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Empirical Investigations

A Training Program for Novice Paramedics Provides Initial Laryngeal Mask Airway Insertion Skill and Improves Skill Retention at 6 Months

Hein, Cindy PhD, BHSc, DipAppSc; Owen, Harry MBBCh, MD, FRCA, FANZCA; Plummer, John PhD, AStat

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Simulation in Healthcare: The Journal of the Society for Simulation in Healthcare: February 2010 - Volume 5 - Issue 1 - p 33-39
doi: 10.1097/SIH.0b013e3181b5c3fb
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Airway management is recognized as a key component in the management of emergency patients within the prehospital environment. The laryngeal mask airway (LMA) has been recognized as a valuable method of securing an airway in an emergency situation1–3 and has been successfully used by novices.4–15 This makes the LMA an ideal airway tool as a rescue device where endotracheal intubation fails and for those less skilled such as volunteer and student ambulance officers.

Currently, airway management programs are formulated by individual ambulance services, and there is no widely defined program specific to the LMA and novice prehospital user. Ongoing research of basic airway management practices provides information for development and implementation of educational programs that optimize emergency healthcare practice. The results of this study will be used to promote such practice, particularly in the area of initial LMA insertion skill, but equally important, retention of skill level. This article describes the evaluation of task-based performances (LMA insertion skills) within differing part task trainers (PTT) and subsequent scenario performance using high- fidelity simulation.


This two-part study was approved by the Flinders Clinical Research Ethics Committee and was conducted entirely within the Clinical Simulation Unit (CSU) [Flinders University, School of Medicine, Adelaide, South Australia (SA)]. Before enrolment, subjects were informed that completion of both parts of the study was necessary. In part 1, a convenience sample of 55 subjects was recruited from the Bachelor of Health Sciences Paramedic undergraduate degree program at Flinders University, Bedford Park, SA. To ensure that participants were true novice users of the LMA, only those who were enrolled in first year topics were recruited. Those who had previously used or had been formally instructed how to use an LMA were excluded as were those <18 years of age. The LMA-Unique (LMA North America, Inc., San Diego, CA) was used throughout the study as it had previously been used by paramedics16,17 and had a 10-minute insertion video, which at the time was freely available online at LMA North America Inc. The participants came to the CSU in small groups where they viewed the video followed by guided practice (by the principal investigator CH) on how to insert the LMA in three different PTTs. The PTTs were used in the following order, which was chosen purely by chance and did not indicate particular level of difficulty: PTT 1, Laerdal Airway Management Trainer; PTT 2, Simulaids Adult Airway Management Trainer Torso; and PTT 3, Life/form CPaRlene Airway Management Trainer. The subjects had four attempts each at inserting the LMA-Unique in the three PTTs (total of 12 attempts). Each insertion attempt was timed and noted as success (adequate chest rise and fall) or failure by the principal author (CH). Once the subjects completed part 1 of the study, they had no planned LMA training until returning for the second part of the study, approximately 6 months later.

In part 2 of the study, the participants returned to the CSU and completed a questionnaire aimed at identifying any extraneous learning that may have occurred in the 6-month lapsed period (eg, clinical experience and/or exposure to literature/videos). Then they were randomized into either a control or an intervention group before being placed one by one in a simulated clinical scenario using high-fidelity simulation with SimMan (Laerdal Medical). Subjects assigned to the intervention group had the intervention first, participated in the scenario, and then had a debriefing watching their own scenario. Subjects assigned to the control group had the scenario first, then the debriefing and so as to not be disadvantaged educationally, they then had access to the intervention. The scenario was video recorded and later assessed by three independent assessors (intensive care paramedics from SA Ambulance Service) and the principal investigator (CH). The debriefing was conducted by an experienced paramedic and operator of SimMan, and all subjects were given a copy of their scenario at the completion of the study. An overview of the study protocol is shown in Figure 1.

Figure 1.:
Overview of study protocol.

The intervention was similar to the initial training program including watching the same insertion video and having 10 minutes unsupervised practice in the same three PTTs used in part 1.

The scenario which lasted approximately 10 minutes began after the participant was informed that he/she was performing the role of a “paramedic” who was to transfer a patient from a country hospital to a major hospital. The subject was informed that the “patient” had earlier collapsed at home and was having visual disturbances. This was based on a brainstem cerebrovascular accident. The “paramedic” was told to enter a standardized room where he/she was met by a “nurse” who will be asking the paramedic to ensure oxygen saturations (SpO2) remained above 94% as the patient was now unconscious and he/she needed to phone the doctor. As soon as the “nurse” left the room, the “patient” deteriorated subsequent to the trends that were previously set for SimMan. It was designed so that a LMA was required, or the “patient” could not be ventilated by any other means. This was done by having laryngospasm and lung resistance on and only removing it when an LMA was inserted successfully. If no LMA was placed, the patient's condition would deteriorate. If an LMA was placed successfully, the pharynx was inflated to create a seal around the LMA, and the patient could be easily ventilated and thus would improve provided the subject maintained adequate ventilations. An overview of the trends set for the scenario is shown in Figure 2.

