A comparison of McGrath and Macintosh laryngoscopes in novice users: a manikin study

Direct laryngoscopy using the Macintosh laryngoscope is a difficult skill to acquire. Videolaryngoscopy is a widely accepted airway management technique that may be easier for novices to learn. We compared the McGrath^® videolaryngoscope and Macintosh laryngoscope by studying the performance of 25 medical students with no previous experience of performing tracheal intubation using an easy intubation scenario in a manikin. The order of device use was randomised for each student. After brief instruction each participant performed eight tracheal intubations with one device and then eight tracheal intubations with the other laryngoscope. Novices achieved a higher overall rate of successful tracheal intubation, avoided oesophageal intubation and produced less dental trauma when using the McGrath. The view at laryngoscopy was significantly better with the McGrath. Intubation times were similar for both laryngoscopes and became shorter with practice. There was no difference in participants' rating of overall ease of use for each laryngoscope.     

Effects of a suction laryngoscope in a model with simulated severe airway hemorrhage

In severe airway hemorrhage, simultaneous suction and laryngoscopy may render intubation difficult. We built a suction laryngoscope that consists of an adjustable stainless steel-guide tube fixed at the lingual surface of a standard Macintosh laryngoscope blade. Via this steel-guide tube, a large suction catheter can be inserted and positioned exactly to suction pharyngeal blood or vomitus, rendering simultaneous suctioning and laryngoscopy possible. In contrast to previous suction laryngoscopes, our suction catheter has a large lumen, which enables fast suctioning and exact placement by adjusting the steel-guide tube. To assess whether our suction laryngoscope could provide better intubation conditions in comparison to a standard Macintosh laryngoscope in a bleeding airway scenario, 44 medical students intubated a manikin with severe simulated airway hemorrhage using our suction laryngoscope and a standard Macintosh laryngoscope in random order. There was no significant difference in time needed for intubation when using the suction versus the Macintosh laryngoscope (mean +/- SD: 43 +/- 13 vs 52 +/- 31 s; P = 0.07), but the number of esophageal intubations was significantly lower when using the suction laryngoscope [6 of 44 (13.6%) vs 19 of 44 (43.2%); P = 0.004]. In conclusion, when compared with a standard Macintosh laryngoscope, using a suction laryngoscope did not result in more rapid intubation, but significantly decreased the likelihood of esophageal intubations.     

The McCoy laryngoscope, external laryngeal pressure, and their combined use

The efficacy of the McCoy laryngoscope, external laryngeal pressure, and their combination to improve the laryngoscopic view was evaluated in 219 patients and compared with the Macintosh laryngoscope. An experienced laryngoscopist performed laryngoscopy twice using the Macintosh laryngoscope and the McCoy laryngoscope in a random sequence, and external laryngeal pressure was applied in each laryngoscopy with the laryngoscopist's right hand. The laryngoscopic view obtained was graded on our modified Cormack's method. Without external laryngeal pressure, the McCoy laryngoscope provided a better laryngoscopic view than that obtained by the Macintosh laryngoscope (P < 0.001, signed rank test), but the view was worse than that with the Macintosh laryngoscope under external laryngeal pressure (P < 0.001). The McCoy laryngoscope combined with external laryngeal pressure provided a better view than the Macintosh laryngoscope with external laryngeal pressure (P < 0.001).     

A new mirrored laryngoscope

A new laryngoscope has been designed, incorporating an adjustable mirror and a levered tip similar to the McCoy blade, in an attempt to bridge the gulf between simple direct laryngoscopy and fiberoptic laryngoscopy. Manual in-line neck stabilisation was used to simulate difficult laryngoscopy in 14 anaesthetised patients after full neuromuscular blockade. The best view at laryngoscopy was assessed using a standard Macintosh laryngsocope, a size 3 McCoy laryngoscope and the mirrored laryngoscope. The best laryngeal view obtained in all cases with the Macintosh blade was a grade 3. The mirrored laryngoscope improved this view in 10 cases (71%) compared with five cases (36%) with the McCoy laryngoscope (p = 0.005); in seven cases (50%), the view improved to a grade 1 compared with no cases when the McCoy was used (p = 0.02). We conclude that the mirrored laryngoscope offers considerable advantages over the Macintosh and the McCoy laryngoscopes in simulated difficult laryngoscopy, is simple to use and requires no special training.     

