a b s t r a c t

Introduction: Cricothyrotomy may be necessary for airway management when a patient’s airway cannot be main- tained through standard techniques such as oral airway placement, blind insertion airway device, or endotra- cheal intubation. Wire-guided cricothyrotomy is one of many techniques used to perform a cricothyrotomy. Although there is some controversy over which cricothyrotomy technique is superior, there is no published data regarding long term retention rates. The purpose of this study is to determine whether ground based para- medics can be taught and are able to retain the skills necessary to successfully perform a wire-guided cricothyrotomy.

Methods: This retrospective study was performed in a suburban county with a population of 160,000 with 23,000 EMS calls per year. Participants were ground-based paramedics who were taught wire-guided cricothyrotomy as part of a standardized paramedic educational update program. After viewing an instructional video, the para- medics were shown each the steps of the procedure on a simulation model, using a low fidelity task trainer pre- viously developed to train emergency medicine residents. Using a 16 step procedural checklist, participants were allowed open-ended practice using the task trainer. Critical steps in the checklist were marked in bold lettering indicating automatic failure. Each paramedic was then individually supervised performing a minimum of 5 suc- cessful simulations. Retention was assessed using the same 16 step checklist 6 to 12 weeks following the initial training.

Results: A total of 55 paramedics completed both the initial training and reassessment during the time period studied. During the initial training Phase 100% (55 of 55) of the paramedics were successful in performing all 16 steps of the wire-guided cricothyrotomy. During the retention phase, 87.3% (48 of 55) of paramedics retained the skills necessary to successfully perform the wire-guided cricothyrotomy. On the 16 step checklist, most steps were performed successfully by all the paramedics or missed by only 1 of the 55 paramedics. The step involving removal of the needle prior to advancing the airway device over the guide wire was missed by 34.5% (19 of 55) of the participants. This was not an automatic failure since most participants immediately self-corrected and com- pleted the procedure successfully.

Conclusion: Paramedics can be taught and can retain the skills necessary to successfully perform a wire-guided cricothyrotomy on a simulator. Future research is necessary to determine if paramedics can successfully transfer these skills to real patients.

(C) 2018

Introduction

Cricothyrotomy may be necessary for airway management when a patient’s airway cannot be maintained through standard techniques such as oral airway placement, bind insertion airway device, or endotra- cheal intubation [1]. Cricothyrotomy is most often reserved as the last method employed to obtain an airway due to its highly invasive nature and relatively high complication rate when performed emergently. Cricothyrotomy is a procedure included in most failed airway protocols for most health care professionals including paramedics in the prehospital environment [2].

* Corresponding author.

E-mail address: [email protected] (J.A. March).

Wire-guided cricothyrotomy is only one of many techniques used to perform to a cricothyrotomy [1, 3-5]. Other techniques used to perform cricothyrotomy include open surgical, catheter over needle, and special- ized cricothyrotomy scissors [1, 2, 3, 5-7]. There is controversy over which technique is superior in regards to success rates, lower complica- tion rates, and operator comfort. Some studies suggest that for inexpe- rienced health care professionals, open techniques are superior to a wire-guided technique [1, 5]. Other research suggests that wire- guided cricothyrotomy has a higher success rate when compared to other techniques such as catheter over needle or open technique [3, 4, 7]. Data also suggests that physicians feel more comfortable and prefer the wire-guided method over other methods due to their familiarity with the Seldinger technique used for central venous catheter place- ment [3, 4].

https://doi.org/10.1016/j.ajem.2018.05.073 0735-6757/(C) 2018

408 J.A. March et al. / American Journal of Emergency Medicine 37 (2019) 407-410

Several published studies suggest that wire-guided cricothyrotomy has a lower complication rates when compared to other techniques [1, 4]. This technique was specifically developed for use by para- medics who do not routinely perform cricothyrotomies and tracheosto- mies [4].

Currently there is no data examining the long term retention rates of cricothyrotomy performed by paramedics. The purpose of this study is to determine whether ground based paramedics can be taught and if they can retain the skills necessary to successfully perform wire- guided cricothyrotomy.

Methods

This study was performed in a suburban county with a population of 160,000 and approximately 23,000 EMS calls per year. Participants were ground-based paramedics in a county-wide EMS system. The participants were taught wire-guided cricothyrotomy as part of a re- quired standardized paramedic educational update program. As part of the educational program paramedics were taught wire-guided cricothyrotomy on a simulation model, using a low fidelity task trainer, previously developed to train emergency medicine residents, see Fig. 1. This low cost task trainer is currently being employed by several emer- gency medicine residency programs in the southeastern US to teach wire-guided cricothyrotomy and is a variation of a previously studied task trainer [8, 9].

A 2 h course was presented including an instructional video on wire- guided cricothyrotomy. Participants were then allowed to practice the technique on the task trainer using a 16 step check-list, see Fig. 2. Steps that appear in bold print were previously identified by our EMS Continuing Education Committee as critical steps and were deemed au- tomatic failure points during instruction and testing. In addition, para- medics were required to successfully complete 14 of the 16 steps in order for an attempt to be considered successful.

Each participant was individually supervised performing a wire- guided cricothyrotomy on the task trainer until the procedure was per- formed successfully without instructor guidance. A minimum of five successful performances were required. Following completion of the training session, short term retention was immediately evaluated using the same 16 step checklist to assure that the paramedic had cor- rectly learned the technique. Paramedics who were unsuccessful re- quired re-education on the simulator until they were successful.

