Simulated Difficult Intubation Research Articles

Evaluation of Flexible Tip bougie in simulated difficult intubation: a randomized cross-over manikin study

Introduction: Both video laryngoscopes and bougies play major role in difficult airway management. Even when a video laryngoscope is available to improve intubation view, there are instances when the vocal cords are visible, but intubation cannot be achieved. In these cases, bougies have a role in assisting intubation. This study aimed to compare the efficacy of the Flexible Tip Bougie with others in simulated difficult intubation. Methods: This study was designed as a randomized, cross-over, simulation manikin study. It involved 42 medical officers from the Department of Anaesthesiology. In the study, participants performed intubation under simulated difficult airway conditions. Three types of bougie were used by each participant in random order: (1) Flexible Tip Bougie, (2) Portex Single-Use Introducer, and (3) Frova Intubating Introducer. Results: The intubation success rate was 100% for the Flexible Tip Bougie, 78.6% for the Frova Intubating Introducer, and only 50% for the Portex Single-Use Introducer (p < 0.001). The median intubation time was shortest with the Flexible Tip Bougie, at 16.08 s (interquartile range [IQR]: 6.13); 18.25 s (IQR: 18.07) with Frova, and 19.39 s (IQR: 37.60) with Portex (p = 0.449). The ease of use was lowest with Portex (69.64, standard deviation [SD]: 32.45), average with Frova (50.59, SD: 29.98), and highest with Flexible Tip (16.67, SD: 21.86; [p < 0.001]). Conclusion: In this manikin study, the Flexible Tip Bougie was more efficient in achieving successful intubation and easier to use than the Portex and Frova introducers in a difficult intubation scenario.

A manikin study comparing the performance of traditional Macintosh laryngoscope, GlideScope®, Airtraq®, and video-optical intubation stylet in endotracheal intubation used by emergency doctors in simulated difficult airway intubation: A pilot study

Background: The video-optical intubation stylet (VS) is a slim, rigid but flexible intubating device that aids physicians to intubate patients, particularly with difficult airways. Objectives: The objective of this study was to compare the performance of emergency department doctors in using different intubating devices for intubation in an airway manikin simulating different difficult airway scenarios. Methods: Thirty emergency department doctors were recruited in a pilot study. Their performance of using traditional Macintosh laryngoscope, GlideScope®, Airtraq® and C-MAC® Video Stylet were compared in three situations: normal, restricted cervical motion and limited oral aperture. The time for intubation, first attempt success rate, failure rate, dental injury and the subjective ease of different devices by the participants were compared. Result: The mean intubation time by VS in each scenario was significantly shorter compared with other devices (Normal: 19.77s vs 24.67–28.19s, p = 0.014; Cervical restriction: 20.85 vs 26.17–31.26s, p = 0.008; Limited oral aperture:19.03 vs 29.35, p = 0.001). However, there was no significant difference in failure rate or first attempt success rate. The incidence of dental injury was significantly lower with VS than other laryngoscopes (p = 0.001, p < 0.05 and p < 0.05 in normal, cervical restriction and limited oral aperture scenarios, respectively). Moreover, participants appreciated that VS was the easiest device to intubate in each scenario. (p < 0.05 in all scenarios) Conclusion: The performance of VS was comparable to or even better than the commonly used laryngoscopes in the emergency department in airway management. When adequate training is provided, VS can be a potentially good alternative for tracheal intubation in different situations.

Comparison between GlideRite® rigid stylet and Parker Flex-It™ stylet to facilitate GlideScope intubation in simulated difficult intubation: a randomized controlled study

