- Email: [email protected]
Use of the intubating laryngeal mask airway by medical and nonmedical personnel
Use of the Intubating Laryngeal Mask Airway by Medical and Nonmedical Personnel RICHARD M. LEVITAN, MD,* E. ANDREW OCHROCH, MD,1- SARAH STUART, RN,* AND JUDD E. HOLLANDER, MD* The intubating laryngeal mask airway (ILMA) is a newly available device designed to allow for blind endotracheal intubation and treatment of patients with difficult airways. We studied the intubation success rates and speed with initial use of this device on an intubation manikin to determine whether this device might be easily used by trained and untrained personnel. Rapid and successful intubation with a device requiring limited or no training could have widespread implications for both health care providers and laypersons. The study consisted of 2 parts. In part 1, health care providers with intubation experience, health care providers without prior intubation experience, and nonmedical personnel were instructed to enter a room and intubate a manikin using the ILMA. A single page set of schematic directions was provided within the ILMA setup. The main outcomes were the intubation success rate and the time required for successful ventilation and intubation. In part 2, participants were retested after a standardized <60 second device demonstration. The 111 participants in the study included 44 emergency physicians (40%), 21 anesthesiologists (19%), and 46 other medical or nonmedical personnel (41%). On first attempted use of the device, and with no prior training, 59% of all participants successfully intubated the manikin. Attending and resident physicians had an 83% initial success rate. The median time to ventilation was 47 seconds, and the median time from ventilation until intubation was 29 seconds. Following the <60 second demonstration, 108 of 111 (97%) participants achieved success, with the median time to ventilation 18 seconds, and the median time from ventilation until intubation 17 seconds. All attending and resident physicians succeeded in intubation following the demonstration. Success rates on first attempt correlated with level of training, prior intubation experience, and prior LMA use (all P < .001). After a <60 second demonstration, medical and nonmedical personnel with and without prior intubation training can successfully use the ILMA to rapidly establish an airway in a manikin model. The ILMA should be further studied to determine if it may permit endotracheal intubation by first responders, paramedical personnel, and other medical staff with limited or no laryngoscopy skills. (Am J Emerg Med 2000;18:12-16. Copyright © 2000 by W.B. Saunders Company) Maintenance of a secure airway is fundamental to resuscitation in critically ill patients. The traditional method used to secure the airway and maintain breathing is endotracheal intubation. When performed by an experienced operator, direct laryngoscopy with a rigid laryngoscope is a highly successful and quick method of inserting endotracheal tubes. 1-5 It is a difficult skill to teach and master, however, and practice opportunities are limited. 6-s Approximately one From the *Department of Emergency Medicine and 1-Department of Anesthesiology, Hospital of the University of Pennsylvania, Philadelphia, PA. Manuscript received November 4, 1998, returned December 22, 1998; accepted March 15, 1999. Address reprint requests to Dr Levitan, Department of Emergency Medicine, Hospital of the University of Pennsylvania, 3400 Spruce St, Philadelphia, PA 19104-4283. E-mail: levitanr@ mail.med.upenn.edu Copyright © 2000 by W.B. Saunders Company 0735-6757/00/1801-0003510.00/0
12
in one-hundred emergency airways require cricothyrotomy, most frequently because of failed laryngoscopy. 24 Emergency cricothyrotomy is the standard rescue technique when laryngoscopy fails and the patient cannot be ventilated, but it is technically challenging and associated with significant morbidity and mortality. 943 Alternative methods of intubation and ventilation have been highly touted but have been slow to be incorporated into emergency department clinical practice because they require extensive training, adjunctive equipment, and periodic retention training.14 The intubating L M A intubating laryngeal mask airway, (ILMA) is a new device that is designed to provide emergency ventilation and subsequent endotracheal intubadon. 15 The I L M A is positioned into the mouth, and an endotracheal tube can be passed through the device and blindly inserted into the trachea. It was our experience that this device was so simple to use that health care providers with and without prior intubation training could probably use it successfully on the first attempt. We studied the speed and success rates of this device on initial use by medical personnel with and without prior airway management experience. In addition, we evaluated a group of nonmedical personnel to determine whether they could use this device without any prior instruction. A simple, easy-to-use device that permits emergency ventilation and subsequent intnbation would be of tremendous value as a primary means of intubation for those with no advanced airway skills, or when laryngoscopy fails. METHODS We conducted a manikin study to determine the success rates of endotracheal intubation using the intubating LMA on health care providers with and without prior intubation experience. Additionally, we examined the use of the ILMA in nonmedical personnel. The University of Pennsylvania institutional review board approved the study. Participants were a convenience sample of hospital staff including faculty, housestaff, nurses, paramedics, and clerical personnel at the Hospital of the University of Pennsylvania. No participants had used or seen the ILMA before the study. Participants were told that they were being tested on a new device for rapid ventilation and intubation. They were instructed to enter an examination room and secure the airway in a manikin using the tools available in the room (see protocol details below). They were also told that this exercise would be observed and timed. They were given no other information about the study, manikin, or airway device. No feedback or questions were permitted during the test.