TruviewEV02喉镜与Macintosh喉镜用于颈椎活动受限患者气管插管的对比研究

目的评价Truview EVO,喉镜与Macintosh喉镜用于颈椎活动受限患者气管插管的临床应用情况。方法择期颈椎活动受限经口气管插管全麻手术49例,静脉麻醉诱导后,随机先后使用TruviewEVO2喉镜与Macintosh喉镜显露喉部,并采用喉部暴露条件好的喉镜行气管插管。比较2种喉镜Cormack．Lehane（C-L）分级,喉部结构显露时间和声门显露时血流动力学改变。结果TruviewEVO,喉镜组c-L分级显著优于Macintosh喉镜组（Z=-5．488,P=0．000）,喉部结构显露时间明显长于Macintosh喉镜组[（15．9±6．7）Svs．（12．3±4．5）S,t=4．304,P=0．000]。2种喉镜声门显露时HR、SBP、MAP变化无统计学差异（P〉0．05）。结论TruviewEVO,喉镜用于颈椎活动受限患者气管插管效果明显优于Macintosh喉镜,可提高气管插管成功率,对于部分困难气道患者具有较好的应用价值。     

Use of the bougie in simulated difficult intubation. 1. Comparison of the single-use bougie with the fibrescope

We studied the success rates for tracheal intubation in 64 healthy patients during simulated grade III laryngoscopy after induction of anaesthesia, using either the single-use bougie or oral flexible intubating fibrescope, both in conjunction with conventional Macintosh laryngoscopy. Patients were randomly allocated to either simulated grade IIIa or grade IIIb laryngoscopy, and also to one of the two study devices. Success rates for tracheal intubation (primary outcome measure) and times taken to achieve intubation (secondary outcome measure) were recorded. For the simulated grade IIIa laryngoscopy group, the fibreoptic scope was more successful than the bougie (16/16 successful intubations vs. 8/16; p = 0.02). For the simulated grade IIIb laryngoscopy group, the fibreoptic scope was also more successful than the bougie (8/16 successful intubations vs. 1/16; p = 0.02), but clearly use of the fibreoptic scope was not as successful as it had been in simulated grade IIIa laryngoscopy (p = 0.04). With either device, median (range) total tracheal intubation times for successful attempts with either grade of laryngoscopy were less than 60 s (19-109) and there were no clinically important differences. We conclude that the fibrescope used in conjunction with Macintosh laryngoscopy is a more reliable method of tracheal intubation than the single-use bougie in both types of grade III laryngoscopy. This finding has implications for the management of patients in whom grade III laryngoscopy is encountered unexpectedly after induction of anaesthesia, and also for the management of patients previously known to have grade III view at laryngoscopy.     

Evaluation of the Airway Scope, a new video laryngoscope, in tracheal intubation by naive operators: a manikin study

BACKGROUND AND AIM: The Airway Scope (AWS) is a new video laryngoscope. The purpose of this study was to compare the AWS and Macintosh laryngoscopes with regard to their usefulness for beginners in tracheal intubation. METHODS: Thirty-one nurses with no previous experience of tracheal intubation used each device 10 times to intubate the trachea of a manikin (Laerdal Airway Managemant Trainer, Laerdal, Stavanger, Norway). Intubation correctly completed within 30 s was regarded as successful. The intubation time, success rate, number of esophageal intubations and dental clicks, and subjective evaluation of difficulty of intubation [rated from 1 (extremely easy) to 5 (extremely difficult)] were recorded. RESULTS: The average intubation time was significantly shorter for AWS than for the Macintosh laryngoscope (16.7 +/- 11.0 s vs. 23.2 +/- 24.9 s; mean +/- standard deviation; P = 0.0297), and the success rate with AWS was significantly greater (91.3% vs. 79.4%; P < 0.001). In the total of 310 intubation attempts for each device, the number of esophageal intubations (0/310 with AWS vs. 20/310 with the Macintosh laryngoscope) and dental clicks (0/310 with AWS vs. 40/310 with the Macintosh laryngoscope) differed significantly (P < 0.001). AWS was rated as easier to use than the Macintosh laryngoscope (P < 0.001). CONCLUSION: AWS is more useful for beginners as it provides quicker and easier tracheal intubation.     