BackgroundThe GlideScope® videolaryngoscope (GVL) is widely used in patients with difficult airways and provides a good glottic view. However, the acute angle of the blade can make insertion and advancement of an endotracheal tube (ETT) more difficult than direct laryngoscopy, and the use of a stylet is recommended. This randomized controlled trial compared Parker Flex-It™ stylet (PFS) with GlideRite® rigid stylet (GRS) to facilitate intubation with the GVL in simulated difficult intubations.MethodsFifty-four patients were randomly allocated to undergo GVL intubation using either GRS (GRS group) or PFS (PFS group). The total intubation time (TIT), 100-mm visual analog scale (VAS) for ease of intubation, success rate at the first attempt, use of laryngeal manipulation, tube advancement rate by assistant, and complications were recorded.ResultsThere was no significant difference between the GRS and PFS groups regarding TIT (50.3 ± 12.0 s in the GRS group and 57.8 ± 18.8 s in the PFS group, P = 0.108). However, intubation was more difficult in the PFS group than in the GRS group according to VAS score (P = 0.011). Cases in which the ETT was advanced from the stylet by an assistant, were more frequent in the GRS group than in the PFS group (P = 0.002). The overall incidence of possible complications was not significantly different.ConclusionsIn patients with a simulated difficult airway, there was no difference in TIT using either the PFS or GRS. However, endotracheal intubation with PFS is more difficult to perform than GRS.

Awake fiberoptic orotracheal intubation: a protocol feasibility study.

ObjectiveTo assess the feasibility of an awake fiberoptic intubation (AFOI) protocol.MethodsWe enrolled 40 patients with simulated difficult intubation. The protocol consisted of conscious sedation (midazolam, 0.03 mg/kg and sufentanil, 0.1 µg/kg), regional anesthesia, and intubation. The time, first-attempt intubation success rate, hemodynamic parameters, blood oxygen saturation (SpO2), intubation amnesia rate, patient satisfaction, and relative complications were recorded.ResultsAFOI was completed in all patients. The average total AFOI time was 14.17 ± 1.47 minutes, and the time to placing the landmark-guided bilateral superior laryngeal nerve block was 1.24 ± 0.42 minutes. The first-attempt intubation success rate was 97.5%, and patient satisfaction was 90%. Blood pressure changed (<20%) briefly after administering conscious sedation. Heart rates did not change significantly, and SpO2 remained stable and ≥95%. Three patients had a sore throat, which resolved on postoperative day 1 without other complications. On postoperative day 1, 82.5% (33/40) of the patients had no recall of AFOI, and 17.5% (7/40) had only an indistinct memory.ConclusionsThe protocol was feasible with a high first-attempt intubation success rate and low complications rate. Hemodynamic parameters and respiration remained stable, with high patient satisfaction and effective amnesia.

Apnoeic Oxygenation during Simulated Difficult Intubation in Obese Patients: Comparison of Buccal Ring, Adair and Elwyn Tube Versus Nasal Cannula: A Prospective Randomized Controlled Trial.

Background:Apnoeic oxygenation is an established method of increasing safe apnoea times during intubation and this is of more importance in obese patients. The usefulness of buccal Ring, Adair and Elwyn (RAE) oxygenation has been established in previous studies, however a head-to-head comparison with nasal cannula (NC) is lacking.Aim:The aim of this study was to compare apnoea time with buccal RAE (BR) versus NC in obese patients.Setting and Design:This was a prospective, nonblinded randomized controlled trial conducted in a tertiary hospital where fifty American Society of Anaesthesiologists Physical Status Class I and II, obese patients with body mass index ≥30, posted for elective surgery were included.Materials and Methods:Following adequate preoxygenation and standard induction of anaesthesia, a prolonged simulated difficult laryngoscopy was performed during which oxygen was provided via either BR or NC. The primary outcome was time to desaturation to <95% or 10 min, which ever occurred first. Other outcomes recorded were lowest saturation, time to resaturation and highest end tidal carbon di oxide.Statistical Analysis:Mean with standard deviation (SD) or median with inter quartile range were used for continuous variables and absolute number with percentage were used for categorical variables. The primary outcome was analyzed using Kaplan-Meier survival curves, and log-rank tests were applied.Results:Patient characteristics were similar in both arms. The mean apnoea time in seconds (SD) in the BR group, 375.3 (116.6) was higher than the NC group 316.1 (94.1), P = 0.054. From the Kapan Meier curves the probability of desaturating to <95% was earlier in the NC group than the BR group (P = 0.092). The other outcomes were similar in both groups.Conclusion:This is the first study that demonstrates that oxygenation via a BR is better than NC in providing apnoeic oxygenation in obese patients and can safely be used when NC are contraindicated.

