|Year : 2018 | Volume
| Issue : 2 | Page : 134-140
Comparison between fiberoptic bronchoscope versus C-MAC video-laryngoscope for awake intubation in obese patients with predicted difficult airway
Abdelazim A.T Hegazy, Helmy Al-Kawally, Ezz F Ismail, Mofeed A Abedlmabood, Usama A Mandour
Department of Anesthesia and Intensive Care, Faculty of Medicine, Al-Azhar University, Cairo, Egypt
|Date of Submission||28-Feb-2017|
|Date of Acceptance||21-Oct-2017|
|Date of Web Publication||28-Jun-2018|
Abdelazim A.T Hegazy
Department of Anesthesia and Intensive Care, Faculty of Medicine, Al-Azhar University, Nasr City, Cairo
Source of Support: None, Conflict of Interest: None
Background Airway care providers are familiar with video-laryngoscopes (VL) that have blades like that of traditional laryngoscope (Macintosh and Miller). Moreover, most of these providers have limited experience with fiberoptic bronchoscope (FOB). C-MAC VL is one of such VLs, and its D-blade was designed for anticipated difficult airway and airway management of obese patients.
Aim The aim of this study was to assess the time required for awake intubation using C-MAC VL versus flexible FOB in morbidly obese patients with anticipated difficult airway assessed by El-Ganzouri simplified risk index.
Patients and methods Sixty adult patients of both sexes were divided into two equal groups (30 patients each). In group FOB, awake patients were intubated using the flexible FOB. In group VL, awake patients were intubated using the C-MAC VL. Intubating time, laryngeal view, intubating attempts, heart rate, mean arterial pressure, oxygen saturation, and sore throat were recorded.
Results Intubation time was significantly longer in FOB group compared with VL group. In VL group, 26 patients were intubated successfully on the first attempt, two patients on the second attempt, and two patients on the third attempt, whereas in FOB group, 22 patients were intubated successfully on the first attempt, six patients on the second attempt, and two patients on the third attempt. In FOB group, all patients had 100% percentage of glottic opening score. In VL group, 24 patients had 100% percentage of glottic opening score, four patients had 50–100% score, and two patients had less than 50%. The intubation success rate was 100% in both groups. There were no significant differences between both the groups at baseline and at first and fifth minute after intubation in hemodynamic parameters, CO2, and O2 saturation.
Conclusion This study concluded that intubation time was shorter using C-MAC VL compared with flexible FOB for awake intubation of morbidly obese patients with anticipated difficult airway. However, flexible FOB provides excellent visualization of the glottic opening.
Keywords: C-MAC video-laryngoscope, difficult airway, fibrotic bronchoscope, morbid obesity
|How to cite this article:|
Hegazy AA, Al-Kawally H, Ismail EF, Abedlmabood MA, Mandour UA. Comparison between fiberoptic bronchoscope versus C-MAC video-laryngoscope for awake intubation in obese patients with predicted difficult airway. Res Opin Anesth Intensive Care 2018;5:134-40
|How to cite this URL:|
Hegazy AA, Al-Kawally H, Ismail EF, Abedlmabood MA, Mandour UA. Comparison between fiberoptic bronchoscope versus C-MAC video-laryngoscope for awake intubation in obese patients with predicted difficult airway. Res Opin Anesth Intensive Care [serial online] 2018 [cited 2018 Sep 22];5:134-40. Available from: http://www.roaic.eg.net/text.asp?2018/5/2/134/235483
| Introduction|| |
Difficult mask ventilation, rapid desaturation, or difficult intubation has been associated with anesthesia in obese patients ,,. The difficult or failed intubation in obese patients is more common than patients who are not obese . For example, Shiga et al.  reported the incidence of difficult intubation in the obese population was greater than 15.8% compared with 5.8% in the general population, whereas Juvin et al.  reported 15.5% compared with 2.2%. Gonzalez et al.  suggest that it is more difficult to perform tracheal intubation or obtain a clear view of the glottis in morbidly obese patients. The multiple airway features should be assessed carefully in anticipated difficult airway management. El-Ganzouri simplified risk index (EGRI) combines and stratifies seven variables derived from parameters and observations individually associated with difficult intubation, and a score of more than 4 has been used as the definition of difficult intubation in different populations .
Noninvasive intervention for management of difficult airway is a widely achieved by fiberoptic-guided intubation (FOI) and has been successful in 88–100% of patients with difficult airway . Awake intubation of a morbidly obese patient with predicted difficult airway has been done successfully with Glide Scope [video-laryngoscope (VL)] .
