American Journal of Emergency Medicine (2010) 28, 499–504

www.elsevier.com/locate/ajem

Brief Report

Verification of airway management during cardiac arrest: a manikin-based observational studyMasanao Kobayashi MDa,⁎, Akira Fujiwara MDa , Hiroshi Morita MDa , Yasuhisa Nishimoto MDa , Takayuki Mishima MDa , Masahiko Nitta MDa

,Toshihiro Hotta MDa , Toshimasa Hayashi MDa , Yasuyuki Hayashi MDb , Kenji Sato EMT c

aDepartment of Emergency Medicine, Osaka Medical College Hospital, Takatsuki-city, Osaka 569-8686, JapanbSenri Critical Care Medical Center, Saiseikai Senri Hospital, Suita-city, Osaka, JapancKawanishi City Fire Bureau, Kawanishi-city Hyogo, Japan

Received 23 January 2009; revised 6 March 2009; accepted 6 March 2009

AbstractIntroduction: The study aimed to clarify the difficulties concerning insertion of advanced airway devices during cardiac arrest.Method: In an observational study using manikins, we examined the airway management techniques of19 teams at the Osaka Senri medical rally. For ex-post verification, we recorded chest compression and ventilation using the Resusci® Anne Advanced Skill Trainer (Laerdal, Norway) and recorded actions of the teams using a video camera.Results: Only a small proportion of teams did not adopt advanced airway management (4 teams,21.1%). Thirteen teams selected tracheal intubation. None showed chest compression interruptions during intubation manipulation, and the median duration of chest compression interruption during confirmation of postintubation was 6.4 seconds. The median duration of ventilation interruption during intubation was 45.5 seconds. When teams were evaluated for the duration of direct laryngoscopy, that is, so-called duration of intubation, the median duration was 19 seconds, which constituted a large underestimate compared with the duration of ventilation interruption. This represents an under- estimation of about 27 seconds. We considered the issues to be identified for shortening the duration of ventilation interruption.Conclusion: From this study, it is clear that the strategy of Guideline 2005 that was designed to minimize chest compression interruption has permeated deeply. The recommendation that the duration of intubation manipulation should not exceed 30 seconds has had various interpretations, but it is important to focus on the duration of ventilation interruption.© 2010 Elsevier Inc. All rights reserved.

1. Introduction

⁎ Corresponding author. Tel.: +81 (0)726 83 1221; fax: +81 (0)726 846262.

E-mail address: emm003@poh.os a ka-med.ac.jp (M. Kobayashi).

Insertion of advanced airway devices, including tracheal intubation, is a routine procedure, but currently, there is no scientific evidence that the rate of hospital discharge in cardiac arrest patients has been improved by this means.

0735-6757/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.ajem.2009.03.006

500 M. Kobayashi et al.

There are various possible reasons for why the effectiveness of advanced airway devices cannot be demonstrated. For example, the duration of chest compression interruption or that of ventilation interruption during device insertion may be unacceptably long. Therefore, it is important to investigate the negative influences of advanced airway device insertion on cardiopulmonary resuscitation. For this reason, we verified the activities of rescuers and clarified problems concerning the insertion of advanced airway devices, including tracheal intubation, at a medical rally.

2. Methods

In the Osaka Senri medical rally, a 6-member team performed a 10-minute competitive exercise at each station [1]. The competing teams consisted of doctors and nurses working at emergency medical care centers and their local emergency medical technicians (EMTs). The 19 teams who participated in the 7th Osaka Senri Medical Rally (2008) were evaluated objectively in the present observational study. Competition teams were selected by lot from applicants from all over Japan. The applicants were required to give consent for participation in the study. In addition, we obtained the contestant's consent for publication about the study after the competition.

A Resusci Anne Advanced Skill Trainer (Laerdal foundation, Stavanger, Norway) was used. Data on chest compression and ventilation obtained from this simulator were stored into a personal computer, and images of the competitors' actions were recorded with a digital video camera for ex-post verification.

