|Year : 2017 | Volume
| Issue : 1 | Page : 164-172
Feasibility and outcome of GlideScope videolaryngoscope versus C-MAC videolaryngoscope in the management of obese patients with potentially difficult intubation
Abd-Elfattah M Daboun, Ezz El-Din F Ismail, Hassanain A Hamzawy, Ayman S Emara
Department of Anesthesia, Intensive Care and Pain Medicine, Faculty of Medicine (for Boys), Al-Azhar University, Cairo, Egypt
|Date of Web Publication||3-Aug-2018|
Ayman S Emara
Lecturer of Anesthesia, Intensive Care & Pain Medicine. Al-Azhar University, Cairo
Source of Support: None, Conflict of Interest: None
Background Difficult and failed tracheal intubation remains a leading cause of morbidity and mortality related to anesthesia practice. Videolaryngoscopes were introduced into practice to increase the success rate of intubation in obese patients with difficult airway.
Aim The aim of this study was to compare GlideScope and C-MAC videolaryngoscopes in obese patients with anticipated difficult intubation as regards feasibility and outcome.
Patients and methods The study was designed as a prospective comparative single-blind study, which was conducted at King Abdullah Hospital, Bisha, KSA, during the period from January 2013 to January 2015. It included 60 obese patients with anticipated difficult intubation. They were randomly divided into two equal groups: the GlideScope group and the C-MAC group. All patients were assessed for demographic characteristics, intubation parameters, and outcome.
Results There were no significant differences between the two groups as regards general characteristics and hemodynamics. However, there was a significantly better glottic view in the GlideScope group compared with the C-MAC group. There was a significantly shorter total intubation time and first attempt intubation time in the GlideScope group compared with the C-MAC group (32.43±2.40 and 28.70±2.15 s vs. 40.40±5.07 and 34.80±2.92 s, respectively). The incidence of failure of the first intubation attempt was significantly higher in the C-MAC group compared with the GlideScope group (33.3 vs. 10.0%, respectively). Overall satisfaction was significantly better in the GlideScope group compared with the C-MAC group.
Conclusion GlideScope had better glottic view, shorter total intubation and first attempt intubation times, and higher success rate of first intubation attempt compared with C-MAC. These results advocate the use of GlideScope in obese patients with potentially difficult intubation.
Keywords: C-MAC, difficult intubation, GlideScope, obese patients, videolaryngoscope
|How to cite this article:|
Daboun AEM, Ismail EDF, Hamzawy HA, Emara AS. Feasibility and outcome of GlideScope videolaryngoscope versus C-MAC videolaryngoscope in the management of obese patients with potentially difficult intubation. Ain-Shams J Anaesthesiol 2017;10:164-72
|How to cite this URL:|
Daboun AEM, Ismail EDF, Hamzawy HA, Emara AS. Feasibility and outcome of GlideScope videolaryngoscope versus C-MAC videolaryngoscope in the management of obese patients with potentially difficult intubation. Ain-Shams J Anaesthesiol [serial online] 2017 [cited 2018 Dec 17];10:164-72. Available from: http://www.asja.eg.net/text.asp?2017/10/1/164/238446
| Introduction|| |
Difficult and failed tracheal intubation remains a leading cause of morbidity and mortality related to anesthesia practice , despite advances in strategies to predict  and to manage  the difficult airway. Several anatomic (e.g. obesity, large tongue, short neck, small mandible, and cervical immobility) and pathologic conditions (e.g. blood, vomit, airway edema, and facial or neck trauma) have been identified as a reliable predictor of difficult airway. In contrast, a failed airway is one that is not predicted but is experienced after three failed attempts, or that has inability to maintain adequate oxygen (O2) saturations .
Standard direct laryngoscopy remains the most widely used method for intubation, irrespective of development of different alternatives. It requires alignment of the oral, pharyngeal, and laryngeal axes to view the vocal cords. However, indirect laryngoscopes require alignment of only the pharyngeal and laryngeal axes, which lie along similar angles as compared with the oral axis. In recent years, videolaryngoscopy is being increasingly used for the routine management of the difficult airway .
