of Medical Sciences, Tehran, Iran * Corresponding author:

Transcription

1 Volume: 4: Issue-7: July-2015 ISSN: Coden : IJAPBS COMPARISON OF LARYNGOSCOPIC GRADE OF GLOTTIS; GLIDESCOPE VIDEOLARYNGOSCOPE VERSUS MACINTOSH LARYNGOSCOPE Alireza Pournajafian M.D. 1 *, Ali Khatibi M.D. 1, Zahra Taghipour M.D. 2 1 Assistant Professor of Anesthesia, Department of Anesthesia, Firoozgar Hospital, Iran University of Medical Sciences, Tehran, Iran 2 Assistant Professor of Anesthesia, Department of Anesthesia, Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran * Corresponding author: pournajafian.ar@iums.ac.ir ABSTRACT: Background and Objective: Airway maintenance is an important task of anesthetists and they should be ready for managing difficult situations. The study was conducted to compare the efficacy of Glide scope video laryngoscope versus Macintosh laryngoscope in grading of glottic view in patients undergoing tracheal intubation for elective surgeries. Methods: A total of 222 patients classified as ASA physical status of I or II with Mallampati grade of II and greater who scheduled to undergo surgery requiring tracheal intubation, were enrolled in this study. All patients underwent laryngoscopy by both Macintosh laryngoscope and Glidescope. Cormack and Lehane (C&L) grading system were used to estimate the laryngeal view. Results: Our result showed that Glide scope significantly improved the laryngeal view in comparison with Macintosh laryngoscope in all patients (p<0.001). Eighty two patients were considered to have difficult airways (Mallampati grade III and IV). Of these patients, the difficult laryngoscopy frequency was significantly lower with Glide scope video laryngoscope (p<0.001). Conclusion: In conclusion, the Glidescope allows a better laryngeal view (and so easier intubation procedure) than Macintosh laryngoscope in both normal and difficult airway patients. We suggest that the Glidescope could be the choice device for tracheal intubation in difficult or emergency situations. Keywords: Glide scope video laryngoscope; Macintosh laryngoscope; Tracheal intubation; difficult intubation; airway management; laryngoscopy; INTRODUCTION Airway maintenance and securing ventilation is an important step during general anesthesia. Difficulties in providing on-time airway may cause brain hypoxia and resulted in brain damage.(1) Also multiple attempts for intubation may cause complications including dental damage, upper airway soft tissue trauma, laryngospasm and bronchospasm.(2) International Journal of Analytical, Pharmaceutical and Biomedical Sciences Page 97

2 Macintosh laryngoscope (MLS) is the gold standard device for tracheal intubation of normal airways during general anesthesia(3), but sometimes this process comes to difficulty. Among the devices used during difficult airway management is the Glidescope videolaryngoscope (GVL; Verathon Medical, Bothell, USA) (4) (figure 1),it is an 18 mm width biomedical rigid plastic blade which is 60 degree angle curved, with an embedded video camera and light source, which can be handled in one piece and used similar to the conventional laryngoscopy technique. The camera is connected to a liquid crystal display (LCD) monitor and provides a view of glottis and laryngeal entrance. Figure 1: Glidescope, Blades and stylet Some researchers have suggested that GVL is performing better than Macintosh laryngoscope in difficult and even normal airway (1, 5-7). GVL has some advantages than MLS like providing better laryngeal and vocal cords view, less cervical spine movement, less manipulation and trauma to the trachea and airways, and unlike MLS, Glidescope does not require the oral, pharyngeal and tracheal axes to be aligned. (8)Glidescopic intubation may not be successful in some pathological conditions of the airways like history of previous surgery, International Journal of Analytical, Pharmaceutical and Biomedical Sciences Page 98