The following scenario was used. When a starting emergency rescue team arrives at the scene after an

emergency request, a bystander from the general public is providing cardiopulmonary resuscitation. Although defi- brillating shock has already been administered 3 times using an automated external defibrillator, ventricular fibrillation is still continuing. It is assumed that the starting emergency rescue team consists of 2 EMTs and 1 nurse. They are allowed to use various airway management devices, including tracheal intubation, and to administer adrenalin intravenously. The starting emergency rescue team requests a doctor-car team, consisting of 2 doctors and1 nurse. Each competitor is allowed to select any airway management technique.

The scenario presented no serious problems regarding airway and breathing conditions, and bag-mask ventilation could be provided normally. However, it was assumed that if direct laryngoscopy was conducted, it would not be possible to observe the glottis due to copious secretions. The person in charge of reporting the situation (the so-called voice of God) described the situation orally: “the glottis cannot be seen because of copious secretion” when direct laryngoscopy is conducted to perform tracheal intubation. If the competitor's accurate suction technique was confirmed, which was, after switching on a portable suction device, connecting a sucker, and inserting the tip of the sucker into the area close to the larynx under the circumstances of direct laryngoscopy, the person in charge of reporting the situation would utter sounds imitating suction and announce that the glottis had become visible. It was assumed that if suction was conducted once, the glottis could be confirmed during direct laryngoscopy after the second attempt.

Numbers derived from the video images and the simulator are represented as median values and inter- quartile ranges. SPSS II Version 11.0J (SPSS Inc, Chicago, Ill) was used for statistical analysis. The Mann-Whitney U test was used for comparisons between 2 unpaired groups

Fig. 1 Time needed for insertion of advanced airway devices.

and the Wilcoxon signed rank test for comparisons between 2 paired groups. The criterion for a significant difference was P b .05.

Time required for tracheal intubation was defined as follows (Fig. 1): (a) before direct laryngoscopy—time between the final ventilation and the initiation of insertion of a laryngoscope; (b) durations of direct laryngoscopy, that is, the so called “duration of intubation”—time between the start of insertion of a laryngoscope and removal of the laryngoscope after completion of secretion aspiration and/or intubation; and (c) after direct laryngoscopy—time between removal of a laryngoscope and restarting ventilation. The sum a + b + c was the duration of ventilation interruption.

3. Results

Fifteen teams selected insertion of advanced airway devices (Table 1). Two teams selected laryngeal tube (LT), one of which achieved their goal by using the first insertion technique. The other ran out of competition time before attempting insertion. Among the 13 teams selecting tracheal intubation, teams 3, 12, and 13 completed intubation during the first direct laryngoscopy. In other words, they performed intubation by a series of actions following suction. The remaining nine teams (nos. 1, 2, 4, 6, and 7-11) aspirated secretions around the larynx during the first direct laryngo- scopy, and returned to bag-mask ventilation, completing intubation during the second direct laryngoscopy. Team 5

could not conduct intubation during the second direct laryngoscopy but were able to complete it during the third direct laryngoscopy. Four teams performed resuscitation without insertion of advanced airway devices and with basic airway management alone. However, no teams selected the Combitube (Tyco-Kendall, Mansfield, MA), laryngeal mask airway, oropharyngeal airway, or nasopharyngeal airway.

Only 3 (nos. 1-3) of 13 teams implemented direct laryngoscopy after preparing for suction. Because 2 (nos. 1 and 2) of these 3 teams promptly returned to bag-mask ventilation after aspiration, the durations of ventilation interruption in the 2 teams were 19 and 29 seconds, respectively, which were short.

On the other hand, 10 teams (nos. 4-13) performing direct laryngoscopy without preparing for aspiration during tracheal intubation encountered a situation in which the glottis could not be confirmed because secretions were present, and they started preparations for aspiration for the first time and abandoned ventilation and continued direct laryngoscopy until preparations for suction were completed. Because 2 (teams 4 and 5) of these 10 teams could perform suction relatively early and returned to bag-mask ventilation, the durations of ventilation interruption in the 2 teams were31 and 24 seconds, respectively, which were short. However,2 teams (nos. 6 and 7) who took the time to prepare for suction had ventilation interruptions of 73 and 62 seconds, respectively, until they returned to bag-mask ventilation after suction. Two teams (nos. 14 and 15) selecting LT and 4 teams accomplishing resuscitation with bag-mask ventilation had no particular problems with airway management.

