a b s t r a c t

Purpose: The utility of the Gum-elastic bougie (GEB) as an assistive device for tracheal intubation during chest compressions has not been sufficiently validated. This study aimed to compare the utility of the GEB during chest compressions on an adult manikin.

Methods: Seventeen novice physicians performed tracheal intubation on an adult manikin using the GEB with or without chest compressions. intubation success rate, intubation time, subjective difficulty of laryngoscopy, and tube passage through the glottis were measured. P b .05 was considered as significantly different.

Results: All novice physicians successfully secured the airway without chest compression with and without the GEB. In contrast, during chest compressions, 7 failed without the GEB, whereas only 1 failed with the GEB (P = .007). Intubation time was significantly longer with chest compressions regardless of GEB use (P b .001). Both laryngoscopy and tube passage through the glottis were perceived as significantly more difficult with chest compressions, regardless of GEB use (P b .001). Subjective difficulty of tube passage through the glottis dur- ing chest compression was perceived as significantly more easy by GEB application (P b .001).

Conclusions: These findings suggest that the GEB facilitates tracheal intubation during chest compressions per- formed by novice physicians in adult simulations.

(C) 2015

Introduction

The American Heart Association (AHA) cardiopulmonary resuscita- tion (CPR) guidelines emphasize the importance of minimizing chest compression interruptions to maximize cerebral and coronary perfu- sion pressure. The guidelines also suggest that rescuers should be able to visualize vocal cords and allow passage of the tracheal tube for secur- ing the airway without interrupting chest compressions [1,2]. However, it is often difficult to perform definite tracheal intubation during chest compressions, especially for novice physicians [3,4].

The gum-elastic bougie (GEB), a tracheal tube introducer, is com- monly used in airway management, and its use is recommended by var- ious guidelines at early stages of difficult intubation [5]. Several studies have been published regarding its utility in the context of difficult adult airway management, particularly for addressing difficult laryngoscopy situations [6].

? Details of author contributions: NK and SC performed study design, conducted the study and data analysis, and wrote the manuscript; TU and RM conducted the study and data analysis; and TM performed study design and manuscript preparation.

?? Conflict of interest and source of funding statements: The authors have no affiliation

with any manufacturer of any device described in the manuscript and declare no financial interest in relation to the material described here. Financial support for the study was pro- vided by our institution and department.

* Corresponding author at: Department of Anesthesiology, Osaka Medical College, Daigaku-machi 2-7, Takatsuki, Osaka, 569-8686, Japan.

E-mail address: [email protected] (N. Komasawa).

Although several reports have demonstrated the utility of the GEB for difficult airway management [7,8], clinical reports and evaluations of GEB application during chest compressions have not been sufficiently validated. Thus, in the present study, we compared the utility of the GEB in assisting tracheal intubation during chest compressions. As direct clinical evaluations are unethical, we performed validations with mani- kins. We hypothesized that the GEB would improve intubation success during Continuous chest compressions. To this end, we evaluated the utility of the GEB with respect to ease of tracheal intubation by novice physicians on an adult manikin with or without chest compressions.

Materials and methods

Ethical approval for this study (Ethical Committee no. 1321) was provided by the Ethical Committee of Osaka Medical College, Osaka, Japan (Chairperson Prof R. Saura) on January 6, 2014, and written in- formed consent was obtained from each participant. From May 2 to June 4, 2015, 17 novice physicians who attended an anesthesiology training module at Osaka Medical College were recruited. Novice physi- cians performed trials when they had completed 1 month of anesthesia training and had experienced 20-30 tracheal intubations using the Macintosh laryngoscope (McL). None of the novice physicians had clin- ical experience with GEB use.

The ALS simulator (Laerdal, Sentrum, Stavanger, Norway) manikin was used to perform intubation and chest compressions. We used a 15F GEB (Tracheal Tube Introducer; Portex, St Paul, MN) in this

http://dx.doi.org/10.1016/j.ajem.2015.09.016

0735-6757/(C) 2015

VAS scores for laryngoscopy and tub”>N. Komasawa et al. / American Journal of Emergency Medicine 34 (2016) 54-56 55

study. Tracheal tubes (Portex) with an internal diameter of 7.5 mm were used [9].

*

*

The manikin was placed on a hard, flat table for an “on the bed” sim- ulation. Chest compressions were performed by the same Advanced Life Support instructor at a depth of about 5 cm and a rate of 100 compres- sions per minute in accordance with current guidelines [10]. Each par- ticipant was instructed to insert the tracheal tube, attach a bag valve mask, and attempt to ventilate the lungs of the manikin. Participants were given 5 minutes to practice intubation, with the instructor avail- able to give advice. The necessary equipment for each trial was placed in a box next to the manikin’s head. Intubations started when the partic- ipant picked up the McL and ended at the point of manual ventilation after tube insertion. intubation times were recorded for both tracheal and oEsophageal intubations. At the end of the study, participants rated the difficulty of using each device for laryngoscopy and passage

time to intubation (sec)

of the tracheal tube through the glottis on a Visual analogue scale (VAS) from 0 mm (extremely easy) to 100 mm (extremely difficult) [11]. The study was designed as a randomized crossover trial to mini- mize the learning curve effect. The order of intervention was random- ized for each participant by a random number table, which yielded a total of 4 interventions per participant.