Figure 2.:
Overview of the SimMan trends set for the scenario.

Statistical Methods

Data from parts 1 and 2 were analyzed using the Stata version 10 statistical software package (Stata Corporation, College Station, TX). In part 1, the primary aim of the study was to assess the 55 novice users of the LMA in relation to insertion success and time to ventilation, and a secondary aim was to determine whether learning continued during the 12 attempts when using three different PTTs. In part 2, the primary aim was to assess whether the subjects who were involved in part 1 would have improved skill retention at 6 months after having a short intervention. Secondary analysis was aimed at determining whether the same intervention in these subjects decreased times to insertion and/or increased insertion success rate.

Descriptive methods for both parts included mean, percent, Kaplan-Meier survival function, standard deviation, median times (to successful insertion), and confidence intervals. In part 2, a box plot was used to display distributions of skill retention scores of the control and intervention groups.

Inferential analysis of time to insertion data in part 1 was performed using Cox proportional hazards regression with the attempt number for each subject being included as a categorical factor. The Cox model is appropriate for analysis of time-to-event data, including cases in which the event (here successful insertion) is not always observed. It makes no assumption about the shape of the distribution of times to event. To allow for correlation of insertion times within subjects, a shared frailty was included in the model. Model specification and the proportional hazards assumption were assessed by a link test and a test based on Schoenfeld residuals.18 Part 2 inferential analysis for time to insertion data was performed using the Peto-Prentice test19 as it is robust against different censoring patterns in the groups being compared18 (in our data, twice as many subjects were censored in one group compared with the other). Time to insertion was measured using the sum of times for each attempt, until first successful attempt or when the subject gave up trying (eg, all insertion times added together until the first successful insertion or abandonment). These figures were taken from those recorded by the primary author (CH) only (who was not blinded to subject group and only recorded times to success or when the subject abandoned the attempt). Where a subject had not made an attempt to insert an LMA (as occurred in one subject), an infinite time was assigned and denoted as not successful so as not to bias the data. The Mann-Whitney U test was used to examine numbers of attempts and skill retention scores. Calculation of LMA skill retention scores was achieved by assigning a score of 0 to 2 (0 = never, 1= inadequate, and 2 = adequate) to each component of LMA insertion: orientation; head position; air in cuff; bite block; secured, and assigning a score of 0–3 (0 = very poor, 1 = poor, 2 = fair, and 3 = good) for performance level: demonstrated level for LMA insertion, from the figures supplied by the three independent assessors who were blinded to which group the subjects were assigned to. Where a figure was not assigned by the three independent assessors, a mean of the other two assessors was given provided they recorded the same score. This occurred in only four (of 750) instances. Once the scores were assigned, the LMA insertion scores and the performance level scores were summed, and the mean of the three independent assessors' scores became the LMA skill retention score. This resulted in a score in the range of 0 to 13 in steps of 1/3. Lin's concordance correlation coefficient20,21 was used to examine agreement in LMA skill retention scores among three independent assessors. A summary of the scoring matrix is shown in Table 1.

Table 1:
LMA Skill Retention Scoring Matrix


Part 1: Combining the observations of the 55 participants, the mean success rates in percent on each PTT are shown in Table 2.

Table 2:
Mean Percent Success of Combined Student Results at Each Attempt

From the very first attempt in PTT 1, to the fourth and final attempt in PTT 3, an increase in success rate from 64% to 100% can be seen. When examining attempts 1 to 4 within each PTT, it is more evident that the students' rate of success was more likely to improve in PTT 1 (64%–100%) and 2 (75%–93%) and not in PTT 3 (100%–100%).

The minimum and maximum times to successful insertion of the LMA (excluding failures) within each individual PTT are shown in Table 3.

Table 3:
Number, Minimum, and Maximum Times to Successful Insertion (s)

Not surprisingly, the longest time to insertion was in the first PTT at the first attempt, (114.8 seconds) and the shortest in the last PTT at the 4th attempt (10.4 seconds).

Median times to successful insertion, derived from the Kaplan-Meier survival function, are displayed in Table 4.

Table 4:
Median Time to Successful Insertion (s) and Confidence Intervals for Attempts 1–4 Within Part Task Trainers 1–3

In Table 4, PTT 1 shows rapidly decreasing median times to insertion from 54.3 to 26.8 seconds from attempts 1 to 4, and in PTT 2, students were seen to drop back to slower insertion times on their first attempt (44.1 seconds), but again, showed rapid improvement toward their last insertion time of 27.6 seconds in this PTT. In PTT 3, the students continued to improve through their four attempts up to the fastest median insertion time measured in their final (12th) attempt (20.2 seconds).

Based on the coefficients in the Cox proportional hazards model, Table 5 shows that performance on each consecutive attempt (from the first attempt) was significantly superior (all have P values <0.001 compared with attempt 1), except for attempt 5 [which was not significantly different (P = 0.112) from the first attempt]. Also, Table 5 shows that improvement in performance continues over all 12 attempts.