Intubating LMA Device The intubating LMA (Fastrach, Gensia Automedics, San Diego, CA) is a modified version of the laryngeal mask airway. Compared to the standard laryngeal mask airway, the device has been
LEVITAN ET AL • INTUBATION SUCCESS WITH THE ILMA
modified with a large bore metal tube, a metal handle, and an epiglottis elevating bar on the distal end of the mask (Figure 1). 15 The standard laryngeal mask airway (which is not designed for endotracheal intubation) has been in use in the United States since 1991. The intubating laryngeal mask airway was released in March 1998. The intubating LMA is positioned into the mouth by following the curvature of the device around the curvature of the tongue (Figure 2). After inflation of the mask (30 mL for size #4 ILMA), the patient can be bag ventilated by connecting the standard 15 mm connector from a ventilation bag to the large-bore metal tube. For endotracheal intubation through the ILMA, the manufacturer supplies a noncurved, reinforced endotracheal tube with a soft plastic tip. The endotracheal tube is lubricated and blindly placed through the metal tube previously used to ventilate (Figure 2). After the endotracheal tube is placed, the ILMA can be removed.
Protocol When participants entered the examination room, a manikin, an ILMA setup, and an instruction sheet were present. The instruction sheet was a single 8.5 × ll-inch piece of paper with 8 schematic illustrations and a 50-word description of the use of the ILMA, based upon an instructional manualis (Figure 3). Equipment included a standard intubation manikin (Medical Plastics Laboratory, Gaitesville, TX), silicone lubricant, mad an ILMA (size #4) with an accompanying 8.0 French endotracheal tube (Gensia Automedics, San Diego, CA). One 30 mL-syringe was attached to the ILMA cuff, and a 10 mL syringe was attached to the endotracheal tube. A standard bag valve mask was also provided. Our study protocol was designed to simulate use of a rescue device on a difficult airway cart. Because of the rarity of failed intubation,24 most providers will have limited or no experience with any one device. It would be ideal if a rescue device could be effectively used with only a one-page instructional sheet.
13
successful intubation. Success was defined as placement of the endotracheal tube in the trachea beneath the level of the vocal cords. This was assessed via direct observation through a window on the anterior neck of the manikin by one of the investigators. The time until successful ventilation was defined as the time between the participant entering the examination room and the time of first ventilation following 1LMA placement. The time until successful intubation was defined as the time between ventilation and successful passage of the endotracheal tube. All times were measured with an electronic timer (Radio Shack Catalogue No. 23-009). If the time exceeded 120 seconds for ILMA insertion, or if the device was inserted in a nonfunctional manner (ie, handle inserted in mouth, laryngeal mask upside down against the hard palate, and so on), the participant was told to stop. These were recorded as failures and no time to ventilation or intubation was recorded. Following completion of the protocol as described above, each participant received a standardized <60 second demonstration of ILMA insertion and endotracheal tube placement. Participants were then retested without any further feedback or questioning. The outcome (success or failure), the time to ventilation following ILMA insertion, and the time to ventilation via the endotracheal tube were recorded as previously described. In addition, we collected information on each participant including level of training, medical specialty, prior intubation experience, and prior use of the standard laryngeal mask airway.
Data Analysis Data were entered into a Excel Spreadsheet (Microsoft, Inc, Redmond, WA) and imported into SPSS 8.0 (SPSS Inc, Chicago, IL) for statistical analysis. Categorical data are presented as the percentage frequency of occurrence, and statistical comparisons were performed using chi-square tests. Continuous data are presented as the median and interquartile ranges.
Measurements
RESULTS
Our main outcomes were success or failure of each intubation attempt, the time until successful ventilation, and the time until
There were 111 people who participated in the study. There were 56 physicians (23 attending physicians [21%], 23 resident physicians [21%], 7 interns [6%], 3 fellows [3%]), 32 registered nurses (29%), 4 paramedics (4%), 1 emergency medical technician (EMT 1%) and 2 students (2%). Of these, 44 participants worked in the emergency department (23 were physicians, 20 nurses, and 1 an emergency medical technician), and 21 worked in the department of anesthesia (19 physicians, 2 nurses). The remaining participants were physicians without intubation training (14), nonmedical clerical staff (16), nurses (10), emergency medical personnel (4), and students (2). On the first intubation attempt using the ILMA, the overall success rate was 59%. Attending and resident physicians had an initial success rate of 83%. Success rate was related to medical specialty (P < 0.001). Anesthesiologists had a 100% success rate, and emergency physicians had a 64% success rate. Other medical personnel (without intubation experience) and nonmedical personnel had a 35% success rate. Success on the first attempt was also related to level of training (attendings, 83%; residents, 83%; nurses, 52%; interns, 15%; nonmedical personnel, 13%; P < 0.001); prior experience with any form of intubation ( > 5 0 intubations, 89%; 10-49 intubations, 75%; < 10 intubations, 40%, and no intubations, 30%; P < 0.001); and prior experience with use of L M A ( > 5 0 prior uses, 100%; 10-49 prior uses, 100%; < 1 0 prior uses, 100%, and no prior uses, 46%;
FIGURE 1. Intubating LMA [LMA Fastrach] showing rigid metal handle (right), airway tube (center), and inflatable cuff with epiglottis elevating bar (left). Photograph courtesy of Gensia Automedics, Inc.
