Tracheal intubation by inexperienced medical residents using the Airtraq and Macintosh laryngoscopes--a manikin study

Validation of a difficult endotracheal intubation simulator designed for use in anaesthesia training

There is a need for a validated endotracheal intubation trainer that has variable difficulty settings for the training and assessment of medical practitioners. In this study three anatomical modifications were retrofitted to a commercial manikin and then validated. These modifications included restricted movements of the mandible as well as changes to the upper incisors. A total of 130 participants comprising specialists, trainees and medical students volunteered for this study. Validity was tested using randomised between-groups comparison of the time taken to intubate the manikin on all settings. Overall, and at each setting, there was a significant difference between the times to intubation among the three levels of experience (P <0.001). Novices were more than 12 times more likely to fail than experts (odds ratio [OR] 12.4, 95% confidence intervals [CI] 3.8, 41.8, P <0.001). The median time to intubation for all three groups changed significantly between settings 1 (easiest) and 4 (most difficult), novice 18 seconds (CI 8.9, 27.1, P <0.001), intermediate 15 seconds (CI 6.5, 23.5, P=0.001), and expert 9 seconds (CI 0.4, 17.6, P=0.04). The novice group was significantly different from the expert group at all attempts (P <0.002), and from the intermediates at all attempts apart from the third (P=0.055). The time for the novice and intermediate groups improved significantly by the fourth attempt, novice 15 seconds (CI 5.4, 24.6, P=0.002) and intermediate 10 seconds (CI 1.0, 19.0, P=0.03). Other aspects of validity were also satisfied during this study. A high degree of validity was established for these modifications, which can be retrofitted to an existing manikin and then used for teaching or assessment.

Intubation Performance of Advanced Airway Devices in a Helicopter Emergency Medical Service Setting

OBJECTIVE

This study attempts to determine if newer indirect laryngoscopes or intubating devices are superior to a standard laryngoscope for intubation success among helicopter emergency medical service (HEMS) personnel.

METHODS

Flight nurses and paramedics intubated standardized mannequins with a normal airway, a trauma airway, and a difficult airway using a standard laryngoscope, a gum elastic bougie, the Airtraq laryngoscope (King System Corp, Noblesville, IN), the Glidescope Ranger laryngoscope (Verathon Inc, Bothell, WA), and the S.A.L.T. device (Microtek Medical, Inc, Lehmberg, IN) in grounded helicopters wearing helmets and flight gear. Participant demographics, time to glottic view, the modified Cormack-Lehane score, total intubation time, number of attempts, and overall successful intubation were recorded for each type of airway.

RESULTS

Two-hundred thirty-six subjects were initially enrolled across 107 bases in 15 states, and 177 completed the study. First-attempt success rates did not vary by device for the normal airway (P = .203), but the Airtraq laryngoscope and the S.A.L.T. device were highest in the difficult airway (82.0% and 85.0%, respectively; P < .0001). The time to first-attempt success in the difficult airway was lowest for the S.A.L.T. device and the Airtraq laryngoscope (mean = 9.72 seconds and 19.70 seconds, respectively; P < .0001).

CONCLUSION

Using HEMS providers, the Airtraq laryngoscope and the S.A.L.T. device showed the fastest and highest intubation success on the first attempt in difficult simulated HEMS airway scenarios.

Comparison between bougies and stylets for simulated tracheal intubation with the C-MAC D-blade videolaryngoscope

BACKGROUND

The C-MAC D-blade is a new, highly angulated, videolaryngoscope blade designed for use in patients with difficult airways. Directing a tracheal tube into the trachea with any indirect viewing laryngoscope can be difficult, even with a good view of the laryngeal inlet.

OBJECTIVE

To determine which introducing strategy is most suitable for use with the C-MAC D-blade videolaryngoscope.

DESIGN

Observational manikin study.

SETTING

Centre for Simulation and Patient Safety.

PARTICIPANTS

Twenty-four anaesthetists of at least 12 months' of experience.

INTERVENTIONS

Six tracheal tube introducer strategies (no tracheal tube introducer (TX); hockey stick stylet (SH); Gliderite stylet (SG); bougie with tube loaded distally, near its curved tip (BD); bougie with tube loaded proximally (BP); bougie unloaded until tracheal placement (BU)) for each of two laryngoscopy settings (easy and difficult) in a SimMan 3G manikin. Two intubation attempts, with a maximum time allowance of 60 s each, were allowed for all laryngoscopy setting/introducer combinations.

MAIN OUTCOME MEASURES

Time to intubate in seconds. Secondary outcome was overall subjective difficulty using a visual analogue scale.

RESULTS

In the easy laryngoscopy setting, time to intubation was [median (interquartile range): SH 8.5 sec (7 to 11); SG 10 (8 to 11.5); BD 11 (10 to 12.5); TX 11 (7 to 31.5); BP 12 (11 to 13.5); BU 13 (11 to 14.5). There was no evidence of an overall difference in introducer strategies for time to intubate (P <  .025) with SG and SH found to be favourable when compared with BU, and SH was also favourable when compared with BP. In the difficult laryngoscopy setting, time to intubation was: SG 11.5 (10 to 17.5); SH 14 (12 to 22); BD 15.5 (12 to 23.5); BU 16.5 (14 to 21); BP 16.5 (15.5 to 20.5); TX 60 (26.5 to 60). There was evidence of an overall difference in introducer strategies for time to intubate (P < 0.025) with all introducers found to be favourable compared with TX. SG was found to be favourable when compared with BU and BP. In groups TX and SH, anaesthetists failed to intubate in 13 of 24 cases and 1 of 24 cases, respectively. The visual analogue scores tended to reflect intubation times, more so in the difficult setting.

