Article

Use of the intubating laryngeal mask airway in the emergency department: A ten-year retrospective review

a b s t r a c t

Background: Extraglottic devices, such as the intubating laryngeal mask airway (ILMA), facilitate ventilation and oxygenation and are useful for Emergency airway management, especially as rescue devices. In the operating room setting the ILMA has been highly successful. However, its performance in the ED has not been described. We sought to describe the indications for and success of the ILMA when used in the ED.

Methods: We performed retrospective, observational study of patients who had an LMA(R) Fastrach(TM) (hereafter termed ILMA) placed in a single ED between 2007 and 2017. Patients were identified by keyword search of ED notes in the electronic medical record. Trained abstractors reviewed charts and videos to determine patient char- acteristics, indication for ILMA placement, success of oxygenation and ventilation, intubation methods and suc- cess, and complications related to the device.

Results: During the study period 218 patients had an ILMA placed in the ED. The ILMA was used as a primary de- vice in 118 patients (54%), and as a rescue device in 100 patients (46%). The median number of ILMA uses per faculty physician during the study period was 3. The ILMA oxygenated and ventilated successfully in 212 instances (98%), including 96 times (96%) when used as a rescue airway. Failure of oxygenation was due to tra- cheal injury (2), abnormal laryngeal inlet anatomy (2), or poor operator technique (1). Intubation through the ILMA was successful in 159 of 192 patients (83%), including a success rate of 81% (112 of 139 patients) with blind intubation.

Conclusion: The ILMA was highly successful in oxygenation, with reasonable intubation success, even when used infrequently by emergency physicians. The ILMA should be considered a valuable primary and rescue Intubation device in the ED.

(C) 2019

Introduction

Extraglottic devices (EGD), such as an intubating laryngeal mask air- way (ILMA), are useful for specific situations within emergency airway management (eg, when definitive airway management can be delayed because of other resuscitation priorities, as a rescue device after oxygen- ation or intubation failure, when a difficult intubation is anticipated). The ILMA sits in the hypopharynx and forms a mask seal around the glottis. It is not considered a definitive airway but can provide oxy- genation and ventilation, offers some protection against gastric aspira- tion [1-4], and can be used as a conduit for intubation.

* Corresponding author at: Department of Emergency Medicine, 701 Park Ave S, Mail Stop R2, Minneapolis, MN 55415, USA.

E-mail address: [email protected] (B.E. Driver).

ILMAs can be used both as a primary airway (often termed a rapid sequence airway [5] when Neuromuscular blockade is administered) and as a rescue device. ILMAs are valuable rescue devices for emergency airway management, where all intubations are unplanned and the- refore should be considered potentially difficult; all modern difficult airway algorithms suggest using an EGD (usually an LMA) in the “can- not-intubate, cannot-ventilate” situation [6]. Despite evidence of the success of the ILMA in the operating room [7-9] and the out-of- hospital setting [10,11], it seems to be infrequently used in the ED. The ILMA may be a valuable primary and rescue device for ED patients. However, descriptions of ILMA use in the ED are limited to case reports and small series, describing in total 20 patients [12-14] — despite the fact this is the go-to rescue device for many emergency physicians.

A systematic description of ILMA use in the ED with significantly more patients, using high-quality video review methods, would be ben- eficial to outline its oxygenation and intubation success rates. We

https://doi.org/10.1016/j.ajem.2019.11.017

0735-6757/(C) 2019

sought to describe the indications, success, and complications of the ILMA when used in the ED setting.

Materials and methods

Study design

We performed a retrospective, observational study at an urban aca- demic ED. The local institutional review board approved this study.