14
AMERICAN JOURNAL OF EMERGENCY MEDICINE • Volume 18, Number 1 • January 2000
LMA.
Lubricate back tip of deflated
RotateLMAintomouth.
Handle shouldbe mldline.
Inflate cuff
.
1
'
4. Ventilatewith bag.
i
i.
Lubricate tip of tracheal tube thoroughly,
2.
1,
~
~
FIGURE 2. Instructional sheet used in study comprised of eight black and white line drawings on a single 8 × ll.5-inch piece of paper. Modified from Brimacombe JR, Brain AIJ: The laryngeal mask airway: A review and practical guide. WB Saunders, Philadelphia, 1997, pp 230-41 with permission. 15
Insert tube; keep black line towards you. Advance until 26 cm.
....
3, InflateETTballoonwithi0 eeair.
4. Ventilatewith bag.
P < 0.001). For successful cases, the median (interquartile range) time from commencement of procedure until ventilation was 47 (35 to 58) seconds and from ventilation until successful intubation was 29 (23.5 to 36.5) seconds. After the 60 second in-service, the overall success rate for LMA placement was 97% (108 of 1 l 1 attempts). Attending and resident physicians had a 100% success rate following the 60-second training. The 3 missed attempts occurred in intubations attempted by 2 nonmedical personnel and a first-day intern. The median (interquartile range) times from commencement of procedure until ventilation was 17 (15 to 21) seconds and from ventilation until successful intubation was 18 seconds (14 to 20).
DISCUSSION Airway-related adverse outcomes have led to the concept of the "difficult airway." Reviews of closed malpractice
claims showed that persistent and prolonged intubation attempts comprised the most common scenario for catastrophic respiratory events. 16 As a result, the American Society of Anesthesiologists advocated an algorithm for management of these airways that incorporated the use of alternative intubation and ventilation devices. 17 Depending upon the precise definition used and setting studied, the incidence of "difficult airways" varies from 0.05% to 18%. 1 In the controlled operating room setting, failed intubations occur in 0.05% to 0.35% of patients. 1 By contrast, emergent intubations in the emergency department (ED) setting have a 3% to 5.3% frequency of requiring multiple attempts. 24 The use of alternative devices has not been widely incorporated into emergency medicine practice. 14 Many practicing emergency physicians have little or no experience with these devices and more than 20% of academic emergency departments do not have any of these devices
LEVITAN ET AL • INTUBATION SUCCESS WITH THE ILMA
available. 14 It is apparent that proper and timely use of rescue intubation devices by practitioners with little or no prior experience with their use would be dependent upon simplicity of use. The ILMA appears to meet this criterion. Prior studies have shown that unskilled personnel insert standard LMAs more rapidly and reliably than tracheal tubes, and that they can ventilate more effectively with an LMA compared to a bag and mask. 17-2~The standard LMA has been used as guide for endotracheal intubation with and without fiberoptic assistance, but even the largest standard LMA only accepts an endotracheal tube of 7.0 mm internal diameter. 22-24 In a small study of nurses who had no prior airway skills and only manikin training, 60% were able to intubate anesthestized patients using the standard LMA. 21 The ILMA provides for rapid and effective ventilation like the standard LMA but with modifications for rapid conversion to endotracheal intubation. The rigid handle, epiglottis elevating bar, and a specialized straight endotracheal are modifications from the standard LMA designed to facilitate positioning and passage of the endotracheal tube. Unlike the standard LMA, all sizes of the 1LMA can accept up to an 8.0 mm endotracheal tube. The ILMA offers several advantages over other rescue devices. It enables both ventilation and intubation in contrast to the tracheal-esophageal Combitube (Kendall-Sheridan, Mansfield, MA). In contrast to transtracheal jet ventilation and fiberoptic laryngoscopy, it does not require extensive training to use. When used by experienced LMA users in the operating room, the ILMA was successful in 149 of 150 (99.3%) cases. 25 Our study, using a manikin model, shows that ILMA is inherently easy to use, but that a <60 second demonstration was very valuable. Prior to the ILMA demonstration, emergency practitioners had a success rate of 64%. Attending and resident physicians had an 83% initial success rate. Medical personnel who lacked any prior airway training were successful in 35% of initial attempts prior to training. The training demonstration made a dramatic improvement in success rates. Following the 60-second demonstration of the ILMA, 97% of participants successfully established the airway in a median time of 35 seconds. Even 14 of 16 nonmedical personnel in our study were able to achieve intubation with the ILMA following the demonstration. The major limitation of our study is that it is a manikin study. Some potential difficulties in intubation may not be present in a manikin model. Specifically, a down-folded epiglottis can prevent adequate ventilation and endotracheal tube passage. 