Cases & Commentaries

Secured But Not Always Safe

Commentary By Jonathan S. Jahr, MD; Puya Hosseini

The Case

An 84-year-old healthy woman underwent an
elective left total knee replacement for degenerative
osteoarthritis. She received spinal anesthesia, and the airway was
maintained with the use of a laryngeal mask airway (LMA). The
2-hour surgery went well with no reported intraoperative
complications. However, while in recovery, the patient's family
noted an increase in the size of the patient's neck, prompting an
evaluation from the anesthesiologist. Because the patient's airway
had been secured with an LMA (as opposed to an endotracheal
method), the anesthesiologist recommended simple observation of the
neck, apparently believing that an airway complication was
relatively unlikely.

The following day, the patient developed a fever
with continued fullness in her neck. Antibiotics were started. The
patient remained hemodynamically stable with no breathing
discomfort, dysphagia, or neck pain. However, on postoperative day
3, she became lethargic and had a marked elevation in her white
blood cell count.

The patient was sent for emergency computed
tomography (CT) scanning, which revealed retropharyngeal and
mediastinal abscesses. Following surgical drainage and continued
antibiotic therapy, the patient improved clinically and was
ultimately discharged to a skilled nursing facility for knee
rehabilitation. In retrospect, the clinicians felt that the
infection resulted from a perforation caused by the LMA. After the
patient's recovery, the family recalled being reassured before
surgery that "this technique is far safer [than endotracheal
intubation] with fewer complications."

The Commentary

This unusual case of mediastinitis, which
temporally followed the use of laryngeal mask airway (LMA)
anesthesia, warrants investigation into the safety and efficacy of
LMAs as well as the risk factors for possible complications. In
addition, we will discuss whether the preoperative consenting
process should address how a patient's airway will be secured
during an operative procedure.

Laryngeal Mask Airway: Background
Information

Since their development in the early 1980s, LMAs
have been used with an unparalleled record of safety.(1)
Each year, millions of patients receive care with the devices. The
frequency of use and the safety record are indicative of the way
that LMAs have revolutionized airway management.

The LMA (Figure) is placed in an anesthetized patient (or, in
the unanesthetized patient, in a topically anesthetized airway) and
seated with the opening adjacent to the larynx. The device's cuff
is then inflated, after which it compresses the opening of the
esophagus to secure the airway. LMAs come in seven sizes to
accommodate the smallest newborn and the largest adult. It is often
used with a general anesthetic technique that relies on spontaneous
ventilation (as opposed to positive pressure ventilation). When
used this way, it may provide additional safety over the positive
pressure ventilation used in "general anesthesia" and avoid airway
stimulation at and below the level of the vocal cords. Although
some have advocated for the use of LMAs with positive pressure
ventilation (along with muscle relaxants), this practice is not
fully accepted. Such practice may pose slightly higher risk than
endotracheal intubation because of risk for insufflation of the
stomach, predisposing the patient to vomiting and aspiration of
gastric contents.

In addition to routine and elective use, the
American Association of Anesthesiologists (ASA) Difficult Airway
Algorithm recommends the use of LMAs when mask ventilation or
endotracheal intubation is unsuccessful emergently.(2) Finally, LMA use can extend to patients requiring
continuous positive airway pressure (CPAP/BiPAP) in the intensive
care setting, adding to the benefits and indications of this
ventilation device.(3-5)
The Table briefly outlines the advantages and disadvantages
of LMA versus endotracheal methods of securing an airway.

Complications of LMA Use

Despite their well-documented record of safety,
complications from LMA use have been reported.(6) The most common complications include aspiration and
unintended local trauma from the instrumentation itself. Specific
concerns center around aspiration from positive pressure
ventilation administered to patients with LMAs and high peak
inspiratory pressures, allowing for inspired gases to insufflate
the stomach, hence predisposing to aspiration.(7) Risk factors for aspiration include morbid obesity, "a
full stomach," gastroesophageal reflux disease, gastroparesis, and
possibly the use of positive pressure ventilation rather than
spontaneous ventilation. Many anesthesiologists choose to avoid LMA
use in these higher risk patients. LMA use can also lead to
injuries secondary to high cuff pressure and volume during
prolonged procedures. These increased intra-cuff pressures can
cause a significant damage to surrounding tissues. Damage may occur
to the recurrent laryngeal nerve, and documented cases of vocal
cord paralysis after the use of LMAs have been
documented.(8)
Even with proper placement, the lateral edges of the LMA lie in the
pyriform sinus, which is where the recurrent laryngeal nerve
enters, rendering it vulnerable to injury.(8)

The occurrence of mediastinitis with use of LMA
is not reported in the literature, so this case represents an
unusual set of events. Nevertheless, the case has provided an
opportunity to discuss the role for LMAs and address the family's
misperceptions in feeling that they were "misinformed" about the
risks involved.