CONCLUSION

The differences in time to intubate in both the easy and difficult laryngoscopy settings were minor for the different introducer strategies studied. The stylet introducers tended to take less time, but this did not result in important statistical differences. When using the C-MAC D-blade videolaryngoscope for simulated tracheal intubation, stylets and bougies performed in a similar fashion.

Intubation after rapid sequence induction performed by non-medical personnel during space exploration missions: a simulation pilot study in a Mars analogue environment

BACKGROUND

The question of the safety of anaesthetic procedures performed by non anaesthetists or even by non physicians has long been debated. We explore here this question in the hypothetical context of an exploration mission to Mars. During future interplanetary space missions, the risk of medical conditions requiring surgery and anaesthetic techniques will be significant. On Earth, anaesthesia is generally performed by well accustomed personnel. During exploration missions, onboard medical expertise might be lacking, or the crew doctor could become ill or injured. Telemedical assistance will not be available. In these conditions and as a last resort, personnel with limited medical training may have to perform lifesaving procedures, which could include anaesthesia and surgery. The objective of this pilot study was to test the ability for unassisted personnel with no medical training to perform oro-tracheal intubation after a rapid sequence induction on a simulated deconditioned astronaut in a Mars analogue environment. The experiment made use of a hybrid simulation model, in which the injured astronaut was represented by a torso manikin, whose vital signs and hemodynamic status were emulated using a patient simulator software. Only assisted by an interactive computer tool (PowerPoint(®) presentation), five participants with no previous medical training completed a simplified induction of general anaesthesia with intubation.

RESULTS

No major complication occurred during the simulated trials, namely no cardiac arrest, no hypoxia, no cardiovascular collapse and no failure to intubate. The study design was able to reproduce many of the constraints of a space exploration mission.

CONCLUSIONS

Unassisted personnel with minimal medical training and familiarization with the equipment may be able to perform advanced medical care in a safe and efficient manner. Further studies integrating this protocol into a complete anaesthetic and surgical scenario will provide valuable input in designing health support systems for space exploration missions.

Intubation after rapid sequence induction performed by non-medical personnel during space exploration missions: a simulation pilot study in a Mars analogue environment

Background

The question of the safety of anaesthetic procedures performed by non anaesthetists or even by non physicians has long been debated. We explore here this question in the hypothetical context of an exploration mission to Mars. During future interplanetary space missions, the risk of medical conditions requiring surgery and anaesthetic techniques will be significant. On Earth, anaesthesia is generally performed by well accustomed personnel. During exploration missions, onboard medical expertise might be lacking, or the crew doctor could become ill or injured. Telemedical assistance will not be available. In these conditions and as a last resort, personnel with limited medical training may have to perform lifesaving procedures, which could include anaesthesia and surgery. The objective of this pilot study was to test the ability for unassisted personnel with no medical training to perform oro-tracheal intubation after a rapid sequence induction on a simulated deconditioned astronaut in a Mars analogue environment. The experiment made use of a hybrid simulation model, in which the injured astronaut was represented by a torso manikin, whose vital signs and hemodynamic status were emulated using a patient simulator software. Only assisted by an interactive computer tool (PowerPoint^® presentation), five participants with no previous medical training completed a simplified induction of general anaesthesia with intubation.

Results

No major complication occurred during the simulated trials, namely no cardiac arrest, no hypoxia, no cardiovascular collapse and no failure to intubate. The study design was able to reproduce many of the constraints of a space exploration mission.

Conclusions

Unassisted personnel with minimal medical training and familiarization with the equipment may be able to perform advanced medical care in a safe and efficient manner. Further studies integrating this protocol into a complete anaesthetic and surgical scenario will provide valuable input in designing health support systems for space exploration missions.

Airtraq(®) versus Macintosh laryngoscope: A comparative study in tracheal intubation

Background:

The curved laryngoscope blade described by Macintosh in 1943 remains the most widely used device to facilitate tracheal intubation. The Airtraq^® (Prodol Meditec S.A, Vizcaya, Spain) is a new, single use, indirect laryngoscope introduced into clinical practice in 2005. It has wan exaggerated blade curvature with internal arrangement of optical lenses and a mechanism to prevent fogging of the distal lens. A high quality view of the glottis is provided without the need to align the oral, pharyngeal and tracheal axis. We evaluated Airtraq and Macintosh laryngoscopes for success rate of tracheal intubation, overall duration of successful intubation, optimization maneuvers, POGO (percentage of glottic opening) score, and ease of intubation.

Materials and Methods:

Patients were randomly allocated by computer-generated random table to one of the two groups, comprising 40 patients each, group I (Airtraq) and group II (Macintosh). After induction of general anesthesia, tracheal intubation was attempted with the Airtraq or the Macintosh laryngoscope as per group. Primary end points were overall success rate of tracheal intubation, overall duration of successful tracheal intubation, optimization maneuvers, POGO score and ease of intubation between the two groups.

Results:

We observed that Airtraq was better than the Macintosh laryngoscope as duration of successful intubation was shorter in Airtraq 18.15 seconds (±2.74) and in the Macintosh laryngoscope it was 32.72 seconds (±8.31) P < 0.001. POGO was also better in the Airtraq group 100% grade 1 versus 67.5% in the Macintosh group, P < 0.001. Ease of intubation was also better in the Airtraq group. It was easy in 97.5% versus 42.5% in the Macintosh group, P < 0.001.

