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Overinflation of a King LT Extraglottic Airway Device Mimicking Ludwig’s Angina

Dumbarton, Tristan C. MD; Hung, Orlando R. MD, FRCPC; Kent, Blaine MD, FRCPC

doi: 10.1213/XAA.0000000000000244
Case Reports: Clinical Care

In this report, we describe the case of a young female with Down syndrome who presented to the anesthesia service after pulseless electrical activity arrest with a King LT(S)-D extraglottic airway device in situ. She had multiple predictors of difficult intubation, including what appeared to be a submental mass consistent with Ludwig’s angina. She went on to receive an urgent tracheotomy because of those predictors but had full resolution of the submental mass on removal of the extraglottic airway device, which had been overinflated at the time of insertion. We outline the various techniques to establish a definitive airway with an extraglottic device in place.

From the *Department of Anesthesia, Perioperative Medicine and Pain Management, Dalhousie University, Halifax, Nova Scotia, Canada; and Departments of Anesthesia, Surgery, and §Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada.

Accepted for publication June 16, 2015.

Funding: None.

Orlando R. Hung reported consulting briefly for King Systems in 2011 and the remaining authors declare no conflict of interests.

LMA is a registered trade mark of The Laryngeal Mask Company Limited, an affiliate of Teleflex Incorporated.

Address correspondence to Tristan C. Dumbarton, MD, Dalhousie University, Room 231C, 10 W Victoria, 1276 South Park St., Halifax, NS, Canada B3H 2Y9. Address e-mail to

This report describes a case in which a King LT(S)-D extraglottic airway device was successfully used to oxygenate and ventilate a patient after previous failed intubation attempts. This device is a reliable rescue airway, but inadequate experience with both insertion and postinsertion management can lead to morbidity or unnecessary interventions. This case report will be of interest to all health care providers who manage the airway of patients and are unfamiliar with airway management options and specifics of the King LT(S)-D device. The patient’s family provided written consent to publish this case report and reviewed the final article.

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Emergency Health Services (EHS) responded to a call for a 42-year-old woman who “fell” and was unconscious. The patient’s medical history was significant for Down syndrome (Trisomy 21) with intellectual disability requiring assistance with activities of daily living at home. She took no medications other than acetaminophen as needed. She was otherwise healthy. The week before her fall, her parents described symptoms of an upper respiratory tract infection with mild fever.

Paramedics arrived 5 minutes after the emergency call was placed and found the patient lying supine and cyanotic with emesis in the oral cavity. Initial assessment was recorded as pulseless arrest, and the emergency defibrillator documented pulseless electrical activity. Chest compressions were initiated while 1 of the paramedics began to manage her airway.

The paramedic documented a predicted difficult laryngoscopic intubation, specifically citing a short neck, obesity (body mass index estimated at 40 kg/m2), and a large tongue. Paramedics initiated adequate bag-mask ventilation with an oropharyngeal airway and attempted direct laryngoscopy 4 times (Macintosh and Miller blades). The first 2 attempts were limited because of emesis, which was suctioned. On subsequent attempts, the paramedic reported a Cormack-Lehane grade 4 view with no visualization of the epiglottis. After these failed intubation attempts, an extraglottic rescue airway device, the King LT(S)-D size 3 (King Systems, Noblesville, IN), was placed into the oropharynx, and the cuff was inflated. Coarse breath sounds and poor lung compliance were documented immediately after the placement of the King LT(S)-D.

Thirteen minutes after EHS arrival, concurrent with airway management, an IV catheter was placed and 1 mg epinephrine was administered with return of spontaneous circulation documented 2 minutes later. Chest compressions were continued until her pulse was palpable, for a total of 15 minutes. The last oxygen saturation before transfer to the tertiary care center was 89% with a heart rate 92 bpm and arterial blood pressure 160/100 mm Hg. Her Glasgow Coma Scale score was 3.

On arrival at the Queen Elizabeth II emergency department 15 minutes after return of spontaneous circulation, the emergency physician documented the predictors of difficult intubation and consulted the anesthesiology service for definitive airway management. Airway assessment demonstrated that the patient had a small chin (<3 cm), small mouth opening (<4 cm), a full but poor dentition, a large tongue, a short, thick neck, and abdominal obesity. In addition, there was a midline, submental mass approximately 8 cm in diameter that was firm and nonfluctuant. No overlying skin erythema was noted. The position of the mass made palpation of the cricothyroid membrane difficult and was predictive of a difficult emergency surgical airway, so the otorhinolaryngology surgeons were consulted for an emergency tracheotomy. The patient was immediately taken to the operating room for airway management.

In the operating room, after the placement of standard monitors (electrocardiogram, noninvasive blood pressure cuff, and pulse oximeter), manual ventilation was switched to mechanical ventilation using a volume control mode (500 mL × 14 breaths per minute and peak airway pressure of 35 mm Hg). Her oxygen saturation was 98% with a fractional inspired oxygen of 100%. Initial end-tidal carbon dioxide was 40 mm Hg. Her arterial blood pressure was 110/68 mm Hg and remained stable throughout the case. Although preparations were being made to definitively manage the airway, a left brachial arterial line and a right femoral central venous catheter were placed.

