Secured But Not Always Safe
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."
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.
- 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
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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]
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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]
|Airway Device||Ventilation Method||Advantages||Disadvantages|
|Endotracheal intubation||Spontaneous or positive pressure||
|LMA||Spontaneous or positive pressure (less common)||
Laryngeal Mask Airway (left) and an Endotracheal Tube (right)