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Using a Laryngeal Tube Suction-Device (LTS-D) Reduces the “No Flow Time” in a Single Rescuer Manikin Study
The Journal of Emergency Medicine, Vol. 41, No. 2, pp. 128 –134, 2011 Copyright © 2011 Elsevier Inc. Printed in the USA. All rights reserved 0736-4679/$–see front matter
doi:10.1016/j.jemermed.2008.08.014
Original Contributions
USING A LARYNGEAL TUBE SUCTION-DEVICE (LTS-D) REDUCES THE “NO FLOW TIME” IN A SINGLE RESCUER MANIKIN STUDY Christoph H. R. Wiese, MD,* Utz Bartels, MD,* Alexander Schultens, MD,* Tobias Steffen, Torney, MD,‡ Jan Bahr, MD,* and Bernhard M. Graf, PHD*
MD,†
Andreas
*Department of Anaesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany, †Department of Anaesthesiology, Klinikum Wolfenbüttel, Wolfenbüttel, Germany, and ‡Department of Anaesthesiology and Intensive Care, Klinikum Braunschweig, Braunschweig, Germany Reprint Address: Christoph H. R. Wiese, Department of Anesthesiology, Emergency and Intensive Care Medicine, Georg-August University of Göttingen, Robert Koch Straße 40, Göttingen D-37075, Germany
e Abstract—Background: In 2005, the European Resuscitation Council and the American Heart Association published new guidelines for Advanced Life Support. One of the points was to reduce the time without chest compressions in the first phase of cardiac arrest. Objective: We evaluated in a manikin model whether using the single-use laryngeal tube with suction option (LTS-D) instead of endotracheal intubation (ET) and bag-mask-valve ventilation (BMV) for emergency airway management could reduce the “no-flow time” (NFT). The NFT is defined as the time during resuscitation when no chest compressions take place. Methods: A randomized, prospective study was undertaken with 150 volunteers who performed management of a standardized simulated cardiac arrest in a manikin. Every participant was randomized to one of three different airway management groups (LTS-D vs. ET vs. BMV). Results: The LTS-D was inserted significantly faster than the ET tube (15 s vs. 44 s, respectively, p < 0.01). During the cardiac arrest simulation, establishing and performing ventilation took an average of 57 s with the LTS-D compared to 116 s with ET and 111 s with the BMV. Using the LTS-D significantly reduced NFT compared to ET and the BMV (125 s vs. 207 s vs. 160 s; p < 0.01). Conclusions: In our manikin study, NFT was reduced significantly when the LTS-D was used when compared to ET and BMV. The
results of our manikin study suggest that for personnel not experienced in tracheal intubation, the LTS-D offers a good alternative to ET and BMV to manage the airway during resuscitation, and to avoid the failure to achieve tracheal intubation with the ET, and the failure to achieve adequate ventilation with the BMV. © 2011 Elsevier Inc.
Conflicts of interests: C. Wiese and all co-authors declare there are no conflicts of interest concerning any product or company mentioned in the following study.
Chest compressions are to be started immediately after cardiac arrest. Chest compression and respiration should be in a ratio of 30:2.
RECEIVED: 7 April 2008; FINAL ACCEPTED: 6 August 2008
SUBMISSION RECEIVED:
e Keywords—Advanced Life Support (ALS); cardiopulmonary resuscitation (CPR); guidelines; orotracheal intubation; out-of-hospital CPR
INTRODUCTION The European Resuscitation Council (ERC) and the American Heart Association released a revised edition of their resuscitation guidelines for cardiac arrest in November 2005 in which the following adjustments were incorporated (1).
Emphasis on Chest Compression
17 June 2008; 128
Laryngeal Tube Suction-Device
Reduction of the Numbers of Defibrillations if Ventricular Fibrillation/Pulseless Ventricular is Confirmed After each 2-min cardiopulmonary resuscitation (CPR) cycle, only one electric shock instead of three should be applied for shockable rhythms. Without reassessing the rhythm, CPR should be resumed immediately after the shock is applied (2). Expansion of Airway Management Options Endotracheal intubation provides the most reliable airway. It should be attempted only by trained health care providers who have adequate ongoing experience with the technique and should take no longer than 30 s to complete. Due to the high incidence of complications (e.g., esophageal intubation), personnel without experience in tracheal intubation should use acceptable alternatives to manage the airway, such as the Combitube, laryngeal mask airway (LMA), intubating LMA, or laryngeal tube (LT) (1). If it is not possible to manage the airway with alternative methods, personnel may resort to bag-mask-valve ventilation. Alternative airway devices for use during resuscitation should meet the following criteria: They should be easy to handle, especially by persons unfamiliar with the use of the endotracheal tube, and they should guarantee reasonable protection against aspiration (1). In 1999, the LT was introduced as an alternative for protecting the difficult airway (3–7). The LT version with a gastric suction option (i.e., the LTS-D), in particular, meets the above-mentioned criteria, as recent studies suggest (8,9). This alternative airway device seems to meet the criteria of the ERC (1). Reduction of No-flow Time (NFT), the Time during Which There are No Chest Compressions The chest compression ratio of 30 per respiratory cycle and the reduction of the number of defibrillations if ventricular fibrillation (VF) is confirmed reduce the NFT during resuscitation. In our study, we evaluated whether the use of the LTS-D for emergency airway management could contribute to reducing the NFT, compared to endotracheal intubation (ET) and bag-mask-valve (BMV) ventilation. METHODS There were 150 volunteers (paramedics) prospectively randomized to one of three groups (LTS-D group, ET
129 Table 1. ALS Course Schedule Activity
Duration
Introduction Pre-course test Basic Life Support (BLS) Defibrillation Intraosseous access Airway management
10 min 20 min 45 min 45 min 30 min 90 min (30 min each for LTS-D, BMV, and ET) 30 min 180 min 20 min 10 min
CPR drugs ALS training Post-course test Summary and feedback
ALS ⫽ Advanced Live Support; CPR ⫽ cardiopulmonary resuscitation; LTS-D ⫽ laryngeal tube suction-device; BMV ⫽ bagmask-valve ventilation; ET ⫽ endotracheal intubation.