1 The manikin epiglottis is made of molded plastic that is positioned along the curvature of the tongue and does not hang downwards. Vomiting and aspiration could not be assessed. Esophageal intubation did occur, however, when the device was inserted too superficially or when the axis of the handle was rotated from the midline. The use of a manikin model prevents evaluation of some of these potential problems. On the other hand, manikin-only LMA training has been shown to be equivalent to LMA training that utilizes both manikins and live patients. 26 Another limitation of the study is that we did not require users to select the proper size ILMA. Incorrect size selection can impede endotracheal tube placement. 1 There are 3 sizes of the device: one each for small, medium, and large adults (sizes 3, 4, and 5). Our results may have been negatively impacted because
15
the schematic instructional diagrams were relatively small, black-and-white line drawings. Perhaps the use of larger color diagrams or photographs with labels would have led to better performance with initial use. Finally, we did not assess skill retention. Ease of use and inherent simplicity is critical for rescue airway devices. Experienced laryngoscopists have low failure rates of intubation, varying between 0.03% and 1.0%, depending on the setting. 1-5 Accordingly, any rescue device will be used infrequently by any one provider. Ease of use and inherent simplicity is even more critical for first responders, nurses, basic-level prehospital personnel, and medical staff who do not regularly provide advanced airway management. In conclusion, our data suggest that the ILMA is a simple to use device in a manikin model following minimal training. This is an important requirement for any device used in the emergent management of patients with "difficult airways" and in emergent medical situations that occur outside the hospital setting. The simplicity of the device suggests that it could be used by persons with limited or no laryngoscopy skills, but further studies involving real patients are warranted to address this issue.
REFERENCES 1. Benumof J: Definition and incidence of the difficult airway, in Benumof J (ed): Airway Management, Principles and Practice. Mosby, St Louis, 1996 pp 122-124 2. Sakles JC, Laurin EG, RantapaaAA, et al: Airway management in the emergency department: A one-year study of 610 tracheal intubations. Ann Emerg Med 1998;31:325-332 3. Calderon Y, Gennis P, Martinez C, et al: lntubations in an emergency medicine residency: The selection and performance of intubators. Acad Emerg Med 1995;2:411-412 (abstr) 4. Riggs RW, Tayal VS, Tomaszewski CA, et al: Rapid-sequence intubation at an emergency medicine residency: Success rate and complications encountered during a two-year period. Acad Emerg Med 1996;3:528 (abstr) 5. Vissers RJ, Barton ED, Sagarin MJ, et al: Success and complications rates of rapid-sequence vs non-rapid-sequence intubation in 1,200 emergency intubations. Acad Emerg Med 1998;5:481 (abstr) 6. Sayre MR, Sakles JC, Mistier AF, et al: Field trial of endotracheal intubation by basic-EMTs. Ann Emerg Med 1998;31:228-233 7. Konrad C, Schupfer G, Wiettlisbach M, et al: Learning manual skills in anesthesiology: Is there a recommended number of cases for anesthetic procedures? Anesth Analg 1998;86:635-639 8. Benfield DG, Flaksman RJ, Lin TH, et al: Teaching intubation skills using newly deceased infants. JAMA 1991;265:2360-2363 9. Erlandson MJ, Clinton JE, Ruiz E, et al: Cricothyrotomy in the emergency department revisited. J Emerg Med 1989;7:115-118 10. Wallace CT: Cdcothyrotomy. JAMA 1973;224:248 11. Miklus RM, Elliott C, Snow N: Surgical cricothyrotomy in the field: Experience of a helicopter transport team. J Trauma 1989;29: 506 12. Xeropotamos NS, Coats TJ, Wilson AW: Prehospital surgical airway management: 1 year's experience from the Helicopter Emergency Medical Service. Injury 1993;24:222 13. Boyle MF, Hatton D, Sheets C: Surgical cricothyrotomy performed by air ambulance flight nurses: A 5-year experience. J Emerg Med 1993; 1t :41-45 14~ Levitan RM, Kush S, Hollander JE: Emergency medicine residency programs and compliance with national guidelines for difficult airway management. Acad Emerg Med 1998;5:482 (abstr) 15. Brimacombe JR, Brain AIJ: The laryngeal mask airway: A review and practical guide. Saunders, Philadelphia, 1997, pp 230241
16
AMERICAN JOURNAL OF EMERGENCY MEDICINE • Volume 18, Number 1 • January 2000
16. Caplan RA, Posner KL, Ward RJ, et al: Adverse respiratory events in anesthesia: A closed claims analysis. Anesthesiology 1990;72:828 17. Pennant JH, Walker MB: Comparison of the endotracheal tube and laryngeal mask in airway management by paramedical personnel. Anesth Anal 1992;74:531-534 18. Davies PRF, Tighe SQ, Greenslade GL, et al: Laryngeal mask airway and tracheal tube insertion by unskilled personnel. Lancet 1990;336:977-979 19. Reinhart DJ: Laryngeal mask airway (LMA) vs endotracheal tube (ETT) placement by paramedics, respiratory therapists, and registered nurses. Anesthesiology 1993;79:A105 (abstr) 20. Hayes A, MacCarrol SM: Airway management by unskilled personnei--a comparison of laryngeal mask airway, pocket mask and bag-valve mask techniques. Anesthesiology 1995;83:A223 (abstr) 21. Stone BJ, Leach AB, Alexander CA, et al: The use of the