Table 5:
Cox Proportional Hazards Model Analyzing Each Attempt as a Separate Unordered Category

In part 2 of the study where three independent assessors were used, agreement among skill retention scores showed satisfactory agreement of assessors 1 and 2, rL = 0.81 and assessors 1 and 3, rL = 0.61 but unsatisfactory agreement between assessors 2 and 3, rL = 0.54.

Subjects in the intervention group had higher LMA skill retention scores than those in the control group. This was statistically significant (P = 0.019). The distributions of skill retention scores in the two groups can be seen in the box plot below (Fig. 3). Similarly, the intervention group generally performed better (based on the Kaplan-Meier survival estimates); however, in both groups, there were some subjects that had longer insertion times (>200 seconds) (n = 12 control: four intervention group) (Fig. 4).

Figure 3.:
Distribution of skill retention scores between the control and intervention groups.
Figure 4.:
Kaplan-Meier plot showing the percentage of subjects still not having successfully inserted the LMA at various times.

Median times and the range until the first successful insertion (or abandonment) for the intervention and control group were 94 (38–565) and 209 (41–566) seconds, respectively. The intervention group had significantly shorter times to successful insertion than the control group (P = 0.029), and this remained significant (P = 0.027) even after omitting subjects (n = 15) who had any extracurricular information about LMAs since their initial training approximately 6 months prior.

Of the 50 subjects who completed part 2 of this study, 49 attempted to insert the LMA at some stage during the scenario (one subject did not make any attempt and was therefore excluded from this analysis). Those in the intervention group had significantly fewer attempts to achieve success (or to give up trying) compared with the control group (P = 0.033), and this remained significant (P = 0.0004) even after omitting subjects who had any extracurricular information about LMAs since their initial training.


The data provided in Table 2 suggest that students had a fall in success rate (100% down to 75%) when changing from PTT 1 (after attempt 4) to PTT 2 (attempt 1) but maintained similar success rates between PTT 2 and PTT 3 (93%–100%). It is difficult to interpret what this means, but one hypothesis is that by the end of PTT 2 (or by the 8th attempt), the students had already achieved near maximal learning in terms of success rate. Another possibility in interpreting this change in success rate is that the last PTT (PTT 3) was easy to use or the second PTT produced some level of difficulty although all three PTTs used in this study had previously been shown to be “good” to insert an LMA.22 When we examined subject performance based on both success/failure and time taken (instead of success rate alone), we found each subsequent attempt was significantly better than the subjects' first attempt except for attempt 5, which again equated to the first attempt at PTT 2 (Cox model, Table 5). If this change was purely due to changing PTTs as has previously been shown,23 we would expect to see the same detriment in learning when our subjects changed from PTT 2 to PTT 3. However, that did not occur, so it would seem that PTT 2 created some level of difficulty for the subjects in this study. Still this change in difficulty may be useful in simulating differences within patients as no one person would have the same features as another, and so their level of difficulty to perform a skill in clinical context may also alter.

Learning a skill is only one aspect of training being able to retain that skill level and then implement it when needed is another. Advanced life support (ALS) skills decline when practice is not frequent. This has been shown by many24–30 but seems even more relevant to those who are still acquiring skill perfection (such as novices)31 and for highly technical skills such as endotracheal intubation.32 Globally, skill decay has not gone unnoticed, and this was a feature discussion at the 2005 international “Consensus on Science and Treatment Recommendations” conference held in Dallas, TX, where evidence surveyed showed a decline in healthcare provider ALS skills and knowledge after just 6 weeks.33

Part 2 of our study went beyond initial training and incorporated a simple intervention, which led to significantly higher skill retention scores in those who experienced it compared with those who did not. Although we cannot definitively extrapolate these findings into clinical application, intuitively it can be conceived that a paramedic who has a higher LMA insertion skill would quite conceivably provide better patient management. When clinical skills are not reinforced in real-life clinical experiences, skill level quickly declines,34 and so high-fidelity simulation such as that shown in our study could incorporate a cardiac arrest scenario for paramedics to ensure that fewer attempts and less time “trying” to inert an LMA (or any airway management regimen for that matter) detracts less from other critical skills such as defibrillation and chest compressions.


The data presented here demonstrate that our training program was adequate for both initial LMA training and retention of skill level. We used a combination of low- and high-fidelity simulation, which may give the novice paramedics in our study an appreciation for varying patient anatomy and environmental conditions that they may encounter in their future clinical experiences. However, we found that not all PTTs are equivalent, and to our knowledge, what happens at each attempt within different PTTs has not been tested previously. This knowledge may have significant implications for teaching and selecting PTTs to teach this skill in the future. Furthermore, as the program used an online training video and three commonly used PTTs, it can be used for self-directed practice (thus reducing extra instructor time) and can potentially be used worldwide by any health professional, particularly those who use this skill infrequently.


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Airway management; Laryngeal mask airway; Resuscitation; Simulators; Training; Paramedics

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