GlideScope videolaryngoscope (GVL) has been available since 2003 and consists of a handle and nondetachable blade, which has a maximum width of 18 mm and a curvature of 60° in the midline. A digital camera and two light-emitting diodes are embedded at the tip of the blade. The video camera is recessed for protection from blood and secretions, which might obstruct the view, and has a relatively wide viewing angle of 50°. The heated lens innovation helps to prevent fogging of the lens, which might otherwise obscure the view. The wide-angle lens, central insertion of the blade, and the fact that the camera always remains remote from the laryngeal structures result in a rather wide visual field ([Figure 1]). Early studies with the GVL reported that it may make intubation easier when difficulty is caused by insufficient exposure of the larynx . It is a relatively novel device used for endotracheal intubation in patients with normal and difficult airways . It has been associated with high success rates and minor complications .
C-MAC was introduced into clinical practice in 2002. It is usually composed of a standard Macintosh blade that is connected to a video unit to which images are transmitted from a distal lens placed two-thirds of the way along the blade ([Figure 2]). A potential advantage of the C-MAC is that it can be used as a standard direct laryngoscope or as an indirect laryngoscope. In addition, as the C-MAC design incorporates a Macintosh blade, learning curve is expected to be easier compared with the other indirect laryngoscopes .
Platts-Mills et al.  compared direct laryngoscopy and videolaryngoscopy in the emergency department setting. They reported an equivalent success rate between the devices with minimal to no previous experience with videolaryngoscopy, suggesting that it is at least as good as, if not superior to, direct laryngoscopy. However, subsequent studies recommended videolaryngoscopy to be superior to direct laryngoscopy. The 2013 report from the American Society of Anesthesiologists (ASA) Task Force on the management of the difficult airway even advocates videolaryngoscope devices as an initial approach to intubation (Practice guidelines for management of the difficult airway, 2013; Special article: An Updated Report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. nesthesiology 2013; 118:XX–XX).
| Aim|| |
The current study aimed to compare GlideScope and C-MAC videolaryngoscopes in obese patients with anticipated difficult intubation as regards glottic view, intubation criteria, and overall satisfaction, and to record any complication during intubation.
| Patients and methods|| |
The study was designed as a prospective comparative single-blind study, which was held at King Abdullah Hospital, Bisha, KSA, during the period from January 2013 to January 2015. The study protocol was approved by the local ethics committee of King Abdullah Hospital, and all patients signed an informed consent for participation in the study after full explanation of the study procedure. It included 60 obese patients with anticipated difficult intubation who were scheduled to undergo elective surgeries under general anesthesia.
The patients included in this study were of ASA physical status I–II with a BMI>30 kg/m2. Exclusion criteria were as follows: age younger than 18 years, presence of pulmonary diseases, uncontrolled hypertension, ischemic heart disease, cervical spine fracture, tumors or polyps in the upper airway, history of difficult intubation or difficult bag mask ventilation, and patients with difficult bag mask ventilation after induction of anesthesia. All patients were examined for difficult intubation according to El-Ganzouri Risk Index score.
The preanesthetic visit was carried out by an anesthesiologist not involved in this study, to assess all cases for age, sex, ASA physical status, body weight, and height, and then, BMI was calculated from the equation [BMI=weight (kg)/height (m2)]. On the basis of BMI, patients were classified as obese (>30 kg/m2), morbidly obese (>35 kg/m2), and super-morbidly obese (>55 kg/m2) . He also carried out airway assessment, including measurement of common predictive indices for difficult intubation (mouth opening, thyromental distance, modified Mallampati score, neck movement, ability to prognath, body weight, and history of difficult intubation) according to El-Ganzouri Risk Index score for difficult intubation. The minimum score is 0 and maximum score is 12. A score less than 4 is unlikely to be difficult intubation and score greater than and equal to 4 is likely to be difficult intubation . The score of each patient was recorded. The patients included in this study had score greater than and equal to 4 and likely to be difficult intubation.
They were randomly divided into two equal groups according to the type of videolaryngoscope used: group I, the GlideScope group (n=30), and group II, the C-MAC group (n=30). Randomization was carried out using a sealed envelope method, wherein number 1 was assigned for 30 envelopes and another 30 were assigned number 2. The envelopes were then sealed and opened by a nurse not included in the study just before inducing anesthesia.