group, or BMV group) to manage the airway. Study subjects were recruited from the participants of a oneday Advanced Life Support (ALS) course designed for emergency personnel, after written informed consent. The study was conducted after completion of the course (ALS course schedule, Table 1). During a 90-min airway training period, use of the different airway devices was demonstrated in a manikin (“Resusci Anne Advanced Skilltrainer”; Laerdal™ Inc., Stavanger, Norway). The technique of using the LTS-D was taught according to the manufacturer’s instructions (8). The simulated scenario required participants to resuscitate a “patient” (manikin, Laerdal Inc.) with VF, in a team consisting of two people. Scenarios were set to last 420 s (BMV scenario), 430 s (LTS-D scenario), and 450 s (ET scenario). Time frames are shown in Table 2. The courses had a maximum of 12 participants and were held by the same instructors to reduce intra-observer bias. Data were recorded on the computer of the manikin (Laerdal™ Norway, PC-Skill reporting Software) and on a standardized paper sheet to allow retrospective analysis. The statistical analyses were performed using SPSS for Windows, release 12.0 (SPSS, Chicago, IL). The non-parametric analysis of variance test (differences between the three groups and repeated performance) and the Wilcoxon signed rank test (inter-group testing) were used. There was a correction of P for multiple tests. Descriptive values of variables are expressed as average and percentages. All p values of ⬍ 0.05 were considered to indicate statistical significance. According to the Declaration of Helsinki, data were made anonymous (10). Demographic data, age, sex, professional experience, previous ALS courses, and satisfaction with the ALS course retrospectively, were obtained and compared. The primary study endpoints were defined as the total NFT
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Table 2. Scenario Time-frames Activity
LTS-D Time (Total Time)
ET Time (Total Time)
BMV Time (Total Time)
Access to the patient LTS-D placement (after first 30 chest compressions) 1st CPR cycle 1st defibrillation ET placement 2nd CPR cycle 2nd defibrillation 3rd CPR cycle 3rd defibrillation
15 s (15 s) 10 s (25 s) 120 s (145 s) 15 s (160 s) 0 s (160 s) 120 s (280 s) 15 s (295 s) 120 s (415 s) 15 s (430 s)
15 s (15 s) 0 s (15 s) 120 s (135 s) 15 s (150 s) 30 s (180 s) 120 s (300 s) 15 s (315 s) 120 s (435 s) 15 s (450 s)
15 s (15 s) 0 s (15 s) 120 s (135 s) 15 s (150 s) 0 s (150 s) 120 s (270 s) 15 s (285 s) 120 s (405 s) 15 s (420 s)
LTS-D ⫽ laryngeal tube suction-device; ET ⫽ endotracheal intubation; BMV ⫽ bag-mask-valve ventilation; CPR ⫽ cardiopulmonary resuscitation.
and adherence to ERC ALS guidelines 2005 (e.g., three defibrillation cycles during the scenario must be applied). The secondary study endpoints were the total ventilation time (sum of individual ventilation cycle times with BMV, LTS-D, and ET, including time for LTS-D and for ET tube placement), the tidal volume, adequacy of ventilation concerning the type of technique to secure the airway, time to confirmation of cardiac arrest, and participants’ retrospective evaluation of airway management. Times required for each defibrillation were based on time needed by the semi-automatic electrical defibrillator (AED; CorPuls 08/16™ Inc., Kaufering, Germany) for analysis and shock. Remaining times in the scenarios are in accordance with the ERC ALS guidelines of 2005 (1). To ensure the reliability of comparing times, the following setup was chosen. Two participants were involved in each scenario. The first was designated as the main resuscitator and the other was the secondary resuscitator. Main resuscitators were responsible for airway management and chest compression during the scenario (as in a single rescuer resuscitation scenario). The secondary resuscitator assisted the main resuscitator (e.g., by using the semi-automated defibrillator for analysis and shock). Each participant was assigned once to the main position, and once to the secondary position. In the LTS-D group, the insertion and placement of the LTS-D was to be started after determining unconsciousness and the first chest compressions. During placement, chest compressions were stopped. Until successful insertion and placement of the LTS-D, the resuscitator had to ventilate the patient by using BMV. If unsuccessful in the first attempt, the resuscitator had to re-attempt insertion of the LTS-D after first defibrillation and the following 30 chest compressions. Until the reattempt, the resuscitator had to use BMV to ventilate the manikin. At the end of the 1-day ALS course, all participants were asked to complete a questionnaire concerning their preferences of the different airway devices.
RESULTS The study included 150 participants who were all paramedics. The demographic data are presented in Table 3. All participants were active workers in Emergency Medicine. The three groups were comparable in demographic data.
Study Group 1 (LTS-D Group) Ninety-six percent (n ⫽ 48) of the participants placed the LTS-D correctly on first attempt. Adequate tidal volumes (500 – 600 mL) were achieved through the LTS-D in all attempts. Test subjects required an average of 15 s to successfully put the LTS-D in place after initiation of the sequence (range 7–25 s). Average ventilation required 1.3 s (for inspiration and expiration). Total respiration time was 57.4 s (range 48 – 65 s). This included the time to place the LTS-D, and the inspiration and expiration time overall. The “No Flow Time” until the first respi-
Table 3. Demographic Data n (%) Sex Male Female Age (years) 18–25 26–30 31–35 36–40 41–45 ⬎ 50 Number of previous ALS courses attended 0 1 ⬎1 ALS ⫽ Advanced Life Support.
89 (59%) 61 (41%) 21 (14%) 41 (27%) 36 (24%) 35 (23%) 16 (11%) 1 (1%) 44 (29%) 93 (62%) 13 (9%)
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Table 4. Defibrillation during the Scenarios Time-to-shock Seconds (Range) Defibrillation
LTS-D
ET
BMV
1st 139 (99–195) 137 (85–211) 164 (124–210) Defibrillation 2nd 256 (198–317) 316 (219–420) 311.4 (285–321) Defibrillation 3rd 369 (314–420) 438 (392–447) 413 (404–420) Defibrillation LTS-D ⫽ laryngeal tube suction-device; ET ⫽ endotracheal intubation; BMV ⫽ bag-mask-valve ventilation.
ration in the LTS-D group occurred was 21.3 s (range 15–24 s). This included the time to confirm unconsciousness of the manikin and the time to place the LTS-D (excluding the time for the first 30 chest compressions after confirming cardiac arrest).
safely use the ET tube to secure the airway during the simulation. Most of the participants were insecure with the use of the ET tube (i.e., they rated themselves unfamiliar with the method).