Comparison of the Glidescope(R), the Pentax AWS(R), and the Truview EVO2(R) with the Macintosh laryngoscope in experienced anaesthetists: a manikin study

Background: The Pentax Airwayscope®, the Glidescope®, and the TruviewEVO2® constitute three novel laryngoscopes that facilitatevisualization of the vocal cords without alignment of the oral,pharyngeal, and tracheal axes. We compared these devices withthe Macintosh laryngoscope in a simulated easy and difficultlaryngoscopy. Methods: Thirty-five experienced anaesthetists were allowed up to threeattempts to intubate in each of four laryngoscopy scenariosin a Laerdal® SimMan® manikin. The time required toperform tracheal intubation, the success rate, number of intubationattempts and of optimization manoeuvres, and the severity ofdental compression were recorded. Results: In the simulated easy laryngoscopy scenarios, there was no differencebetween the study devices and the Macintosh in success of trachealintubation. In more difficult tracheal intubation scenarios,the Glidescope® and Pentax AWS®, and to a lesser extentthe Truview EVO2® laryngoscope demonstrated advantages overthe Macintosh laryngoscope including a better view of the glottis,greater success of tracheal intubation, and ease of device use.The Pentax AWS® was more successful in achieving trachealintubation, required less time to successfully perform trachealintubation, caused less dental trauma, and was considered bythe anaesthetists to be easier to use. Conclusions: The Pentax AWS® laryngoscope demonstrated more advantagesover the Macintosh laryngoscope than either the Truview EVO2®or the Glidescope® laryngoscope, when used by experiencedanaesthetists in difficult tracheal intubation scenarios.     

Randomized evaluation of the performance of single-use laryngoscopes in simulated easy and difficult intubation

Background. Single-use laryngoscopes are becoming used morewidely. Methods. We compared six types of single-use laryngoscope withthe standard Macintosh laryngoscope using the Laerdal SimMan^TMpatient simulator. Twenty anaesthetists attempted to intubatethe simulator with standardized airway settings allowing a fullview of the vocal cords (‘easy intubation’). Theairway settings were then changed so that only the posteriorpart of the glottis was visible (‘difficult intubation’)and the anaesthetists were asked to intubate the simulator again. Results. The time to intubate with the standard laryngoscopewas less in both easy (P<0.05) and difficult (P<0.01)intubations. The performance of five laryngoscopes during easyintubation (P<0.01) and four during difficult intubation(P<0.001) was significantly worse than that of the Macintosh.There was a significant difference in Cormack and Lehane gradingbetween the laryngoscopes tested in both easy (P<0.05) anddifficult (P<0.05) intubation. The percentage of glotticopening visible (POGO score) also differed between laryngoscopesin both the easy (P<0.01) and difficult (P<0.001) groups.The highest POGO scores were obtained with the Macintosh laryngoscope.During the difficult intubation simulation, the reusable Macintoshlaryngoscope needed less use of a bougie and had fewer failedintubations than the single-use laryngoscopes, but these differencesdid not reach statistical significance. Conclusions. Of the laryngoscopes tested, the standard reusableMacintosh laryngoscope performed best. The Europa^TM was thebest single-use laryngoscope. Some single-use laryngoscopestested were significantly inferior to the Macintosh. This raisesconcern over their use in clinical practice, particularly ifintubation is difficult. Br J Anaesth 2003; 90: 8–13     

Comparison of the Flexiblade levering laryngoscope with the English Macintosh laryngoscope in patients with a poor laryngoscopic view

The effectiveness of two laryngoscopes, the English Macintosh and the Flexiblade (a levering laryngoscope), were compared in a clinical setting. An investigation was carried out in 100 patients admitted for surgery under general anaesthesia, to compare intubation with the Flexiblade or the Macintosh laryngoscope. The patients had two anatomical characteristics that may predict difficult intubation - Mallampati score II and III, and a thyromental distance 相似文献   