laryngeal mask by airway by nurses during cardiopulmonary resuscitation-results of a multicentre trial. Anaesthesia 1994;49:3-7 22. Brimacombe JR, Brain AIJ: The laryngeal mask airway: A review and practical guide. Saunders, Philadelphia, 1997, p 63. 23. Heard CMB, Caldicott LD, Fletcher JE, et al: Fiberoptic guided intubation via the laryngeal mask airway in pediatric in pediatric patients. A report of a case series. Anesth Analg 1996;82:1287-1289 24. Bryden DC, Gwinnutt CL: Tracheal intubation via the laryngeal mask airway: A viable alternative to direct laryngoscopy for nursing staff during cardiopulmonary resuscitation. Resuscitation 1998;36: 19-22 25. Brain AI, Verghese C, Addy EV, et al: The intubating laryngeal mask. I1: A preliminary report of a new means of intubating the trachea. Br J Anaesth 1997;79:704-709 26. Roberts I, AIIsop P, Dickinson M, et al: Airway management training using the laryngeal mask airway: A comparison of two different training programs. Resuscitation 1997;33:211-214
12
in one-hundred emergency airways require cricothyrotomy, most frequently because of failed laryngoscopy. 24 Emergency cricothyrotomy is the standard rescue technique when laryngoscopy fails and the patient cannot be ventilated, but it is technically challenging and associated with significant morbidity and mortality. 943 Alternative methods of intubation and ventilation have been highly touted but have been slow to be incorporated into emergency department clinical practice because they require extensive training, adjunctive equipment, and periodic retention training.14 The intubating L M A intubating laryngeal mask airway, (ILMA) is a new device that is designed to provide emergency ventilation and subsequent endotracheal intubadon. 15 The I L M A is positioned into the mouth, and an endotracheal tube can be passed through the device and blindly inserted into the trachea. It was our experience that this device was so simple to use that health care providers with and without prior intubation training could probably use it successfully on the first attempt. We studied the speed and success rates of this device on initial use by medical personnel with and without prior airway management experience. In addition, we evaluated a group of nonmedical personnel to determine whether they could use this device without any prior instruction. A simple, easy-to-use device that permits emergency ventilation and subsequent intnbation would be of tremendous value as a primary means of intubation for those with no advanced airway skills, or when laryngoscopy fails. METHODS We conducted a manikin study to determine the success rates of endotracheal intubation using the intubating LMA on health care providers with and without prior intubation experience. Additionally, we examined the use of the ILMA in nonmedical personnel. The University of Pennsylvania institutional review board approved the study. Participants were a convenience sample of hospital staff including faculty, housestaff, nurses, paramedics, and clerical personnel at the Hospital of the University of Pennsylvania. No participants had used or seen the ILMA before the study. Participants were told that they were being tested on a new device for rapid ventilation and intubation. They were instructed to enter an examination room and secure the airway in a manikin using the tools available in the room (see protocol details below). They were also told that this exercise would be observed and timed. They were given no other information about the study, manikin, or airway device. No feedback or questions were permitted during the test.
Intubating LMA Device The intubating LMA (Fastrach, Gensia Automedics, San Diego, CA) is a modified version of the laryngeal mask airway. Compared to the standard laryngeal mask airway, the device has been
LEVITAN ET AL • INTUBATION SUCCESS WITH THE ILMA
modified with a large bore metal tube, a metal handle, and an epiglottis elevating bar on the distal end of the mask (Figure 1). 15 The standard laryngeal mask airway (which is not designed for endotracheal intubation) has been in use in the United States since 1991. The intubating laryngeal mask airway was released in March 1998. The intubating LMA is positioned into the mouth by following the curvature of the device around the curvature of the tongue (Figure 2). After inflation of the mask (30 mL for size #4 ILMA), the patient can be bag ventilated by connecting the standard 15 mm connector from a ventilation bag to the large-bore metal tube. For endotracheal intubation through the ILMA, the manufacturer supplies a noncurved, reinforced endotracheal tube with a soft plastic tip. The endotracheal tube is lubricated and blindly placed through the metal tube previously used to ventilate (Figure 2). After the endotracheal tube is placed, the ILMA can be removed.