Study Group 3 (BMV Group) The NFT until the first respiration occurred in the BMV group was 12.6 s (range 9 –17 s). This included the time to confirm unconsciousness of the manikin and the time to place the BMV for ventilation (excluding the time for the first 30 chest compressions). Nineteen participants (38%) attained effective tidal volumes of 500 – 600 mL with BMV. The majority of the participants were unable to achieve efficient ventilation. Each single respiration averaged 4.2 s (range 2–7 s). None of the participants was able to ventilate the manikin in an average time of 1 s for every respiration (inspiration and expiration). Total respiration time was 110.8 s (63–160 s).
Study Group 2 (ET Group) Fifty-four percent (n ⫽ 27) of the participants placed the ET tube correctly on the first attempt. Forty-six percent (n ⫽ 23) required a second attempt. Volunteers required an average of 44 s (range 19 –95 s) to successfully position the ET. The second attempt required an average of 43 s (range 15– 64 s). With regard to the ERC guidelines of 2005, 11 (22%) participants were able to place the ET tube within 30 s. The endotracheal intubation started 207 s (range 95–367 s) after the beginning of the scenario. Participants had to manage the airway by BMV until successful placement of the ET tube. The NFT until the first respiration occurred in the ET group was 12.9 s (range 8 –18 s). This included the time to confirm unconsciousness of the manikin and the time to place the BMV for first ventilation (excluding the time for the first 30 chest compressions). Each single respiration averaged 4.7 s (range 3–7 s) using BMV. Twelve (24%) participants attained effective tidal volumes of 500 – 600 ml with BMV. The majority were unable to generate efficient ventilation. Total time needed for respiration (including times using BMV and times using ET) amounted to 115.6 s (range 75–149 s). At the end of the study, 15 (30%) participants of this group were able to
Defibrillation/NFT Table 4 summarizes the times required for defibrillation. Significantly more participants completed three defibrillation sequences in the LTS-D group (98%) than in either of the other two groups (ET 18%, BMV 34%) within the set time frames (p ⬍ 0.01). In the ET group, only nine participants completed three defibrillation sequences. NFT in the LTS-D group was significantly shorter than in both other groups (p ⬍ 0.01). The total NFT and approximated NFT are shown in Table 5. After managing the airway with either LTS-D or ET, breaths were given in a ratio of 2:30 (breath to chest compression). The airway was managed by ET between 2-min cycles and by LTS-D after the first 30 chest compressions.
Questionnaire Results At the end of the study, 94% of the participants favored the LTS-D over the other two devices. A major reason for this was that handling of the device was reported to
Table 5. No-Flow Time
NFT NFT NFT NFT
(unavoidable) (total) fraction (percent of total time) (suspected by participants)
LTS-D (Range)
ET (Range)
BMV (Range)
100 s 125 s (89 s–145 s) 0.29 146 s (80 s–240 s)
120 s 207 s (118 s–287 s) 0.46 166 s (100 s–240 s)
90 s 160 s (129 s–183 s) 0.38 173 s (120 s–240 s)
LTS-D ⫽ laryngeal tube suction-device; ET ⫽ endotracheal intubation; BMV ⫽ bag-mask-valve ventilation; NFT ⫽ no-flow time.
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be easy to learn, and this resulted in a feeling of security in the user compared to ET and BMV.
DISCUSSION The effective use of bag-mask-valve ventilation and endotracheal intubation requires a certain level of skill and experience. Therefore, the ERC Guidelines of 2005 recommend the following alternatives to manage the airway: the LT, the Combitube, the laryngeal mask airway (LMA), and the LMA Fastrach™ (LMA Inc., San Diego, CA) (1). These are recommended as second-line alternatives to ET and to BMV, especially for those unfamiliar with endotracheal intubation (1). The ERC defines “familiar with endotracheal intubation” as those personnel with extensive training and regular practice. Thus, most paramedics are defined as unfamiliar with endotracheal intubation. Therefore, it is recommended that during resuscitation they refrain from attempting endotracheal intubation, and BMV should be their first choice for airway management. The design of our course specifically took this into account. In 1999, the LT was introduced as an alternative for protecting the difficult airway (3–7,11). The LT version with a gastric suction option (LTS-D), especially, meets the above-mentioned criteria, as recent studies suggest (8,9). We evaluated, in a manikin model, whether the use of the LTS-D for emergency airway management is feasible for participants unfamiliar with this method, compared to ET and BMV. In the total respiration time, the differences between the three methods of airway management were significant (LTS-D 57.7 s, ET 115.6 s, and BMV 110.8 s; p ⬍ 0.01). Most of the participants were not able to generate efficient ventilation with BMV. Another aim of the ERC Guidelines of 2005 was to reduce the time without chest compression during the initial phase of cardiac arrest (1). In our study, we evaluated whether the use of the LTS-D for emergency airway management could contribute to reducing the NFT, compared to the ET and BMV. The following NFTs were unavoidable in the standardized scenario of this study: ● ● ● ●
15 s to confirm unconsciousness 10 s for insertion of the LTS-D (after airway check) 10 s for respiration during each cycle of CPR 30 s for insertion of the ET (after at least one defibrillation) ● 15 s for each defibrillation with a semi AED (CorPuls 08/16™) This adds up to a total minimal NFT of 90 s with BMV, 100 s with the LTS-D, and 120 s with ET. Only
with the LTS-D did the participants meet the guidelines criteria with as short an NFT as possible (1). No participant was able to meet the guidelines with BMV, and only one in the ET group achieved the guidelines criteria. Moreover, only 18% of the ET group and 34% of the BMV group were able to apply three defibrillations within the time frame of the ERC guidelines, whereas 98% of participants in the LTS-D group adhered to the ERC guidelines including three defibrillations. Thus, the results of our study suggest that personnel unfamiliar with endotracheal intubation should use an alternative type of airway management. The results of this study should be considered in developing the contents and structure of future ALS courses. Our findings that paramedics found the LTS-D to be easy to handle are in accordance with previously published results concerning the laryngeal tube, and also with the laryngeal tube with suction unit (3–9,12,13). A 30-min practice block on airway management enabled 96% of participants to place the LTS-D correctly on the first attempt, compared to only 54% using the ET. Personnel familiar with the use of the ET were able to place it on the first attempt in 73% of cases (p ⬍ 0.01). The failure to achieve tracheal intubation and adequate ventilation are also important results of this manikin study. Thus, the LTS-D might be considered a good alternative, especially for those