Study setting

This study was conducted at Hennepin County Medical Center, an urban, academic ED with an annual census of approximately 100,000 visits. Treating emergency physicians make all airway management de- cisions and perform all airway procedures. Senior emergency medicine residents (post-graduate year 3 or higher) perform the majority (N85%) of intubations; junior residents and Attending emergency physicians perform the remainder. We have used the intubating laryngeal mask airway in the ED since 2000. After initial experience using LMA(R) Fastrach(TM) for routine intubations [14,15], its use quickly expanded to its current role, as our primary rescue device in cases of failed intuba- tion. We use the LMA(R) Fastrach(TM) (hereafter termed ILMA) because it reliably achieves ventilation and oxygenation and was specifically de- signed for blind intubation [16]. We have 4 difficult airway carts in our ED and each is stocked with reusable ILMAs, sizes 3, 4 and 5. In gen- eral, we use size 4 for adult females, size 5 for adult males, and size 3 for very small adults or adolescents. When intubating through the ILMA, we used a standard polyvinyl chloride (PVC) endotracheal tube, fed into the ILMA with a reversed curve. When removing the ILMA after tracheal in- tubation, we have previously used the semi-rigid obturator rod pack- aged with the ILMA but have recently switched to a longer removal stylet, because of increased ease of use (Air-Q removal stylet, Cookgas, St. Louis, MO). All residents receive didactic and hands-on manikin- based training including hands-on practice with the ILMA.

Selection of participants

Using the electronic medical record (EMR) (Epic Systems, Verona, WI), we identified ED patients who had an ILMA placed in our ED from 2007 through 2017 with a text search of all ED notes for the fol- lowing keywords: intubating laryngeal mask airway, laryngeal mask airway, LMA, or ILMA. Based on local experience, physicians write one of these keywords when documenting an intubation course when the ILMA was used. The study dates were selected based on the date we started routine video recording of all airway management. We do not routinely place other laryngeal mask airways or extraglottic devices and thus did not search for alternate devices such as the laryngeal tube. For patients identified using this text search, an abstractor manu- ally reviewed each chart to determine whether the patient had an ILMA placed in the ED.

Methods of measurement

Trained, unblinded abstractors performed a chart and video review (if available) for each identified patient and entered data into a stan- dardized form using REDcap [17]. The initial data collection form was refined after review of the first several patients. The study team met pe- riodically to re-train and answer questions about data collection to en- sure data uniformity.

Using manual chart review, abstractors collected patient demo- graphics, the indication for intubation and ILMA placement, whether the patient had abnormal airway anatomy, mental status at the time of ILMA placement, and whether a neuromuscular blocking agent was used.

In the ED, critically ill or injured patients receive care in a 4-bay sta- bilization room. Each resuscitation bay has 3 ceiling-mounted video cameras activated by motion sensors. Automated software combines the video streams with output from the patient cardiac and vital sign monitor, as well as audio recording of the room. The videos are stored on a secure database and are used for peer review, quality assurance, and research purposes. Using video review, abstractors recorded ED air- way management, including other intubation attempts and devices, whether ILMA was inserted as a primary or rescue airway, whether the ILMA successfully oxygenated and ventilated the patient, details re- garding intubation attempts through the ILMA, and complications asso- ciated with ILMA use. Successful oxygenation and ventilation was defined as apparent chest rise with bag ventilation and no removal of the device because of apparent failure; waveform capnography was not uniformly used during ILMA use, but if available, this was also reviewed to determine successful ventilation. Successful intubation through the ILMA was defined as successful endotracheal tube place- ment through the ILMA into the trachea, confirmed with waveform capnography. Complications included hypoxemia (oxygen saturation drop to b90%), cardiac arrest during or within 2 min of ILMA placement, and vomiting or aspiration (as seen on video or recorded in the physi- cian note). For patients who were unable to be intubated through the ILMA, we recorded apparent reasons for intubation failure.

If the resuscitation video was not available, the abstractor reviewed nursing and physician notes in the electronic medical record to ascer- tain the variables planned to be abstracted from the video. In some in- stances, these variables were not able to be collected from chart review and were recorded as missing with no assumed value. We tabu- lated the number of observations with missing data for each variable and displayed them as table footnotes.

Outcome measures

The primary outcome measure was whether the ILMA provided ad- equate oxygenation and ventilation. Secondary outcomes included intu- bation success through the ILMA and complications associated with ILMA use.

Primary data analysis

Baseline characteristics and intubation process measures and out- comes were analyzed using descriptive techniques; frequencies, pro- portions, and medians are presented as appropriate.