C-MAC VL, one of the VLs, has a flexible monitor that allows physicians to secure the airway under vision and additionally capture pictures and videos in real time, and its D-blade was designed for anticipated difficult airway and airway management of obese patients ,. Indirect visualization of the laryngeal inlet provided by the newly designed VLs facilitates tracheal intubation . Airway care providers are familiar with laryngoscopes that have blades like that of the traditional laryngoscope (Macintosh and Miller). As most of the providers have limited experience with FOI, the present study was designed to appreciate and confirm which of the studied devices [C-MAC D-blade or fiberoptic bronchoscope (FOB)] is more feasible in clinical settings, and it attempts to provide results that may make the operator (airway care provider) more relaxed and increasingly confident during intubation procedure for a morbid obese patient with anticipated difficult intubation.
The aims of the present study are as follows: the primary outcome was to assess the time required for awake intubation using C-MAC VL versus flexible FOB in morbidly obese patients with anticipated difficult airway assessed by EGRI. Secondary outcomes were to evaluate the success rate of awake intubation and glottis exposure by both devices.
| Patients and methods|| |
This prospective, randomized and controlled study was carried out at Al-Hussain Hospital, Al-Azhar University, Cairo, Egypt. After obtaining approval from the Research/Ethics Committee and informed written consents from all patients, 60 adult patients of both sexes with American Society of Anaesthesiologists physical status class II, aged 18–60 years, with BMI of at least 35 kg/m2undergoing elective surgeries and necessitating endotracheal intubation were included in this study. EGRI was used for airway assessment ([Table 1]). Inclusion criteria were as follows: any obese patients (BMI≥35 kg/m2) with EGRI of at least 4 were included in the study, whatever the surgical operation is. Exclusion criteria were as follows: patients have increased risk of pulmonary aspiration; have significant medical diseases in term of cardiac, respiratory, hepatic, renal, etc.; have cervical spine pathology; have upper airway pathology; and who had refused to give consent.
The patients were randomly assigned into two groups (30 patients each) per computer-generated randomization technique. Group FOB included patients undergoing awake intubation using the flexible FOB. Group VL included patients undergoing awake intubation using the C-MAC VL D-blade. Premedication was employed for all patients and included the following: atropine: 0.5 mg intramuscularly 30 min before manipulation of the airway and midazolam 1 mg intravenously and fentanyl 30 μg intravenously before the airway procedure, but after topicalization of the airway.
Technique: all patients were subjected to the same anesthetic protocol: preparation of patient was done in induction room, and planning of the procedure was explained to the patient. Lignocaine 10% pump spray (each metered dose ‘puf’ delivers 0.1 ml, which contains 10 mg lignocaine)  had been used by applying two puffs on tonsillar pillars and back of the throat; the patients were asked to keep the medication in their mouth after puffing, and then the operator gave the patients soaked gauze by lignocaine 10% pump spray and asked them to keep it in mouth until achieving numbing of the upper airway for all patients in both groups. The used lignocaine dose did not exceed the maximum dose (3 mg/kg of lean patient’s body weight). The sufficiency of the oropharyngeal analgesia was evaluated by the patient’s acceptance of Guedel airway being placed in their mouth or introduction of the blade of laryngoscope after lidocaine application. Once the patient tolerated the introduction of the blade of the laryngoscope and a good view of the glottis was obtained, two puffs of lignocaine 10% pump spray were administered on the glottic opening to anesthetize the vocal cords, and then the patient was shifted to the operating room. In operating room, standard airway and emergency equipment were kept on standby and were available. Ramping position of the patient was attained by placing multiple folded blankets under the patient’s upper body, neck, and head until the external auditory meatus and the sternal notch were horizontally aligned. .
Intubation procedure in group VL was as follows: patients were intubated using the C-MAC VL D-blade. The blade was inserted into the mouth in the midline, over the center of the tongue, and the tip was positioned in the vallecula. The view was shown on the LED monitor until the epiglottis and the vocal cords were seen, and then the endotracheal tube (ETT) was advanced until it was seen passing through the vocal cords (a semirigid stylet preshaped as a hockey stick was used to guide the ETT).
The response of the patient to introduction of the ETT was graded as follow: 0=no coughing or gagging, 1=mild coughing or gagging that did not hinder intubation, 2=moderate coughing and/or gagging that interfere minimally with intubation, and 3=severe coughing and/or gagging that made intubation difficult. If severe gagging or coughing occurred, two more puffs of lidocaine 10% were administered under direct vision, and intubation was reattempted after 60 s. Only three intubation attempts were allowed for each patient, and if failed (an intubation attempt was considered unsuccessful if the VL was removed from the oral cavity owing to coughing, gagging, or inability to view the vocal cords), plan B was implemented using awake flexible FOB.
Intubation time is measured from insertion of C-MAC D-blade in the mouth till confirmation of ETT placement by capnography.