When the patients arrived at the operating room, they were connected to standard monitoring devices (ECG, noninvasive blood pressure, and pulse oximetry) and received O2 for at least 3 min until end-tidal O2 reached above 80%. Anesthesia induction consisted of intravenous fentanyl 1.5 µg/kg and propofol 2 mg/kg based on estimated lean body weight. Manual mask ventilation and inflation of the lungs was attempted through a bag face mask using sevoflurane in O2 before muscle relaxant injection. Once the ability of the bag mask ventilation was verified, atracurium 0.5 mg/kg was administered. Patients with difficult bag mask ventilation were awakened after insertion of laryngeal mask airway to facilitate manual ventilation of lungs and then intubated with awake fiberoptic bronchoscope and excluded from our study.
After ∼3 min with bag mask positive pressure ventilation and ensuring maximum neuromuscular blocking effect as assessed by train of four count=0, the trachea was intubated using the GlideScope (Saturn Biomedical Systems Inc., Burnaby, British Columbia, Canada) or C-MAC (Karl Storz GmbH & Co., Tuttlingen, Germany) videolaryngoscope. During the intubation procedure, passive O2 supply was administered using a nasal cannula at 8 l/min, which was removed after successful intubation. At first, the glottic view was assessed using both videolaryngoscopes according to the modified Cormack and Lehane grading system. Scores 1, 2a, and 2b are unlikely to be difficult intubation and scores 3 and 4 are more likely to be difficult intubation .
All trial of tracheal intubation were performed by three different anesthesiologists, all of whom were experienced in anesthesia and the use of the videolaryngoscope [they received introductory videolaryngoscopy course in the airway skills laboratory and had performed a minimum of 50 procedures of each video laryngoscope (VLS)]. A rigid stylet was routinely used to facilitate intubation in the GlideScope group (as recommended by the manufacturer), whereas it was used only when required in the C-MAC group. During intubation, the dependent variables of intubation such as total intubation time, first attempt intubation time, and number of attempts were recorded. If tracheal placement of the tube was unsuccessful on the first attempt, one more attempt was allowed. If the second attempt was not successful, one more attempt was allowed. After three failed intubation attempts or the time to successful intubation exceeded 120 s, a laryngeal mask airway was inserted and fiberoptic intubation performed through it , and such patient was excluded from the study.
Attention was paid to insert and remove the VLS smoothly so as to not damage the oral cavity, the tongue, or the patient’s dentition. After removal of the VLS, the oral cavity was inspected for any bruises, lacerations, bleeding, dental damage, or other possible complications.
Emergency materials for difficult intubation (such as emergency drugs, fiberoptic bronchoscope, laryngeal masks, and tracheostomy sets) were prepared for all patients before induction of anesthesia for any emergency during trial of intubation such as difficult bag mask ventilation or after failure of third attempt in the two groups ([Figure 3] and [Figure 4]).
We recorded the mean blood pressure, heart rate, and oxygen saturation (SpO2) before and after induction, during trial of intubation, and 1, 2, and 3 min after intubation. In addition, we recorded complications associated with tracheal intubation such as hypoxia (SpO2<95%), esophageal intubation, lip or dental injury, mucosal bleeding, and postoperative sore throat assessed in the anesthetic recovery area. An independent observer, not involved in the trial, assessed these outcomes.
The intubating anesthesiologist was asked to provide an overall satisfaction score of the intubation conditions scoring from 0 to 4: 0, failure (intubation not possible); 1, poor (had to use an adjunct other than the VLS); 2, fair (need for an extra adjunct plus intubation time >90 s); 3, moderate (need for extra adjunct to intubate the trachea but intubation time <90 s); and 4, good (intubation successful on first or second attempt, within 90 s, and no need for extra adjunct to secure the airway) .
Outcome measures and definitions
Primary outcomes were first-pass success and overall intubation success. First-pass success was defined as successful intubation on the first attempt. Overall intubation success was defined as successful intubation with the initial device regardless of number of attempts required. An attempt was defined as insertion of the laryngoscope blade into the oropharynx regardless of whether an attempt was made to pass the endotracheal tube or not. Total intubation time was defined as the interval from insertion of the laryngoscope blade into the mouth to inflation of the tracheal tube cuff. Successful intubation was defined as correct placement of the endotracheal tube in the trachea, as confirmed by end-tidal carbon dioxide, pulse oximetry, chest auscultation, observation of chest excursion, absence of epigastric sounds, and clouding of the endotracheal tube . Again, an independent observer, not involved in the trial, recorded these measures.