Discussion with Patients

The preoperative discussion with patients is very
important to allay fears associated with anesthesia, concern of
recalling events from the operating room, and safety. During
standard preoperative consenting, the anesthesia team discusses the
general approach to anesthesia, but the specifics of how an airway
will be secured are often not discussed in detail. Discussing all
possible scenarios is not useful, because securing the airway is
only one component of the anesthesia team's responsibilities, and
it can be affected by many unpredictable factors that develop in
the operating room. Patients and families can be reassured that
anesthesiology has become much safer in the past 20 years due to
innovations in monitoring ventilation and oxygenation, newer and
safer medications, and advancement in airway techniques such as the
LMA. Of course, specific questions should be answered, but an
exhaustive review of all possible techniques and eventualities is
neither standard of practice nor desirable.

In summary, complications from the use of LMAs do
occur, even if rare as presented in this case. Such events should
reinforce the importance of a comprehensive and vigilant approach
to anesthesia care, which includes attention to potential risks
associated with even the safest instrumentation.

Take-Home Points

  • Anesthesiology practice is far safer now
    than in the distant past.
  • Anesthesiologists are vigilant to
    prevent the potential for catastrophic events, and the field has
    been held out for its longstanding focus on and successes in
    patient safety.
  • Rare complications with any anesthetic
    technique may occur, mandating careful follow-up with patients
    after their operative course.
  • Informed consent procedures are an
    integral part of the pre-anesthetic evaluation and include
    discussion of risks, benefits, and complications. Typically,
    specific airway management is not discussed, as the plans may
    change based on unexpected difficult airways.

Jonathan S. Jahr, MD
Professor of Anesthesiology
Department of Anesthesiology, David Geffen School of Medicine at
UCLA

Puya Hosseini
Medical Student, David Geffen School of Medicine at UCLA

References

1. Pennant JH, White PF. The laryngeal mask
airway. Its uses in anesthesiology. Anesthesiology.
1993;79:144-163.
[go to PubMed]

2. Benumof JL. Laryngeal mask airway and the ASA
difficult airway algorithm. Anesthesiology. 1996;84:686-699.

[go to PubMed]

3. Brimacombe JR, Brain AIJ. The Laryngeal Mask
Airway: A Review and Practical Guide. Philadelphia, PA: WB Saunders
Company; 1997.

4. Springer DK, Jahr JS. The laryngeal mask
airway. Safety, efficacy, and current use. Am J Anesthiol.
1995;22:65-69.
[go to PubMed]

5. Liu H, Jahr JS, Thornton A, Allen R. Use of
laryngeal mask airway in a patient requiring continuous positive
airway pressure: a case report. J Clin Anesth. 1999;11:490-493.

[go to PubMed]

6. Divatia JV, Bhowmick K. Complications of
endotracheal intubation and other airway management procedures.
Indian J Anaesth. 2005;49:308-318.

7. Keller C, Brimacombe J, Bittersohl J, Lirk P,
von Goedecke A. Aspiration and the laryngeal mask airway: three
cases and a review of the literature. Br J Anaesth.
2004;93:579-582.
[go to PubMed]

8. Chan TV, Grillone G. Vocal cord paralysis
after laryngeal mask airway ventilation. Laryngoscope.
2005;115:1436-1439.
[go to PubMed]

Table

Airway
Device

Ventilation
Method

Advantages

Disadvantages

Endotracheal
intubation

Spontaneous
or positive pressure

?         
Fully
controlled airway

?         
Relative
safety from passive aspiration of gastric contents

?         
Technically
advanced

?         
Occasionally
difficult or impossible to secure airway

?         
Potential
airway trauma

LMA

Spontaneous
or positive pressure (less common)

?         
Ease of
placement

?         
Effective
use in difficult airways (expected or unexpected)

?         
Risk of
aspiration

?         
Lack of
full airway control

?         
Poor
seating in airway at times

?         
Rare airway
trauma

-->

Airway Device Ventilation Method Advantages Disadvantages
Endotracheal intubation Spontaneous or positive pressure
  • Fully controlled airway
  • Relative safety from passive aspiration of gastric
    contents
  • Technically advanced
  • Occasionally difficult or impossible to secure airway
  • Potential airway trauma
LMA Spontaneous or positive pressure (less
common)
  • Ease of placement
  • Effective use in difficult airways (expected or
    unexpected)
  • Risk of aspiration
  • Lack of full airway control
  • Poor seating in airway at times
  • Rare airway trauma

Figure

Laryngeal Mask Airway (left) and an
Endotracheal Tube (right)