Comparison of endotracheal intubation, combitube, and laryngeal mask airway between inexperienced and experienced emergency medical staff: A manikin study.

BACKGROUND: Emergency Medical Service (EMS) personnel manage the airway, but only a group of them are allowed to engage in Endotracheal Intubation (ETI). Our purpose was to evaluate if the use of laryngeal mask airway (LMA) or Combitube can be used by inexperienced care providers.
MATERIALS AND METHODS: A randomized, prospective manikin study was conducted. Fifty-nine participants were randomly assigned into two groups. Experienced group included 16 paramedics, eight anesthetic-technicians, and inexperienced group included 27 Emergency Medical Technician-Basic (EMT-B) and eight nurses. Our main outcomes were success rate and time to airway after only one attempt.
RESULTS: Airway success was 73% for ETI, 98.3% for LMA, and 100% for Combitube. LMA and Combitube were faster and had greater success than ETI (P = 0.0001). Inexperienced had no differences in time to securing LMA compared with experienced (6.05 vs. 5.4 seconds, respectively, P = 0.26). One failure in inexperienced, and no failure in experienced group occurred to secure the LMA (P = 0.59). The median time to Combitube placement in experienced and inexperienced was 5.05 vs. 5.00 seconds, P = 0.65, respectively. Inexperienced and experienced groups performed ETI in 19.15 and 17 seconds, respectively (P = 0.001). After the trial, 78% preferred Combitube, 15.3% LMA, and 6.8% ETI as the device of choice in prehospital setting.
CONCLUSION: Time to airway was decreased and success rate increased significantly with the use of LMA and combitube compared with ETI, regardless of the experience level. This study suggests that both Combitube and LMA may be acceptable choices for management of airway in the prehospital setting for experienced and especially inexperienced EMS personnel.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

Fast establishment of an airway in emergency situations such as airway compromise is a priority for prehospital rescue team. To achieve this goal, highly skilled staffs are needed to serve in prehospital settings for critically ill and injured patients.[123]

In the paramount conditions, Endotracheal Intubation (ETI) has 30% failure rate in prehospital settings by non-physicians.[4] Although ETI is an optimal and lifesaving procedure for securing the airway,[5] there are some limitations for using it in prehospital settings. The most important ones are that ETI, based on accepted guidelines,[56] should be performed only by expert, skillful and current personnel like practitioners or paramedics; however, in most of the emergency settings, especially in suburban and rural areas, we lack such staffs due to financial crises. Furthermore, in some situations such as trauma patients, ETI should be done by paralyzing the patient to prevent the head movement or gag reflexes or laryngeal spasm. Using drugs in this area is prohibited for Emergency Medical Technician-Basic (EMT-B) and Emergency Medical Technician-Intermediate and controversial for paramedics. Because the intubation failure rate is relatively high, continual and multiple intubation attempts are associated highly with respiratory problems.[7] Finally, intubation is a time consuming and technically difficult procedure, which makes it unfeasible in some situations such as trauma patients suffering from bleeding.[8]

All the above mentioned problems cause a quarter of the prehospital patients encounter several complications during ETI such as misplacement of the tube, unsuccessful intubation and more than four times of laryngoscopy.[9] Therefore, we decided to evaluate if EMT care providers can use other options instead of ETI with lesser complications.

The two most available options with successful previous usage are laryngeal mask airway (LMA) and combitube, which has been used for several years by anesthesiologists.[101112] The aim of this study was to compare success rate of insertion between Combitube, LMA, and ETI after enough instruction and training of healthcare staff with different degrees of professional experience. We used a manikin model to determine how groups of an emergency team with no previous airway management experience and background can perform these procedures in the prehospital settings compared with the skilled ones.

MATERIALS AND METHODS

Study method

The study was conducted in Tabriz Red Crescent Emergency Department. This project was approved by the human investigation committee of Tabriz University School of Medicine with consent waiver. Without explanation of the scenario to the participants, they were randomly assigned first to use one of the three devices. The selected equipment was arranged next to the manikin, within easy reach. The participants performing the airway management were given no assistance, and both the participants and examiners were blinded to the hypotheses of the project.

A 6.5 mm outside diameter (OD) non-cuffed endotracheal tube (Mallinckrodt, St Louis, MO), a Macintosh three laryngoscope blade and handle, a size 4 classic LMA (LMA of North America, San Diego, CA), a Combitube SA 41 F (Covidien, Mansfield, MA, USA), the lubricating gel, and finally, a Laerdal Airway Management Trainer (Laerdal Medical, Pucheim, Germany) were provided. All devices were used according to the manufacturer's instructions.