Conclusion:

Both Airtraq and Macintosh laryngoscopes are equally effective in tracheal intubation in normal airways. Duration of successful tracheal intubation was shorter in the Airtraq group which was statistically significant.

Successful airtraq use in an air medical transport system

INTRODUCTION

There is a large body of literature that shows that the AirTraq device achieves equal or superior rates of successful intubation in all classes of user. A recent prospective human trial of the device questioned the first pass success rate and whether effective training could occur outside the Operating Room (OR). The purpose of this study was to investigate the first pass success rate for intubation with the AirTraq (AT) device utilizing only mannequin training in an air ambulance setting from Aug. 1 2009 to Aug. 1 2012 and compare it to direct laryngoscopy (DL).

HYPOTHESIS

We hypothesize that the AirTraq device will be as effective overall as direct laryngoscopy, and that this requires no OR training to achieve.

METHODS

A retrospective chart review of 161 intubations by air ambulance flight nurses from Aug. 1, 2009 to Aug. 1, 2012 was conducted. Data regarding date of service, devices used, number of attempts, rescue device use, and complications was gathered and analyzed. The generalized estimating equation and the chi-squared test were used to evaluate the data.

RESULTS

161 intubations were reviewed. 135 met inclusion criteria. Overall first pass success rate for AT was 82% (68/83) and DL was 74% (35/47). Overall first use success rate for AT was 79% (71/90) and DL was 70% (43/61). The overall success rate of intubation for any patient in which either AT or DL was attempted is 96% (130/135).

CONCLUSION

AirTraq was shown to be as effective as direct laryngoscopy. All air crew training for the AirTraq device was performed on mannequins. The successof the device compared to DL shows that mannequin training is sufficient to implement the AirTraq device for pre-hospital intubation.

Comparison of Airtraq optical laryngoscope and Storz video laryngoscope in a cadaver model

BACKGROUND

Airway management in the emergency department is a critical intervention that requires both standard techniques and rescue techniques to ensure a high rate of success. Recently, video laryngoscope (VL) systems have become increasingly common in many large urban EDs, but these systems may exceed the budgets of smaller rural EDs and EMS services and the Airtraq optical laryngoscope (OL) may provide an effective, low-cost alternative. We hypothesized that laryngeal view and time to endothracheal tube placement for OL and VL intubations would not be significantly different.

METHODS

This was a prospective, crossover trial.

SETTING

University-based emergency medicine residency program procedure laboratory utilizing lightly embalmed cadavers.

SUBJECTS

PGY1-3 emergency medicine residents. The study subjects performed timed endotracheal intubations alternately using the OL and VL. The subjects then rated the Cormack-Lehane laryngeal view for each device.

STATISTICAL ANALYSIS

Mean time to intubation and the mean laryngeal view score were calculated with 95% confidence intervals and statistical significance was determined by Student's t test.

RESULTS

Fourteen subjects completed the study. The average laryngeal view achieved with the OL vs. the VL was not significantly different, with Cormack-Lehane grade of 1.14 vs. 1.07, respectively. Time to endotracheal intubation, however, was significantly different (P<0.001) with the average time to intubation for the OL 25.49 seconds (95% CI: 17.95-33.03) and the VL 13.41 seconds (10.27-16.55).

CONCLUSION

The Airtraq OL and the Storz VL yielded similar laryngeal views in the lightly embalmed cadaver model. Time to endotracheal tube placement, however, was less for the VL.

Comparison of Bullard and Airtraq laryngoscopes with conventional laryngoscopy in a manikin study of simulated difficult intubation

BACKGROUND

When airway management is difficult, various measures can be taken to facilitate tracheal intubation. The Bullard and Airtraq laryngoscopes were developed for this purpose. We hypothesised that the Bullard and Airtraq laryngoscopes would perform better than a conventional laryngoscope in the management of a simulated difficult airway. We also hypothesised that the indirect laryngoscopes would perform comparably.

METHODS

In a randomised controlled study, 60 anaesthetists (30 with no or little experience and 30 with broader experience in the use of the Bullard laryngoscope, referred to as beginners and experts, respectively) performed three successive intubation attempts using conventional, Bullard and Airtraq laryngoscopes in two simulated difficult airway scenarios: neck immobilisation (scenario A) and neck immobilisation with additional tongue oedema (scenario B). The primary endpoint was overall intubation success rate. Secondary endpoints were time required for successful intubation, the amount of dental stress exerted during laryngoscopy and satisfaction with each airway device.

RESULTS

In scenario A, intubation success rates were 97-100% with all devices. In scenario B, all participants failed to intubate the trachea using the conventional laryngoscope. When using the Bullard laryngoscope, intubation success rates of 87-97% did not differ significantly (P > 0.05) from those during scenario A and between groups (beginners vs. experts). In contrast, when using the Airtraq laryngoscope, the overall intubation success rate was significantly lower (P < 0.05) compared with scenario A and compared with use of the Bullard laryngoscope, and differed between beginners and experts (20 and 50%, respectively). In cases of successful intubation, intubation times were comparable between devices and groups. Intubation times were longer during scenario B. Dental stress was always lower (P < 0.05) during use of the Bullard and Airtraq laryngoscopes compared with the conventional laryngoscope, lowest (P < 0.05) during use of the Bullard laryngoscope and (with the exception of use of the conventional laryngoscope by the experts) higher during scenario B than during scenario A. In scenario A, participants preferred both video laryngoscopes to the conventional laryngoscope.

