Airway management in cardiac arrest is essential for successful resuscitation [
In CPR for OHCA patients, advanced airway device insertions such as SAD or endotracheal intubation (ETI) are not prior to chest compressions (CCs). When CCs are performed properly, advanced airway device insertion should be considered for optimal oxygenation. Especially in OHCA caused by serious respiratory causes such as acute respiratory distress syndrome or airway obstruction, ETI can be more appropriate than SAD insertion to correct hypoxia and to improve survival ultimately [
Nevertheless, ETI using direct laryngoscope during CPR could not be easily achieved even if it is performed by experienced emergency physicians [
ETI through inserted i-gel has already been attempted by anesthesiologists in the form of fiberoptic bronchoscope-guided ETI [
We assumed that IGI could minimize interruptions of CCs and achieve successful ETI during CPR. In addition, when using conventional polyvinyl chloride (PVC) endotracheal tube (ETT) in IGI, the PVC tube can be folded and compressed when passing through i-gel. We thought it might result in an increase of hands-off time and decrease of ETI accuracy. So, we assume that the use of wire-reinforced silicone (WRS) tube instead of PVC tube could overcome this problem [
This study aimed to compare intubation performances among IGI, i-gel bronchoscopic intubation (IBRI), and intubation using Macintosh laryngoscope (MCL) applying two kinds of ETT during CCs. We hypothesized that IGI using WRS tube could achieve ETI most rapidly and successfully.
We conducted a randomized crossover manikin study to examine intubation performance using two intubation techniques through i-gel (IGI and IBRI), direct laryngoscopy (MCL), and two ETTs during CCs. This study was performed at Hallym University’s simulation center in February 2015. The local ethics committee approved this study in February 2015 (IRB Number: 2015-02-30; the institutional review board (IRB) of Hallym University Kangnam Sacred Heart Hospital). We registered the study protocol in Clinical Trials before study initiation (Clinicaltrials.gov:
The sample size was calculated based on a previous study regarding the time required for intubation with CCs [
We use direct laryngoscopy (Macintosh blade #4) and i-gel™ (Intersurgical, Workingham, UK, size 4), flexible intubation scope (Ambu® aScope™, Ambu co., Ballerup, Denmark) for ETI with fiberoptic guidance. We use two types of ETT, e.g., PVC tube (Mallinckrodt™ Hi-Lo Oral/Nasal Tracheal Tube Cuffed Murphy Eye, Covidien, Ireland #7.0) and WRS tube (Mallinckrodt™ Oral/Nasal ETT with TaperGuard™ cuff, Reinforced, Covidien, Ireland #7.0).
Participants performed IGI and IBRI using size-4 i-gel (Intersurgical, Workingham, UK) for medium adult (50–90 kg). A flexible intubation scope was used to guide ETT in IBRI. For direct laryngoscope, Macintosh blade (MCL) was used; this device has a size-4 curved blade with a Satin Slip Stylet (Mallinckrodt Medical, St. Louis, MO, USA). Two types of ETTs with an internal diameter of 7.0 mm were used in this study.
We used a high-fidelity manikin (ALS simulator, Laerdal, Stavanger, Norway) to perform CCs and ETI. The normal (nondifficult) airway setting was maintained in the manikin during the study.
The bed-height setting of this study was simulated using a bed (Transport stretcher® No. 747, 76 × 211 cm, 228 kg, Stryker Co., Kalamazoo, MI, USA) with a foam mattress (66 × 192 × 7.6 cm, soft foam with polyurethane covering, Stryker Co., Kalamazoo, MI, USA). A backboard (45 × 60 × 1 cm, 3 kg Lifeline Plastic, Sung Shim Medical Co., Bucheon, Korea) was placed on the bed. The height of the stretcher bed was adjusted to 88.6 cm (bed height: 80 cm + foam mattress: 7.6 cm + backboard: 1 cm) for both ETI and CCs.
Instructors gave 1-hour lecture and 2-hour practice for high-quality CPR, ETI using i-gel as blind conduit (IGI), and ETI using i-gel as conduit with fiberoptic guidance (IBRI) for 23 subjects and 4 chest compressors. All instructors were advanced cardiovascular life support (ACLS) instructors certificated by AHA (American Heart Association). They also had more than 500 times experience for ETI and more than 50 times experience for IGI and IBRI. The CPR lecture was constituted with the appropriate chest compression (CC) rate (100–120 bpm), CC depth (5–6 cm), and complete chest recoil and avoiding hyperventilation. The lecture for IGI and IBRI was constituted with the method of i-gel insertion, how to use flexible intubation scope, and the confirmation method of successful intubation. In the IGI and IBRI practice, the subjects were required for more than 10 times drill for IGI and IBRI, respectively. The successful intubation was confirmed by chest rise during bag mask ventilation via ETT. All chest compressors during ETI were AHA-BLS providers. They performed 2 min high-quality CC during ETI on an ALS simulator to prevent fatigue. In the CPR practice, they were requested more than 5 times drill for 2 min hands-only CPR under guidance by ACLS instructors. The CPR quality was monitored by the feedback system of high-fidelity manikin.