Duration of safe apnea in patients with morbid obesity during passive oxygenation using high-flow nasal insufflation versus regular flow nasal insufflation, a randomized trial

Obese patients are at risk for rapid oxygen desaturation during anesthesia induction. Apneic oxygenation with regular flow oxygen insufflation has successfully been used to prolong the duration of safe apnea without desaturation (DAWD) in morbidly obese patients. Using high-flown nasal insufflation of oxygen (HFNI) for apneic oxygenation might further increase the DAWD. To compare the duration of safe apnea using high-flown nasal insufflation of oxygen or standard flow oxygen insufflation for apneic oxygenation in a simulated difficult intubation scenario in patients with morbid obesity. Operating room, University Hospital, Austria. In a prospective, randomized, clinical trial, patients received standardized preoxygenation and anesthesia induction. Apneic oxygenation was performed using standard nasal prongs (10 L/min) or HFNI (120 L/min) during laryngoscopy. A Cormack-Lehane 3° view was maintained until the oxygen saturation on pulse oximetry (SpO2) dropped ≤95% or for a maximum of 15 minutes. The primary outcome of this study was to compare the duration of safe apnea using HFNI or standard flow oxygen insufflation for apneic oxygenation. In addition, arterial blood gas results, and airway pressures were investigated. In 40 patients with morbid obesity (body mass index [BMI] >40 kg/m2) and the American Society of Anesthesiologists physical classification ≤3 who underwent bariatric surgery, the median duration of safe apnea was 601 (268-900) seconds in the standard group and 537 (399-808) seconds in the HFNI group (P = .698). No differences in arterial blood gas results were observed between the groups. The median airway pressure was 0 (0-0) cm H2O in the standard group and 1 (0-2) cm H2O in the HFNI group (P = .005). Compared with standard nasal apneic oxygenation, HFNI did not increase the duration of safe apnea in patients with morbid obesity. A significant but clinically negligible higher airway pressure was observed when using HFNI.

Comparison of the Parker flex tip and the unoflex reinforced endotracheal tube for orotracheal fibreoptic intubation in simulated difficult intubation patients.

The choice of endotracheal tube (ETT) is important for successful orotracheal fibreoptic intubation (OFI). The aim of this study was to compare the use of the Parker flex tip (PFT) with the unoflex reinforced (UFR) ETT during OFI. A total of 58 patients who underwent elective surgery under general anaesthesia were randomised to two ETT groups, the PFT group (n = 29) and the UFR group (n = 29), for OFI in simulated difficult intubation patients using a rigid cervical collar. After successful standardised induction and relaxation, OFI and railroading of selected ETT were subsequently performed by a similarly experienced practitioner. Ease of insertion, degree of manipulation, time to successful intubation, post-intubation complications and haemodynamic changes were recorded for both groups. he percentage of easy intubation was comparable between both groups with a slightly higher percentage in the UFR group than the PFT group (69.0% vs. 62.0%; P = 0.599). Degree of manipulation was also comparable between the two groups; the percentage of cases in which manipulation was not required was slightly higher in the UFR group than the PFT group (69.0% vs. 62.1%; P = 0.849). Time to successful intubation was also comparable between the groups, although the time was slightly shorter for the UFR group than the PFT group (56.9 s ± 39.7 s vs. 63.9 s ± 36.9 s; P = 0.488). There were also no significant differences in other parameters. The Parker flex tip ETT was comparable to the unoflex reinforced ETT for OFI in simulated difficult airway patients.

Comparison of video and conventional laryngoscopes for simulated difficult emergency tracheal intubations in the presence of liquids in the airway