SPSS (IBM corporation Company headquartered in Armonk, New York, United States) (version 17) programs were used to enter data and for statistical analysis. Data were presented as mean±SD, range, and number. Comparison between the two groups was made using unpaired Student’s t-tests for parametric data and the Mann–Whitney test for nonparametric ordinal data. For data collected as proportions the χ2-test and the Fisher exact test were performed. A P value less than 0.05 was considered statistically significant.
| Results|| |
In the present study, there were no significant differences between the GlideScope group and the C-MAC group in patients’ characteristics as regards age, sex, weight, BMI, ASA status ([Table 1]), as well as El-Ganzouri Risk Index score for difficult intubation ([Table 2]).
There was a significantly better glottic view in the GlideScope group compared with the C-MAC group according to the modified Cormack and Lehane grading system ([Table 3]).
The total intubation time and the time of intubation from first attempt were significantly shorter in the GlideScope group compared with the C-MAC group (32.43±2.40 and 28.70±2.15 s vs. 40.40±5.07 and 34.80±2.92 s, respectively) ([Table 4]).
On the other hand, there was a significantly high percentage of first attempt failed intubation in the C-MAC group compared with the GlideScope group (33.3 vs. 10.0%, respectively). No significant differences were found between the two groups as regards rate of second and third attempt failure. The overall satisfaction of the intubation for anesthesiologist was significantly higher with the GlideScope group compared with the C-MAC group ([Table 4]). We did not detect any complication such as failed intubation, injury of the palatoglossal arch, or dental injury in any of the patients. We detected three cases in the GlideScope group and two cases in the C-MAC group with mild postoperative sore throat ([Table 4]).
Finally, there were no significant differences between the GlideScope group and the C-MAC group as regards pulse, mean arterial blood pressure, and SpO2 at the start, after induction, during intubation, and at 1, 2, and 3 min after intubation ([Table 5]).
| Discussion|| |
Nowadays, videolaryngoscopies are applied to overcome the pitfalls of direct laryngoscopy by placing a microvideo camera on the undersurface of the blade. This allows the operator to see around the anterior curvature of the supraglottic structures, visualizing the airway anatomy by transporting the view from inside the mouth to a video monitor placed either on or next to the device. There are several devices commercially available, including the GVL system, Pentax airway scope (Pentax Medical Company, Montvale, New Jersey, USA), McGrath (Aircraft Medical Limited, Edinburgh, UK), Res-Q-Scope (Res-Q-Tech, Fuquay Varina, New Carolina, USA), and C-MAC (Karl Storz GmbH & Co.). Some devices (GlideScope and C-MAC) are equipped with an antifog mechanism to provide better optical clarity . Previous investigators have reported the use of videolaryngoscopy in patients at a higher risk for difficult intubation and in obese patients. The various VLSs available in the market differ significantly in their ease of use (in terms of intubation time, number of attempts, and the need for additional adjuncts), even when the visual quality is essentially identical ,.
In the present study, the failure of the first intubation attempt was higher in the C-MAC group compared with the GlideScope group (33.3 vs. 10.0%, respectively). This is comparable to that reported by Aziz et al. , who reported 94% success rate with GlideScope in a retrospective study.
There was a significantly better glottic view in the GlideScope group compared with the C-MAC group. These results are in accordance with many previous studies, which concluded that videolaryngoscopes improve the laryngeal view in routine and in difficult airway patients , and in manikins .
Serocki et al.  compared C-MAC, GlideScope, and direct laryngoscope in patients with difficult intubation and concluded that GlideScope was better than C-MAC and direct laryngoscope as regards success of first attempt of intubation and that both videolaryngoscopes had glottic view better than direct laryngoscope.
Furthermore, in a comparison of the use of Macintosh direct laryngoscope versus the use of the C-MAC in groups of patients who had a difficult laryngoscopy during a scheduled surgical procedure, the use of the C-MAC improved the glottic view in 94% (49/52) of patients . In the operating room, use of the C-MAC in patients with a predicted difficult airway improved optical access to the glottis compared with direct Macintosh laryngoscope and resulted in more successful intubations at the first attempt .