No more than one attempt was permitted for insertion of the device, after which the procedure was considered to be failed. The time taken to secure the airway with the device was measured from the time the participant starting the procedure to the time they could effectively ventilate the manikin. The successful ventilation was defined as the complete and equal inflation of the both manikin's lungs using ambo bag attached to the end of device and checked by attending physicians. The unsuccessful procedure was defined as (a) taking more than 60 seconds to secure airway, (b) no ventilation, (c) esophageal intubation, and (d) no lung's inflation.

After the participants successfully secured the airway, the procedure was repeated by using the alternative device. At the conclusion of the trial, the participants were asked which of the three devices they preferred.

Participants

The participants were randomly assigned from 200 volunteers, without considering work history, into two groups of experienced (n = 24) and inexperienced (n = 35). Experienced group included 16 paramedics, eight anesthetic technicians, and inexperienced group included 27 EMT-B and eight nurses.

The paramedics had attended the emergency courses for 2 years and had performed at least 25 intubations correctly. In Iran, the paramedics are approved for placing LMA, Combitube, and ETI unsupervised in the prehospital setting.

The EMT-B had not used these devices before and their curriculum, similar to other countries, consists of basic life-support training for at least 176 hours. In our country, nurses, similar to EMT-B personnel, does not have any previous experience of intubation and are not allowed to secure the airway.

To make EMT-B and nurses familiar with intubation devices, emergency medicine attending physicians administered a 2-hour training session with lectures and hands-on time with LMA, Combitube, and ETI 1 day prior to the trial.

Statistical analysis

Because our data were not normally distributed, nonparametric statistical analysis was used for ordinal data. Categorical data such as success rate for insertions were changed to numbers and analyzed using the χ2 test. Descriptive statistics are also reported. Data were analyzed with Statistical Package for Social Sciences (SPSS) software (SPSS version 14.0, SSPS Inc., Chicago) with a statistical significance set at the 0.05 level.

RESULTS

The LMA, and Combitube insertion, and ETI were each attempted by 59 participants. The median age of the participants was 35 years old, and all of them were male. The overall rate of successful airway management was 90%. Time to perform the procedures in different groups of participants and their success rate is charted in Table 1.

Table 1

Time and success rate to insert laryngeal mask airway, combitube, and tracheal intubation

Endotracheal intubation

Median values and interquartile ranges (IQRs) are used for objective data. ETI was successful in 73% of airway attempts.

Inexperienced group (n = 35) secured the airway in a median of 19.15 seconds (IQR, 13.95-23.97 seconds) compared with experienced group (n = 24), who secured the airway in a median of 17 seconds (IQR, 12-23 seconds, P = 0.001, Mann-Whitney test; Figure 1).

Figure 1

Median time and IQR to successful airway management for the different methods of airway management for two groups of experienced and inexperienced

Fifteen failures occurred in the inexperienced group compared with one in the experienced group (P = 0.001, Fisher exact test; Figure 2).

Figure 2

Number of failed airways for the different methods of airway management for two groups of experienced and inexperienced

Laryngeal mask airway

LMA had an overall success rate of 98.3%. In comparing inexperienced and those who were experienced, there were no differences in time to securing an airway (P = 0.26, Mann-Whitney test). with inexperienced group requiring a median of 6.05 seconds (IQR, 5.20-7.60 seconds) and experienced group requiring a median of 5.4 seconds (IQR, 4.15-6.87 seconds, Figure 1). One failure occurred in the 35 participants who were inexperienced, and no failure occurred in the 24 experienced who had used LMA before (P = 0.59, Fisher exact test). The only participant who failed the LMA was a nurse with no previous intubation skill, who failed the ETI, too. He preferred Combitube as the device of choice for the intubation. Considering those with successful ETI, no difference was seen between experienced and inexperienced group in LMA placement (P = 0.79).

Combitube

Participants using Combitube, both experienced and inexperienced, had an airway management success rate of 100%. The median time to Combitube placement was 5.05 seconds (IQR,4.55-7.52 seconds) in those experienced (n = 24) and a median of 5.00 seconds (IQR, 4.30-7.10 seconds) in those inexperienced (n = 35, P = 0.65, Mann-Whitney test).

Intergroup comparisons

Time to airway management was faster with LMA compared with ETI (median, 6 vs. 17.2 seconds, P = 0.0001). Failure rate with ETI was higher than that with LMA (P = 0.0001). The time to airway management was faster with Combitube than with ETI (median, 5 vs. 17.2 seconds, P = 0.0001).

Failure rate with ETI was higher than that with Combitube (P = 0.0001).

Subjectively, 20 (34%) of participants, regardless of skill level, stated that ETI was difficult. Also, after the trial, 46 (78%) preferred Combitube, nine (15.3%) preferred LMA, and four (6.8%) preferred ETI as the airway device of choice in prehospital setting. Of four participants who preferred ETI, three were anesthetic technicians, and one was paramedic.

DISCUSSION

The goal of this study was to compare the rate of successful performance and the time to successful insertion between Combitube, LMA, and ETI by healthcare system professionals with different levels of experience in airway resuscitation.