The presence of vomit, blood, or other foreign liquid materials in the upper airway is a major obstacle in difficult tracheal intubations (TIs) especially in prehospital care. However, the usefulness of video laryngoscopes (VLs) in these situations has not been investigated. The objective of this study was to compare the Airway Scope (AWS) and the Macintosh laryngoscope (ML) for their performance in TIs performed by emergency medical technicians (EMTs) using mannequin models with liquids in the airway. Rice gruel and mock blood were used to fill the upper airways of mannequins to create mock vomit and hematemesis models, respectively. TIs were performed by certified EMTs after visualizing the glottis using an AWS with an 18-Fr suction catheter and a ML with an 18-Fr suction catheter. TIs with AWS and ML were performed in random order in a comparative crossover trial. The TI success rate was evaluated based on the following: (a) the time taken from laryngoscope insertion into the oral cavity to glottis visualization, tracheal tube passage through the glottis, until the initiation of ventilation and (b) the subjective level of difficulty, which was assessed using a visual analog scale (VAS). TIs in vomiting and hematemesis scenarios were performed by 25 and 26 EMTs, respectively. The TI success rates for these scenarios were 100% with both AWS and ML. The median time required until successful ventilation was significantly shorter with AWS than with ML in both the vomiting (42 vs. 58 s) and hematemesis models (33 vs. 39 s), respectively. In the hematemesis scenarios, difficulty assessed using a VAS was lower with AWS than with ML (13 vs. 38 in median), respectively. Compared to the ML, the AWS was capable of faster and easier TIs, in a simulated model of liquid foreign material in the upper airway.

Comparison of Intubating Supraglottic Airways LMA Fastrach™ and ILTS-D® under Normal and Simulated Difficult Airways — a Manikin Study

Objectives. The goal of study was to compare the effectiveness of using Fastrach ™ and iLTS-D® on a manikin by novices 1st year resident-anesthesiologists under normal and simulated difficult airways. Material and Methods. At the first stage the participants conducted four consecutive trials on a manikin. Each trial included insertion, ventilation and blind intubation the manikin using iLTS-D® and Fastrach™. ‘Time to ventilation’, ‘time to tracheal ventilation’, success rates and number of attempts were recorded for the both devices. At the second stage participants performed one attempt of ventilation and blind intubation under simulated difficult airways (midline head stabilization and limited mouth opening 3 cm). It was estimated the difference between devices in ‘time to ventilation’ and ‘time to tracheal ventilation’; differences in success rates at trial 4 and at the second stage. Results. There was no difference in ‘time to ventilation’ between either device in trial 4 (median: Fastrach: 14.7 s, iLTS-D: 13.2 s, p = 0.14). Also there was no difference in ‘time to tracheal ventilation’ between either device in trial 4 (median: Fastrach: 15.4 s., iLTS-D: 13.9 s, p = 0.55). Both devices were equally effective in a simulated difficult airway, ventilation and intubation at the first attempt was successful in all cases, there was no significant difference in ‘time to ventilation’ (Fastrach: 12.3 s, iLTS-D: 13.5 s, p = 0.14) and ‘time to tracheal ventilation’ (Fastrach: 12.6 s, iLTS-D: 12.5 s, p = 0.77).

Comparison between the Trachway video intubating stylet and Macintosh laryngoscope in four simulated difficult tracheal intubations: A manikin study

ObjectivesIt remains to be determined whether the TVI-4000 Trachway video intubating (TVI) stylet (Markstein Sichtec Medical Corp, Taichung, Taiwan), an airway device for novices, improves airway management practice by experienced anesthesiologists. The aim of this study was to evaluate the feasibility of using the TVI stylet in difficult tracheal intubation situations compared with that of using the Macintosh laryngoscope on an airway manikin. Materials and MethodsTen anesthesiologists (with 3–21 years' experience), including three senior residents, participated. We compared tracheal intubation in four airway scenarios: normal airway, tongue edema, cervical spine immobilization, and tongue edema combined with cervical spine immobilization. The time of tracheal intubation (TTI), success rate, and perceived difficulty of intubation for each scenario were compared and analyzed. ResultsThe TTI was significantly shorter in both the tongue edema and combined scenarios with the TVI stylet compared with the Macintosh laryngoscope (21.60 ± 1.45 seconds vs. 24.07 ± 1.58 seconds and 23.73 ± 2.05 seconds vs. 26.6 ± 2.77 seconds, respectively). Success rates for both devices were 100%. Concomitantly, participants rated using the TVI stylet in these two scenarios as being less difficult. ConclusionThe learning time for tracheal intubation using the TVI stylet in difficult airway scenarios was short. Use of the TVI stylet was easier and required a shorter TTI for tracheal intubation in the tongue edema and combined scenarios.