3 radiotherapy, presence of a local mass.(8) GVL view may become obscure during active bleeding. Trismus, infections, tumors of oropharynges, and foreign bodies may cause difficulties on the insertion of the GVL blade (8). The aim of this study was to compare of Macintosh laryngoscope and Glidescope in grading of glottis view, in a clinical trial. MATERIALS AND METHODS This study is in accordance with the tents of the Declaration of Helsinki. The ethics committee of the Iran University of Medical Sciences, Tehran, Iran, approved the study design and protocol and written inform consent was obtained from all patients. Before the start of the study, based on a previous study (1), a power calculation was performed to determine the minimum sample size of the patients required to achieve a statistical power of 80% with α value of 0.05 and effective size of 0.2, and a minimum sample size of 52 patients with mallampathy 2 was obtained. A total of 291 patients classified as ASA physical status of I or II who scheduled to undergo surgical procedures requiring general anesthesia and tracheal intubation, were enrolled in this study. Preoperative airway assessment was performed to determine Mallampati classification (9) (class 1: soft palate, uvula, fauces and pillars visible; class 2: soft palate, fauces and pillars visible; class 3: only soft palate visible; and class 4: soft palate not visible), atlanto-occipital extension, inter-incisor distance, and thyromental distance. Patients with Mallampati of 2 and greater were included in the study.based on our inclusion criteria, 222 patients who were classified as Mallampati grade 2 and higher were enrolled in the study and 69 patients who were Mallampati grade 1 were excluded from the study. Also patients with a history of cardiac and lung disease, hypertension, morbid obesity, patients at risk of aspiration or regurgitation, drug allergy, cervical injury, were not included to the study. Before the induction of anesthesia, all patients were oxygenated with for 5 minutes with a high flow of oxygen. Anesthesia was induced with midazolam 0.02 μg/kg, fentanyl 3µg/kg, and after confirmation of sufficient bagmask ventilation, thiopental 5 mg/kg and atracurium 0.5 mg/kg were administered for neuromuscular blockade. In cases of mallampathi 3 after premedication, 2 mg/kg thiopental were injected and after confirmation of sufficient bag-mask ventilation the rest of hypnotic dose and muscle relaxant were administered. Standard monitoring including non-invasive arterial blood pressure, arterial oxygen saturation (Spo2), end-tidal carbon dioxide measurement and ECG were continuously recorded. Other alternative instruments such as fiberoptic bronchoscope, sizes 3, 4, and 5 of Laryngeal Mask Airway (LMA) and bugie stylet were available for managing difficult situations. All patients underwent laryngoscopy by Macintosh laryngoscope size 3 and then by Glidescope. Cormack and Lehane (C&L) grading system (10) were used when the anesthesiologist seen the glottis entrance to estimate the laryngeal view and the results were recorded. The intubation attempt was considered to be failed if the tracheal tube with the glottis could not be aligned in three different attempts and the tracheal intubation could not be performed. In these cases which intubation was not performed with both devices, the standard Difficult Airway Society failed Intubation algorithm (11) was followed. International Journal of Analytical, Pharmaceutical and Biomedical Sciences Page 99

4 Statistical Analysis Data analysis was performed using IBM SPSS Statistics (Version 21; IBM Inc., New York, USA). Paired t-test and 2 test was used to compare each grade group. Measurements were expressed as mean ± standard deviation. A p value of less than 0.05 was considered statistically significant. RESULTS Demographics and baseline characteristics of all patients are shown in table 1. There were 113 (50.9%) male patients and 109 (49.1%) female patients. Patients aged from 18 to 66 years. One hundred and forty patients were class II of Mallampati, 63 patients class III and 19 patients class IV. Laryngeal views obtained by each device are shown in table 2. From the preoperative assessment it was determined that 82 patients were considered to have difficult airways (Mallampati III and IV). Of these patients, 63 (76.8%) were Mallampati grade III and 19 (23.2%) were grade IV. The laryngeal view grades of these patients are demonstrated in table 3. The difficult laryngoscopy frequency (C&L grade III and IV) was significantly lower with Glidescope (grade III 3[3.7%] and grade IV 0[0%]) in comparison with Macintosh laryngoscope (grade III 24[29.3%] and grade IV 1[1.9%]). All patients were intubated without any serious problem or adverse effects. No alternative instruments used for intubation. Table1. Characteristics of the Study Population Feature Value (n= 222) Age (years) ± 8.48 (range 18 to 66) Gender (male) 113 (50.9%) ASA physical status I II 151 (68%) 71 (32%) Mallampati class II III IV 140 (63.1%) 63 (28.4%) 19 (8.6%) Data are reported as mean ± SD, or as number (%) International Journal of Analytical, Pharmaceutical and Biomedical Sciences Page 100

5 Table2. Comparison of laryngeal views obtained by Macintosh laryngoscope and Glide Scope video laryngoscope in all Patients Laryngeal views Glidescope Macintosh P value Videolaryngoscope Laryngoscope I 99 (44.6%) 81 (36.5%) <0.001 II 120 (54.1%) 103 (46.4%) III 3 (1.4%) 37 (16.7%) IV 0 (0%) 1 (0.5%) Data presented as number (%) of patients Table3. Comparison of laryngeal views obtained by Macintosh laryngoscope and GlideScopevideolaryngoscope in Patients with Difficult Airways Patients (Mallampati III and IV) Laryngeal views Glidescope Videolaryngoscope Macintosh Laryngoscope P value I 6 (7.3%) 0 (0%) <0.001 II 73 (89%) 57 (69.5%) III 3 (3.7%) 24 (29.3%) IV 0 (0%) 1 (1.9%) Data presented as number (%) of patients DISCUSSION Dental damage, bleeding, bronchospasm, laryngospasm, hypoxia and hypercarbia, and more severe and fatal conditions like brain damage are the results of tracheal intubation failure. Thus, improving the ease and success rate of intubation is an important issue for anesthetics. Our study findings showed that in comparison with Macintosh laryngoscope, GVL provideda better laryngeal view and reduced the tracheal intubation difficulty in normal and difficult airways. These finding are consistent with previous studies which compared Macintosh laryngoscope with the GVL in patients (1, 7, 12, 13) and manikins (14). International Journal of Analytical, Pharmaceutical and Biomedical Sciences Page 101

