R. Maassen

A comparison of three videolaryngoscopes: the Macintosh laryngoscope blade reduces, but does not replace, routine stylet use for intubation in morbidly obese patients

BACKGROUND: Many manufacturers are producing videolaryngoscopes (VLSs) with differing specifications, user interfaces, and geometry. It is clinically relevant to know the relative performance of the blades. Visualization of the glottis and intubation are often problematic in (extremely) obese patients, and the new video technology may offer better functionality and performance. Although many tracheal intubations with direct laryngoscopy are performed with an unstyletted endotracheal tube, it is recommended to use a stylet for intubation using videolaryngoscopy. In this study, we compared 3 VLSs in morbidly obese patients undergoing intubation for elective surgery and tested whether it is feasible to intubate the tracheas of morbidly obese patients without using a stylet. METHODS: One hundred fifty consecutive adult morbidly obese patients (body mass index >35 kg/m2) were randomly selected to receive one of 3 VLSs: GlideScope®, Storz® V-Mac™, and McGrath®. Direct laryngoscopy scored the best possible view of the glottis; subsequently, the respective VLS was used, and the patients trachea was intubated. Common preprocedural (e.g., Mallampati grade) and intraprocedural (Cormack-Lehane grade) metrics of intubation difficulty were measured, as well as the dependent variables of intubation time, number of attempts, and subjective difficulty. RESULTS: All 3 VLSs tested offered an equal or better view of the glottis compared with traditional direct laryngoscopy. The number of attempts necessary to intubate the trachea differed significantly among VLSs (average 2.6 ± 1.0 attempts for the GlideScope, 1.4 ± 0.7 for the Storz, and 2.9 ± 0.9 for the McGrath VLS). The average intubation times were 33 ± 18 s for the GlideScope, 17 ± 9 s for the Storz, and 41 ± 25 s for the McGrath VLS. CONCLUSIONS: In this study, the VLS with the Macintosh blade (Storz VLS) had a better overall satisfaction score, intubation time, number of intubation attempts, and necessity of extra adjuncts, compared with the 2 other tested devices.

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

Summary 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 laryngoscopy 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.

A Macintosh Laryngoscope Blade for Videolaryngoscopy Reduces Stylet Use in Patients with Normal Airways

BACKGROUND:Although most tracheal intubations with direct laryngoscopy are not performed with a styletted endotracheal tube, it is recommended that a stylet can be used with indirect videolaryngoscopy. Recently, there were several reports of complications associated with styletted endotracheal tubes and videolaryngoscopy. In this study, we compared three videolaryngoscopes (VLSs) in patients undergoing tracheal intubation for elective surgery: the GlideScope® Ranger™ (GlideScope, Bothell, WA), the V-MAC™ Storz® Berci DCI® (Karl Storz, Tuttlingen, Germany), and the McGrath® (McGrath series 5, Aircraft medical, Edinburgh, UK) and tested whether it is feasible to intubate the trachea of patients with indirect videolaryngoscopy without using a stylet. METHODS:Four hundred fifty consecutive adults (ASA PS I–II) undergoing tracheal intubation for elective surgery were randomly allocated for airway management with one of the three devices. Anesthesia induction for tracheal intubation consisted of fentanyl-propofol-rocuronium. An independent anesthesiologist used the Cormack-Lehane grading system to score an initial direct laryngoscopic view using a classic metal Macintosh blade. After subsequent positive-pressure ventilation using a face mask and an oxygen-sevoflurane mixture for 1 min, the trachea was intubated using one of the three VLSs. During intubation, the following data were collected: intubation time, number of intubation attempts, use of extra tools to facilitate intubation, and overall satisfaction score of the intubation conditions. RESULTS:The trachea of every patient was intubated using the VLSs, and none of the patients required conversion to the classic Macintosh laryngoscope. All three VLSs offered equal or better view of the glottis as assessed by the mean Cormack-Lehane grade, compared with the traditional Macintosh laryngoscopy, including a larger viewing angle of the glottic entrance. The average intubation time was 34 ± 20 s for the GlideScope, 18 ± 12 s for the V-MAC Storz, and 38 ± 23 s for the McGrath VLS. Intubation with the Storz was faster (P < 0.05) than the other two VLS tested and necessitated fewer additional tools (P < 0.01), resulting in a higher first-pass successful intubation rate. A stylet had to be used in 7% of the patients in the Storz group versus about 50% of the patients when the other two VLS were used. CONCLUSIONS:The trachea of a large proportion of patients with normal airways can be intubated successfully with certain VLS blades without using a stylet, although the three studied VLSs clearly differ in outcome. The Storz VLS displaces soft tissues in the fashion of a classic Macintosh scope, affording room for tracheal tube insertion and limiting the need for stylet use compared with the other two scopes. Although VLSs offer several advantages, including better visualization of the glottic entrance and intubation conditions, a good laryngeal view does not guarantee easy or successful tracheal tube insertion. We recommend that the geometry of VLSs, including blade design, should be studied in more detail.