unfamiliar with the use of the ET. Another significant difference between the LTS-D group and the other two groups (BMV and ET) was the average time required to place the LTS-D and ET devices. The effectiveness of the laryngeal tube for airway management and ventilation has been shown in studies on patients undergoing anesthesia for operative procedures (14 –16). The LTS-D reported is equally effective as the Combitube (1,17–21). The fact that the time required to check the placement of the Combitube has been reported to be longer than for the LTS-D favors the latter. Because our data are derived from simulated scenarios, drawing conclusions for real resuscitation situations is difficult. Studies investigating the impact of the type of airway management on survival or outcome are lacking. The participants of our study were able to adhere to the ERC Guidelines 2005 using the LTS-D, whereas the use of the ET and BMV were shown to be less effective (1). If this carries over to the real world, use of the LTS-D might have a positive effect on patients’ survival and neurological outcome. Further studies in actual resuscitation situations are needed to confirm our preliminary simulation results. On the questionnaire given at the end of the 1-day training course, 94% of the participants favored the LTS-D over the other two devices to manage the airway of the manikin. The major reason for this was that handling was reported to be easy to learn, resulting in a
Laryngeal Tube Suction-Device
feeling of security in the user. Studies in real cardiac arrest situations should be conducted to ascertain if this preference carries over to use in the human patient.
133
3. 4.
Limitations
5.
One weakness of this study may be that the LTS-D is easier to insert in manikins than the ET tube and BMV, which may be more difficult to use in Laerdal manikins than real patients (22,23). Insertion of a supraglottic airway device like the LTS-D used in our study requires far fewer motor skills and less coordination than using the ET tube or the BMV. Another weakness of the study was the single-rescuer resuscitation that was employed in our approach to approximate a typical situation in our emergency system into a manikin scenario. The results might be different in paramedics in different systems. For example, the Chicago paramedics in districts where intubation skills are practiced frequently would be more familiar with endotracheal intubation. However, this practice is not typical of many paramedics. Only about half the participants could intubate a paralyzed manikin with no vomit or secretions, with excellent lighting, ready equipment, and otherwise perfect conditions. In real life, the success rate might be lower.
6.
7. 8. 9. 10. 11.
12. 13.
14. 15.
CONCLUSIONS 16.
We demonstrated in a manikin study that the LTS-D is an easy-to-handle alternative for airway management during resuscitation, especially for paramedics who are unfamiliar with endotracheal intubation. We were able to demonstrate in a manikin study the potential importance of the LTS-D as an alternative to the ET and BMV, especially in the reduction of NFT and better adherence to the ERC guidelines of 2005. For all participants, the LTS-D was superior to the ET and BMV, as demonstrated in the significant reduction of NFT. Participants in this study were able to adhere to the time-frame of the ERC guidelines of 2005 only when using the LTS-D.
17.
18. 19.
20.
21.
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success during out-of-hospital cardiac arrest. Circulation 2002; 105:2270 –3. Agro F, Cataldo R, Alfano A, Galli B. A new prototype for airway management in an emergency: the Laryngeal Tube. Resuscitation 1999;41:284 – 6. Doerges V, Ocker H, Wenzel V. The laryngeal tube: a new simple airway device. Anaesth Analg 2000;90:1220 –2. Genzwuerker HV, Dhonau S, Ellinger K. Use of the laryngeal tube for out-of-hospital resuscitation. Resuscitation 2002;52:221– 4. Genzwuerker HV, Oberkinkhaus J, Finteis T, Kerger H, Gernotti C, Hinkelbein J. Emergency airway management by first responders with the laryngeal tube—intuitive and repetive use in a manikin. Scand J Trauma Resusc Emerg Med 2005;13:1– 4. Kette F, Reffo I, Giordani G, et al. The use laryngeal tube by nurses in out-of-hospital emergencies: preliminary experience. Resuscitation 2005;66:21–5. Doerges V, Ocker H, Wenzel V, Steinfath M, Gerlach K. The laryngeal tube S: a modified simple airway device. Anaesth Analg 2003;96:618 –21. Genzwuerker HV, Finteis T, Hinkelbein J, Krieter H. The LTS (Laryngeal Tube Suction): a new device for emergency airway management. Scand J Trauma Emerg Med 2003;11:125–31. Salako SE. The declaration of Helsinki 2000: ethical principles and the dignity of difference. Med Law 2006;25:341–54. Doerges V, Wenzel V, Schumann T, Neubert E, Ocker H, Gerlach K. Intubating laryngeal mask airway, laryngeal tube, 1100 ml self-inflating bag—alternatives for basic life support? Resuscitation 2001;51:185–91. Genzwuerker HV, Finteis T, Slabshi D, Groeschel J, Ellinger K. Assessment of the use of the laryngeal tube for cardiopulmonary resuscitation in a manikin. Resuscitation 2001;51:291– 4. Thierbach A, Piepho T, Kleine-Weischede B, Haag G, Maybauer M, Werner C. Comparison between the laryngeal tube S and endotracheal intubation. Simulation of securing the airway in an emergency situation. Anaesthesist 2006;55:154 –9. Asai T, Shingu K, Cook T. Use of the laryngeal tube in 100 patients. Acta Anaesthesiol Scand 2003;47:828 –32. Ocker H, Wenzel V, Schmucker P, Steinfath M, Doerges V. A comparison of the laryngeal tube with the laryngeal mask airway during routine surgical procedures. Anaest Analg 2002;95:1094 –7. Wrobel M, Grundmann U, Wilhelm W, Wagner S, Larsen R. Laryngeal tube versus laryngeal mask airway in anaesthetised non-paralysed patients. A comparison of handling and postoperative morbidity. Anaesthesist 2004;53:702– 8. Rabitsch W, Schellongowski P, Staudinger T. Comparison of a conventional tracheal airway with the Combitube in an urban emergency medical services system run by physicians. Resuscitation 2003;57:27–32. Rabitsch W, Krafft P, Lackner FX, et al. Evaluation of the oesophagealtracheal double-lumen tube (Combitube) during general anaesthesia. Wien Klin Wochenschr 2004;116:90 –3. Rabitsch W, Kostler WJ, Burgmann H, Krafft P, Frass M. Recommendation of the minimal volume technique to avoid tongue engorgement with prolonged use of the esophageal-tracheal combitube. Ann Emerg Med 2005;45:565– 6. Rumball C, Macdonald D, Barber P, Wong H, Schmecher C. Endotracheal intubation and esophageal tracheal Combitube insertion by regular ambulance attendants: a comparative trial. Prehosp Emerg Care 2004;8:15–22. Venzia D, Lessard MR, Bussieres J, Topping C, Trepanier CA. Complications associated with the use of the Esophageal-TrachealCombitube. Can J Anaesth 1998;45:76 – 80. Cook TM, Bayley G, Jordan G, Silsby J. A comparison of four different advanced airway mannequins for training DAS guidelines. Anaesthesia 2007;62:708 –12. Jackson KM, Cook TM. A comparison of four different advanced airway mannequins for training SAD insertion. Anaesthesia 2007; 62:388 –93.