Results obtained from each trial were compared using 2-way analy- sis of variance for intubation time and VAS, and Fisher exact test for the success rate. Data are presented as mean +- SD. P b .05 was considered statistically significant.

A preliminary study involving 8 novice physicians showed that the time required for successful intubation with the McL was approximately 13 +- 3 seconds. We considered 5 seconds as a Clinically meaningful dif- ference. We estimated that 15 participants would be adequate for 2 in- dependent groups, and set ? = 0.05 and ? = 0.2. To compensate for missing data, the trial was performed with 17 novice physicians.

Results

Tracheal intubation success with or without chest compressions

The number of successful tracheal intubations for each condition is shown in the Table. Without chest compressions, all intubation at- tempts were successful, regardless of GEB use. With chest compres- sions, 7 novice physicians failed without the GEB, whereas only 1 failed with the GEB. Intubation success rate was significantly worse with chest compressions without the GEB (P = .007) but not with the GEB (P = 1.00).

Intubation time with or without chest compressions

Fig. 1 shows intubation times with or without the GEB. Intubation time was significantly longer with chest compressions than without, re- gardless of GEB use (without GEB: 12.2 +- 3.2 seconds in normal situa- tion, 20.0 +- 5.3 seconds during chest compression; with GEB: 12.2 +-

2.8 seconds in normal situation, 20.4 +- 6.3 seconds during chest com- pression) (P b .001 for both conditions). Intubation time did not signif- icantly differ with or without the GEB, regardless of chest compressions.

Normal During CC Normal During CC

Without GEB With GEB

Fig. 1. Box-and-whisker plot (median, IQR, and range) of time elapsed for simulated tra- cheal intubation by GEB use with and without chest compressions. Laryngoscopy

(A) and tube passage (B) through the glottis. White box: without GEB; black box: with GEB. Results are expressed as mean +- SD and were analyzed by 2-way analysis of vari- ance. *P b .05 compared to without chest compression. #P b .05 compared to without GEB. CC: chest compressions.

VAS scores for laryngoscopy and tube passage through the glottis with or without chest compressions

The VAS scores for laryngoscopy and tube passage through the glot- tis are shown in Fig. 2. Subjective difficulty regarding laryngoscopy was perceived as significantly more difficult with chest compressions, re- gardless of GEB use (without GEB: 21.8 +- 9.0 mm in normal situation,

37.1 +- 26.2 mm during chest compression; with GEB: 17.6 +- 6.6 mm in normal situation, 39.4 +- 24.9 mm during chest compression) (P b

.001 for both conditions). Subjective difficulty regarding tube passage through the glottis was also perceived as significantly more difficult with chest compressions, regardless of GEB use (without GEB: 17.4 +-

11.1 mm in normal situation, 76.8 +- 11.0 mm during chest compres- sion; with GEB: 14.7 +- 8.2 mm in normal situation, 48.2 +- 22.4 mm during chest compression) (P b .001 for both condition).

Subjective difficulty of tube passage through the glottis during chest compression was perceived as significantly more easy by GEB applica- tion (P b .001).

Discussion

Current AHA CPR guidelines emphasize the importance of continu- ous chest compressions with as few interruptions as possible [1,2]. Sev- eral studies have shown that prolonged interruption of chest compressions is associated with both decreased Coronary and cerebral perfusion and reduced venous return to the heart, resulting in low sur- vival rates and impaired postresuscitation myocardial function [12]. Air- way management is essential, particularly for In-hospital CPR. Although conventional direct-view laryngoscopes such as the McL are the most

Table

Tracheal intubation success rates by GEB use with and without chest compressions

	Without chest compressions (successful/total)	With chest compressions (successful/total)	P value (Fisher exact test)
Without GEB	17/17	10/17	.007?
With GEB	17/17	16/17	1.00

Values are presented as number of participants who achieved successful intubation/number of participants who attempted intubation.

* P b .05.

56 N. Komasawa et al. / American Journal of Emergency Medicine 34 (2016) 54-56

a) pharynx, which occur in clinical settings [15]. In cases which involve bleeding or vomiting, the GEB may be more useful. Second, use of the

Normal During CC Normal During CC

Without GEB With GEB

b)

?

GEB may be less than ideal in patients with severely Restricted mouth openings. Third, chest compressions and intubations were performed on a manikin, which led to shorter airway intervention times than those required for actual patients [16,17]. Finally, homogeneity of CPR techniques cannot always be assured in clinical situations.

(mm)

Future studies should investigate the utility of the GEB in view of clinical experience. Randomized trials involving GEB use on actual pa- tients receiving CPR may also be informative.

Conclusion

Normal During CC

(mm)

Normal During CC

Our findings suggest that GEB use facilitates definite tracheal intuba- tion during chest compressions in adult simulations performed by novice physicians.

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   Without GEB With GEB

   Fig. 2. Box-and-whisker plot (median, IQR, and range) of subjective difficulty of laryngos- copy and tube passage through the glottis by GEB use with and without chest compres- sions. Laryngoscopy (A) and tube passage (B) through the glottis. White box: without GEB; black box: with GEB. Results were analyzed by 2-way analysis of variance. *P b .05 compared to without chest compression. #P b .05 compared to without GEB.

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