Randomised Controlled Trial of Portex Tracheal Tube and Frova Intubating Introducers used with the GlideScope Videolaryngoscope in Simulated Difficult Intubation

Background: A ‘bougie’ may be less traumatic than the GlideScope-specific intubating stylet during videolaryngoscopy-guided intubation, but no comparative studies of bougies have been performed. Study objective: To compare the Portex tracheal tube introducer (PTTI) and Frova intubating introducer (FII) used with the GlideScope videolaryngoscope in simulated difficult intubation. Design: Randomised controlled study. Setting: A metropolitan tertiary referral and teaching hospital in Brisbane, Australia. The study was conducted from August 2011 to July 2013. Patients: Forty patients with American Society of Anaesthesiologists (ASA) grade 1 or 2 physical status who required tracheal intubation for elective surgery were randomly assigned to two equal groups. All completed the study. Those with known or suspected difficult intubation, cervical spine injury, raised intracranial pressure, risk of pulmonary aspiration, and risk of rapid oxygen desaturation were excluded. Interventions: After standardised intravenous induction, cervical manual in-line stabilisation was performed to increase intubation difficulty. Intubation was performed under GlideScope videolaryngoscopy assisted by either the PTTI or the FII. Measurements: The primary outcome measures were intubation time (s) and success rate (%). The secondary outcome measures were visual analogue scale (0-100 mm) and ordinal scale (1-4) scores of intubation difficulty. Main results: The median intubation times (interquartile ranges) in the PTTI and FII groups were 46 (35.3-68) and 55.8 (37.5-112.5) s, respectively (P>0.05). All intubations were successful in the PTTI group, but two intubations (10%) initially failed in the FII group (P>0.05). The median visual analogue scale score was significantly lower in the PTTI group (20 [10-40] vs. 40 [30-60]; P<0.01). The bougies did not cause any injury.

Comparison of the GlideScope and the McGrath method using vascular forceps and a tube exchanger in cases of simulated difficult airway intubation.

BackgroundA "difficult airway" can be simulated with an extrication collar, which restricts cervical motion and mouth opening. The purpose of this study is to compare the efficacy of the GlideScope and the McGrath in difficult airway simulation.MethodsPatients were randomized using computer-generated numbers and were placed into the GlideScope group or the McGrath group. The total intubation time was defined as the time measured from when the anesthesiologist picks up the device to the time at which three successive end-tidal CO2 values are acquired after intubation.ResultsThere was no significant difference in total intubation time between the two groups (73.0 ± 25.3 sec vs. 72.3 ± 20.9 sec, P = 0.92). The success rates of the first intubation attempt did not differ between the two groups (82.8% vs. 83.3%, P = 0.95).ConclusionsOur results suggest that there are no significant differences in the intubations with GlideScope and McGrath using vascular forceps and tube exchangers in difficult intubation scenarios.

Comparison of a disposable bougie versus a newly designed malleable bougie in the intubation of a difficult manikin airway.

The endotracheal bougie is used for difficult intubations when only a minimal glottic view is obtained. Standard bougies are designed for use during direct, line-of-sight viewing of the glottic opening. With videolaryngoscopy, intubators "see around the corner", thus requiring a bougie which can be shaped to follow a significant curve. A malleable bougie with an imbedded internal wire was created to enable intubators to shape the curve to best fit a difficult airway. This pilot study examined the malleable bougie compared to the SunMed bougie in a simulated difficult airway intubation using video laryngoscopy.

Stylet‐ or forceps‐guided tube exchanger to facilitate GlideScope® intubation in simulated difficult intubations – a randomised controlled trial

