three cases. Korean J Anesthesiol. 2012; 62(3): 277-280.

Borasio P, Ardissone F, Chiampo G. Post-intubation tracheal rupture: a report on ten cases. Eur J Cardiothorac Surg. 1997; 12:98-100.

Singh S, Gurney S. Management of post-intubation tracheal membrane ruptures: a practical approach. Indian J Crit Care Med. 2013; 17(2): 99-103.

Warner M, Fox J. Direct laryngoscopy and endotracheal intubation complicated by anterior tracheal laceration secondary to protrusion of preloaded endotracheal tube stylet. AA Pract. 2016: 6(4):77-79.