After lecture and practice session, subjects were randomly divided into 2 groups by kinds of ETT firstly. For dividing participants to 2 groups, we used drawing lots. The sequence generator (
We used two kinds of ETT, one was PVC tube with harder tip and the other was WRS tube with softer tip. Then, subjects rerandomized by a sequence of three ETI methods, i.e., direct laryngoscope, IGI, and IBRI. During ETI, certified basic life support (BLS) provider performed chest compression to the ALS simulator at a rate of 100 to 120 per minute and 5 to 6 cm depth with complete chest recoil. We use airway lubricant (Laerdal, Stavanger, Norway) when i-gel was used as a conduit for smooth insertion.
Instructor checked and recorded the time from the subject holding a handle of MCL or i-gel to when vocal cord exposed or i-gel was completely inserted (vocal cord exposure time, VET or i-gel insertion time, IIT), when ETT passed the vocal cord (tube pass time, TPT) and when 1st ventilation and chest rising were achieved through ETT by bagging bag-valve mask (1st ventilation time, FVT). (Figure
Flow diagram.
In the procedure of IGI, subjects inserted i-gel to the ALS simulator, and then ETI was performed using i-gel as a blind conduit. In that order, the subject gave a ventilation through inserted ETT by bagging of bag-valve mask and verified chest rising. Before the subject performed IGI, instructors gave information for successful IGI such as sniffing position and counterclockwise rotation of ETT.
In the procedure of IBRI, we mounted an ETT #7.0 on the bronchoscope before the procedure began. Firstly, subjects inserted i-gel to the ALS simulator, and then subject inserted the bronchoscope to 15 mm connector of i-gel and checked the vocal cord while watching the screen monitor. Then, subjects passed the bronchoscope through vocal cord and verified carina. We pushed the mounted ETT through the bronchoscope and removed it and gave a ventilation through ETT with a bag-valve mask and verified chest rising.
When randomization of three kinds of ETI methods was finished, the subject performed ETI with another type of tube. The sequence of ETI methods was rerandomized.
All recordings were fulfilled by one instructor. We verified successful ETI by inserting the bronchoscope to ETT for visual, confirming carina.
We established intubation time as a primary outcome and cumulative intubation success rate as a secondary outcome.
We regarded esophageal intubation and exceeding 2 minutes from starting intubation to first ventilation as failed intubation. In all ETI attempts, verification of successful ETI using the bronchoscope was done.
The data were collected and arranged using a standard spreadsheet application (Excel, Microsoft, Redmond, WA, USA). Statistical analysis was carried out with the 22.0 version of the Statistical Package for the Social Sciences (SPSS) program for windows (SPSS Inc., Chicago, IL, USA). We described statistics as frequencies and percentages for demographic data and mean ± standard deviation (SD) for continuous data. We used the Shapiro–Wilk test for verifying normal distribution, and we used the Wilcoxon signed-rank test because the result was not according to normal distribution. In addition, we used the Friedman test for comparing three intubation methods and applied Bonferroni’s method for post hoc analysis. Kaplan–Meier analysis was performed to analyze the cumulative success rate for intubation time. A significant difference was considered when
Twenty-three subjects participated in this study. The baseline characteristics of the participants are shown in Table
Baseline characteristics.
| |
---|---|
Age, years | 36.2 ± 5.4 |
Gender, male | 19 (82.6%) |
Intubators | |
EM resident | 8 (34.8%) |
EP | 15 (65.2%) |
Experiences | |
MCL ≥ 50 times | 23 (100%) |
i-Gel insertion ≥ 50 times | 23 (100%) |
Bronchoscopy ≥ 1 times | 0 (0%) |
IGI ≥ 1 times | 0 (0%) |
IBRI ≥ 1 times | 0 (0%) |
EM = emergency medicine; EP = emergency physician; MCL = Macintosh laryngoscopy; IGI = i-gel blind intubation; IBRI = i-gel bronchoscopic intubation.
IIT in IGI (4.1 ± 1.4 sec) was equal to that in IBRI (4.3 ± 1.2 sec) and significantly shorter than VET in MCL (5.8 ± 2.3 sec) regardless of kinds of ETT (IGI vs. IBRI,
Comparisons of intubation time among three intubation techniques regardless of kinds of endotracheal tubes.
MCL ( |
IGI ( |
IBRI ( |
|
|
IBRI vs. MCL | IGI vs. IBRI | |
---|---|---|---|---|---|---|---|
VET/IIT (sec) | 6.1 ± 2.8 | 4.2 ± 1.3 | 4.4 ± 1.4 | <0.001 | <0.001 | <0.001 | 0.12 |
TPT (sec) | 13.2 ± 7.5 | 12.7 ± 6.4 | 23.8 ± 15.0 | <0.001 | 0.59 | <0.001 | <0.001 |
FVT (sec) | 28.0 ± 8.3 | 16.1 ± 6.7 | 28.4 ± 16.0 | <0.001 | <0.001 | <0.001 | <0.001 |
VET-TPT (sec) | 7.0 ± 6.6 | 8.5 ± 6.1 | 19.4 ± 14.9 | <0.001 | 0.008 | <0.001 | <0.001 |
TPT-FVT (sec) | 6.8 ± 1.9 | 3.3 ± 1.0 | 4.6 ± 1.6 | <0.001 | <0.001 | <0.001 | <0.001 |
In the PVC tube, IIT-TPT in IGI (9.8 ± 8.4 sec) was significantly shorter than that of IBRI (20.0 ± 12.2 sec) and longer than that of MCL (7.0 ± 8.9 sec) (IGI vs. IBRI,
Comparisons of intubation time among three intubation techniques according to the kinds of endotracheal tubes.