The GlideScope videolaryngoscope is widely used in the management of the difficult airway. However, passing the tracheal tube through the vocal cords can be awkward, and the use of a stylet to guide insertion is recommended. This randomised controlled trial evaluated a forceps-guided tube exchanger as an alternative to the stylet to aid intubation with the GlideScope in patients undergoing anaesthesia, with a simulated difficult airway created by the application of a semi-rigid cervical collar. Data were analysed from 178 patients randomly assigned to undergo intubation using either the stylet (n = 88) or a forceps-guided tube exchanger (n = 90). All intubations were completed successfully, with first attempt rates of 93.2% using the stylet and 94.4% using the exchanger (p = 0.597). The mean (SD) intubation time was 67.8 (28.7) s in the stylet group and 66.1 (15.5) s in the forceps-guided tube exchanger group (p = 0.11). The frequency of sore throat 1 h after extubation was 34.1% in the stylet group and 2.2% in the tube exchanger group (p < 0.001); 24 h after extubation the corresponding figures were 40.0% and 11.1% (p < 0.001). Using a forceps-guided tube exchanger may offer an advantage over a stylet in guiding tracheal intubation when the GlideScope is used.

A randomised comparison of InnoScope and Macintosh laryngoscope in simulated difficult tracheal intubation in manikins

A randomised comparison of InnoScope and Macintosh laryngoscope in simulated difficult tracheal intubation in manikins

A randomised comparison of InnoScope and Macintosh laryngoscope in simulated difficult tracheal intubation in manikins

We conducted a crossover randomised study to evaluate the performance of a novel optical stylet, the InnoScope, for tracheal intubation in simulated normal and difficult airways. Twenty-five anaesthetists attempted tracheal intubation on a SimMan 3G simulator using the InnoScope first followed by the Macintosh laryngoscope or vice versa. Three airway scenarios were tested: (1) normal airway; (2) difficult airway with swollen pharynx; and (3) limited neck movement. In each scenario, the laryngeal view, duration of and success rate for tracheal intubation were recorded. Compared with the Macintosh laryngoscope, the use of InnoScope increased the percentage of glottic opening seen by 17% in normal airway, 23% in the difficult airway and 32% with limited neck movement, p < 0.01. Despite this better laryngeal view, successful tracheal intubation achieved with the InnoScope (88.0%) was lower than that for the Macintosh laryngoscope (98.7%), p = 0.008. Using the InnoScope, tracheal intubation during the first attempt was only successful in 48% of cases with difficult airway. In this scenario, the median (interquartile range [range]) duration of tracheal intubation was significantly longer with [corrected] InnoScope compared with the Macintosh laryngoscope, (70 (19-120 [15-120)] s vs 30 [21-58 (15-120)] s, [corrected] p = 0.01. We conclude that an improved laryngeal view with the use of the InnoScope did not translate into better conditions for tracheal intubation.

Successful tracheal intubation with the McGrath® MAC video laryngoscope after failure with the Pentax-AWS™ in a patient with cervical spine immobilization