Although the mean of time to insert the LMA in our study was lower than other studies,[61314] it was lower than ETI significantly similar to other studies.[1516] Our finding is in agreement with the results of Levitan et al., who found 94% success rate for the insertion of the LMA in inexperienced participants.[17] Wahlen et al., revealed that anesthetics were the quickest to insert the LMA, but our study showed no meaningful difference between personnel.[6] In their study, contrary to ours, nurses were slower than anesthetics for this device. In our study, all participants from different levels of the health care system inserted the Combitube and LMA in a short time and high success rate. In fact, only by few hours of training and learning, all the groups were successful.

The success rate for insertion of the Combitube in the present study was higher than for the ETI. This result confirms other studies.[1819] However, Wahlen et al., presented that Combitube has higher risk of failure; it is difficult for naïve participants and require time to insert.[6]

In our manikin study, no one was unsuccessful inserting Combitube. The successful insertion of the Combitube in manikins has been reported almost without failure,[19] but in patients, it has been reported differently, such as 74%,[20] 91.4%.[21] The differences between manikin and human are the major limitations of every manikin study.

Although subcutaneous emphysema and lacerations of the esophagus by using Combitube have been reported in a small number of cases,[22] Combitube is still the favorite device. It is shown that Combitube prevents from the aspiration in 93% of the cases.[2324] One can use it blindly and without a laryngoscope. The lack of requirement for direct visualization is an important advantageous in these situations. Therefore, Combitube is well-designed to be used in the difficult situations.[2526]

In the present study, in agreement with other studies,[19] the mean of time to insertion of the Combitube was lower compared to the ETI. That's another considerable value of Combitube to save the time in emergency situations. LMA has similarly similar benefits of Combitube, except that it does not prevent from gastric aspiration.[27] Rumball et al.,[28] the same as our study, showed that Combitube is the most preferred device by a majority of emergency medical team.

Similar to other studies,[5] anesthetic technicians did not insert Combitube faster than the other groups. This can be explained by the fact that Combitube is not the first choice in clinical anesthesia, and they do not practice it frequently, or insertion of it does not need any special experience.

In our study, the level of education only affected the success number of ETI. Anesthetics and paramedics, practicing this method frequently, were more successful as opposed to other two groups. However, no correlation was seen between groups with different experiences in the successful insertion of the LMA and Combitube. Trabold et al.,[29] reported no difference between different groups in the number of successful insertions of Combitube and ETI.

The ETI has different success rate between studies.[3031] The different types of manikins and different setups can be the reason, but success rate of LMA and Combitube have always been high regardless of the setup or manikin's type.

Furthermore, there was no meaningful relation between participants and median time of insertion of one of the devices. This finding was also in accordance with others.[29] This means that in spite the fact that different levels of experience have an impact on success rate of ETI intubation, there is no correlation between time to insertion of this device and different participants.

There is an unclear necessity to refresh one's learning of Combitube or LMA insertion.[3233] However, this is obvious for ETI, because of the deterioration in skills.[34]

Overall, total procedures in our study were done in a shorter time compared with other studies.[152935] This finding may be attributed to different start points. In our study, the initial time was defined as the interval between the time of handling the device and at the end of the insertion of the device. This initial and end time of the study could be different in other studies. In addition, this difference can be due to the use of different types of manikins.

Paramedics generally perform ETI few times a year and they cannot perform intubation in difficult situations. They are allowed to intubate only in respiratory arrest or low level of consciousness. Using devices such as LMA or Combitube that do not need any direct observation is a reasonable solution. On the other hand, lack of array of skilled personnel to intubate the airway in prehospital settings has lead to problems. In these settings and in situations where there is no access to paramedics and only the EMT-B personnel are available, or situations in which the nurse staff has exposure to the patients that need airway management, the LMA or Combitube are useful alternatives. These devices are easy-to-learn, easy-to-use, fast, and successful for anyone.

Based on our data, performing ETI is suggested to be used only by skilled and qualified medical team.

Limitations

Our study has several limitations. We used manikins for our study. The Manikin has several characteristics that may not reflect the reality. For example, in our study, we did not include airway trauma, vomiting, and airway secretions, which often occur in clinical situations. Studies have shown that training on manikin for LMA insertion is as effective as live patient training.[36] However, there are many differences between human body and manikin. Therefore, comparing devices on manikin may not be directly applicable to clinical settings. Controlled clinical studies of these data in the prehospital setting need to be executed to confirm our hypothesis.

CONCLUSION

Airway management time decreased and success rate increased significantly with the use of LMA and Combitube compared with ETI, regardless of the experience level. This study suggests that both Combitube and LMA may be acceptable choices for managing the airway in the pre-hospital setting for both experienced and particularly inexperienced EMS personnel.