Long term retention was assessed using the same 16 step checklist 6 to 12 weeks after the initial training session as part of a recurrent skill assessment. This study was approved by the local Investigational Re- view Board, and participants were required to sign consent forms to re- lease their individual data.

Fig. 1. Task trainer model.

Results

Fifty-five paramedics completed the initial training, short term as- sessment, and long term reassessment during the study period. Fifty (91%) of the participants were male. The mean age of the participants was 39.4 years of age with a range of 23-65. The mean experience was 8.7 years with a range of 0-15 years.

During the initial training and short term retention phase, all 55 (100%) of the paramedics were successful in performing all 16 steps of the wire-guided cricothyrotomy. However, during the initial training phase, two paramedics did require reeducation with each participant performing one additional simulation on the task trainer.

During the long term retention phase, 48 (87.3%) retained the skills necessary to successfully perform the wire- guided cricothyrotomy. Of the 16 step checklist, the majority of steps were per- formed successfully by all the paramedics or missed by only 1 of the 55 paramedics, see Fig. 3. One of the 55 paramedics who failed did miss 11 of the 16 steps.

The step involving removal of the needle prior to advancing the air- way device over the guide wire, step #8, was missed by 19 of the 55 (34.5%) of the participants. This step was not deemed an automatic fail- ure since most participants immediately self-corrected this error and completed the procedure successfully.

Discussion

Wire-guided cricothyrotomy is one of many techniques used to per- form to a cricothyrotomy. Although there is controversy over which technique is superior in regards to success rates, lower complication rates, and operator comfort; there is no published data regarding long term retention rates for the different techniques. Although a checklist was used during the initial training, neither the checklist nor the task trainer were available to the paramedics after the initial training session was completed. Furthermore the checklist was also not in the regional/ county protocols for the paramedic to review prior to the retesting. The long term retention rate of 87.3% noted in this wire-guided cricothyrotomy study, is higher than the reported 68% success rate seen with an open technique in battlefield situations, but this represents a simulated environment in comparison to a failed airway situation in combat [10].

A 100% success rate was recently obtained in a study by Quick et al., which used an open technique together with an elastic bougie and en- dotracheal tube, using a high fidelity simulation model. Yet this study did not examine long term retention and the participants included flight nurses [11]. Another study by Hill et al. noted the medical students and residents using a bougie-assisted cricothyrotomy technique had success rates of only 90% [12]. Furthermore, none of these studies looked at long term retention and none of these studies studied only ground paramedics.

With the advent of BIAD and other advanced techniques, a failed air- way in the prehospital environment is a very rare event. Consequently, this makes it impossible to perform a large prospective study on cricothyrotomy. As such, it is even more important that any future sim- ulation studies comparing different cricothyrotomy techniques exam- ine not just initial success rates but also long term retention rates.

Currently, there are no published studies examining long term retention rates using the different cricothyrotomy techniques. This is the first study to examine the individual steps in the process of cricothyrotomy. This is also the first study that identified which steps were most problematic and difficult to retain. In examining any proce- dural technique, it is important to separate the process into steps in order to analyze each step individually. By having a stepwise analysis, initial and recurring education can be focused on specific problematic steps in an attempt to increase overall short and long term success rates [13].

J.A. March et al. / American Journal of Emergency Medicine 37 (2019) 407-410 409

Fig. 2. SKILL CHECK SHEET - Cricothyrotomy.

Limitations

This study has several limitations including small sample size and a geographically small region within one state. The most important limi- tation was that this was a simulated Training model using a low fidelity task trainer. In addition, there is currently no published data regarding use of wire-guided cricothyrotomy during a failed airway on live pa- tients in the prehospital environment. Yet a recent study by Jayaraman

Fig. 3. - Total number of failures for each of the 16 steps in the check sheet, total N = 55.

et al. suggests that use of a low fidelity task trainer significantly increases the success rate of cricothyrotomy when performed by inexperienced resident physicians using an open technique in a swine model [14].

Another limitation is that this data cannot be extrapolated to other cricothyrotomy techniques. This study also did not determine which cricothyrotomy technique in a paramedic population is easiest to learn and which is best retained. Since cricothyrotomy by paramedics is rarely performed, future studies comparing different cricothyrotomy tech- niques need to include long term retention.

Another limitation of this study is the relatively short time frame of only 6-12 weeks used for retesting. Some will say that this is not true long term retention, yet several studies suggest that significant degrada- tion with other procedural skills begin after only a few short weeks [15- 18]. Nevertheless, there are no other studies looking at “long” term re- tention and attrition of cricothyrotomy skills in paramedics.

Lastly, any future studies need to include a stepwise checklist to help identify problems areas. By identify problems areas future instructors and students can appropriately adjust initial training and retraining.

Conclusion

Paramedics can be taught to perform and retain the skills necessary to successfully perform a wire-guided cricothyrotomy on a simulator. Future research is necessary to determine if paramedics can successfully transfer these skills to real patients.

Acknowledgements

The authors would like to thank the East Carolina University, Brody School of Medicine, Simulation Center for their assistance in this project.

410 J.A. March et al. / American Journal of Emergency Medicine 37 (2019) 407-410

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