CONCLUSION

In a moderately difficult airway scenario, all laryngoscopes performed equally well. However, in a more difficult airway scenario, the Bullard and Airtraq laryngoscopes performed better than the conventional laryngoscope, with the Bullard device performing better than the Airtraq. This may be in part related to differing prior experiences of operators with the respective airway devices.

Video Laryngoscopy in the Prehospital Setting

In the prehospital setting, the emergency care provider must anticipate that some patients will manifest with difficult airways. The use of video laryngoscopy to secure an airway in the prehospital setting has not been explored widely, but has the potential to be a useful tool. This article briefly reviews some of the major video laryngoscopes on the market and their usefulness in the prehospital setting. Studies and case reports indicate that the video laryngoscope is a promising device for emergency intubation, and it has been predicted that, in the future, video laryngoscopy will dominate the field of emergency airway management.

Direct laryngoscopy always should be retained as a primary skill; however, the video laryngoscope has the potential to be a good primary choice for the patient with potential cervical spine injuries or limited jaw or spine mobility, and in the difficult-to-access patient.The role of video laryngoscopes in securing an airway in head and neck trauma victims in the prehospital setting has yet to be determined, but offers interesting possibilities. Further clinical studies are necessary to evaluate its role in airway management by prehospital emergency medical services.

The learning curve for laryngoscopy: Airtraq versus Macintosh laryngoscopes

PURPOSE

Airtraq use by inexperienced personnel has been evaluated in simulator studies, but little is known about the learning process in real patients. This prospective study was designed to compare learning curves for laryngoscopy with the Airtraq or Macintosh laryngoscopes in patients under general anesthesia.

METHODS

Ten medical students with no prior experience in airway management were recruited on a voluntary basis and underwent training in Macintosh and Airtraq laryngoscopy. Patients with no difficult intubation criteria were enrolled after consent. Each student performed laryngoscopy with either device on ten consecutive patients. Success was defined as Cormack-Lehane grading ≤2. We also recorded subjective difficulty scores on an 11-point numerical rating scale. Learning curves were drawn using cumulative success rates and 95% confidence intervals calculated with bootstrap procedures.

RESULTS

The mean (95% CI) success rates for the procedures were 86.0% (76.7-93.3%) for the Airtraq and 64.0% (52.0-75.0%) for the Macintosh laryngoscope. Differences in success rate were significant from the fourth attempt and were 22.0% (8.2-36.5%) after the tenth. Seven students achieved success rates ≥90% using the Airtraq, versus one using the Macintosh (P = 0.022). Median (25th-75th percentile) difficulty scores were 2 (1-4) and 4 (2-6), respectively (P < 0.001).

CONCLUSION

Students achieved higher success rates using the Airtraq laryngoscope during early training on live patients. The Airtraq may be a useful choice for teaching advanced airway management, especially to professionals who will not perform laryngoscopy on a regular basis.

Comparison of intubation performance by junior emergency department doctors using gum elastic bougie versus stylet reinforced endotracheal tube insertion techniques

OBJECTIVE

Endotracheal intubation is a challenging procedure in emergency medicine. Junior doctors lack experience and confidence in this task. The use of a gum elastic bougie (GEB) to facilitate intubation may improve success rates, especially in difficult situations.

METHODS

Junior doctors working in the ED were studied. Endotracheal intubation was simulated using part-task trainers in "easy" positioning and "difficult" positioning modes. Intubation was attempted in both positions using either an endotracheal tube, with re-enforcing stylet (ETT-S), or insertion of a gum elastic bougie (GEB), with subsequent passage of the endotracheal tube over the bougie. Success rates and time to complete intubation were measured with GEB, and with ETT-S. Participants were asked to record the perceived ease of intubation.

RESULTS

One hundred and four intubations were performed by 26 study subjects. Overall, mean time to intubation with ETT-S technique was 16.14 s (14.49-17.98 95% CI), and was faster than with GEB 24.18 (21.45-27.25 95% CI) in both airway difficulty grades (P < 0.01). The success rate for intubation using the GEB was 100%, compared with 92.9% with ETT-S. This difference was not statistically significant. Perceived ease of intubation was similar for GEB and ETT-S (VAS 6.808 vs 6.904).

CONCLUSION

The use of a GEB marginally increases the time taken to perform endotracheal intubation. Success rates for junior doctors attempting endotracheal intubation were not significantly different between the two techniques. Success rates for novice practitioners using a GEB were high after even limited instruction and practice.

Comparison of the Laryngeal View during Tracheal Intubation Using Airtraq and Macintosh Laryngoscopes by Unskillful Anesthesiology Residents: A Clinical Study

Background and Objective. The Airtraq laryngoscope (Prodol Meditec, Vizcaya, Spain) is a novel tracheal intubation device. Studies, performed until now, have compared the Airtraq with the Macintosh laryngoscope, concluding that it reduces the intubation times and increase the success rate at first intubation attempt, decreasing the Cormack-Lehane score. The aim of the study was to evaluate if, in unskillful anesthesiology residents during the laryngoscopy, the Airtraq compared with the Macintosh laryngoscope improves the laryngeal view, decreasing the Cormack-Lehane score. Methods. A prospective, randomized, crossed-over trial was carried out on 60 patients. Each one of the patients were intubated using both devices by unskillful (less than two hundred intubations with the Macintosh laryngoscope and 10 intubations using the Airtraq) anesthesiology residents. The Cormack-Lehane score, the success rate at first intubation attempt, and the laryngoscopy and intubation times were compared. Results. The Airtraq significantly decreased the Cormack-Lehane score (P = 0.04). On the other hand, there were no differences in times of laryngoscopy (P = 0.645; IC 95% 3.1, +4.8) and intubation (P = 0.62; C95%  −6.1, +10.0) between the two devices. No relevant complications were found during the maneuvers of intubation using both devices. Conclusions. The Airtraq is a useful laryngoscope in unskillful anesthesiology residents improving the laryngeal view and, therefore, facilitating the tracheal intubation.

