Evaluation of the Pentax-AWS(®) and the Macintosh laryngoscope in difficult intubation: a manikin study

Background: The Pentax‐AWS (AWS^®), a new video laryngoscope, has been shown to be useful in cases of difficult intubation. We hypothesized that the AWS^® would be more useful in the settings of a narrow upper airway than the Macintosh laryngoscope. We compared each device in simulated scenarios of representative difficulty of tracheal intubation using a manikin. The primary endpoint was the rate of successful intubation. Methods: With each device, 23 anesthesiologists performed tracheal intubation in a SimMan^® manikin in the following scenarios: (1) normal airway, (2) tongue edema, (3) cervical spine rigidity, (4) pharyngeal obstruction, (5) jaw trismus, (6) tongue edema with pharyngeal obstruction. The intubation time and success rate were measured. Each participant was asked to rate the difficulty of intubation (1=very easy; 5=very difficult). Results: In the scenarios of tongue edema and tongue edema with pharyngeal obstruction, the AWS^® yielded a higher success rate (100% vs. 34.8%; P<0.001, 65.2% vs. 21.7%; P=0.006), a shorter intubation time [14.6 (7.0) vs. 33.4 (13.0) s; P<0.001, 24.5 (12.0) vs. 37.6 (11.9); P=0.047; mean (standard deviation)], and a lower difficulty score [2 (1–4) vs. 5 (1–5); P<0.001, 4 (2–5) vs. 5 (3–5); P<0.001; median (range)], compared with the Macintosh laryngoscope. Conclusion: The AWS^® has an advantage over the Macintosh laryngoscope in simulated tongue edema and tongue edema with pharyngeal obstruction. Further studies in a clinical setting are necessary to confirm these findings.     

A randomised controlled trial comparing the McGrath(®) videolaryngoscope with the straight blade laryngoscope when used in adult patients with potential difficult airways

Studies show that both straight blade laryngoscopy and videolaryngoscopy can improve the view of the larynx when compared with the Macintosh blade laryngoscopy. However, no study has compared these two devices. A total of 80 patients with Mallampati grade ≥ 3 were randomly assigned to either have orotracheal intubation with the McGrath^® videolaryngoscope or the Henderson straight blade. The primary outcome was laryngoscopic view. Time to intubation, number of attempts, ease of intubation and complications were also recorded. Thirty‐nine out of 40 patients had grade‐1 views in the McGrath group, compared with 29 out of 40 cases in the Henderson group (p = 0.003). There were no statistically significant differences in the secondary outcomes. Two patients suffered from minor oropharyngeal injuries in the Henderson group. Apart from offering significantly more grade‐1 laryngoscopic views, the McGrath videolaryngoscope did not improve other clinical outcomes compared with the straight blade, when used in patients with poor Mallampati scores.     

Comparison of the GlideScope® videolaryngoscope and the Macintosh laryngoscope for double-lumen tube intubation

Intubation with a double‐lumen tube is important for achieving one‐lung ventilation and facilitating thoracic surgery. The GlideScope^® videolaryngoscope (Verathon Inc., Bothell, WA, USA) is designed to assist tracheal intubation for patients with a difficult airway. We wished to compare the GlideScope and direct laryngoscopy for double‐lumen tube intubation. Sixty adult patients requiring a double‐lumen tube for thoracic surgery and predicted uncomplicated laryngoscopy were randomly assigned to a direct Macintosh laryngoscopy group (n = 30) or a GlideScope group (n = 30). The mean (SD) duration of intubation was longer in the Macintosh group (62.5 (29.7) s) than in the GlideScope group (45.6 (10.7) s; p = 0.007). There was no difference in the success of the first attempt at intubation (26/30 (87%) and 30/30 (100%) for Macintosh and GlideScope groups, respectively; p = 0.112). The incidence of sore throat and hoarseness was higher in the Macintosh group (18 (60%) and 14 (47%), respectively) than in the GlideScope group (6 (20%) and 4 (13%), respectively; p = 0.003 and 0.004). We conclude that double‐lumen tube intubation in patients with predicted normal laryngoscopy is easier using the GlideScope videolaryngoscope than the Macintosh laryngoscope.     