An evaluation of the TruView EVO2 laryngoscope

The TruView EVO2 laryngoscope was compared with the traditional Macintosh laryngoscope in 200 patients who required tracheal intubation for elective surgery. Mallampati score determined prior to laryngoscopy was significantly related to the view of the glottis during laryngoscopy for both laryngoscopes. The view of the larynx was better with the TruView EVO2 laryngoscope than with the Macintosh laryngoscope in patients with a Cormack and Lehane grade greater than 1 (p < 0.01). The mean time to intubate was significantly shorter with the Macintosh laryngoscope (34 s) than with the TruView laryngoscope (51 s) (p < 0.01).     

A comparison of the forces applied to a manikin during laryngoscopy with the GlideScope and Macintosh laryngoscopes

The force applied during laryngoscopy can cause local tissue trauma and can induce cardiovascular responses and cervical spine movement in susceptible patients. Previous studies have identified numerous operator and patient factors that influence the amount of force applied during intubation. There are few studies evaluating the effect of different laryngoscope blades and no study involving video laryngoscopes. In this study we measured the forces using two laryngoscopic techniques. Three FlexiForce Sensors (A201-25, Tekscan, Boston, MA, USA) were attached to the concave blade surface of a Macintosh and a GlideScope laryngoscope. Experienced anaesthetists performed Macintosh and GlideScope intubations on the Laerdal Airway Management Trainer manikin. Compared to Macintosh intubations, the GlideScope intubations had equal or superior views of the glottis with 55%, 58% and 66% lower median peak, average and impulse forces applied to the tongue base. The distal sensor registered the most force in both devices and the force distribution pattern was similar between the devices. The findings suggest that the GlideScope requires less force for similar or better laryngoscopic views, at least in a manikin model.     

Comparison of the Airway Scope, gum elastic bougie and fibreoptic bronchoscope in simulated difficult tracheal intubation: a manikin study

We compared the Airway Scope with a gum elastic bougie and fibreoptic bronchoscope in a manikin with a simulated Cormack and Lehane Grade 3 laryngoscopic view. Twenty-seven anaesthetists intubated the trachea of the manikin with these devices and the time required for intubation was measured. They were then asked to rate the subjective difficulty of intubation (1 = very easy; 5 = very difficult). Mean (SD) intubation times were 16.6 (11.2) s with the Airway Scope, 29.4 (10.9) s with the gum elastic bougie (p < 0.0001), and 30.6 (20.0) s with the fibreoptic bronchoscope (p < 0.0001). The median (range) difficulty was 2 (1-4) with the Airway Scope, 3 (2-4) with the gum elastic bougie (p < 0.001), and 2 (1-5) with the fibreoptic bronchoscope (p = 0.014). In Cormack and Lehane grade 3 laryngoscopic views, the Airway Scope may enable faster and easier tracheal intubation than does a Macintosh laryngoscope with a gum elastic bougie or a fibreoptic bronchoscope.     

Comparação do C‐MAC convencional e C‐MAC D‐blade com laringoscópios diretos em simulação de lesão da coluna cervical–estudo em modelo

Background

CMAC videolaryngoscope has recently been introduced for videoscope guided intubation. The aim of our study was to compare and evaluate the efficacy of the conventional blade and the angulated D blade of the CMAC videolaryngoscope with the direct laryngoscopes in simulated cervical spine injury patients on the airway manikin.

Materials and methods

Following power analysis, 33 resident doctors were enrolled to perform endotracheal intubation using all the 4 different laryngoscopes namely the Macintosh laryngoscope, McCoy laryngoscope, conventional CMAC videolaryngoscope and the D blade of the CMAC videolaryngoscopes on the airway manikin in simulated cervical spine injury. The demographic variables of the resident doctors were recorded. The outcomes measured included vocal cord visualization (Cormack–Lehane grading), time taken to intubate, number of attempts for successful intubation and optimizing maneuvers required.