Use of the Airtraq laryngoscope for emergency intubation in the prehospital setting: a randomized control trial

OBJECTIVES

The optical Airtraq laryngoscope (Prodol Meditec, Vizcaya, Spain) has been shown to have advantages when compared with direct laryngoscopy in difficult airway patients. Furthermore, it has been suggested that it is easy to use and handle even for inexperienced advanced life support providers. As such, we sought to assess whether the Airtraq may be a reliable alternative to conventional intubation when used in the prehospital setting.

DESIGN, SETTING, AND PATIENTS

Prospective, randomized control trial in emergency patients requiring endotracheal intubation provided by anesthesiologists or emergency physicians responding with an emergency medical service helicopter or ground unit associated with the Department of Anesthesiology, General Hospital, Wiener Neustadt, Austria.

MEASUREMENTS AND MAIN RESULTS

During the 18-month study period, 212 patients were enrolled. When the Airtraq was used as first-line airway device (n=106) vs. direct laryngoscopy (n=106), success rate was 47% vs. 99%, respectively (p<.001). Reasons for failed Airtraq intubation were related to the fiber-optic characteristic of this device (i.e., impaired sight due to blood and vomitus, n=11) or to assumed handling problems (i.e., cuff damage, tube misplacement, or inappropriate visualization of the glottis, n=24). In 54 of 56 patients where Airtraq intubation failed, direct laryngoscopy was successful on the first attempt; in the remaining two and in one additional case of failed direct laryngoscopy, the airway was finally secured employing the Fastrach laryngeal mask. There was no correlation between success rates and body mass index, age, indication for airway management, emergency medical service unit, or experience of the physicians.

CONCLUSIONS

Based on these results, the use of the Airtraq laryngoscope as a primary airway device cannot be recommended in the prehospital setting without significant clinical experience obtained in the operation room. We conclude that the clinical learning process of the Airtraq laryngoscope is much longer than reported in the anesthesia literature.

Comparison of optic laryngoscope Airtraq(®) and Miller laryngoscope for tracheal intubation during infant cardiopulmonary resuscitation

BACKGROUND

Recent resuscitation guidelines for infant cardiopulmonary resuscitation (CPR) emphasize that all rescuers should minimize interruption of chest compressions, even for endotracheal intubation. We compared the utility of the Miller laryngoscope (Mil) with Airtraq (ATQ) during chest compression in an infant manikin.

METHODS

Twenty staff doctors in intensive care and emergency medicine performed tracheal intubation on an infant manikin with Mil and ATQ with or without chest compression.

RESULTS

In Mil trials, no participants failed without chest compression, but 6 of them failed during chest compression (P < 0.05). In ATQ trials, all participants successfully secured the airway regardless of chest compression. Intubation time was significantly lengthened due to chest compression in Mil trials, but not in ATQ trials. The visual analog scale (VAS) for laryngoscope image did not significantly change due to chest compression for ATQ or Mil trials. In contrast, chest compression worsened VAS scores for tube passage through the glottis in Mil trials, but not in ATQ trials.

CONCLUSION

We conclude that ATQ performed better than Mil for endotracheal intubation during chest compression in infant simulations managed by expert doctors.

Video-laryngoscopes in the adult airway management: a topical review of the literature

The aim of the present paper is to review the literature regarding video-laryngoscopes (Storz V-Mac and C-Mac, Glidescope, McGrath, Pentax-Airway Scope, Airtraq and Bullard) and discuss their clinical role in airway management. Video-laryngoscopes are new intubation devices, which provide an indirect view of the upper airway. In difficult airway management, they improve Cormack-Lehane grade and achieve the same or a higher intubation success rate in less time, compared with direct laryngoscopes. Despite the very good visualization of the glottis, the insertion and advancement of the endotracheal tube with video-laryngoscopes may occasionally fail. Each particular device's features may offer advantages or disadvantages, depending on the situation the anaesthesiologist has to deal with. So far, there is inconclusive evidence indicating that video-laryngoscopy should replace direct laryngoscopy in patients with normal or difficult airways.

A comparison between the Airtraq and Macintosh laryngoscopes for routine airway management by experienced anesthesiologists: a randomized clinical trial

BACKGROUND

The Airtraq Optical Laryngoscope is a new type of laryngoscope that provides a direct view of the glottis without alignment of the mouth, pharynx and trachea. Data show that it has advantages over the Macintosh laryngoscope.

OBJECTIVE

The aim of this study was to compare the use of the Airtraq laryngo-scope versus the No. 3 Macintosh blade for routine airway management in terms of intubation time, complications during and after laryngoscopy, and ease of use.