To the Editor, It is generally difficult to visualize or locate the glottis with a Macintosh laryngoscope or a fibreoptic bronchoscope in patients with spine injury after application of a halo-vest. Video laryngoscopes have been shown to be useful for tracheal intubation in these patients. The McGrath MAC (Aircraft Medical Lt., Edinburgh, UK) has recently been developed as a new video laryngoscope modified from the McGrath Series 5. We report a case of successful tracheal intubation using the McGrath MAC in a patient with a halo-vest after failure to intubate this patient’s trachea using a Pentax Airway Scope (PentaxAWS) (Hoya Co., Tokyo, Japan). Written consent was obtained from the patient for publication of this report together with the photographs. A 43-yr-old male (height, 172 cm; weight, 64 kg) with cervical fractures of C3 and C4 from a traffic accident nine days earlier was scheduled to undergo cervical laminoplasty. The patient’s spinal cord was not judged to be injured, but since there was a high risk of subsequent spinal cord injury due to the unstable cervical spine, his head and neck were stabilized with a halo-vest. Computed tomography showed no abnormal findings in the pharynx or larynx, and the Mallampati scoring indicated a class 3 view with a thyromental distance of 85 mm and an interincisor distance of 30 mm. Since we considered the airway to be patent in this patient under mask ventilation, we planned to intubate the patient’s trachea using a Pentax-AWS video laryngoscope after induction of general anesthesia. After setting up alternative devices to secure the airway, including equipment for percutaneous tracheostomy and a transtracheal jet ventilator, general anesthesia was induced with propofol 100 mg iv and remifentanil infused at 0.3 lg kg min. Since mask ventilation was successfully achieved, neuromuscular block was induced with rocuronium 50 mg iv. Despite several attempts to insert the Pentax-AWS Intlock blade into the larynx, the Intlock blade tip could not be advanced over the pharynx (Figure A), and bleeding was observed from the patient’s mouth and pharynx. An attempt was then made to intubate the patient’s trachea using a McGrath MAC video laryngoscope. The McGrath MAC (blade 3) was easily inserted and exposed the epiglottis and the vocal cords (Figure B). The patient’s trachea was then intubated successfully with an 8.5-mm internal diameter reinforced (spiral) tracheal tube (Fuji Systems, Tokyo, Japan). The time taken from insertion of the McGrath MAC to tracheal intubation was\20 sec, and the oxygen saturation did not decrease to\99%. Surgery was completed uneventfully, and the patient’s trachea was extubated after surgery without any complications. In patients with an unstable cervical spine, stabilization of the head and neck is required to prevent subsequent spinal cord injury; however, stabilization of the neck makes it difficult to perform tracheal intubation using a Macintosh laryngoscope or fibreoptic bronchoscope. Of the various video laryngoscopes available, the Pentax-AWS and the Glidescope (Verathon Inc., Bothell, WA, USA) have been reported to be useful for tracheal intubation in patients with a halo-vest. When compared with the Glidescope, the Pentax-AWS has been shown to improve the success rate of tracheal intubations in patients with a simulated difficult intubation due to manual in-line stabilization. This finding suggests that the Pentax-AWS is a better tool than the Glidescope for tracheal intubation in patients with S. Hyuga, MD T. Sekiguchi, MD T. Ishida, MD K. Yamamoto, MD Y. Sugiyama, MD M. Kawamata, MD (&) Shinshu University School of Medicine, Matsumoto, Japan e-mail: kawamata@shinshu-u.ac.jp

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

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. 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. 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. 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.

The Shikani optical stylet as an alternative to the GlideScope® videolaryngoscope in simulated difficult intubations – a randomised controlled trial

The GlideScope(®) videolaryngoscope is widely utilised in the management of the difficult airway. However, complications such as mucosal injury, palatal and tonsillar perforations have been reported with its use. The Shikani optical stylet has shown promise in aiding difficult intubations. This randomised controlled trial evaluates the Shikani optical stylet as an alternative to the GlideScope videolaryngoscope in patients undergoing anaesthesia, with a simulated difficult airway. Sixty patients were randomised to undergo tracheal intubation with either the GlideScope videolaryngoscope (n = 30) or the Shikani optical stylet (n = 30). All patients had rigid cervical collars applied to simulate a difficult airway. Tracheal intubation was successful in all patients, with first attempt success rates of 97% (29/30) the GlideScope group compared with 93% (28/30) in the Shikani group compared with 93% (28/30) in the Shikani group (p = 0.5). The mean (SD) time to intubation was 64 (37) s when using the GlideScope and 58 (26) s in the Shikani group (p = 0.48). A higher incidence of airway mucosal injury was noted in patients intubated with the GlideScope videolaryngoscope, compared with the Shikani optical stylet (5 vs 0, respectively, p = 0.05). This trial suggests that the Shikani optical stylet is a viable alternative to the GlideScope videolaryngoscope in the management of the difficult airway.

Comparison of malleable stylet and reusable and disposable bougies by paramedics in a simulated difficult intubation

In a randomised crossover study, 60 ambulance paramedics attempted tracheal intubation of a manikin model of a Cormack and Lehane grade 3/4 view using a Portex stylet, Portex and Frova single-use bougies, and a Portex reusable bougie. Tracheal intubation within 30 s was achieved by 34/60 (57%) using the stylet, 18/60 (30%) using a Portex single-use bougie, 16/60 (27%) using a Frova single-use bougie and 5/60 (8%) using a Portex reusable bougie. The proportion intubating within 30 s was significantly higher with the stylet compared with any bougie (p < 0.001), but significantly lower with a Portex reusable bougie than any other device (p < 0.004). Participants rated the Portex reusable bougie as significantly more difficult to use than the other devices (p < 0.001). There was no evidence of a relationship between previous experience and success rate for any device.