Results

The use of indirect videolaryngoscopes resulted in better glottic visualization in comparison to the direct laryngoscopes (CL‐I) in 20/33 (60.6%) in the Macintosh group, 24/33 (72.7%) in McCoy group, 30/33 in (90.9%) in Vlc group and 32/33 (96.9%) in Vld group. The time taken to intubate averaged to 15.54 ± 2.6 in Macintosh group, 18.90 ± 4.47 in McCoy group, 20.21 ± 7.9 in Vlc group and 27.42 ± 9.09 in Vld group. The 1st attempt intubation success rate was 84.8% (Macintosh), 72.7% (McCoy), 90.9% (Vlc) and, 78.7% (Vld).

Conclusions

The overall performance of the conventional CMAC blade proved to be the best when compared with the D‐blade CMAC, Macintosh blade and the McCoy blade for intubation in simulated cervical spine patients by anesthesia residents.     

Nasotracheal intubation using the Airtraq versus Macintosh laryngoscope: a manikin study

The Airtraq laryngoscope is a new intubation device that provides a non-line-of-sight view of the glottis. We evaluated this device by comparing the ease of nasotracheal intubation on a manikin with the use of Airtraq versus the Macintosh laryngoscope with and without Magill forceps. Nasotracheal intubation on a manikin was performed by 20 anesthesiologists and 20 residents with the Airtraq or Macintosh laryngoscope. The mean (+/- SD) time required for nasotracheal intubation by the residents was significantly shorter with the Airtraq laryngoscope than with the Macintosh laryngoscope (16 +/- 7 sec vs 22 +/- 10 sec; P < .001), but no difference in intubation time was observed between Airtraq (15 +/- 11 sec) and Macintosh (13 +/- 6 sec) laryngoscopy by the anesthesiologists. The Magill forceps was used more frequently to facilitate intubation with the Macintosh laryngoscope than with the Airtraq laryngoscope in both groups of operators 7(P < .001). The Airtraq laryngoscope scored better on the visual analog scale than did the Macintosh laryngoscope in both groups of operators (P < .05). The Airtraq laryngoscope offers potential advantages over standard direct laryngoscopy for nasotracheal intubation.     

Videolaryngoscopy vs. direct Macintosh laryngoscopy in tracheal intubation in adults: a ranking systematic review and network meta-analysis

Videolaryngoscopes are thought to improve glottic view and facilitate tracheal intubation compared with the Macintosh direct laryngoscope. However, we currently do not know which one would be the best choice in most patients undergoing anaesthesia. We designed this systematic review with network meta-analyses to rank the different videolaryngoscopes and the Macintosh direct laryngoscope. We conducted searches in PubMed and a further five databases on 11 January 2021. We included randomised clinical trials with patients aged ≥16 years, comparing different videolaryngoscopes, or videolaryngoscopes with the Macintosh direct laryngoscope for the outcomes: failed intubation; failed first intubation attempt; failed intubation within two attempts; difficult intubation; percentage of glottic opening seen; difficult laryngoscopy; and time needed for intubation. We assessed the quality of evidence according to GRADE recommendations and included 179 studies in the meta-analyses. The C-MAC and C-MAC D-Blade were top ranked for avoiding failed intubation, but we did not find statistically significant differences between any two distinct videolaryngoscopes for this outcome. Further, the C-MAC D-Blade performed significantly better than the C-MAC Macintosh blade for difficult laryngoscopy. We found statistically significant differences between the laryngoscopes for time to intubation, but these differences were not considered clinically relevant. The evidence was judged as of low or very low quality overall. In conclusion, different videolaryngoscopes have differential intubation performance and some may be currently preferred among the available devices. Furthermore, videolaryngoscopes and the Macintosh direct laryngoscope may be considered clinically equivalent for the time taken for tracheal intubation. However, despite the rankings from our analyses, the current available evidence is not sufficient to ensure significant superiority of one device or a small set of them over the others for our intubation-related outcomes.     

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.     