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ARTICLE SUMMARY 1. Why is this topic important? Due to the high incidence of complications, personnel without experience in endotracheal intubation should use acceptable alternatives to manage the airway during resuscitation. 2. What does this study attempt to show? This study evaluates in a manikin model an alternative airway device that may be employed during cardiac arrest due to its ease of use and the reduction of no flow time (NFT) during resuscitation. 3. What are the key findings? A laryngeal tube suction-device (LTS-D) is fast to insert; using a LTS-D, NFT is reduced compared to endotracheal intubation and bag-mask-valve ventilation. 4. How is patient care impacted? This was a manikin study; therefore, clinical studies should follow.
doi:10.1016/j.jemermed.2008.08.014
Original Contributions
USING A LARYNGEAL TUBE SUCTION-DEVICE (LTS-D) REDUCES THE “NO FLOW TIME” IN A SINGLE RESCUER MANIKIN STUDY Christoph H. R. Wiese, MD,* Utz Bartels, MD,* Alexander Schultens, MD,* Tobias Steffen, Torney, MD,‡ Jan Bahr, MD,* and Bernhard M. Graf, PHD*
MD,†
Andreas
*Department of Anaesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany, †Department of Anaesthesiology, Klinikum Wolfenbüttel, Wolfenbüttel, Germany, and ‡Department of Anaesthesiology and Intensive Care, Klinikum Braunschweig, Braunschweig, Germany Reprint Address: Christoph H. R. Wiese, Department of Anesthesiology, Emergency and Intensive Care Medicine, Georg-August University of Göttingen, Robert Koch Straße 40, Göttingen D-37075, Germany
e Abstract—Background: In 2005, the European Resuscitation Council and the American Heart Association published new guidelines for Advanced Life Support. One of the points was to reduce the time without chest compressions in the first phase of cardiac arrest. Objective: We evaluated in a manikin model whether using the single-use laryngeal tube with suction option (LTS-D) instead of endotracheal intubation (ET) and bag-mask-valve ventilation (BMV) for emergency airway management could reduce the “no-flow time” (NFT). The NFT is defined as the time during resuscitation when no chest compressions take place. Methods: A randomized, prospective study was undertaken with 150 volunteers who performed management of a standardized simulated cardiac arrest in a manikin. Every participant was randomized to one of three different airway management groups (LTS-D vs. ET vs. BMV). Results: The LTS-D was inserted significantly faster than the ET tube (15 s vs. 44 s, respectively, p < 0.01). During the cardiac arrest simulation, establishing and performing ventilation took an average of 57 s with the LTS-D compared to 116 s with ET and 111 s with the BMV. Using the LTS-D significantly reduced NFT compared to ET and the BMV (125 s vs. 207 s vs. 160 s; p < 0.01). Conclusions: In our manikin study, NFT was reduced significantly when the LTS-D was used when compared to ET and BMV. The
results of our manikin study suggest that for personnel not experienced in tracheal intubation, the LTS-D offers a good alternative to ET and BMV to manage the airway during resuscitation, and to avoid the failure to achieve tracheal intubation with the ET, and the failure to achieve adequate ventilation with the BMV. © 2011 Elsevier Inc.
Conflicts of interests: C. Wiese and all co-authors declare there are no conflicts of interest concerning any product or company mentioned in the following study.
Chest compressions are to be started immediately after cardiac arrest. Chest compression and respiration should be in a ratio of 30:2.
RECEIVED: 7 April 2008; FINAL ACCEPTED: 6 August 2008
SUBMISSION RECEIVED:
e Keywords—Advanced Life Support (ALS); cardiopulmonary resuscitation (CPR); guidelines; orotracheal intubation; out-of-hospital CPR
INTRODUCTION The European Resuscitation Council (ERC) and the American Heart Association released a revised edition of their resuscitation guidelines for cardiac arrest in November 2005 in which the following adjustments were incorporated (1).