Our working diagnosis in the operating room was a floor-of-mouth expanding infection (Ludwig’s angina), which would present as a “woody” submental mass and could have caused the hypoxic arrest. When the paramedics were questioned, the only history they were able to give was that the family felt the patient was sick the week before her arrest. They did not know about or document a submental mass. The possibility that the mass was the balloon of the King LT(S)-D device was discussed, but the pilot balloon was not tense to palpation nor did the pressure vary with external manual pressure on the submental mass.

Although the possibility of replacing the King LT(S)-D with an endotracheal tube (ETT) over a flexible bronchoscope was considered, no pediatric flexible bronchoscope was available to pass through the ventilation lumen of the King LT(S)-D. Passing a tracheal introducer (“gum elastic bougie”) blindly was not deemed prudent because of potential trauma. For the same reason, we did not attempt direct laryngoscopy with the King LT(S)-D in place while we were achieving adequate ventilation and oxygenation.

Under general anesthesia using sevoflurane, the surgeons proceeded with an uneventful tracheotomy, and the King LT(S)-D was deflated and removed once the end-tidal carbon dioxide was verified through the tracheostomy tube. The submental mass resolved immediately on the removal of the King LT(S)-D, which required 180 mL of air to be removed from the cuff for deflation. Subsequent direct laryngoscopy with a Macintosh 3 blade revealed a Cormack-Lehane grade 4 view with no epiglottis visible. C-MAC Video Laryngoscope (Karl Storz Endoscopy Canada Ltd., Mississauga, ON, Canada) with a D-Blade revealed a full view of the glottis.

Postoperatively the patient was transferred to the medical surgical intensive care unit, where she was ventilated, treated with antibiotics, and cooled as per the postarrest cooling protocol for neuroprotection. Unfortunately, on postadmission day 3, she had made no meaningful neurologic recovery, and the family, in consultation with the critical care team, decided to withdraw life-sustaining treatment. The patient died quickly thereafter.

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This case illustrates a number of important points that may be of interest to any health care provider who uses a King LT(S)-D or other extraglottic airway devices such as the laryngeal mask airway (LMA®; Teleflex Medical, ON, Canada) or the Combitube (Kendall Sheridan Healthcare Products Company, Argyle, NY). We will briefly discuss the manufacturer’s specifications for the King LT(S)-D as they relate to subsequent airway management and tracheal intubation. In hindsight, we will discuss options available in the management of this difficult airway that could have obviated the need for a tracheotomy. However, this case also provides an opportunity to discuss a common misconception among airway practitioners: a surgical airway represents a “failure” in airway management.

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King LT(S)-D Specifications

Extraglottic devices (EGDs) such as the King LT(S)-D, Combitube, or LMA® have gained widespread acceptance in the prehospital, critical care, and perioperative arenas.1–3 Indeed, the use of an EGD is recommended as a backup emergency airway device in the event of difficult bag-mask ventilation and failed intubation attempts on numerous difficult airway algorithms.4–7 Based on the accepted airway management guidelines, the use of the King LT(S)-D device by paramedics in this case was an appropriate rescue maneuver after failed intubation. EHS stock the King LT(S)-D as the sole EGD on every ambulance in Nova Scotia, because of their relative ease of insertion and reliable ventilation and oxygenation.8,9 As such, paramedics, emergency physicians, intensivists, and anesthesiologists should be familiar with the characteristics of the King LT(S)-D, particularly as it relates to subsequent definitive airway management.

The King LT(S)-D is a disposable airway with a distal tip and a small balloon designed to sit within the esophagus, a ventilation lumen more proximally that approximates the glottic opening, and a large supraglottic balloon to seal the oropharynx, allowing ventilation and gas exchange. The King LT(S)-D connects to standard airway circuits or self-inflating bags. The King LT(S)-D device is also designed with a channel that can accommodate an 18-French nasogastric tube for esophageal and gastric suctioning. There are several sizes of King LT(S)-D designed to accommodate pediatric to large adult patient populations. The King LT(S)-D in this case was a size 3, designed for adults between 4 and 5 feet tall. Its outer diameter is 18 mm with a ventilation lumen diameter of 10 mm. The oropharyngeal balloon is designed to hold 45 to 60 mL of air. Detailed specifications are available at the King Systems web site10 or from numerous published reports.2,8,11,12

Figure 1

Figure 1

In this case, the cuff was overinflated with 3 times the manufacturer’s recommended volume, which was likely contributory to the appearance and feel of the submental mass. Anatomical features of the patient such as the large tongue and small thyromental distance might have accentuated the overinflation appearance of the supraglottic balloon in the oropharynx, thus making the “mass” more prominent. An example of the effect of overdistension of the balloon on the external soft tissues of the neck of a freshly prepared cadaver is demonstrated in Figure 1. An important lesson to be learned from this case is that the supraglottic balloon of a King LT(S)-D can create a clinical scenario that mimics the presentation of Ludwig’s angina or a supraglottic mass lesion. We also urge careful adherence to the recommended manufacturer’s cuff inflation volumes, because many studies have reported significant tongue swelling associated with prolonged and overinflated balloons.13 The recommended volume is printed on each extraglottic airway device. To minimize a potential adverse outcome associated with the use of an EGD, we also recommend the careful documentation of the inflation volume and the cuff pressure after the placement of the device and routinely when a patient’s care is transferred between health care providers. In our case, we did not measure the pilot balloon pressure with a manometer (manufacturer guidelines suggest a standard filling pressure of 50 cm H2O).