6 A meta-analysis by Mihai and colleagues (15) which was consisted with a total of 1076 patients with normal and 213 patients with possible difficult airway intubation revealed that GVL had a 69% improvement in laryngoscopic view than Macintosh laryngoscope. Xue et al.(16)have found that GVL provides better laryngeal view in potentially difficult airway patients. In their study 80% of patients were C&L grade 1, 20% grade 2 and no one were grade 3 and 4 with GVL but by using Macintosh laryngoscope 25% were grade 1, 16% grade 2, 50% grade 3 and 8% grade 4 (16). Armstrong and coworkers(17) have found a significant improvement in laryngeal view obtained by GVL in caparison with Macintosh laryngoscope in pediatric patients. They found with GVL, 89% of patients had better or the same laryngeal view(17). Lili et al. (18)conducted a study to compare intubation of ankylosing spondylitis patients with GVL and Macintosh laryngoscope, found that GVL significantly improved the C&L grade and laryngeal view and reduced the difficulty of intubation. On the contrary, some studies have not found a significant GVL advantage over Macintosh laryngoscope (19) and moreover some other studied reported that GVL may be even take more time during intubation.(6, 20) The reason that why tracheal intubation with GVL is easier may be that GVL does not need to a line of sight or alignment of the 3 axes to view the glottis and vocal cords, which allows viewing the structures that Macintosh laryngoscope, is unable to view. This condition significantly reduces the oropharyngolaryngeal tract compression needed for the glottis exposure in comparison with Macintosh laryngoscope and helps to decrease and reduce the trauma and injury to the airway tissue during intubation and laryngoscopy. (21) The GVL has several advantages over Macintosh laryngoscope. First, GVL magnifies the airway viewand with an anti-fog device, helps complete airway observation. Second, the GVL has a camera at the tip of a 60 degree angle curved blade and helps the operator to see those parts of the airway that with a Macintosh laryngoscope are impossible to observe. On the other hand, the location of the camera on a curved blade makes the operator to thinks the epiglottis is posterior to where it is actually located. Sakles and colleges (4) suggested that GVL may be a good device in education, because with its monitor the others can easily observe the intubation procedure. Some of the GVL disadvantages are prolonged preparation time, limited movement and mobility, difficult sterilization process and difficulty of insertion of the blade in head and neck diseases. Also since the actual view is separated from the LCD monitor, it may cause difficulties in performing the procedure. The GVL is an expensive device and has various shapes and blades which are not possible for many institutions and hospitals to purchase. Although GVL may not completely replace the traditional laryngoscopes, but its increasing availability and its superiority over Macintosh laryngoscope on tracheal intubation, may lead to more prevalent usage of GVL in university and teaching hospitals. Our study has some limitations leading to potential biases. First is that it was not possible to blind the anesthetists regarding which intubation device is being used. The second limitation is the laryngoscopic grading method used in this study which is subjective by nature. In order to minimize this bias, all patients were examined by just one anesthetist, although this may cause another bias. Although combination of indirect laryngoscopy with Cormack and Lehane classification may lead to obtaining easier and better glottic view, but since it does not reduce the difficulty of tracheal tube insertion, its appropriateness is under question. Another limitation is that all the intubations performed by anesthetist who was expert in using each device, then the results may be different with less experienced anesthetists. Among strengths of our study are: using the Cormack and Lehane classification which is more familiar with specialists and widely used in clinical practice, International Journal of Analytical, Pharmaceutical and Biomedical Sciences Page 102

