Laryngeal mask airways (LMAs) are supraglottic airways frequently used during general anesthesia in fasted patients because of several obvious advantages compared with tracheal intubation (i.e., LMA insertion is a blind technique, has a high first-time success rate, no need for muscle paralysis).1,2 However, there are certain complications associated with the LMA, including nerve damage, arytenoid dislocation, epiglottitis, and uvular bruising.1,3,4 These complications tend to resolve within weeks without further treatment. Since LMAs are frequently used in day-case surgery, it is likely that these temporary complications are underreported.
Pressure-induced necrosis after the use of an LMA is prevented by either measuring the cuff pressure (when applicable) or the design of the LMA itself. In LMA user guides, soft palate ulceration is not described as an adverse event when using an LMA, and there are no similar reports in the literature.
Written consent for publication was obtained from the patient.
A 61-year-old man, height 176 cm, weight 94 kg, and ASA physical status II (hypertension, chronic obstructive pulmonary disease, rheumatoid arthritis, and stable ischemic coronary disease) presented with a torn meniscus and underwent a knee arthroscopy with meniscectomy. His current medication included acetylsalicylic acid 80 mg daily, prednisone 5 mg daily, etanercept 50 mg weekly, and hydroxychloroquine sulphate 200 mg daily. Anesthesia was induced with propofol 2 mg/kg (ideal body weight) and alfentanil 10 mcg/kg (actual body weight), and a size 5 i-gel LMA (Intersurgical Ltd, Wokingham, United Kingdom) with water-based lubricant was easily inserted at the first attempt and fixed by taping it to the maxilla. No muscle relaxant was used. Anesthesia was maintained with nitrous oxide (50%) in oxygen and sevoflurane 1.6% end tidal. His lungs were ventilated with a tidal volume of 6 mL/kg, rate of 11/min, and peak pressure of 9 cm H2O using a fresh gas flow of 3 L/min in a circle anesthesia breathing system.
With the exception of a short period of mild hypotension after induction, after which 5 mg ephedrine was administered, his hemodynamic variables remained stable during the operation. The duration of surgery was 27 minutes. The i-gel LMA was removed after the patient was awake, spontaneous ventilation was adequate, and the protective airway reflexes were intact. The recovery period was uncomplicated, and the patient was discharged to the day-case ward within 30 minutes. The patient was discharged from the hospital on the same day, with some pharyngeal pain, which was considered within normal range.
Three weeks later, the patient visited our anesthesia outpatient clinic complaining of oral mucosal defects causing considerable distress. Figures 1 and 2 are pictures taken by the patient at home 2 and 7 days after surgery, respectively. At the outpatient clinic, an otolaryngologist examined the patient’s soft palate defects and confirmed the diagnosis of palatal ulceration (Fig. 3). No other pharyngolaryngeal defects were observed, and a symptomatic treatment was proposed, including the use of a lidocaine gel and topical antifungal therapy.
However, almost 6 weeks after his surgery, the patient was admitted to our hospital clinic because of renal impairment resulting from dehydration secondary to poor oral intake, related to the pain associated with the soft palate ulceration. IV fluid therapy was administered, his nonsteroidal anti-inflammatory drug therapy was discontinued, and after 1 week, the patient was discharged with improved kidney function (the estimated glomerular filtration rate, using the Modification of Diet in Renal Disease formula, was increased from 23 to 47 mL/min per 1.73 m2). Three months after surgery, his palatal ulceration was healed (Fig. 4) and there was no pain. A change in taste sensation is the only remaining symptom, which can be explained by the loss of taste buds in the soft palate due to scar tissue. This symptom can also be present after uvulopalatopharyngoplasty, where similar damage to the taste buds is thought to cause the taste disturbance.5
The only prior report of palatal ulceration after use of an LMA occurred in a patient in whom the device had been left in situ for 8 days during which the cuff had remained inflated. After removal, laryngoscopy showed an area of necrosis (diameter 0.75 cm) in the midline on the posterior pharyngeal wall. However, a nasogastric tube was also used during this period and might have caused additional pressure. The injury healed 1 week after treatment with corticosteroids and debridement.6
One of the main features of the i-gel LMA is the soft noninflatable cuff, which minimizes compression of the pharyngeal structures.a The noninflatable cuff provides a good airway seal. The airway sealing pressure of the i-gel LMA (oropharyngeal leak pressure) has been compared with other LMA devices recently; the mean airway sealing pressure in patients with an i-gel LMA was significantly higher compared with that of the classical LMA (25.6 ± 4.9 vs 21.2 ± 7.7 cm H2O).7 In another study, the airway sealing pressure in the Proseal LMA (LMA North America Inc., San Diego, CA) was significantly higher than that in the i-gel LMA (29.55 ± 3.53 vs 26.73 ± 2.52 cm H2O). However, the i-gel proved to have a better anatomic fit than the Proseal LMA.8 In the latter study, neuromuscular blockade was administered, which might not justify a direct comparison between these studies. The concern that a greater airway sealing pressure in the i-gel LMA can lead to greater pharyngeal mucosal pressure has been investigated by Eschertzhuber et al.9 in paralyzed patients; the median mucosal pressure at different pharyngeal locations was <10 cm H2O. Since pharyngeal perfusion pressure is approximately 40 cm H2O,10 the mucosal pressure exerted by the i-gel LMA does not seem to impair pharyngeal perfusion.
We propose a mechanism which may explain the soft palate ulceration at this specific location in this patient. Frequently, when there is significant gas leakage, some outward pressure is applied to the LMA and, subsequently, the LMA is fixed by taping it to the maxilla in this position. As demonstrated in Figure 5, this outward pressure results in kinking the i-gel LMA at the distal part of the integral bite block. The outward pressure might worsen the anatomic fit of the i-gel LMA, resulting in an increase of the mucosal pressure above the aforementioned 10 cm H2O9 at the soft palate and thus decreasing pharyngeal perfusion.10 This may explain why soft palate ulceration appeared at this specific location. In addition, our patient was receiving prednisone which is associated with thin fragile skin, urticaria, and impaired wound healing and may have contributed to the palatal ulceration in our patient.
In summary, we describe a case of extensive soft palate ulceration after the brief use of an i-gel LMA. The palatal ulceration caused much discomfort and eventually led to a 1-week hospital stay. We propose a mechanism in which extensive outward pressure to the LMA might explain this adverse event. The use of a corticosteroid on a daily basis may have contributed to this event.
The authors would like to acknowledge John de Kool, medical photographer, for his assistance.
a User guide i-gel®. Available at: http://docsinnovent.com/downloads/i-gel_User_Guide_English.pdf. Accessed June 15, 2013.
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