The first major clinical study that compared the GlideScope with the conventional laryngoscope in 728 patients (in whom both GlideScope and conventional laryngoscopy were performed) found that excellent laryngeal exposure was obtained with more successful intubation in GVL patients, compared with conventional laryngoscopy, and suggested that GlideScope is a useful alternative in the management of difficult tracheal intubation .
In addition, results of the present work revealed that there was a statistically significantly shorter total intubation time and shorter time of intubation from first attempt in the GlideScope group when compared with the C-MAC group (32.43±2.40 and 28.70±2.15 s vs. 40.40±5.07 and 34.80±2.92 s, respectively).
Previous studies are consistent with our findings as regards shorter total intubation time and shorter time of intubation from first attempt in the GlideScope group compared with the C-MAC group ,,.
McElwain et al.  reported that the duration of both the first intubation attempt and the successful intubation time were significantly shorter with the C-MAC laryngoscope group compared with all other devices tested (one of these devices was the GlideScope), which was contradictory to our results because anesthetists were more familiar with the curvature of the Macintosh blade of C-MAC and could maneuver the tracheal tube more precisely toward the glottis when using the C-MAC.
Nelson et al.  reported that C-MAC was ranked first as regards performance and preference for use in a simulated difficult airway with higher first attempt and overall success rates of intubation compared with GlideScope, AirTraq (Prodol Meditec S.A., Vizcaya, Spain), and direct laryngoscope but with no statistical difference between these devices; this was contradictory to our results and may be due to easy use of C-MAC Macintosh blade.
Drenguis and Carlson  reported that GlideScope provided views superior to C-MAC in awake upright laryngoscopy in healthy volunteers and that GlideScope had shorter time to first view of the glottis and better Cormack–Lehane views compared with C-MAC. However, time to best view of the glottis was similar between devices. Moreover, the number of attempts was similar across devices.
In the present work, there were no significant differences between the GlideScope group and the C-MAC group as regards pulse, mean arterial blood pressure, and SpO2 at the start, after induction, during intubation, and at 1, 2, and 3 min after intubation. In addition, patients in the present study demonstrated stable hemodynamic effects in the first 3 min after intubation in both groups and also SpO2 did not decrease below 95% in both groups. These results are comparable to those reported by Zhang et al. , who demonstrated a similar hemodynamic response to orotracheal intubation with either fiberoptic bronchoscope or GVL. To the best of the researcher’s knowledge, the present study is the first to assess hemodynamic changes to GlideScope compared with C-MAC videolaryngoscope.
However, Mosier et al. , in a series in a large urban academic emergency department, observed no difference in either first-pass or overall intubation success rates between C-MAC and the GVL. The similar success rates persisted among important subgroups (including operator training level) and after multivariable adjustment. These data suggest that it may not be the specific device design, but rather the fundamental incorporation of video technology that provides the improved success observed in studies comparing videolaryngoscopy with direct laryngoscopy. According to these findings, clinicians may opt for either GVL or C-MAC, based on individual and institutional preference.
First, our study is the first study that compared GVL and C-MAC videolaryngoscope in obese patients with difficult intubation. Thus, this can be the cause of conflict of results between our study and other studies. Second, the subjective nature of grading the difficulty of the airway and tracheal tube insertion, and the quality of views obtained. We attempted to minimize this by limiting the number of investigators to obtain a consistent standard. Third, the use of alternative classifications other than modified Cormack and Lehane laryngeal view such as Cormack and Lehane laryngeal view or other scoring systems similar to the percentage of glottic opening  and the other intubation difficulty score . Thus, the results may be more discriminating from other studies. Fourth, only Arab patients were included in our study, and hence the results may not be readily extrapolated to other patient populations.
| Conclusion|| |
Videolaryngoscopy offers superior viewing of the glottis, which can be problematic in obese patients with difficult intubation. GlideScope was better in overall satisfaction, good glottic view, shorter total intubation time, shorter first attempt time, and higher success rate of intubation from first attempt without the need for extra adjuncts to help in intubation when compared with C-MAC videolaryngoscope. These results are in favor of GlideScope use in difficult intubation obese patients. The results of the present study should be taken cautiously until comparing both video-scopes in a larger number of patients.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]