In order to calculate Interobserver agreement a second abstractor reviewed 10% of the encounters to review primary and secondary out- come values; an unweighted ? value was calculated. For whether venti- lation was adequate, agreement was 95% (k = 0.79); for intubation success, agreement was 94% (k = 0.85). We used Stata 15.1 (Statacorp, College Station, TX) for data analysis.

Results

We identified 218 eligible patients during the study period, of whom 118 had the ILMA used as a primary device; for the remainder the ILMA was used as a rescue device after failure of other intubation methods. Of these, video was available for review for 166 (76%); the remainder underwent chart review only. Baseline characteristics and indications for intubation are displayed in Table 1. ILMAs were placed under the su- pervision of 44 different faculty, with a median of 3 uses per faculty (IQR 2-6, range 1-38) during the study period. When the ILMA was used as a rescue device, a variety of intubation methods failed before ILMA use, including video and direct laryngoscopy, and flexible endoscopic intu- bation (Table 1).

Details, stratified by primary and rescue uses, regarding ventilation, intubation methods, success, ILMA removal, and complications are pre- sented in Table 2 and in Fig. 1. The ILMA was able to provide adequate

Table 1

Baseline characteristics, reasons for ILMA use, and prior devices.

Variable Value

Table 2

Details of ILMA use, removal, and complications.

Variable Primary

Rescue

Age (IQR) – y Male Gender

49 (36-59)

159 (73)

device

(N = 118)

device

(N = 100)

Primary reason for intubation

ILMA effective for oxygenation & ventilationa

117 (99)

96 (96)

Altered mental status

128 (59)

Intubation through ILMA attemptedb

108 (92)

84 (84)

Cardiac arrest (medical)

29 (13)

Intubation success rate, overall

95/108

64/84 (76)

Asthma/COPD

28 (13)

(88)

Polytrauma

10 (5)

Methods of intubation through ILMA – successful intubation/attempts

(% success)c

Angioedema

6 (3)

Unassisted (blind) 75 / 87

37 / 52

Head or facial injury

4 (2)

(86)

(71)

Other

13 (6)

Endoscopic-assisted 8/13 (62)

4/12 (33)

Abnormal airway anatomy presenta

22 (10)

Unable to determine 12/13 (92)

23/25 (92)

Sedated or comatose at time of ILMA placement

216 (99)

Method of intubation if ILMA intubation failed N = 13

N = 20

Neuromuscular blocking agent before ILMA placement

176 (81)

video laryngoscopy 9/13 (69)

7/20 (35)

ILMA used as rapid sequence airwayb

94 (43)

Direct laryngoscopy 4/13 (31)

8/20 (40)

ILMA used as primary device

118 (54)

nasal intubation 0

2/20 (10)

Reason used as primary device

Cricothyrotomy 0

2/20 (10)

Educational

29 (25)

retrograde intubation 0

1/20 (5)

Hypoxemia after preoxygenation

14 (12)

ILMA removed after successful ILMA intubationd 94/95 (99)

59/64 (92)

Predicted difficult airway

4 (3)

Method of ILMA removal

Unknown reason

71 (60)

Semi-rigid obturator rod 65 (69)

34 (58)

ILMA used as rescue device

100 (46)

Removal stylet 6 (6)

0

Devices tried before ILMA placed for rescue:c

second tracheal tube 5 (5)

0

Video laryngoscopy

47 (47)

Other 2 (2)

0

number of attempts, median (IQR; range)

1 (1-3; 1-5)

Unable to determine 16 (17)

25 (42)

Direct laryngoscopy

67 (67)

Complications

Number of attempts, median (IQR; range)

2 (1-3; 1-5)

Hypoxemia during placement or use 12 (10)

11 (11)

Bougie used with VL or DL

55 (55)

Cardiac arreste 1 (1)

1 (1)

Nasotracheal intubationd

8 (8)

Vomiting or aspiration 0

3 (3)

Oral endoscopic intubation

8 (8)

Extubation during ILMA removal, after successful 1/94 (1)

2/59 (3)

Failed Faculty attempt before ILMA placement

31 (31)

intubation through ILMAf

All values are counts (%) unless otherwise stated.