Forces applied to the maxillary incisors during video-assisted intubation

BACKGROUND: Modern, video laryngoscopes provide an easier view of the glottis, possibly facilitating easier intubations. We describe an objective method for evaluating the benefits of video-assisted laryngoscopy, compared with standard techniques using force measurements. METHOD: Macintosh and video laryngoscopes (both Karl Storz, Tuttlingen, Germany) were used on the patients until the anesthesiologist was convinced he or she had the best possible view of the glottis. Actual intubation was only performed with the second of the laryngoscopes. Sensors measured the forces directly applied to the patients’ maxillary incisors. Additionally, common subjective pre- (e.g., Mallampati) and intraintubation (e.g., Cormack-Lehane [C&L]) metrics of intubation difficulty were evaluated by the anesthesiologists. RESULTS: All patients (24 female, [50 ± 16 yr], 20 male [56 ± 13 yr]) included in the study were successfully intubated with both the classic and video laryngoscopes. The forces recorded for the classic Macintosh blade ranged from 0 to 87.4 N with a median of 15.3 N, whereas the video laryngoscope forces ranged from 0 to 45.2 N, with a median of 2.1 N. The only factor determined to be significantly influential on the associated forces applied to the maxillary incisors was the laryngoscope type (P < 0.01). Video-assisted laryngoscopes reduced the applied forces over standard blades. Mallampati and C&L grade were not predictive of the forces applied. CONCLUSIONS: Video-assisted laryngoscopes seem beneficial when considering forces applied to the maxillary incisors as an objective metric of intubation difficulty. In this study, we could not support that Mallampati and C&L grades predict the forces that are applied to the maxillary incisors.

The videolaryngoscope is less traumatic than the classic laryngoscope for a difficult airway in an obese patient.

This report describes the anesthetic management of an obese patient with a difficult airway and the merits of videolaryngoscopy, specifically in terms of the reduced risk of dental damage during intubation. A 49-year-old woman (body mass index; BMI, 36 kg·m−2), was scheduled to undergo an elective laparoscopic cholecystectomy because of cholelithiasis. Based upon the obesity of the patient and preoperative metrics (Mallampati grade IV; interdental distance of 2.9 cm; thyromental distance, 5.5 cm) a difficult airway was anticipated. Classic direct laryngoscopy using a Macintosh blade size IV failed, despite three intubation attempts—each resulting in a Cormack-Lehane grade IV view. Intubation using a video-assisted Macintosh laryngoscope (V-Mac; Karl Storz, Tuttlingen, Germany) was successful upon the first attempt. The maximum force exerted on the patient’s maxillary incisors was 61 N by direct laryngoscopy and 7.6 N using the indirect videolaryngoscope, both using a Macintosh blade.

A comparison of the quality of intubation conditions in 300 patients using three video-laryngoscopes.

(baseline), b) immediately before intubation, c) immediately after intubation (at intubation), and d) 1, 2, 3, 4, and 5 min after intubation. Statistical comparisons were performed by analysis of variance (ANOVA), followed by Student’s t test. Results and Discussion: The Macintosh laryngoscope produced significantly greater changes in the systolic blood pressure (SBP) (!P) from the baseline from the time point of “at intubation” to ”4 min after intubation” than did the AWS group (p < 0.05, Figure 1). The heart rate (HR) change was also greater with the Macintosh laryngoscope at intubation (p < 0.01, Figure 2). All values in these figures are expressed as mean ± SD. Conclusion(s): The AWS causes less haemodynamic responses to tracheal intubation than does conventional Macintosh laryngoscope. Therefore, the AWS may be valuable when haemodynamics disturbances should be limited. Disclosure: The Airway Scope used in this study was provided by Pentax, Tokyo, Japan, with no charge.