Intubation procedure in group FOB was as follows: this was facilitated by intubating oral airway used to protect the bronchoscope, maintain a midline position, and displace the tongue more easily. Patient reassurance was done by the operator. Awake FOI was performed with the patient in the supine position and the operator at the patient‘s head. The FOB was inserted in the intubating oral airway, and its tip was tilted ∼45° upward and advanced forward until it is beyond the base of the tongue where it was directed to the glottic opening and vocal cords. Once the scope had entered the trachea, it was advanced forward till the carina appeared on the LED monitor. A previously loaded ETT (on shaft of FOB) was railroaded into the trachea keeping its tip 2–3 cm above the carina. Then, the scope was withdrawn as the tube was held in place by the assistant.
Intubation time is measured from insertion of FOB in intubating oral airway till confirmation of ETT placement by capnography.
In both groups, proper ETT position was reconfirmed by auscultation of equal bilateral chest air entry and observance of the equality of chest movement bilaterally.
Measured parameters were recorded in preanesthetic check visit in term of demographic data (age, weight, height, BMI, and sex) and predictors of difficult airway (mouth opening, thyromental distance, modified Mallampatti Score, neck movement, ability to prognath, weighing the body weight, and history of previous difficulty intubation) and intraoperatively using duration of intubation, number of attempts of intubation, and success rate of intubation. Hemodynamic measurements such as heart rate and mean arterial blood pressure, end-tidal CO2, and O2% saturation were recorded at just before starting intubation procedure as baseline reading and then at first and fifth minute after intubation procedure.
The laryngeal view was assessed by the percentage of glottic opening (POGO) scale . The POGO scale represents the linear span from the anterior commissure to the inter-arytenoid notch ([Figure 1]) that was visualized during endoscopy (either by C-MAC or FOB). POGO score represents the glottic opening ranging from 1 to 100%. We found that POGO scale was more practical than Cormack–Lehane scale as only three grades could be recorded: grade 1 (<50%), grade 2 (50–100%), and grade 3 (100%).
|Figure 1 The percentage of glottic opening score for laryngeal grading .|
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The following intubation criteria were recorded for both groups: visualization of the laryngeal inlet (POGO scale), duration of the intubation procedure (mentioned before for each group), number of intubation attempts (an intubation attempt was considered unsuccessful if C-MAC VL or FOB was removed from the oral cavity owing to coughing, gagging, or inability to view the vocal cords), success rate of endotracheal intubation as well as hemodynamic and O2 saturation changes during the procedure. End-tidal CO2 was recorded after intubation and at first and fifth minute after intubation.
Sample size calculation was based on previous studies. The time of successful intubation in the C-MAC group was 35 s compared with 59 s in the flexible fiberoptic scope group (with SD=22 and 36, respectively) . In the present study, 26 patients would be required for each group, and these were sufficient to give α of 0.05, with 95% confidence interval, actual power 80%, and β=0.2. The total sample size was increased to 30 patients per group to compensate for patient dropout. Data were coded and entered using the statistical package SPSS, version 21 (IBM International Business Machines Corporation) is an American Multinational Technology Company Headquartered in Armonk, New York, United States). Data were summarized using mean, SD, median, minimum, and maximum for quantitative variables and frequencies (number of cases) and relative frequencies (%) for categorical variables. Comparisons between groups were done using unpaired t-test in normally distributed quantitative variables, whereas the nonparametrical Mann–Whitney test was used for non-normally distributed variables. For comparing categorical data, χ2-test was performed. Fisher’s exact test was used instead when the expected frequency is less than 5. P values less than 0.05 were considered significant.
| Results|| |
Demographic data were comparable in both studied groups. There were no statistically significant differences between the study groups regarding age, sex, weight, height, BMI, and ASA physical status ([Table 2]).
All patients were assessed by El-Ganzouri scoring system, and there were nonsignificant differences between both studied groups regarding mouth opening, thyromental distance, modified Mallampatti Score, neck movement, ability to prognath, body weight, and history of difficult intubation ([Table 3]).
Regarding POGO Scale, in group VL, 24 (80%) patients had grade 3, four (13.3%) patients had grade 2, and only two (6.7%) patients had grade 1, whereas, all patients in FOB group had grade 3 POGO score ([Table 4]).
The intubation success rate was 100% in both groups, with no statistically significant difference. Intubation time was significantly longer in FOB group than VL group (68±4.47 vs. 28.4±4.53). In VL group, 26 patients were intubated successfully on the first attempt, two patients on the second attempt, and two patients on the third attempt, whereas in FOB group, 22 patients were intubated successfully on the first attempt, six patients on the second attempt, and two patients on the third attempt, with no statistically significant difference between both groups ([Table 5]).
|Table 5 Duration of intubation, number of intubation attempts, and success rate|
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There were no significant differences between both groups at baseline (at starting of procedure) and at first and fifth minute after intubation in hemodynamic parameters such as heart rate and mean blood pressure ([Table 6]).