Protocol When participants entered the examination room, a manikin, an ILMA setup, and an instruction sheet were present. The instruction sheet was a single 8.5 × ll-inch piece of paper with 8 schematic illustrations and a 50-word description of the use of the ILMA, based upon an instructional manualis (Figure 3). Equipment included a standard intubation manikin (Medical Plastics Laboratory, Gaitesville, TX), silicone lubricant, mad an ILMA (size #4) with an accompanying 8.0 French endotracheal tube (Gensia Automedics, San Diego, CA). One 30 mL-syringe was attached to the ILMA cuff, and a 10 mL syringe was attached to the endotracheal tube. A standard bag valve mask was also provided. Our study protocol was designed to simulate use of a rescue device on a difficult airway cart. Because of the rarity of failed intubation,24 most providers will have limited or no experience with any one device. It would be ideal if a rescue device could be effectively used with only a one-page instructional sheet.
13
successful intubation. Success was defined as placement of the endotracheal tube in the trachea beneath the level of the vocal cords. This was assessed via direct observation through a window on the anterior neck of the manikin by one of the investigators. The time until successful ventilation was defined as the time between the participant entering the examination room and the time of first ventilation following 1LMA placement. The time until successful intubation was defined as the time between ventilation and successful passage of the endotracheal tube. All times were measured with an electronic timer (Radio Shack Catalogue No. 23-009). If the time exceeded 120 seconds for ILMA insertion, or if the device was inserted in a nonfunctional manner (ie, handle inserted in mouth, laryngeal mask upside down against the hard palate, and so on), the participant was told to stop. These were recorded as failures and no time to ventilation or intubation was recorded. Following completion of the protocol as described above, each participant received a standardized <60 second demonstration of ILMA insertion and endotracheal tube placement. Participants were then retested without any further feedback or questioning. The outcome (success or failure), the time to ventilation following ILMA insertion, and the time to ventilation via the endotracheal tube were recorded as previously described. In addition, we collected information on each participant including level of training, medical specialty, prior intubation experience, and prior use of the standard laryngeal mask airway.
Data Analysis Data were entered into a Excel Spreadsheet (Microsoft, Inc, Redmond, WA) and imported into SPSS 8.0 (SPSS Inc, Chicago, IL) for statistical analysis. Categorical data are presented as the percentage frequency of occurrence, and statistical comparisons were performed using chi-square tests. Continuous data are presented as the median and interquartile ranges.
Measurements
RESULTS
Our main outcomes were success or failure of each intubation attempt, the time until successful ventilation, and the time until
There were 111 people who participated in the study. There were 56 physicians (23 attending physicians [21%], 23 resident physicians [21%], 7 interns [6%], 3 fellows [3%]), 32 registered nurses (29%), 4 paramedics (4%), 1 emergency medical technician (EMT 1%) and 2 students (2%). Of these, 44 participants worked in the emergency department (23 were physicians, 20 nurses, and 1 an emergency medical technician), and 21 worked in the department of anesthesia (19 physicians, 2 nurses). The remaining participants were physicians without intubation training (14), nonmedical clerical staff (16), nurses (10), emergency medical personnel (4), and students (2). On the first intubation attempt using the ILMA, the overall success rate was 59%. Attending and resident physicians had an initial success rate of 83%. Success rate was related to medical specialty (P < 0.001). Anesthesiologists had a 100% success rate, and emergency physicians had a 64% success rate. Other medical personnel (without intubation experience) and nonmedical personnel had a 35% success rate. Success on the first attempt was also related to level of training (attendings, 83%; residents, 83%; nurses, 52%; interns, 15%; nonmedical personnel, 13%; P < 0.001); prior experience with any form of intubation ( > 5 0 intubations, 89%; 10-49 intubations, 75%; < 10 intubations, 40%, and no intubations, 30%; P < 0.001); and prior experience with use of L M A ( > 5 0 prior uses, 100%; 10-49 prior uses, 100%; < 1 0 prior uses, 100%, and no prior uses, 46%;
FIGURE 1. Intubating LMA [LMA Fastrach] showing rigid metal handle (right), airway tube (center), and inflatable cuff with epiglottis elevating bar (left). Photograph courtesy of Gensia Automedics, Inc.
14
AMERICAN JOURNAL OF EMERGENCY MEDICINE • Volume 18, Number 1 • January 2000
LMA.
Lubricate back tip of deflated
RotateLMAintomouth.
Handle shouldbe mldline.
Inflate cuff
.
1
'
4. Ventilatewith bag.
i
i.
Lubricate tip of tracheal tube thoroughly,
2.
1,
~
~
FIGURE 2. Instructional sheet used in study comprised of eight black and white line drawings on a single 8 × ll.5-inch piece of paper. Modified from Brimacombe JR, Brain AIJ: The laryngeal mask airway: A review and practical guide. WB Saunders, Philadelphia, 1997, pp 230-41 with permission. 15
Insert tube; keep black line towards you. Advance until 26 cm.
....
3, InflateETTballoonwithi0 eeair.
4. Ventilatewith bag.
P < 0.001). For successful cases, the median (interquartile range) time from commencement of procedure until ventilation was 47 (35 to 58) seconds and from ventilation until successful intubation was 29 (23.5 to 36.5) seconds. After the 60 second in-service, the overall success rate for LMA placement was 97% (108 of 1 l 1 attempts). Attending and resident physicians had a 100% success rate following the 60-second training. The 3 missed attempts occurred in intubations attempted by 2 nonmedical personnel and a first-day intern. The median (interquartile range) times from commencement of procedure until ventilation was 17 (15 to 21) seconds and from ventilation until successful intubation was 18 seconds (14 to 20).
