Comparative Essay Sample: Stylet Angulation of 60 and 90 for the Ease of Intubation with Videolaryngoscope

Management of the patient's airway is an important skill for anaesthetists. Even though serious airway complications are rare during anaesthesia, the adverse complications can be life threatening. According to the Fourth Audit Project of the anaesthetists reported that out of the 133 reported airway complications, 16 led to death and 3 patients sustained brain damage. Therefore, to minimize mortality and morbidity, it is essential that anaesthestists the endowed with best airway management techniques (John & Ahmad, 2015).

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The MCGrath Viedolaryngoscope (VL) provides laryngoscopic views. However, it is difficult to direct the endotracheal tube (John & Ahmad, 2015). The VLs facilitates the tracheal intubation by enabling anaesthetists to have improved vision of the larynx without exposing the oral-pharyngeal-laryngeal. Studies have indicated that VLs improve the overall success rate of intubation and significantly reduce intubation difficulties. The McGrath, like other VLs offers a superior laryngeal view and also provides better airway management for patients (Zaouter, Calderon, & Hemmerling, 2015). However, an improved view is not always an assurance of intubation success as the larynx axes are not aligned and hence the endotracheal tube tip must pass through an acute angle to enter the larynx. Manufactures recommend an angle between 45o and 90o to have optimal view of the larynx. This study was conducted to determine the optimal angles (between 60o and 90o) of the stylet when using McGrath VL.

Methods

This study involved 100 patients of both male and female who were undergoing selective urgeries that required endotracheal intubation. Approval by the institutional officials and a written assent was obtained from the participating patients. The patients involved were aged between 19 years and 70 years. This study excluded patients that required rapid sequence intubation; ASA III, IV, and V; patients that required emergency surgeries; and patients with mallampati score 4.

Patients were randomly divided in two equal groups, 50 patients for 60o (n=50) and 50 patients for 90o (n=50). Standard monitors (ECG, SPO2, and NIBP) were attached after patients arrived in the operation room. A standardized anaesthetic was introduced. Patients were also premeditated with midazolam 0.05mg/kg, glycopyrolat 0.005mg/kg, and inj fentanyk 2 micrograms/KG iv. Patients were also induced with propofol 1-2 mg/kg. To aid tracheal intubation, the participant patients were given the neuromuscular blocking drug vecuronium 0.1 mg/kg. Laryngoscopy was done using McGrath videolaryscope and the Glottic opening was visualized. For the 90o group, intubation was done with 90o angled stylet ETT while for 60o group; intubation was done with 60o angled stylet ETT. Time of intubation was recorded for each patient. Other outcomes recorded were as follows: ease of intubation, failed intubation at 1st attempt, Glottic grade, and presence of oropharyngeal bleeding. If change of tube was necessary, only the time of the 1st tube was noted.

Statistical Analysis

Category variables were analyzed using the Chi square test while continuous variables were analyzed using the independent t test between 60o and 90o groups. P 0.05 was considered statistically significant for 95% confidence level. The table bellow summarizes the study findings.

Table 1

Summary of study findings

Parameters Group 600 Group 900 P Value

Intubation time (Sec) 28.2 6.8 33.5 9.8 0.022

Glottic Grade 1/2a/2b/3/4 38/8/2/2/0 32/10/8/0/0 0.658

Failed First Attempt 50/0 38/12 0.116

Ease of Intubation Easy/Intermediate/Difficult 45/5/0 38/6/6 0.070

Bleeding Yes/No 48/2 43/7 0.718

Results

A total of 100 patients completed this study. All the patients in 60o group intubated successfully with 1st attempt and within 50 seconds. On the other hand, intubation of six patients failed in the group 90o. The degree of intubation difficulty and glottic grade were not significantly different between the 60o and 90o groups.

Discussion

Currently, the incidence of difficulties direct intubation in intensive care units is as high as 20%. Video technology in the healthcare sector has facilitated the development of video laryngoscopes like the McGrath to help in difficulties in airway management. VLs have improved safety by avoiding preventable intubation attempts. VLs make it possible for the entire anesthesia team to assess the progress congruently. This facilitates cohesion and communication of the team and improving coordination between the operator and the assistant(s) (Paolini, Donati & Drolet, 2013).

Conclusion

In the present study, it was found that McGrath VL with 60o stylletted tube is an effective aid for airway management considering the high intubation success rates and the ability to rapidly secure the airway. In this study in 600 group the time of intubation was significantly shorter than in 900 group. The possible explanation is it was easier to use the 60 than the 90 angle to deliver the tube to the glottic opening through the oral cavity. Additionally, the distal tip of the 90 styletted tube had a tendency to veer toward the anterior commissure, and it was difficult to advance the tube into the trachea at the vocal cord. In the open airway model during GlideScope VL intubation, it was easier to advance the tube and TTI was shorter using the 60 styletted tube rather than the 90 tube (Paolini, Donati & Drolet, 2013). In addition, despite the application of lubricant, removing the stylet and advancing the tube into the trachea were more difficult in the 90 group than in the 60 group. Therefore, McGrath videolaryngoscope, 60 angled stylet is more effective than 90angled stylet as it allowed for faster orotracheal intubation.

References

John M, Ahmad I, Preloading bougies during videolaryngoscopy. Anaesthesia. 2015;70:111-2

Lafferty BD, Ball DR, Williams D. Videolaryngoscopy as a new standard of care. Br J Anaesth 2015;115:136-7

Paolini JB, Donati F, Drolet P. Review article: video-laryngoscopy: another tool for difficult intubation or a new paradigm in airway management? Can J Anaesth 2013;60:184-91. [PubMed]

Zaouter C, Calderon J, Hemmerling TM. Videolaryngoscopy as a new standard of care. Br J Anaesth2015;114:181-3. [PubMed]