"Tube scratching" in the trachea on nasotracheal intubation: comparison of Macintosh and McCoy laryngoscopes

BACKGROUND: "Tube scratching" in the trachea, the intratracheal resistance of a tube, on nasotracheal intubation was evaluated using the Macintosh and the McCoy laryngoscope blade. METHODS: Fifty young patients requiring nasotracheal intubation were studied. Following induction of anesthesia, X-ray was taken before and during the use of two types of laryngoscopes. For analysis of the configuration of the upper airway, we drew three straight lines [axis of pharynx (P), larynx (L) and trachea (T)] on each film. "Tube scratching" was evaluated and graded to four by a supporting anesthesiologists. RESULTS: "Tube scratching" in the trachea was observed in 14/25 patients with McCoy laryngoscope and 4/25 patients with Macintosh laryngoscope (P < 0.05). Intubation with McCoy laryngoscope decreased more the angles formed by P and L, and L and P those that with Macintosh laryngoscope (P < 0.01). These data indicate that the lines of P, L and T tend not to align with McCoy laryngoscope, preventing the tracheal tube to be passed smoothly. CONCLUSION: An excessive lifting of the epiglottis, often observed in using McCoy laryngoscope, causes "Tube scratching" in the trachea on nasotracheal intubation.     

A ventilation-exchange bougie for fibreoptic intubations with the laryngeal mask airway

The ventilation-exchange bougie is a new airway device which can be mounted on a fibreoptic laryngoscope for passage through the larynx into the trachea via a laryngeal mask airway. Subsequent removal of the fibreoptic laryngoscope and laryngeal mask airway allows a tracheal tube to be railroaded into position over the ventilation-exchange bougie. This study described the use of this technique for elective tracheal intubation in two groups of 12 subjects in whom difficulty with intubation was not expected. All the subjects were successfully intubated by one of two anaesthetists, one experienced and the other inexperienced with fibreoptic intubation techniques. Neither had had prior experience with the ventilation-exchange bougie. Because ventilation was maintained throughout the procedure, intubation did not need to be hurried. Cusum analysis confirmed the impression of a learning curve and the technique could be considered learnt after four and six intubations for the experienced and inexperienced fibreoptic larvngoscopists respectively. No difficulty was found either in intubating the larynx with the fibreoptic laryngoscope and ventilation-exchange bougie or when railroading the tracheal tube over the ventilation-exchange bougie. It is suggested that this new device could have an important role in teaching fibreoptic techniques, management of the difficult airway and failed intubations.     

A clinical assessment of the Glidescope videolaryngoscope in nasotracheal intubation with general anesthesia

STUDY OBJECTIVES: To evaluate the efficacy and safety of the Glidescope videolaryngoscope as a device to aid nasotracheal intubation, and to determine whether the GSVL provides a better laryngeal view in patients with difficult laryngoscopy compared with the Macintosh laryngoscope. DESIGN: Prospective, clinical study. SETTING: Two university hospitals. PATIENTS: 156 healthy adult ASA physical status I and II undergoing elective plastic and intraoral surgery with general anesthesia. INTERVENTIONS: After anesthesia induction with intravenous injection of fentanyl 2 microg/kg, propofol 2 mg/kg, and vecuronium 0.1 mg/kg, nasotracheal intubation was performed using GSVL. MEASUREMENTS: Preoperative airway measurements were taken to predict potential difficult airways. During nasotracheal intubation using GSVL, laryngeal views, times required for full visualization of glottis and successful intubation, difficulty encountered and auxiliary maneuvers adopted, and upper airway trauma were recorded. The laryngeal views obtained by GSVL and by Macintosh laryngoscope were compared. MAIN RESULTS: The laryngeal views obtained by GSVL in all patients were Cormack and Lehane (C&L) grades I and II, and the success rate of intubation using GSVL at one attempt was 98.1%. The times required for visualization of the glottis and successful intubation were 40.2 +/- 11.5 s and 52.7 +/- 12.3 seconds, respectively. Patients with C&L grade II needed more auxiliary maneuvers to achieve successful intubation than did those with C&L grade I (P < 0.001). In 36 patients with potential difficult airways, the frequency of difficult laryngoscopy (C&L grades III and IV) with the Macintosh laryngoscope (58.3%) was significantly higher than with the GSVL (0%, P < 0.05). The frequency of minor upper airway trauma was 4.5%. CONCLUSIONS: The GSVL is an effective device for nasotracheal intubation and may be incorporated easily into routine clinical practice. Compared with the Macintosh laryngoscope, the GSVL can provide an improved laryngeal view in the patient with difficult airway.