Including facial trauma, Neck trauma, angioedema, airway mass or swelling, or other ab- normal anatomy.
  • Rapid sequence airway defined as ILMA placement as the primary device, facilitated with use of a neuromuscular blocking agent.
  • Patients could have more than one technique tried before ILMA placement.
  • Including 2 blind attempts and 6 flexible endoscopic attempts.
  • oxygenation and ventilation in the vast majority of patients (98%), in- cluding in 99% of primary uses and 96% of uses as a rescue device. On video review, abnormal patient anatomy was the cause of ILMA oxygen- ation failure in 4 of the 5 patients — 2 had trauma to the trachea resulting in an air leak through the wound with positive pressure, and 2 had abnormal anatomy of the laryngeal inlet precluding achievement of a good seal. Only 1 of these 4 patients were able to be effectively mask ventilated. The remaining patient unable to be oxygenated through the ILMA was the result of poor patient positioning, with a flat position in an obese patient, and a failure to hold the metal ILMA handle to provide a good seal. Mask ventilation and intubation for this patient were also dif- ficult until a ramped position was used, and then both were easily accomplished.

    Intubation was commonly attempted in both primary and rescue uses, and was successful in 83% of patients, including a success rate of 81% with blind intubation. Details of use and success of ventilation and intubation are presented in the Fig. 1. Complications were infre- quent (Table 2). Following successful intubation through the ILMA, 3 patients were inadvertently extubated during ILMA removal. All were successfully re-intubated through the ILMA using a blind technique.

    There were 8 patients with failure of both laryngoscopy and flexible endoscopic methods before ILMA use, of whom 7 were able to be suc- cessfully ventilated and intubated through the ILMA.

    Of the patients who had unsuccessful intubation attempts through the ILMA, we noted several probable reasons for failure. We observed instances of ILMA use with the metal handle tilted so that it pointed to- ward the ceiling, likely displacing the laryngeal mask out of the correct location, rather than maintaining the handle parallel to the patient’s face. Failure to stabilize the metal handle in the correct position oc- curred commonly: in some, the metal handle was not lifted directly

    All values are counts (%) unless othrewise stated.

    Causes of oxygenation/ventilation failure: Penetrating neck trauma with air leak through wound (2), abnormal laryngeal inlet anatomy with good ILMA technique (2), suboptimal patient positioning in an obese patient, and not gripping ILMA handle (1).
  • Details for patients without an intubation attempt through the ILMA: 13 intubated using laryngoscopy after ILMA, 7 died with ILMA in place, 5 patients underwent cricothyrotomy, 1 ILMA used for procedural sedation.
  • 10 patients total, 5 each in primary and rescue, had both flexible endoscopic and blind intubation attempted.
  • Of these patients, 5 died with the ILMA in place. The last had severely abnormal airway anatomy; the ILMA was placed and intubated through after failure of multiple methods. The ILMA was left in place for approximately 24 h, at which point a tracheostomy was per- formed in the operating room. He was found to have severe supraglottic swelling and a right tonsillar infection. There were no apparent complications related to the ILMA being left in place for a prolonged period.
  • Both patients had severe hypoxemia and shock prior to ILMA use; cardiac arrest not ap- parently related to ILMA use.
  • After accidental extubation, all 3 patients had the ILMA replaced, were blindly intubated through the ILMA, and the ILMA was removed successfully without further complication.
  • upwards (ie, lifting anteriorly while maintaining the handle parallel to the patient’s face) to create a tight seal and achieve the correct position of the laryngeal mask (often referred to as the “Chandy maneuver”); in others, the metal handle was not held at all; that is, the ILMA was not stabilized in any manner during tube passage. These shortcomings also make successful oxygenation and ventilation unlikely. Additionally, some had attempts at intubation occur before any attempt at ventila- tion; this can be problematic because the ILMA should be positioned at the point of optimal ventilation (which supports proper anatomic placement) before intubation is attempted. We observed missized ILMAs, with either too small or too large an ILMA placed for the patient’s gender and weight. Finally, in several instances the ILMA was placed 10 or more minutes after succinylcholine administration, and it appeared the patient no longer had neuromuscular blockade, and likely had vocal cord adduction with attempted tube passage.