Emphasis on Chest Compression
17 June 2008; 128
Laryngeal Tube Suction-Device
Reduction of the Numbers of Defibrillations if Ventricular Fibrillation/Pulseless Ventricular is Confirmed After each 2-min cardiopulmonary resuscitation (CPR) cycle, only one electric shock instead of three should be applied for shockable rhythms. Without reassessing the rhythm, CPR should be resumed immediately after the shock is applied (2). Expansion of Airway Management Options Endotracheal intubation provides the most reliable airway. It should be attempted only by trained health care providers who have adequate ongoing experience with the technique and should take no longer than 30 s to complete. Due to the high incidence of complications (e.g., esophageal intubation), personnel without experience in tracheal intubation should use acceptable alternatives to manage the airway, such as the Combitube, laryngeal mask airway (LMA), intubating LMA, or laryngeal tube (LT) (1). If it is not possible to manage the airway with alternative methods, personnel may resort to bag-mask-valve ventilation. Alternative airway devices for use during resuscitation should meet the following criteria: They should be easy to handle, especially by persons unfamiliar with the use of the endotracheal tube, and they should guarantee reasonable protection against aspiration (1). In 1999, the LT was introduced as an alternative for protecting the difficult airway (3–7). The LT version with a gastric suction option (i.e., the LTS-D), in particular, meets the above-mentioned criteria, as recent studies suggest (8,9). This alternative airway device seems to meet the criteria of the ERC (1). Reduction of No-flow Time (NFT), the Time during Which There are No Chest Compressions The chest compression ratio of 30 per respiratory cycle and the reduction of the number of defibrillations if ventricular fibrillation (VF) is confirmed reduce the NFT during resuscitation. In our study, we evaluated whether the use of the LTS-D for emergency airway management could contribute to reducing the NFT, compared to endotracheal intubation (ET) and bag-mask-valve (BMV) ventilation. METHODS There were 150 volunteers (paramedics) prospectively randomized to one of three groups (LTS-D group, ET
129 Table 1. ALS Course Schedule Activity
Duration
Introduction Pre-course test Basic Life Support (BLS) Defibrillation Intraosseous access Airway management
10 min 20 min 45 min 45 min 30 min 90 min (30 min each for LTS-D, BMV, and ET) 30 min 180 min 20 min 10 min
CPR drugs ALS training Post-course test Summary and feedback
ALS ⫽ Advanced Live Support; CPR ⫽ cardiopulmonary resuscitation; LTS-D ⫽ laryngeal tube suction-device; BMV ⫽ bagmask-valve ventilation; ET ⫽ endotracheal intubation.
group, or BMV group) to manage the airway. Study subjects were recruited from the participants of a oneday Advanced Life Support (ALS) course designed for emergency personnel, after written informed consent. The study was conducted after completion of the course (ALS course schedule, Table 1). During a 90-min airway training period, use of the different airway devices was demonstrated in a manikin (“Resusci Anne Advanced Skilltrainer”; Laerdal™ Inc., Stavanger, Norway). The technique of using the LTS-D was taught according to the manufacturer’s instructions (8). The simulated scenario required participants to resuscitate a “patient” (manikin, Laerdal Inc.) with VF, in a team consisting of two people. Scenarios were set to last 420 s (BMV scenario), 430 s (LTS-D scenario), and 450 s (ET scenario). Time frames are shown in Table 2. The courses had a maximum of 12 participants and were held by the same instructors to reduce intra-observer bias. Data were recorded on the computer of the manikin (Laerdal™ Norway, PC-Skill reporting Software) and on a standardized paper sheet to allow retrospective analysis. The statistical analyses were performed using SPSS for Windows, release 12.0 (SPSS, Chicago, IL). The non-parametric analysis of variance test (differences between the three groups and repeated performance) and the Wilcoxon signed rank test (inter-group testing) were used. There was a correction of P for multiple tests. Descriptive values of variables are expressed as average and percentages. All p values of ⬍ 0.05 were considered to indicate statistical significance. According to the Declaration of Helsinki, data were made anonymous (10). Demographic data, age, sex, professional experience, previous ALS courses, and satisfaction with the ALS course retrospectively, were obtained and compared. The primary study endpoints were defined as the total NFT
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Table 2. Scenario Time-frames Activity
LTS-D Time (Total Time)
ET Time (Total Time)
BMV Time (Total Time)
Access to the patient LTS-D placement (after first 30 chest compressions) 1st CPR cycle 1st defibrillation ET placement 2nd CPR cycle 2nd defibrillation 3rd CPR cycle 3rd defibrillation
15 s (15 s) 10 s (25 s) 120 s (145 s) 15 s (160 s) 0 s (160 s) 120 s (280 s) 15 s (295 s) 120 s (415 s) 15 s (430 s)
15 s (15 s) 0 s (15 s) 120 s (135 s) 15 s (150 s) 30 s (180 s) 120 s (300 s) 15 s (315 s) 120 s (435 s) 15 s (450 s)
15 s (15 s) 0 s (15 s) 120 s (135 s) 15 s (150 s) 0 s (150 s) 120 s (270 s) 15 s (285 s) 120 s (405 s) 15 s (420 s)
LTS-D ⫽ laryngeal tube suction-device; ET ⫽ endotracheal intubation; BMV ⫽ bag-mask-valve ventilation; CPR ⫽ cardiopulmonary resuscitation.
and adherence to ERC ALS guidelines 2005 (e.g., three defibrillation cycles during the scenario must be applied). The secondary study endpoints were the total ventilation time (sum of individual ventilation cycle times with BMV, LTS-D, and ET, including time for LTS-D and for ET tube placement), the tidal volume, adequacy of ventilation concerning the type of technique to secure the airway, time to confirmation of cardiac arrest, and participants’ retrospective evaluation of airway management. Times required for each defibrillation were based on time needed by the semi-automatic electrical defibrillator (AED; CorPuls 08/16™ Inc., Kaufering, Germany) for analysis and shock. Remaining times in the scenarios are in accordance with the ERC ALS guidelines of 2005 (1). To ensure the reliability of comparing times, the following setup was chosen. Two participants were involved in each scenario. The first was designated as the main resuscitator and the other was the secondary resuscitator. Main resuscitators were responsible for airway management and chest compression during the scenario (as in a single rescuer resuscitation scenario). The secondary resuscitator assisted the main resuscitator (e.g., by using the semi-automated defibrillator for analysis and shock). Each participant was assigned once to the main position, and once to the secondary position. In the LTS-D group, the insertion and placement of the LTS-D was to be started after determining unconsciousness and the first chest compressions. During placement, chest compressions were stopped. Until successful insertion and placement of the LTS-D, the resuscitator had to ventilate the patient by using BMV. If unsuccessful in the first attempt, the resuscitator had to re-attempt insertion of the LTS-D after first defibrillation and the following 30 chest compressions. Until the reattempt, the resuscitator had to use BMV to ventilate the manikin. At the end of the 1-day ALS course, all participants were asked to complete a questionnaire concerning their preferences of the different airway devices.