Effectiveness and safety of the Levitan FPS Scope? for tracheal intubation under general anesthesia with a simulated difficult airway

Purpose

Studies show that the Levitan FPS (first pass success) Scope? (LFS) is analogous to a bougie in simulated difficult airways with comparable tracheal intubation success rates. In this study, the efficacy and safety of tracheal intubation with the LFS was compared with that of the Macintosh laryngoscope utilizing manual in-line stabilization (MILS) to simulate difficult airways.

Methods

Ninety-four subjects successfully completed the trial. Manual in-line stabilization of the cervical spine was applied and the initial laryngoscopy was performed using either the Macintosh or the LFS in conjunction with the Macintosh. Following the initial grading, a second laryngoscopy was repeated using the second randomized technique. Cormack-Lehane grades, percentage of glottic opening (POGO) scores, time to intubate, number of intubation attempts, and the use of alternate techniques were recorded. The anesthesiologist rated the subjective difficulty in using each technique with a numeric rating scale and a visual rating scale.

Results

There was no significant difference in the primary outcome ??good laryngoscopic views?? (Cormack-Lehane grade 1 and 2) compared with ??poor laryngoscopic views?? (Cormack-Lehane grade 3 and 4) between the LFS and the Macintosh. There were higher POGO scores with the LFS compared with the Macintosh (80% vs 20%, respectively; P?<?0.0001), but this did not translate to easier intubations, as documented by the need for an alternate intubation technique or time to intubate (< 30 and < 60?sec, respectively). The incidence of mucosal trauma, sore throat, and hemodynamic responses did not differ significantly between the two techniques.

Conclusion

The LFS in conjunction with the Macintosh laryngoscope does not improve the efficacy or safety of tracheal intubation in a simulated difficult airway.     

Use of the Laryngeal Tube™ in two unexpected difficult airway situations: lingual tonsillar hyperplasia and morbid obesity

PURPOSE: The 2003 ASA Practice Guidelines for Management of the Difficult Airway suggest the early use of the Laryngeal Mask Airway and Combitube as rescue airway devices in the cannot ventilate-cannot intubate situation, switching the focus from laryngoscopy and intubation to ventilation and oxygenation. The Practice Guidelines are not intended as standards but as recommendations. Multiple new alternative airway devices were described in the last ten years. The Laryngeal Tube (LT) is a new Food and Drug Administration approved supraglottic airway device. The device is in use in Europe since 1999 and in the United States since 2002. CLINICAL FEATURES: We report two cases in which the LT was used to solve two unexpected difficult airway situations. The first case ("cannot intubate-inadequate mask ventilation") involved an undiagnosed lingual tonsillar hyperplasia and the LT provided the means to ventilate and administer the anesthetic. In the second case ("cannot ventilate-cannot intubate") we report the successful use of the LT to rescue the airway in a morbidly obese patient. In both cases an endotracheal tube was ultimately inserted using an awake fibreoptic technique with the patient in the sitting position. CONCLUSIONS: In these clinical situations of unexpected difficult airway with significant periglottic obstruction the LT provided adequate ventilation after the first insertion. The LT may complement the laryngeal mask airway in difficult airway management. Further research is needed to define the role of the LT in the management of difficult airways.     

Use of Bioglue™ to seal a difficult to treat air leak in a complicated empyema patient

Surgical sealants have been used in thoracic surgery in an effort to reduce air leak duration, intercostal drain duration, length of stay and complications. They are instilled over a defect usually treated with other means. We herein present the technique of controlling a difficult to treat defect by directly instilling Bioglue? alone into a crater, caused during empyema Video-assisted thoracic surgery in a 50-year-old patient with a trapped lung. This deep crater had caused a significant air leak rendering intraoperative ventilation challenging. After instillation, the dependent lung was kept blocked. With this technique, the Bioglue? polymerized and the air leak was dramatically decreased making ventilation and eventually extubation of the patient feasible. Instillation of Bioglue? directly into a large lung defect could be a choice of action to decrease complicated air leaks, otherwise impossible to treat with other means, in patients with trapped lung.