    Limitations

    Retrospective reviews can be challenging, though video availability for more than 3/4 of the patients and higher interobserver agreement

    Fig. 1. This figure displays the success of the ILMA for ventilation and intubation in this cohort.

    support the reliability of the data. Assessing for complications retro- spectively, even with video review, can be inaccurate and it is possible that some complications were missed, especially aspiration. Identifying patients by key word search inevitably misses some eligible cases, and although we are not aware of any missed cases, it is possible we missed some cases where the ILMA was used unsuccessfully as an interim step during a course of intubation. Most patients in this cohort were intubated for reasons other than hypoxemic respiratory failure; thus, the results may not generalize to patients intubated for parenchymal lung disease. Similarly, the ILMA was used for educational purposes in at least 13% of cases, probably in low-risk patients; the results from this cohort do not generalize to ILMA rescue use. All physicians had lim- ited manikin training prior to use, so the results demonstrate that the device is robust to limited and infrequent experience; however, the re- sults may not generalize to physicians who have never practiced with an ILMA. One physician accounted for 17% of ILMA uses, which intro- duces some clustering by provider; this is somewhat mitigated by the high number of attending physicians who used the ILMA, and the low median uses per faculty. We studied the LMA(R) Fastrach(TM), as this was the only device routinely used in our ED; future research should study the ED use of other common EGDs, especially those that can be used for intubation.

    Discussion

    In this retrospective observational study we found the LMA(R) Fastrach(TM) to be highly successful for oxygenation and ventilation as well as for blind intubation in the ED setting, both as a primary intuba- tion device and as a rescue device after failed intubation attempts. To our knowledge, a systematic description of the use of EGDs or ILMAs in the ED has not previously been completed. This could be due to low ILMA utilization in the ED, perhaps because it is viewed primarily as an operating room and out-of-hospital device. These data support the use of the ILMA in the ED as a reliable primary and rescue device.

    The use of Neuromuscular blocking agents for intubation is associated with fewer complications [18], and most ED patients are appropriately

    intubated using traditional rapid sequence intubation [19]. Given this, it is crucial for emergency providers to have a reliable and well-tested rescue device for failed RSI. The most important role of an EGD is oxygen- ation and ventilation, especially when used as a rescue device. We report a 98% success for oxygenation and ventilation, similar to out-of-hospital and most anesthesia literature [9,20-22], though some authors have re- ported 100% success [23,24]. Despite recommendations to avoid EGDs in patients with abnormal anatomy (eg, angioedema) [25], these and prior data [26] support the use of these devices in select patients even if Supraglottic structures are distorted, and support the efficacy of the ILMA for rescue oxygenation in the “cannot-intubate, cannot-ventilate” setting, consistent with international guidelines [6]. Failure to oxygenate was rare and usually related to tracheal injury, abnormal laryngeal inlet anatomy, or poor technique.

    Though the primary value of the ILMA is the ability to provide gas ex- change, it can also serve as a conduit for tracheal intubation, unlike the non-intubating laryngeal mask airway. This is important because the ILMAs are commonly used as backup devices after failed laryngoscopic intubation, and the ability to intubate through the device provides a dis- tinct advantage, avoiding the scenario of removing the rescue device in order to repeat the intubation attempt of a difficult airway. Historically, success rates for blind intubation through the LMA(R) Fastrach(TM) have ranged from 84 to 99% [9,20-22,24,27,28]. The success rate of blind in- tubation in this series, however, was only 81%. This lower success rate is likely due to patient selection and operator inexperience. Most ILMA literature has studied patients requiring intubation for elective surgery, not patients undergoing emergency intubation. Furthermore, emer- gency physicians do not use the ILMA as frequently as anesthesiologists; in this series the median number of ILMA uses per faculty was just 3 over a 10-year period. Available data suggests that 8-20 uses of the ILMA are required to achieve high levels of blind intubation success with the device [9,24,29]. In contrast, most of our physicians learned the mechanics of using ILMA on manikins, and then used the device for the first time on a real patient during a difficult emergency airway. Therefore, given the very small number of ILMA uses per faculty over an extended period of time, oxygenation success of 98% and intubation

    success of 81% indicate that the ILMA is fairly robust to operator inexpe- rience and should be able to be successfully used by relative novices. These data should be encouraging for other emergency providers who store an ILMA as a rescue device and will likely use it for the first time in a difficult or failed airway. Importantly, the ILMA was successfully used for oxygenation and intubation of 7 patients in whom both video laryngoscopy and flexible endoscopic intubation had failed – patients who would likely have received a Surgical airway if the ILMA was not utilized.