Table 1 List of teams that selected insertion of advanced airway devices

No. Device Occupation who managed airway

Preparing for aspiration at direct laryngoscopy

Returning to bag- mask ventilation after aspiration immediately

Use of AED coincided with the timing of defibrillating shock

Duration of ventilation interruption/duration of so-called device insertion (s)

First Second Third

Duration of chest compression interruption during confirmation of inserted device (s)

1 ETT EMT + + + 19/7 87/23 * 8.12 ETT Doctor + + − 29/16 34/20 * 3.73 ETT EMT + − + 194/39 * * 10.94 ETT EMT − + − 31/14 30/10 * 11.35 ETT Doctor − + − 24/21 56/50 23/11 06 ETT Doctor − + + 73/8 41/13 * 6.37 ETT EMT − + + 62/24 62/18 * 9.88 ETT Doctor − − + 59/48 120/28 * 3.29 ETT EMT − − + 83/59 50/17 * 4.510 ETT Doctor − − + 97/58 30/20 * *11 ETT Doctor − − + 80/67 76/32 * 012 ETT EMT − − − 91/73 * * 11.813 ETT EMT − − + 96/64 * * 6.414 LT EMT * * − 31/15 * * 7.115 LT EMT * * − * * * *

AED, automated external defibrillator; ETT, endotracheal tube.

* No data.

Fig. 2 Durations of chest compression interruption during confirmation of ventilation after tracheal intubation.

Next, we examined chest compression interruption associated with intubation manipulation. Of the 13 teams that selected tracheal intubation, none showed chest compression interruptions during intubation manipulation. Of these, one ran out of time and we could not confirm ventilation after device insertion. Therefore, we studied the duration of chest compression interruption during confirmation of postintubation ventilation in 12 teams (Fig. 2). None showed chest compression interruptions during intubation manipulation. The median duration of chest compression interruption during confirmation of

postintubation ventilation was 6.4 seconds. Duration of more than 10 seconds was observed in 3 teams (25%). The duration of chest compression interruption by the doctors was significantly shorter compared to the EMTs (P = .007).

We also studied the duration of ventilation interruption and that of direct laryngoscopy during tracheal intubation (Fig. 3). In this study, we excluded 3 cases in which both aspiration and intubation manipulation were performed in a series; we analyzed data only on the duration of intubation manipulation purely. The median duration of ventilation

Fig. 3 Durations of ventilation interruption and direct laryngoscopy during tracheal intubation.

interruption was 45.5 seconds, and only 3 teams (30%) were able to limit the duration of ventilation interruption to30 seconds or less. On the other hand, evaluation using the duration of direct laryngoscopy showed that these 10 teams had a median of 19 seconds, which was significantly shorter (P = .005) than the duration of ventilation interruption as an index; this represents an underestimation of about27 seconds.

4. Discussion

From this study, it is clear that the strategy of Guideline2005 that was designed to minimize chest compression interruption has permeated deeply. As a result of emphasis on venous return and cardiac output, the number of ventilations and tidal volume is obviously moving toward hypoventilation. The priority of the ventilation become surely low, but its degree has not been clarified and is still controversial. Conversely, the importance of performing each ventilation securely is increasing. Therefore, the duration of ventilation interruption requires closer attention than previously thought necessary. Persons conducting resuscitation on a routine basis at least should not underestimate ventilation. We want to warn against any tendency to underestimating ventilation. Of course, it is necessary to perform ventilation properly on having performed chest compression surely.

The so-called 30-second rule for intubation, that is, that intubation manipulation should be performed within 30 seconds, is widely recognized by healthcare professionals. Specifically, the European Resuscitation Council Advanced Life Support course manual says that, “No intubation attempt should take longer than 30 sec” [2], and the American Heart Association Advanced Cardiovascular Life Support Provider Manual states that, “If a laryngoscope and tube are not readily available or if the intubation attempt is not successful within 30 seconds, return to bag-mask ventilation” [3]. However, no manual provides clear definitions of intubation attempts, so there are no clear answers to the questions of when an intubation attempt begins and ends (eg, whether it starts from the final ventilation, opening the patient's mouth, or insertion of a laryngoscope; or whether it ends with the passage of a tracheal tube through the glottis, the completion of cuff inflation, or the restarting of ventilation).