DISCUSSION Airway-related adverse outcomes have led to the concept of the "difficult airway." Reviews of closed malpractice
claims showed that persistent and prolonged intubation attempts comprised the most common scenario for catastrophic respiratory events. 16 As a result, the American Society of Anesthesiologists advocated an algorithm for management of these airways that incorporated the use of alternative intubation and ventilation devices. 17 Depending upon the precise definition used and setting studied, the incidence of "difficult airways" varies from 0.05% to 18%. 1 In the controlled operating room setting, failed intubations occur in 0.05% to 0.35% of patients. 1 By contrast, emergent intubations in the emergency department (ED) setting have a 3% to 5.3% frequency of requiring multiple attempts. 24 The use of alternative devices has not been widely incorporated into emergency medicine practice. 14 Many practicing emergency physicians have little or no experience with these devices and more than 20% of academic emergency departments do not have any of these devices
LEVITAN ET AL • INTUBATION SUCCESS WITH THE ILMA
available. 14 It is apparent that proper and timely use of rescue intubation devices by practitioners with little or no prior experience with their use would be dependent upon simplicity of use. The ILMA appears to meet this criterion. Prior studies have shown that unskilled personnel insert standard LMAs more rapidly and reliably than tracheal tubes, and that they can ventilate more effectively with an LMA compared to a bag and mask. 17-2~The standard LMA has been used as guide for endotracheal intubation with and without fiberoptic assistance, but even the largest standard LMA only accepts an endotracheal tube of 7.0 mm internal diameter. 22-24 In a small study of nurses who had no prior airway skills and only manikin training, 60% were able to intubate anesthestized patients using the standard LMA. 21 The ILMA provides for rapid and effective ventilation like the standard LMA but with modifications for rapid conversion to endotracheal intubation. The rigid handle, epiglottis elevating bar, and a specialized straight endotracheal are modifications from the standard LMA designed to facilitate positioning and passage of the endotracheal tube. Unlike the standard LMA, all sizes of the 1LMA can accept up to an 8.0 mm endotracheal tube. The ILMA offers several advantages over other rescue devices. It enables both ventilation and intubation in contrast to the tracheal-esophageal Combitube (Kendall-Sheridan, Mansfield, MA). In contrast to transtracheal jet ventilation and fiberoptic laryngoscopy, it does not require extensive training to use. When used by experienced LMA users in the operating room, the ILMA was successful in 149 of 150 (99.3%) cases. 25 Our study, using a manikin model, shows that ILMA is inherently easy to use, but that a <60 second demonstration was very valuable. Prior to the ILMA demonstration, emergency practitioners had a success rate of 64%. Attending and resident physicians had an 83% initial success rate. Medical personnel who lacked any prior airway training were successful in 35% of initial attempts prior to training. The training demonstration made a dramatic improvement in success rates. Following the 60-second demonstration of the ILMA, 97% of participants successfully established the airway in a median time of 35 seconds. Even 14 of 16 nonmedical personnel in our study were able to achieve intubation with the ILMA following the demonstration. The major limitation of our study is that it is a manikin study. Some potential difficulties in intubation may not be present in a manikin model. Specifically, a down-folded epiglottis can prevent adequate ventilation and endotracheal tube passage. 1 The manikin epiglottis is made of molded plastic that is positioned along the curvature of the tongue and does not hang downwards. Vomiting and aspiration could not be assessed. Esophageal intubation did occur, however, when the device was inserted too superficially or when the axis of the handle was rotated from the midline. The use of a manikin model prevents evaluation of some of these potential problems. On the other hand, manikin-only LMA training has been shown to be equivalent to LMA training that utilizes both manikins and live patients. 26 Another limitation of the study is that we did not require users to select the proper size ILMA. Incorrect size selection can impede endotracheal tube placement. 1 There are 3 sizes of the device: one each for small, medium, and large adults (sizes 3, 4, and 5). Our results may have been negatively impacted because
15
the schematic instructional diagrams were relatively small, black-and-white line drawings. Perhaps the use of larger color diagrams or photographs with labels would have led to better performance with initial use. Finally, we did not assess skill retention. Ease of use and inherent simplicity is critical for rescue airway devices. Experienced laryngoscopists have low failure rates of intubation, varying between 0.03% and 1.0%, depending on the setting. 1-5 Accordingly, any rescue device will be used infrequently by any one provider. Ease of use and inherent simplicity is even more critical for first responders, nurses, basic-level prehospital personnel, and medical staff who do not regularly provide advanced airway management. In conclusion, our data suggest that the ILMA is a simple to use device in a manikin model following minimal training. This is an important requirement for any device used in the emergent management of patients with "difficult airways" and in emergent medical situations that occur outside the hospital setting. The simplicity of the device suggests that it could be used by persons with limited or no laryngoscopy skills, but further studies involving real patients are warranted to address this issue.
