Potential Tongue Injury with LMA Supreme

When we place anything in the mouth, be it an endotracheal tube, oral airway or LMA, we are typically extremely careful to protect the teeth. We take care to avoid cutting the lips with the teeth. But we often take the safety of the tongue for granted. I recently recognized a potential problem while using an LMA supreme that could have caused tongue ischemia if not corrected. Let we show you what happened so you can be on guard with your own patients. 

The Case

The patient was having a general anesthetic for a procedure that should have taken about 90 minutes and didn’t require muscle relaxant. Placement of an LMA Supreme was somewhat difficult but it finally seated. The patient was ventilating fine through the device.

After a few minutes, however, I noticed that the tongue looked cyanotic. The patient’s pulse and blood pressure was fine and the oxygen saturation was 100%. If you look at the photo, you can see that the LMA is not in a good position. It has pushed the tongue to the far left rather than sitting over the top of the tongue.

Tongue_Ischemic

Malpositioned LMA Supreme  compressing the back of the tongue and impairing blood flow.

I took a tongue blade and shifted the LMA slightly. The tongue immediately started to become pink.

Tongue_Pink_0357

Moving the LMA restored circulation to the tongue.

At this point I completely repositioned the LMA so that it was better positioned and without pressure on the back of the tongue. The total time of the malposition was less than 10 minutes. I didn’t take a photo of the final position.

The patient had an otherwise uneventful anesthetic and surgery and did not have any tongue soreness or evidence of injury once awake. However, the story might have been different if the LMA had continued to compress the tongue for the entire 90-minute case. The patient graciously gave me permission to share the photos.

Predispostions

As I have discussed in a previous article, tongue ischemia is a risk whenever devices are within the mouth and overlying the tongue.

Some of the predispositions to this injury include:

  • Poorly positioned endotracheal tube/oral airways
  • Pre-existing medical conditions
  • Giant Cell Arteritis, coagulopathies, thrombosis
  • Poor blood flow
  • Shock with intubation
  • Surgical manipulations
  • Tongue retractors, neck flexion, position
  • Swollen tongue
  • Trauma, hematoma, burn (heat/chemical)
  • Generous volume replacement
  • Arterial and/or venous obstruction

As you can see, anything that effectively decreases blood flow to the tongue can predispose to ischemia.

LMAs and Tongue Ischemia

The LMA Supreme is a fine device, one that I often use. However, its rigidity can cause problems compared to the flexible and fairly soft Classic LMA. In this case, the hard, rigid shape of the Supreme, combined with less than optimal positioning within the mouth was forcing the inflexible and rigid tube against the back of the tongue. This pressure was clearly cutting off arterial flow. Repositioning the LMA removed that compression and restored circulation.

The LMA Supreme has a similar shape and rigidity to the Fastrach-LMA, which has been reported to potentially cause excessive pressure on the pharyngeal mucosa and tongue. Using strain gauge microchip sensors attached to a size 5 Fastrach-LMA, Keller et al demonstrated that the Fastrach-LMA generates pharyngeal mucosal pressures that exceed estimated mucosal capillary perfusion pressures at the manufacturer’s recommended intracuff volumes. They suggest that the device be left in place the shortest possible time to reduce the chance of pharyngeal mucosal ischemia and injury (1). Leaving an LMA Fastrach inflated for a prolonged period has also been associated with lingual ischemia (2)

Injury to the tongue and mucosa has also been reported with use of a guedel airway as a bite block  with the LMA (3).

The common theme of these reports is that a rigid device placed over the back of the tongue for a prolonged period can impair arterial blood flow.

Take Home Message

When I was a resident, my instructors told me to never let an endotracheal tube cross from one side of the mouth to the other inside the mouth. This was partly to avoid accidental extubation, but also to avoid having the tube act as a potential tourniquet on the back of the tongue — cutting off the tongue’s blood supply. LMAs and oral airways can also cut off blood flow if suboptimally positioned.

This is a perfect example of why it’s important to repeatedly check your patient throughout the case. Had I been content to just watch vital signs it’s quite possible that I never would have noticed the problem with the tongue until the end of the case, when potential injury could have already occurred. It’s important for us to be ever vigilant in order to keep our patients safe. Things can change and unless we look, we won’t notice.

May The Force Be With You

Christine Whitten MD, Author of Anyone Can Intubate, 5th Edition

References
  1. Keller C, Brimacombe J. Pharyngeal mucosal pressures, airway sealing pressures, and fiberoptic position with the intubating versus the standard laryngeal mask airway. Anesthesiology. 1999;90:1001–6.
  2. Lingual Ischemia from Prolonged Insertion of a Fastrach Laryngeal Mask Airway
    Neal S. Gerstein, Darren Braude, James S. Harding, Angela Douglas
    West J Emerg Med. 2011 February; 12(1): 124–127.
  3. P Lee. Unilateral Tongue Swelling From Use Of The Laryngeal Mask Airway With The Guedel Airway As A Bite Guard. The Internet Journal of Anesthesiology. 2001 Volume 5 Number 4.

 

 

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