MCL | IGI | IBRI |
|
|
| ||
---|---|---|---|---|---|---|---|
VET (IIT) | PVC | 6.4 ± 3.2 | 4.3 ± 1.3 | 4.5 ± 1.6 | 0.002 | 0.002 | 0.205 |
WRS | 5.8 ± 2.3 | 4.1 ± 1.4 | 4.3 ± 1.2 | 0.001 | 0.009 | 0.277 | |
|
0.615 | 0.306 | 0.173 | ||||
|
|||||||
TPT | PVC | 13.5 ± 9.3 | 14.3 ± 8.3 | 24.7 ± 12.5 | 0.543 | <0.001 | 0.001 |
WRS | 12.9 ± 5.3 | 11.2 ± 3.2 | 22.8 ± 17.3 | 0.173 | <0.001 | <0.001 | |
|
0.548 | 0.114 | 0.189 | ||||
|
|||||||
FVT | PVC | 20.2 ± 9.7 | 17.6 ± 8.9 | 29.3 ± 12.5 | 0.016 | <0.001 | 0.001 |
WRS | 19.9 ± 6.7 | 14.6 ± 3.4 | 27.4 ± 19.1 | <0.001 | 0.001 | <0.001 | |
|
0.426 | 0.217 | 0.189 | ||||
|
|||||||
VET-TPT | PVC | 7.0 ± 8.6 | 9.8 ± 8.4 | 20.0 ± 12.2 | 0.007 | <0.001 | 0.001 |
WRS | 7.1 ± 4.0 | 7.3 ± 2.3 | 18.8 ± 17.5 | 0.314 | <0.001 | <0.001 | |
|
0.098 | 0.259 | 0.355 | ||||
|
|||||||
TPT-FVT | PVC | 6.7 ± 1.8 | 3.3 ± 1.0 | 4.6 ± 0.9 | <0.001 | <0.001 | <0.001 |
WRS | 7.0 ± 2.0 | 3.3 ± 0.9 | 4.6 ± 2.0 | <0.001 | 0.001 | 0.001 | |
|
0.346 | 0.348 | 0.291 |
§
In the PVC tube, TPT-FVT in IGI (3.3 ± 1.0 sec) was significantly shorter than that of IBRI (4.6 ± 0.9 sec) and MCL (7.0 ± 2.0 sec) (IGI vs. MCL,
In PVC tube, FVT in IGI (17.6 ± 8.9 sec) was shorter than that of IRBI (29.3 ± 12.5 sec) and MCL (20.2 ± 9.7 sec) (IGI vs. MCL,
In the comparisons of three intubation techniques, IGI showed significantly shortest time (about 20 seconds) to reach 100% cumulative success rate (IGI vs. MCL,
Comparisons of cumulative success rate among three intubation techniques regardless of kinds of endotracheal tubes.
This study demonstrated that the IGI was equally successful and faster technique compared with IBRI or MCL regardless of the use of PVC or WRS tube. To our knowledge, this is the first study which compares the intubation performance of IGI with that of IBRI during chest compressions.
According to the instruction manual for i-gel, IBRI is recommended for i-gel-guided intubation [
The blind intubation through SAD such as IGI is not a usual method for emergent intubation in arrest patients [
Regarding the nature of blind technique of IGI, the success rate for IGI has been reported from 75% to 100% despite the high speed of IGI [
In this study, we compared the efficacy of the PVC tube compared with that of the WRS tube in IGI and IBRI. The WRS tube can be more advantageous than the PVC tube, because the WRS tube is more flexible and noncompressible during the passage through i-gel [
This study has some limitations. First, the results of this study were based on manikin simulation. In a clinical setting, there will be several significant factors affecting the intubation performance. These factors include the dynamic hindrance for glottic view during chest compressions, the anatomical variation of airway, and the hindrance by blood or vomitus of arrest patients [
Second, this study is a small sample pilot study for IGI and IBRI. Recently published regarding studies showed similar study design with this study [
Third, although all participants had more than 50 times intubation experiences, the possibility of the experience difference still exists among junior and senior residents and EPs. These unequal experiences for intubation could affect the intubation performance such as intubation time or success rate.
IGI was an equally successful and faster technique comparing with IBRI or MCL regardless of the use of PVC or WRS tube. Therefore, IGI might be an appropriate technique for emergent intubation by experienced intubators during CCs.
The data used to support the findings of this study are available from the corresponding author upon request.
This study was presented as a poster presentation in ESICM 2015 (A547) (
All authors declare that they do not have any potential conflicts of interest.
HY Choi and W Kim contributed equally to this study.