REFERENCES 1. Benumof J: Definition and incidence of the difficult airway, in Benumof J (ed): Airway Management, Principles and Practice. Mosby, St Louis, 1996 pp 122-124 2. Sakles JC, Laurin EG, RantapaaAA, et al: Airway management in the emergency department: A one-year study of 610 tracheal intubations. Ann Emerg Med 1998;31:325-332 3. Calderon Y, Gennis P, Martinez C, et al: lntubations in an emergency medicine residency: The selection and performance of intubators. Acad Emerg Med 1995;2:411-412 (abstr) 4. Riggs RW, Tayal VS, Tomaszewski CA, et al: Rapid-sequence intubation at an emergency medicine residency: Success rate and complications encountered during a two-year period. Acad Emerg Med 1996;3:528 (abstr) 5. Vissers RJ, Barton ED, Sagarin MJ, et al: Success and complications rates of rapid-sequence vs non-rapid-sequence intubation in 1,200 emergency intubations. Acad Emerg Med 1998;5:481 (abstr) 6. Sayre MR, Sakles JC, Mistier AF, et al: Field trial of endotracheal intubation by basic-EMTs. Ann Emerg Med 1998;31:228-233 7. Konrad C, Schupfer G, Wiettlisbach M, et al: Learning manual skills in anesthesiology: Is there a recommended number of cases for anesthetic procedures? Anesth Analg 1998;86:635-639 8. Benfield DG, Flaksman RJ, Lin TH, et al: Teaching intubation skills using newly deceased infants. JAMA 1991;265:2360-2363 9. Erlandson MJ, Clinton JE, Ruiz E, et al: Cricothyrotomy in the emergency department revisited. J Emerg Med 1989;7:115-118 10. Wallace CT: Cdcothyrotomy. JAMA 1973;224:248 11. Miklus RM, Elliott C, Snow N: Surgical cricothyrotomy in the field: Experience of a helicopter transport team. J Trauma 1989;29: 506 12. Xeropotamos NS, Coats TJ, Wilson AW: Prehospital surgical airway management: 1 year's experience from the Helicopter Emergency Medical Service. Injury 1993;24:222 13. Boyle MF, Hatton D, Sheets C: Surgical cricothyrotomy performed by air ambulance flight nurses: A 5-year experience. J Emerg Med 1993; 1t :41-45 14~ Levitan RM, Kush S, Hollander JE: Emergency medicine residency programs and compliance with national guidelines for difficult airway management. Acad Emerg Med 1998;5:482 (abstr) 15. Brimacombe JR, Brain AIJ: The laryngeal mask airway: A review and practical guide. Saunders, Philadelphia, 1997, pp 230241
16
AMERICAN JOURNAL OF EMERGENCY MEDICINE • Volume 18, Number 1 • January 2000
16. Caplan RA, Posner KL, Ward RJ, et al: Adverse respiratory events in anesthesia: A closed claims analysis. Anesthesiology 1990;72:828 17. Pennant JH, Walker MB: Comparison of the endotracheal tube and laryngeal mask in airway management by paramedical personnel. Anesth Anal 1992;74:531-534 18. Davies PRF, Tighe SQ, Greenslade GL, et al: Laryngeal mask airway and tracheal tube insertion by unskilled personnel. Lancet 1990;336:977-979 19. Reinhart DJ: Laryngeal mask airway (LMA) vs endotracheal tube (ETT) placement by paramedics, respiratory therapists, and registered nurses. Anesthesiology 1993;79:A105 (abstr) 20. Hayes A, MacCarrol SM: Airway management by unskilled personnei--a comparison of laryngeal mask airway, pocket mask and bag-valve mask techniques. Anesthesiology 1995;83:A223 (abstr) 21. Stone BJ, Leach AB, Alexander CA, et al: The use of the
laryngeal mask by airway by nurses during cardiopulmonary resuscitation-results of a multicentre trial. Anaesthesia 1994;49:3-7 22. Brimacombe JR, Brain AIJ: The laryngeal mask airway: A review and practical guide. Saunders, Philadelphia, 1997, p 63. 23. Heard CMB, Caldicott LD, Fletcher JE, et al: Fiberoptic guided intubation via the laryngeal mask airway in pediatric in pediatric patients. A report of a case series. Anesth Analg 1996;82:1287-1289 24. Bryden DC, Gwinnutt CL: Tracheal intubation via the laryngeal mask airway: A viable alternative to direct laryngoscopy for nursing staff during cardiopulmonary resuscitation. Resuscitation 1998;36: 19-22 25. Brain AI, Verghese C, Addy EV, et al: The intubating laryngeal mask. I1: A preliminary report of a new means of intubating the trachea. Br J Anaesth 1997;79:704-709 26. Roberts I, AIIsop P, Dickinson M, et al: Airway management training using the laryngeal mask airway: A comparison of two different training programs. Resuscitation 1997;33:211-214