There were no significant differences between both groups in end-tidal CO2 and O2 saturation at baseline (at starting of procedure) at first and fifth minute after intubation ([Table 7]).
| Discussion|| |
More than two-thirds of adults in the USA are overweight or obese, and an increasing percentage is morbidly obese . Patients with a BMI over 40 (or BMI of 35 with one additional comorbidity) are considered candidates for bariatric surgery . There are many well-known obesity-related challenges in airway management including difficulty with mask ventilation, endotracheal intubation, more frequent and rapid oxygen desaturation, increased oxygen consumption, and increased sensitivity to the respiratory depressant effects of anesthetic and analgesic drugs . So, the search for safety anesthesia and easy endotracheal intubation is indicated.
The current study showed longer intubation time in patients intubated with the FOB (68±4.47) than patients intubated with the C-MAC VL (28±4.53). This was in line with the Elvir Lazo et al. , who compared tracheal intubation with the C-MAC VL versus FOB in patients undergoing cervical spine surgery and found that time of intubation was longer in the FOB group. Moreover, Yumul et al.  reported that the use of the Video-Mac VL device significantly reduced the intubation time compared with standard direct laryngoscope.
The current study showed higher first-attempt success rate using the C-MAC VL than using FOB [26 (86.7%) vs. 22 (73.3%)]. This was in line with the Abdellatif et al.  who compared Glide Scope video-laryngoscope (GVL) with flexible FOB for awake intubation of morbidly obese patients with predicted difficult intubation, and they concluded that intubation success rate on the first attempt was 80.6 and 75% in GVL and FOB, respectively, with no statistical difference between the two groups.
All patients in the FOB group had 100% POGO score, whereas 80% of patients intubated with VL had 100% POGO score. This was in line with the Abdellatif et al.  who found that GVL group had grade I/II glottic view in 30 (96.7%) of 31 patients and only one patient had grade III glottic view, but with FOB, the researchers reported a grade I/II glottic view in 32 (100%) of 32 patients using Cormack–Lehane grading system. In the present study, all patients in FOB group had 100% POGO score, whereas 80% of patients intubated with C-MAC VL had 100% POGO score. Moreover, Yumul et al.  used the Video-Mac VL device for tracheal intubation of obese patients and showed improvement in the visualization of the larynx. In same way, the Gaszyński et al. , who used the V-MAC VL) an earlier version of the C-MAC) in a group of morbidly obese patients to see if it improves intubation conditions, concluded that the V-MAC improves laryngeal view and allows for fast endotracheal intubation. Bhat et al. , comparing the easiness of intubation in right and left lateral positions using C-MAC VL, found that the success rate was 100%, and they reported a successful first-attempt intubation in 92% of patients and no difference between right and left lateral positions.
The current study also demonstrated that hemodynamic parameters were well maintained during the intubation procedure and were comparable in both groups, despite the prolonged duration of intubation in the fiberoptic group. This was in line with Aqil  who studied the stress response to endotracheal intubation comparing Glide Scope and flexible FOB and found no significant difference in hemodynamic parameters. Moreover, Sabry et al.  compared the efficacy of the C-MAC D-blade with the McCoy laryngoscope in intubating patients during cervical spine immobilization and concluded that the C-MAC D-blade laryngoscope causes less hemodynamic stress and allows better intubation in the first trial.
Current study demonstrates sore throat postoperatively in only one patient in VL group and in two patients in FOB group. This was in line with the Elvir Lazo et al. , who compared tracheal intubation with C-MAC VL versus FOB in patients undergoing cervical spine surgery and found that a small number of patients complained of sore throat after surgery, and this was nonsignificantly higher in the C-MAC group (5 vs. 1) compared with the fiberoptic group.
| Conclusion|| |
This study concluded that intubation time was shorter when C-MAC VL was used for awake intubation of morbidly obese patients with anticipated difficult airway compared with flexible FOB. However, flexible FOB provides excellent visualization of laryngeal structures.
The present study has some limitations. The study was conducted on morbidly obese patients with anticipated difficult airway, so its results cannot be extrapolated to patients with significant medical diseases such as uncontrolled hypertension, ischemic heart disease, or having other comorbidities. Moreover, the study was limited to only 60 patients considering intubation time as the primary outcome parameter, so bigger sample may be required to assess other parameters.
The problems of the current study design were related in part to the fact that this prospective randomized study could not be performed in a blinded fashion; hence the possibly of operator bias exists with respect to intubating conditions and adverse effects on the airway. The standardized scales used to perform the assessment of the glottis view at the time of tracheal tube placement can be criticized.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]