METHODS

In this single-center, randomized, clinical trial, 63 patients scheduled for elective operation were randomly allocated to two groups. Thirty-five patients were intubated with the Airtraq laryngoscope and 28 with the traditional Macintosh laryngoscope. All intubations were performed by experienced anesthesiologists who had a similar level of experience with the Airtraq laryngoscope. The time needed for intubation, any assistance required, complications during and after laryngoscopy and intubation, and the number of unsuccessful intubation attempts were documented and compared between the groups.

RESULTS

Intubation with the Macintosh laryngoscope was quicker (mean+/-standard deviation: 23.7+/-5.9 seconds) than with the Airtraq laryngoscope (29.6+/-8.5 seconds). Although the difference (5.9 seconds) was statistically significant (p<0.05), it was not clinically significant. The anesthesiologists who used the Airtraq laryngo-scope less frequently required assistance (p<0.05) to place the endotracheal tube. No differences were found regarding complications during and after laryngoscopy and intubation. There were no differences in any of the outcomes in patients with Mallampati class > 2.

CONCLUSION

The Airtraq laryngoscope is easier to use but it does not have any significant advantages compared with the Macintosh laryngoscope for routine airway management. More studies are needed to evaluate its use in patients with a difficult airway, and in emergency procedures.

Cormack-Lehane classification revisited

BACKGROUND

The Cormack-Lehane (CL) classification is broadly used to describe laryngeal view during direct laryngoscopy. This classification, however, has been validated by only a few studies reporting inconclusive data concerning its reliability. This discrepancy between widespread use and limited evidence prompted us to investigate the knowledge about the classification among anaesthesiologists and its intra- and inter-observer reliability.

METHODS

One hundred and twenty interviews were performed at a major European anaesthesia congress. Participants were interviewed about their general knowledge on grading systems to classify laryngeal view during laryngoscopy and were subsequently asked to define the grades of the CL classification. Inter- and intra-observer reliabilities were tested in 20 anaesthesiologists well familiar with the CL classification, who performed 100 laryngoscopies in a full-scale patient simulator.

RESULTS

Although 89% of interviewed subjects claimed to know a classification to describe laryngeal view during laryngoscopy, 53% were able to name a classification. When specifically asked about the CL classification, 74% of the interviewed subjects stated to know this classification, whereas 25% could define all four grades correctly. In the simulator-based part of the study, inter-observer reliability was fair with a kappa coefficient of 0.35 and intra-observer reliability was poor with a kappa of 0.15.

CONCLUSIONS

The CL classification is poorly known in detail among anaesthesiologists and reproducibility even in subjects well familiar with this classification is limited.

Tracheal intubation of a difficult airway using Airway Scope, Airtraq, and Macintosh laryngoscope: a comparative manikin study of inexperienced personnel

BACKGROUND

The Airway Scope (AWS) (Pentax-AWS, Hoya Corp., Tokyo, Japan) and the Airtraq (ATQ) (Prodol, Vizcaya, Spain) have similarities in the novel structures of their blades. In this study, we evaluated the ease of use of the AWS and ATQ compared with the Macintosh laryngoscope (ML) by inexperienced personnel in a simulated manikin difficult airway.

METHODS

Twenty-four fifth-year medical students with no previous experience in tracheal intubation participated in this study. We used an advanced patient simulator (SimMan(R), Laerdal Medical, Stavanger, Norway) to simulate difficult airway scenarios including cervical spine rigidity, limited mouth opening, and pharyngeal obstruction. The sequences in selecting devices and scenarios were randomized. Success rates for tracheal intubation, and the time required for visualization of the glottis, tracheal intubation, and inflation of the lungs, and the number of optimization maneuvers and dental click sounds were analyzed. The 3 different intubation devices were tested in 4 different scenarios by 24 students.

RESULTS

Both the AWS and ATQ had very high success rates of tracheal intubation compared with the ML (AWS 100%*; ATQ 98%*; and ML 89%; *P < 0.05 AWS, ATQ versus ML). The time to intubation with the AWS was significantly shorter than with the ATQ and ML (AWS 11 +/- 6 seconds; ATQ 16 +/- 12 seconds; and ML 16 +/- 11 seconds; *P < 0.05 AWS versus ATQ, ML). The number of optimization maneuvers with the AWS was significantly lower than with the ATQ and ML. There were significantly more audible dental click sounds with the ML than with the AWS and ATQ.

CONCLUSION

Both the AWS and ATQ may be suitable devices for difficult intubation by inexperienced personnel in this manikin simulated scenario. Further studies in a clinical setting are necessary to confirm these findings.

Comparison of the C-MAC videolaryngoscope with the Macintosh, Glidescope, and Airtraq laryngoscopes in easy and difficult laryngoscopy scenarios in manikins

The C-MAC comprises a Macintosh blade connected to a video unit. The familiarity of the Macintosh blade, and the ability to use the C-MAC as a direct or indirect laryngoscope, may be advantageous. We wished to compare the C-MAC with Macintosh, Glidescope and Airtraq laryngoscopes in easy and simulated difficult laryngoscopy. Thirty-one experienced anaesthetists performed tracheal intubation in an easy and difficult laryngoscopy scenario. The duration of intubation attempts, success rates, number of intubation attempts and of optimisation manoeuvres, the severity of dental compression, and difficulty of device use were recorded. In easy laryngoscopy, the duration of tracheal intubation attempts were similar with the C-MAC, Macintosh and Airtraq laryngoscopes; the Glidescope performed less well. The C-MAC and Airtraq provided the best glottic views, but the C-MAC was rated as the easiest device to use. In difficult laryngo-scopy the C-MAC demonstrated the shortest tracheal intubation times. The Airtraq provided the best glottic view, with the Macintosh providing the worst view. The C-MAC was the easiest device to use.