7 studying a relatively large population rather than manikins, and performing both GVL and Macintosh blade on each patient. CONCLUSION In summary, the Glidescope allows a better laryngeal view and easier intubation procedure than Macintosh laryngoscope in both normal and difficult airway patients. Because the Glidescope is an effective device for tracheal intubation, we suggest that the Glidescope should be the choice device for tracheal intubation at least in patients with possible airway difficulties. Acknowledgment: - Financial Disclosures: None. No funds, grants or other support were received. - This article has not been presented at a meeting or published or submitted for publication elsewhere. - The research was supported by Iran University of Medical Sciences. - The authors have no funding or conflicts of interest to disclose. - We should thank to Dr. Farhad Zamani (Firoozgar Hospital chief) who agreed to pay for buying the Glidescope and also the anesthesia technicians who helped us in preparing and washing the devices. REFERENCES 1. Serocki G, Bein B, Scholz J, Dorges V. Management of the predicted difficult airway: a comparison of conventional blade laryngoscopy with video-assisted blade laryngoscopy and the GlideScope. European journal of anaesthesiology. 2010;27(1): Lee LA, Posner KL, Domino KB, Caplan RA, Cheney FW. Injuries associated with regional anesthesia in the 1980s and 1990s: a closed claims analysis. Anesthesiology. 2004;101(1): Foregger R. Richard von Foregger, Ph.D., Manufacturer of anesthesia equipment. Anesthesiology. 1996;84(1): Sakles JC, Rodgers R, Keim SM. Optical and video laryngoscopes for emergency airway management. Internal and emergency medicine. 2008;3(2): Bathory I, Frascarolo P, Kern C, Schoettker P. Evaluation of the GlideScope for tracheal intubation in patients with cervical spine immobilisation by a semi-rigid collar. Anaesthesia. 2009;64(12): Narang AT, Oldeg PF, Medzon R, Mahmood AR, Spector JA, Robinett DA. Comparison of intubation success of video laryngoscopy versus direct laryngoscopy in the difficult airway using high-fidelity simulation. Simulation in healthcare : journal of the Society for Simulation in Healthcare. 2009;4(3): Malik MA, O'Donoghue C, Carney J, Maharaj CH, Harte BH, Laffey JG. Comparison of the Glidescope, the Pentax AWS, and the Truview EVO2 with the Macintosh laryngoscope in experienced anaesthetists: a manikin study. British journal of anaesthesia. 2009;102(1): International Journal of Analytical, Pharmaceutical and Biomedical Sciences Page 103

8 8. Pott LM, Murray WB. Review of video laryngoscopy and rigid fiberoptic laryngoscopy. Current opinion in anaesthesiology. 2008;21(6): Mallampati SR, Gatt SP, Gugino LD, et al. A clinical sign to predict difficult tracheal intubation: a prospective study. Canadian Anaesthetists' Society journal. 1985;32(4): Cormack RS, Lehane J. Difficult tracheal intubation in obstetrics. Anaesthesia. 1984;39(11): Henderson JJ, Popat MT, Latto IP, Pearce AC. Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia. 2004;59(7): Choi GS, Lee EH, Lim CS, Yoon SH. A comparative study on the usefulness of the Glidescope or Macintosh laryngoscope when intubating normal airways. Korean journal of anesthesiology. 2011;60(5): Griesdale DE, Liu D, McKinney J, Choi PT. Glidescope(R) video-laryngoscopy versus direct laryngoscopy for endotracheal intubation: a systematic review and meta-analysis. Canadian journal of anaesthesia = Journal canadien d'anesthesie. 2012;59(1): Stroumpoulis K, Xanthos T, Bassiakou E, et al. Macintosh and Glidescope(R) performance by Advanced Cardiac Life Support providers: a manikin study. Minerva anestesiologica. 2011;77(1): Mihai R, Blair E, Kay H, Cook TM. A quantitative review and meta-analysis of performance of non-standard laryngoscopes and rigid fibreoptic intubation aids. Anaesthesia. 2008;63(7): Xue F, Zhang G, Liu J, et al. A clinical assessment of the Glidescope videolaryngoscope in nasotracheal intubation with general anesthesia. Journal of clinical anesthesia. 2006;18(8): Armstrong J, John J, Karsli C. A comparison between the GlideScope Video Laryngoscope and direct laryngoscope in paediatric patients with difficult airways - a pilot study. Anaesthesia. 2010;65(4): Lili X, Zhiyong H, Jianjun S. A comparison of the GlideScope with the Macintosh laryngoscope for nasotracheal intubation in patients with ankylosing spondylitis. Journal of neurosurgical anesthesiology. 2014;26(1): Kim HJ, Chung SP, Park IC, Cho J, Lee HS, Park YS. Comparison of the GlideScope video laryngoscope and Macintosh laryngoscope in simulated tracheal intubation scenarios. Emergency medicine journal : EMJ. 2008;25(5): Powell L, Andrzejowski J, Taylor R, Turnbull D. Comparison of the performance of four laryngoscopes in a high-fidelity simulator using normal and difficult airway. British journal of anaesthesia. 2009;103(5): Malik MA, Subramaniam R, Maharaj CH, Harte BH, Laffey JG. Randomized controlled trial of the Pentax AWS, Glidescope, and Macintosh laryngoscopes in predicted difficult intubation. British journal of anaesthesia. 2009;103(5): International Journal of Analytical, Pharmaceutical and Biomedical Sciences Page 104