RESULTS The study included 150 participants who were all paramedics. The demographic data are presented in Table 3. All participants were active workers in Emergency Medicine. The three groups were comparable in demographic data.
Study Group 1 (LTS-D Group) Ninety-six percent (n ⫽ 48) of the participants placed the LTS-D correctly on first attempt. Adequate tidal volumes (500 – 600 mL) were achieved through the LTS-D in all attempts. Test subjects required an average of 15 s to successfully put the LTS-D in place after initiation of the sequence (range 7–25 s). Average ventilation required 1.3 s (for inspiration and expiration). Total respiration time was 57.4 s (range 48 – 65 s). This included the time to place the LTS-D, and the inspiration and expiration time overall. The “No Flow Time” until the first respi-
Table 3. Demographic Data n (%) Sex Male Female Age (years) 18–25 26–30 31–35 36–40 41–45 ⬎ 50 Number of previous ALS courses attended 0 1 ⬎1 ALS ⫽ Advanced Life Support.
89 (59%) 61 (41%) 21 (14%) 41 (27%) 36 (24%) 35 (23%) 16 (11%) 1 (1%) 44 (29%) 93 (62%) 13 (9%)
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Table 4. Defibrillation during the Scenarios Time-to-shock Seconds (Range) Defibrillation
LTS-D
ET
BMV
1st 139 (99–195) 137 (85–211) 164 (124–210) Defibrillation 2nd 256 (198–317) 316 (219–420) 311.4 (285–321) Defibrillation 3rd 369 (314–420) 438 (392–447) 413 (404–420) Defibrillation LTS-D ⫽ laryngeal tube suction-device; ET ⫽ endotracheal intubation; BMV ⫽ bag-mask-valve ventilation.
ration in the LTS-D group occurred was 21.3 s (range 15–24 s). This included the time to confirm unconsciousness of the manikin and the time to place the LTS-D (excluding the time for the first 30 chest compressions after confirming cardiac arrest).
safely use the ET tube to secure the airway during the simulation. Most of the participants were insecure with the use of the ET tube (i.e., they rated themselves unfamiliar with the method).
Study Group 3 (BMV Group) The NFT until the first respiration occurred in the BMV group was 12.6 s (range 9 –17 s). This included the time to confirm unconsciousness of the manikin and the time to place the BMV for ventilation (excluding the time for the first 30 chest compressions). Nineteen participants (38%) attained effective tidal volumes of 500 – 600 mL with BMV. The majority of the participants were unable to achieve efficient ventilation. Each single respiration averaged 4.2 s (range 2–7 s). None of the participants was able to ventilate the manikin in an average time of 1 s for every respiration (inspiration and expiration). Total respiration time was 110.8 s (63–160 s).
Study Group 2 (ET Group) Fifty-four percent (n ⫽ 27) of the participants placed the ET tube correctly on the first attempt. Forty-six percent (n ⫽ 23) required a second attempt. Volunteers required an average of 44 s (range 19 –95 s) to successfully position the ET. The second attempt required an average of 43 s (range 15– 64 s). With regard to the ERC guidelines of 2005, 11 (22%) participants were able to place the ET tube within 30 s. The endotracheal intubation started 207 s (range 95–367 s) after the beginning of the scenario. Participants had to manage the airway by BMV until successful placement of the ET tube. The NFT until the first respiration occurred in the ET group was 12.9 s (range 8 –18 s). This included the time to confirm unconsciousness of the manikin and the time to place the BMV for first ventilation (excluding the time for the first 30 chest compressions). Each single respiration averaged 4.7 s (range 3–7 s) using BMV. Twelve (24%) participants attained effective tidal volumes of 500 – 600 ml with BMV. The majority were unable to generate efficient ventilation. Total time needed for respiration (including times using BMV and times using ET) amounted to 115.6 s (range 75–149 s). At the end of the study, 15 (30%) participants of this group were able to
Defibrillation/NFT Table 4 summarizes the times required for defibrillation. Significantly more participants completed three defibrillation sequences in the LTS-D group (98%) than in either of the other two groups (ET 18%, BMV 34%) within the set time frames (p ⬍ 0.01). In the ET group, only nine participants completed three defibrillation sequences. NFT in the LTS-D group was significantly shorter than in both other groups (p ⬍ 0.01). The total NFT and approximated NFT are shown in Table 5. After managing the airway with either LTS-D or ET, breaths were given in a ratio of 2:30 (breath to chest compression). The airway was managed by ET between 2-min cycles and by LTS-D after the first 30 chest compressions.
Questionnaire Results At the end of the study, 94% of the participants favored the LTS-D over the other two devices. A major reason for this was that handling of the device was reported to
Table 5. No-Flow Time
NFT NFT NFT NFT
(unavoidable) (total) fraction (percent of total time) (suspected by participants)
LTS-D (Range)
ET (Range)
BMV (Range)
100 s 125 s (89 s–145 s) 0.29 146 s (80 s–240 s)
120 s 207 s (118 s–287 s) 0.46 166 s (100 s–240 s)
90 s 160 s (129 s–183 s) 0.38 173 s (120 s–240 s)
LTS-D ⫽ laryngeal tube suction-device; ET ⫽ endotracheal intubation; BMV ⫽ bag-mask-valve ventilation; NFT ⫽ no-flow time.
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be easy to learn, and this resulted in a feeling of security in the user compared to ET and BMV.