Determination of the optimal stylet strategy for the C-MAC videolaryngoscope

The C-MAC videolaryngoscope is a novel intubation device that incorporates a camera system at the end of its blade, thereby facilitating obtaining a view of the glottis without alignment of the oral, pharyngeal and tracheal axes. It retains the traditional Macintosh blade shape and can be used as a direct or indirect laryngoscope. We wished to determine the optimal stylet strategy for use with the C-MAC. Ten anaesthetists were allowed up to three attempts to intubate the trachea in one easy and three progressively more difficult laryngoscopy scenarios in a SimMan manikin with four tracheal tube stylet strategies: no stylet; stylet; directional stylet (Parker Flex-It); and hockey-stick stylet. The use of a stylet conferred no advantage in the easy laryngoscopy scenario. In the difficult scenarios, the directional and hockey-stick stylets performed best. In the most difficult scenario, the median (IQR [range]) duration of the successful intubation attempt was lowest with the hockey-stick stylet; 18 s (15-22 [12-43]) s, highest with the unstyletted tracheal tube; 60 s (60-60 [60, 60]) s and styletted tracheal tube 60 s (29-60 [18-60]) s, and intermediate with the directional stylet 21 s (15-60 [8-60]) s. The use of a stylet alone does not confer benefit in the setting of easy laryngoscopy. However, in more difficult laryngoscopy scenarios, the C-MAC videolaryngoscope performs best when used with a stylet that angulates the distal tracheal tube. The hockey-stick stylet configuration performed best in the scenarios tested.

Tracheal intubation with the PENTAX-AWS (airway scope) reduces changes of hemodynamic responses and bispectral index scores compared with the Macintosh laryngoscope

The PENTAX-AWS, a novel video laryngoscope, allows indirect visualization of the vocal cords on a color monitor display and enables tracheal intubation without upward lifting force required to expose the glottis. This study compared hemodynamic changes, bispectral index scores, and postoperative sore throat before and after laryngoscopy between the Macintosh laryngoscope and the airway scope (AWS). Forty patients (American Society of Anesthesiologists I-II), randomly assigned to either the Macintosh group (n=20 each) or AWS group, were enrolled in this study. After induction with fentanyl (0.001 mg/kg), propofol (1.5 mg/kg), and vecuronium (0.1 mg/kg), tracheal intubation was performed. Hemodynamic parameters were compared before and after laryngoscopy. Patients were assessed for postoperative sore throat at 24 hours after extubation. No significant differences in patient characteristics were observed between groups. Significant increases in both systolic blood pressure (P<0.05 vs. baseline) and heart rate (P<0.001 vs. baseline) after laryngoscopy were seen using the Macintosh blade, whereas the AWS provided no increases in either parameter. The AWS also caused a lesser increase in bispectral index (P<0.05 vs. Macintosh group). Postoperative sore throat was observed in both groups (2 out of 20 in AWS and 6 out of 20 in Macintosh), although this difference did not reach statistically significant level (P=0.23). In conclusion, the AWS offers a reduced degree of hemodynamic stimulation compared with the Macintosh laryngoscope, suggesting that tracheal intubation with the AWS is advantageous to prevent hypertension after laryngoscopy in neurosurgical patients.

Comparison of the Glidescope and Pentax AWS laryngoscopes to the Macintosh laryngoscope for use by advanced paramedics in easy and simulated difficult intubation

Background

Intubation of the trachea in the pre-hospital setting may be lifesaving in severely ill and injured patients. However, tracheal intubation is frequently difficult to perform in this challenging environment, is associated with a lower success rate, and failed tracheal intubation constitutes an important cause of morbidity. Novel indirect laryngoscopes, such as the Glidescope^® and the AWS^® laryngoscopes may reduce this risk.

Methods

We compared the efficacy of these devices to the Macintosh laryngoscope when used by 25 Advanced Paramedics proficient in direct laryngoscopy, in a randomized, controlled, manikin study. Following brief didactic instruction with the Glidescope^® and the AWS^® laryngoscopes, each participant took turns performing laryngoscopy and intubation with each device, in an easy intubation scenario and following placement of a hard cervical collar, in a SimMan^® manikin.

Results

Both the Glidescope^® and the AWS^® performed better than the Macintosh, and demonstrate considerable promise in this context. The AWS^® had the least number of dental compressions in all three scenarios, and in the cervical spine immobilization scenario it required fewer maneuvers to optimize the view of the glottis.

Conclusion

The Glidescope^® and AWS^® devices possess advantages over the conventional Macintosh laryngoscope when used by Advanced Paramedics in normal and simulated difficult intubation scenarios in this manikin study. Further studies are required to extend these findings to the clinical setting.

Comparison of use of the the Airtraq with direct laryngoscopy by paramedics in the simulated airway

INTRODUCTION

Paramedics often encounter patients with difficult airways requiring emergent airway management.

OBJECTIVE

The purpose of this study was to compare intubation utilizing the Airtraq with direct laryngoscopy (DL) in the manikin model. We evaluated the number of attempts, the time to successful intubation, and the Airtraq's learning curve.

METHODS

This was a randomized, crossover study involving paramedics. Each participant was given a standardized lecture and a demonstration of the Airtraq device. After a 5-minute practice session on a Laerdal Airway Management Trainer with the Airtraq and DL, participants managed the following four scenarios on a Laerdal SimMan manikin: 1) normal airway; 2) tongue edema; 3) cervical spine immobilization; and 4) repeated normal airway. Results were analyzed using the Wilcoxon signed rank test.