    Though operator inexperience and patient selection may explain the low intubation success, we observed several simple shortcomings that would increase the likelihood of oxygenation and intubation success through the ILMA. Well known adjustment maneuvers such as rotating the device in the sagittal plane until maximal ventilation is achieved, and lifting upward with the metal handle to better seal and position the mask around the glottis (also known as the Chandy maneuver)

    [27] can facilitate both oxygenation and endotracheal tube passage. The use of neuromuscular blockade reduces coughing, gagging, and vocal cord adduction during tube passage. An excellent review by Gerstein et al highlights other suggestions that should increase success, such as using an appropriately sized ILMA, pre-warming the endotra- cheal tube, using a Parker flex-tip tube, and, if using a standard PVC endotracheal tube (as in this data set), reversing the tube curve so that the tube approach angle is shallower and the tube is less likely to impinge on anterior airway structures [30]. Knowing that the endotra- cheal tube exits the ILMA at 15 cm, some authors have proposed trou- bleshooting solutions depending on the depth of the tube when resistance is met [31]. Finally, using the ILMA more routinely by incorporating the ILMA into the standard emergency airway algorithm should improve familiarity, technical skills, and overall device success [15,23,32].

    These suggestions do not apply to endoscopic-assisted intubation through the ILMA, a technique that has high success with most ILMA brands and can be attempted if blind intubation fails. In this series, how- ever, endoscopic-facilitated intubation success was low, probably be- cause patients this method was attempted only after blind intubation failed, selecting a more challenging population with less straightfor- ward airway anatomy; additionally, not all intubators utilized concom- itant oxygenation through the ILMA with use of a swivel adapter while performing endoscopic attempts, curtailing available time before the onset of hypoxemia. The ILMA used in this series, however, has repeat- edly been shown to have higher success rates for blind intubation com- pared to other ILMAs, highlighting its practical utility for EDs without endoscopic availability [16,28,30,33].

    Three patients were inadvertently extubated during ILMA removal, an avoidable complication of ILMA use. This might be avoided with the understanding that there is no urgency to ILMA removal, which should be a planned and methodical procedure performed after other resuscitation priorities are addressed [34]. Additionally, we have switched from the semi-rigid obturator rod packaged with the ILMA to a removal stylet, which is longer, more flexible, and easier to use.

    EGDs are valuable airway tools used in many clinical arenas, and are

    recommended as rescue devices in intubation algorithms [6]. Despite this, it is not clear how often these devices are used in EDs; better de- scriptions of their success and complications in the ED, especially for modern devices, are needed. The high success rates experienced at our institution should be encouraging to other emergency physicians who use EGDs infrequently, but further study is needed in a wider variety of clinical settings to confirm these findings and determine if differences in success exist between different types of EGDs.

    Conclusion

    In conclusion, we observed the LMA(R) Fastrach(TM) to be highly suc- cessful in oxygenation and ventilation, with reasonable blind intubation success, even when used infrequently by emergency physicians. The

    ILMA should be considered a valuable primary and rescue device for ED airway management.

    Previous presentation

    This was presented at the Annual Meeting of the Society of Academic Emergency Medicine, May 2018, Indianapolis, IN

    Financial disclosures

    This was an unfunded investigation. No authors have any conflicts of interest to report.

    Declaration of Competing Interest

    None.

    Acknowledgements

    None.

    Author contributions

    BD, MM, and RR conceived and designed the study. TM performed chart and video review. BD performed the data analysis. BD, MM, TL, and RR drafted the initial manuscript, and all authors contributed sub- stantially to its revision. BD takes responsibility for the study as a whole.

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