DISCUSSION The effective use of bag-mask-valve ventilation and endotracheal intubation requires a certain level of skill and experience. Therefore, the ERC Guidelines of 2005 recommend the following alternatives to manage the airway: the LT, the Combitube, the laryngeal mask airway (LMA), and the LMA Fastrach™ (LMA Inc., San Diego, CA) (1). These are recommended as second-line alternatives to ET and to BMV, especially for those unfamiliar with endotracheal intubation (1). The ERC defines “familiar with endotracheal intubation” as those personnel with extensive training and regular practice. Thus, most paramedics are defined as unfamiliar with endotracheal intubation. Therefore, it is recommended that during resuscitation they refrain from attempting endotracheal intubation, and BMV should be their first choice for airway management. The design of our course specifically took this into account. In 1999, the LT was introduced as an alternative for protecting the difficult airway (3–7,11). The LT version with a gastric suction option (LTS-D), especially, meets the above-mentioned criteria, as recent studies suggest (8,9). We evaluated, in a manikin model, whether the use of the LTS-D for emergency airway management is feasible for participants unfamiliar with this method, compared to ET and BMV. In the total respiration time, the differences between the three methods of airway management were significant (LTS-D 57.7 s, ET 115.6 s, and BMV 110.8 s; p ⬍ 0.01). Most of the participants were not able to generate efficient ventilation with BMV. Another aim of the ERC Guidelines of 2005 was to reduce the time without chest compression during the initial phase of cardiac arrest (1). In our study, we evaluated whether the use of the LTS-D for emergency airway management could contribute to reducing the NFT, compared to the ET and BMV. The following NFTs were unavoidable in the standardized scenario of this study: ● ● ● ●
15 s to confirm unconsciousness 10 s for insertion of the LTS-D (after airway check) 10 s for respiration during each cycle of CPR 30 s for insertion of the ET (after at least one defibrillation) ● 15 s for each defibrillation with a semi AED (CorPuls 08/16™) This adds up to a total minimal NFT of 90 s with BMV, 100 s with the LTS-D, and 120 s with ET. Only
with the LTS-D did the participants meet the guidelines criteria with as short an NFT as possible (1). No participant was able to meet the guidelines with BMV, and only one in the ET group achieved the guidelines criteria. Moreover, only 18% of the ET group and 34% of the BMV group were able to apply three defibrillations within the time frame of the ERC guidelines, whereas 98% of participants in the LTS-D group adhered to the ERC guidelines including three defibrillations. Thus, the results of our study suggest that personnel unfamiliar with endotracheal intubation should use an alternative type of airway management. The results of this study should be considered in developing the contents and structure of future ALS courses. Our findings that paramedics found the LTS-D to be easy to handle are in accordance with previously published results concerning the laryngeal tube, and also with the laryngeal tube with suction unit (3–9,12,13). A 30-min practice block on airway management enabled 96% of participants to place the LTS-D correctly on the first attempt, compared to only 54% using the ET. Personnel familiar with the use of the ET were able to place it on the first attempt in 73% of cases (p ⬍ 0.01). The failure to achieve tracheal intubation and adequate ventilation are also important results of this manikin study. Thus, the LTS-D might be considered a good alternative, especially for those unfamiliar with the use of the ET. Another significant difference between the LTS-D group and the other two groups (BMV and ET) was the average time required to place the LTS-D and ET devices. The effectiveness of the laryngeal tube for airway management and ventilation has been shown in studies on patients undergoing anesthesia for operative procedures (14 –16). The LTS-D reported is equally effective as the Combitube (1,17–21). The fact that the time required to check the placement of the Combitube has been reported to be longer than for the LTS-D favors the latter. Because our data are derived from simulated scenarios, drawing conclusions for real resuscitation situations is difficult. Studies investigating the impact of the type of airway management on survival or outcome are lacking. The participants of our study were able to adhere to the ERC Guidelines 2005 using the LTS-D, whereas the use of the ET and BMV were shown to be less effective (1). If this carries over to the real world, use of the LTS-D might have a positive effect on patients’ survival and neurological outcome. Further studies in actual resuscitation situations are needed to confirm our preliminary simulation results. On the questionnaire given at the end of the 1-day training course, 94% of the participants favored the LTS-D over the other two devices to manage the airway of the manikin. The major reason for this was that handling was reported to be easy to learn, resulting in a
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feeling of security in the user. Studies in real cardiac arrest situations should be conducted to ascertain if this preference carries over to use in the human patient.
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3. 4.
Limitations
5.
One weakness of this study may be that the LTS-D is easier to insert in manikins than the ET tube and BMV, which may be more difficult to use in Laerdal manikins than real patients (22,23). Insertion of a supraglottic airway device like the LTS-D used in our study requires far fewer motor skills and less coordination than using the ET tube or the BMV. Another weakness of the study was the single-rescuer resuscitation that was employed in our approach to approximate a typical situation in our emergency system into a manikin scenario. The results might be different in paramedics in different systems. For example, the Chicago paramedics in districts where intubation skills are practiced frequently would be more familiar with endotracheal intubation. However, this practice is not typical of many paramedics. Only about half the participants could intubate a paralyzed manikin with no vomit or secretions, with excellent lighting, ready equipment, and otherwise perfect conditions. In real life, the success rate might be lower.
6.
7. 8. 9. 10. 11.
12. 13.
14. 15.
CONCLUSIONS 16.
We demonstrated in a manikin study that the LTS-D is an easy-to-handle alternative for airway management during resuscitation, especially for paramedics who are unfamiliar with endotracheal intubation. We were able to demonstrate in a manikin study the potential importance of the LTS-D as an alternative to the ET and BMV, especially in the reduction of NFT and better adherence to the ERC guidelines of 2005. For all participants, the LTS-D was superior to the ET and BMV, as demonstrated in the significant reduction of NFT. Participants in this study were able to adhere to the time-frame of the ERC guidelines of 2005 only when using the LTS-D.
17.
18. 19.
20.
21.
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ARTICLE SUMMARY 1. Why is this topic important? Due to the high incidence of complications, personnel without experience in endotracheal intubation should use acceptable alternatives to manage the airway during resuscitation. 2. What does this study attempt to show? This study evaluates in a manikin model an alternative airway device that may be employed during cardiac arrest due to its ease of use and the reduction of no flow time (NFT) during resuscitation. 3. What are the key findings? A laryngeal tube suction-device (LTS-D) is fast to insert; using a LTS-D, NFT is reduced compared to endotracheal intubation and bag-mask-valve ventilation. 4. How is patient care impacted? This was a manikin study; therefore, clinical studies should follow.