On the other hand, there are strict stipulations that the duration of ventilation interruption should be no longer than 30 seconds: Barbara Aehlert states in the Advanced Cardiovascular Life Support study guide, “Do not exceed30 seconds from ventilation to ventilation for each intubation attempt” [4]. American Heart Association Guidelines 2000 states “During the process of tracheal intubation, the maximum interruption to ventilation should be 30 seconds” [5].

We found that even if the duration of direct laryngo- scopy could be limited to 30 seconds or less, it was greatly exceeded by the actual duration of ventilation interruption. The difference has not been discussed frequently, and we demonstrated that the difference was larger than the expected value. Considering the original purpose to set this rule, the duration should be for ventilation interruption, not for device insertion. If this is not understood, unacceptable events might occur in medical practice. If the duration of direct laryngoscopy was limited to 30 seconds or less, direct laryngoscopy should be performed after preparation for suction, and if viewing the glottis is likely to take time, mask ventilation should be performed promptly.

To shorten the duration of ventilation interruption, it is important to make certain preparations for tracheal intuba- tion, such as considering stylets and shapes of the tracheal tube and lubricant agents, and to place a pillow beneath the head of the patient beforehand to ensure a sniffing position, in addition to the above-mentioned preparation for suction during the period between the final ventilation and direct laryngoscopy. In addition, it is important to shift to intubation manipulation immediately after performing venti- lation twice.

5. Limitations

The present study cannot show how the duration of ventilation interruption associated with the insertion of an advanced airway device influences the prognosis of a patient. It is possible that the abnormal stress associated with competition led to results different from those that would be obtained in daily clinical practice.

6. Conclusions

The duration of ventilation interruption associated with the insertion of advanced airway devices was considerably longer than expected. It is important to focus on the duration of ventilation interruption. Although it may be difficult to perform tracheal intubation with 30 seconds or less duration of ventilation interruption, the basic points of tracheal intubation should be emphasized.

Acknowledgments

We thank the organizers of the Osaka Senri medical rally; the volunteer participants who took part in station management; the manufacturers who lent us medical equipment; the competing teams who took part in the study; and Dr Yoshio Horikawa (Department of Anesthesia,

Nishi-Kobe Medical Center) and Dr Seiji Miyahara (Department of Anesthesia, Kanzaki Municipal General Hospital), who have provided valuable suggestions.

References

[1] Kobayashi M, Fujiwara A, Morita H, et al. A manikin-based observational study on cardiopulmonary resuscitation skills at the Osaka Senri medical rally. Resuscitation 2008;78:333-9.

[2] European Resuscitation Council. Airway management and ventilation.In: Nolan J, Gabbott D, Lockey A, Mitchel S, Perkins G, Pitcher D, et al, editors. Advanced life support course manual. 5th ed. Antwerp

(Belgium): European Resuscitation Council; 2006. p. 41-55. [Chapter 6].

[3] American Heart Association. ACLS_supplementary (PDF file in CD-R), Advanced airway management, endotracheal intubation. In: Field JM, Gonzales L, Hazinski MF, editors. Advanced cardiovascular life support provider manual. Dallas, Texas: American Heart Associa- tion; 2006. p. 18-29. [Part 2].

[4] No authors listed. Airway management: oxygenation and ventilation. In:Aehlert B, editor. ACLS study guide. 3rd ed. St. Louis, Missouri: Mosby Jems Elsevier; 2007. p. 53-117. [Chapter 2].

[5] Guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care. Part 6: advanced cardiovascular life support: section 3: adjuncts for oxygenation, ventilation and airway control. The American Heart Association in collaboration with the International Liaison Committee on Resuscitation. Circulation 2000;102:I95-I104.

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