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Airway Management with an EGD in Place

If a health care provider encounters a similar situation in the future, several airway management options may be considered before performing a surgical airway. The first priority in any emergency airway scenario is to maintain oxygenation, and one should carefully consider the clinical context before removing the King LT(S)-D. In our case, one option would have been to remove the King LT(S)-D and attempt further tracheal intubation with a video laryngoscope such as the C-MAC Video Laryngoscope, Glidescope (Verathon, Bothell, WA), or King Vision (King Systems). Like with the esophageal/tracheal Combitube and EasyTube, the cuff of the King LT(S)-D can be deflated during direct or indirect laryngoscopy to determine whether the glottis could be viewed by a more experienced airway practitioner.14 However, even if the glottis was visualized, removing the King LT(S)-D to attempt tracheal intubation in the context of a possible Ludwig’s angina would not have been prudent. Although it might have been possible to reinsert the King LT(S)-D if the intubation attempt failed, the risk of a complete airway obstruction secondary to the submental mass could not be ignored. We recommend that any rescue extraglottic airway device that can reliably oxygenate and ventilate an unconscious patient be left in place while preparing for a definitive airway with adjunct airway equipment and additional resources. Although aspiration is a potential risk without a cuffed ETT, oxygenation should always remain the priority until definitive airway control can be achieved.

An extraglottic airway can be exchanged for a cuffed ETT by using a tracheal introducer, which will pass through the ventilation lumen of most devices. However, blindly advancing the tracheal introducer through the lumen of the King LT(S)-D may lead to tissue trauma and can potentially worsen the ability to oxygenate should laryngospasm, bleeding, edema, or significant obstruction occur. A lighted stylet within the lumen of a 6.0-mm internal diameter ETT will pass through the lumen of most adult size EGDs (LMA® Proseal or Intubating LMA®, Teleflex Medical, ON, Canada)15–17 and may give early confirmation of glottis entrance but may also cause trauma and will not easily allow the EGD to be removed over the ETT.

An indirect visualization technique, using a pediatric flexible bronchoscope, in conjunction with the Aintree tracheal introducer (ATI; Cook Medical Inc., Bloomington, IN) is an effective means of safely exchanging the EGD, and successful tracheal intubation has been reported for the LMA® (both LMA®-Classic and LMA®-Supreme),18–23 the iGel (Intersurgical Inc., Liverpool, NY),24,25 and the King LT.26–28 The ATI is a flexible, 50-cm long catheter with a 6-mm lumen, large enough to accommodate a pediatric flexible bronchoscope. With the ATI loaded onto the bronchoscope, the tip of the bronchoscope can be introduced through the lumen of the EGD and through the distal aperture into the glottis. The ATI can then be advanced into the trachea followed by the removal of the bronchoscope and EGD. A cut (26 cm long) ETT can then be advanced over the ATI. After removing the ATI and confirmation of ETT placement, the ETT should be secured. Alternatively, case reports describe flexible bronchoscopic intubation through the nose or mouth with a King LT in place and maintaining ventilation simply by navigating the bronchoscope around the supraglottic balloon.28 In some situations, the balloon can be deflated momentarily to allow the bronchoscope to advance into the glottis opening. However, Budde et al.29 reported that it is easier to exchange a laryngeal tube with an intraluminal, rather than extraluminal, technique.

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Surgical Airway

Although ATI-assisted bronchoscopic intubation is the preferred technique to replace an EGD, visualization of the glottis is not always easy or even possible.30 In those situations, like in our case, the safest course is to establish a surgical airway. The surgical airway is 1 of only 5 broad techniques that health care providers can use to oxygenate and ventilate an apneic patient (bag and mask, EGD, ETT, and extracorporeal membrane oxygenation are the other options) and should not be considered a failure of airway management. In fact, persistent intubation efforts and avoidance of the surgical airway can tragically result in anoxic brain injury and death, as it is speculated in the widely cited case of Elaine Bromiley in England.31

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The King LT(S)-D EGD is an increasingly popular airway device that health care providers should be familiar with. In this case, the improper use of the device resulted in a clinical presentation similar to Ludwig’s angina, necessitating an emergency tracheotomy. Health care providers should ensure proper training and use with airway devices, including techniques that will allow establishment of a definitive airway. Training and regular practice in tracheal intubation through most EGDs using the ATI together with a flexible pediatric bronchoscope are recommended. Finally, a surgical airway should be considered an acceptable outcome and performed early if tracheal intubation through the glottis is anticipated to be unsafe or has failed.

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