RESULTS

Thirty paramedics participated in this study. For scenario 1, there were no significant differences in either the number of attempts or the time to ventilation between the devices. For scenario 2, the mean time to ventilation was significantly faster, and fewer intubation attempts were observed with the Airtraq when compared with DL. For scenario 3, there were no significant differences in number of attempts and time to ventilation. Scenario 4 demonstrated significantly less time to ventilation and fewer intubation attempts with the Airtraq. A significant decrease in time to ventilation was observed with the Airtraq when comparing scenarios 1 and 4.

CONCLUSIONS

The Airtraq was shown to be equal to or faster than DL. The Airtraq has a rapid learning curve demonstrated by a significantly decreased time to ventilation between scenarios 1 and 4.

Video and optic laryngoscopy assisted tracheal intubation--the new era

With advances in technology, videoscopy and optic intubation have been gaining popularity particularly in patients with difficult airways or as rescue devices in failed intubation attempts. Their routine use is, however an uncommon occurrence. This review paper will summarise some of those newly developed devices currently available to assist tracheal intubation, their advantages, disadvantages when compared with the conventional laryngoscope and finally, evidence to support their use in both elective and emergency airway management.

Faster intubation with direct laryngoscopy vs handheld videoscope in uncomplicated manikin airways

OBJECTIVE

To compare average time to successful intubation and success rates using direct laryngoscopy (DL) with those using a battery-operated videoscope (VS) in uncomplicated manikin intubations.

METHODS

Forty-four paramedics and emergency medicine faculty and residents received training with DL and VS. Participants performed 3 timed trials using each device. A single group repeated-measures analysis of variance for average time measurements was performed.

RESULTS

Grouping physicians and paramedics, mean time to successful intubation for DL was 14.6 seconds (SD, 4.3 seconds) and for VS was 25.9 seconds (SD, 9.2 seconds; P < .001). All attempts were successful with both devices. A secondary measure compared intubation times for physicians and paramedics on both devices. For DL, mean time to successful intubation for physicians was 13.2 seconds (SD, 3.8 seconds) and for paramedics, 15.9 seconds (SD, 4.3 seconds; P > .43). For VS, mean time for physicians was 26.0 seconds (SD, 10.0 seconds) and for paramedics, 25.7 seconds (SD, 8.6 seconds; P > .43).

CONCLUSIONS

Intubation with DL in uncomplicated manikin airways was faster than with VS (P < .001). Success rates were equal.

Comparison of the Airtraq and Truview laryngoscopes to the Macintosh laryngoscope for use by Advanced Paramedics in easy and simulated difficult intubation in manikins

BACKGROUND

Paramedics are frequently required to perform tracheal intubation, a potentially life-saving manoeuvre in severely ill patients, in the prehospital setting. However, direct laryngoscopy is often more difficult in this environment, and failed tracheal intubation constitutes an important cause of morbidity. Novel indirect laryngoscopes, such as the Airtraq and Truview laryngoscopes may reduce this risk.

METHODS

We compared the efficacy of these devices to the Macintosh laryngoscope when used by 21 Paramedics proficient in direct laryngoscopy, in a randomized, controlled, manikin study. Following brief didactic instruction with the Airtraq and Truview laryngoscopes, each participant took turns performing laryngoscopy and intubation with each device, in an easy intubation scenario and following placement of a hard cervical collar, in a SimMan manikin.

RESULTS

The Airtraq reduced the number of optimization manoeuvres and reduced the potential for dental trauma when compared to the Macintosh, in both the normal and simulated difficult intubation scenarios. In contrast, the Truview increased the duration of intubation attempts, and required a greater number of optimization manoeuvres, compared to both the Macintosh and Airtraq devices.

CONCLUSION

The Airtraq laryngoscope performed more favourably than the Macintosh and Truview devices when used by Paramedics in this manikin study. Further studies are required to extend these findings to the clinical setting.

Comparison of the Glidescope, the McGrath, the Airtraq and the Macintosh laryngoscopes in simulated difficult airways*

SUMMARY

Several indirect laryngoscopes have recently been developed, but relatively few have been formally compared. In this study we evaluated the efficacy and the usability of the Macintosh, the Glidescope, the McGrath and the Airtraq laryngoscopes. Sixty anaesthesia providers (20 staff, 20 residents, and 20 nurses) were enrolled into this study. The volunteers intubated the trachea of a Laerdal SimMan manikin in three simulated difficult airway scenarios. In all scenarios, indirect laryngoscopes provided better laryngeal exposure than the Macintosh blade and appeared to produce less dental trauma. In the most difficult scenario (tongue oedema), the Macintosh blade was associated with a high rate of failure and prolonged intubation times whereas indirect laryngoscopes improved intubation time and rarely failed. Indirect laryngoscopes were judged easier to use than the Macintosh. Differences existed between indirect devices. The Airtraq consistently provided the most rapid intubation. Laryngeal grade views were superior with the Airtraq and McGrath than with the Glidescope.

Optical and video laryngoscopes for emergency airway management

Direct laryngoscopy for airway management was introduced into clinical medicine almost 70 years ago and is still the dominant modality. The recent development of video and optical laryngoscopy could be the most important change in this paradigm. This paper examines state of the art devices and makes recommendations regarding specific advantages they advance for the field of emergency medicine.