Table of Contents  
ORIGINAL ARTICLE
Year : 2015  |  Volume : 9  |  Issue : 1  |  Page : 8-13

A prospective randomized comparative study between Macintosh and GlideScope in adult patients undergoing cardiac surgery


1 Department of Cardiac Anesthesia, Madinah Cardiac Center, Almadinah Almonourah Saudi Arabia; Department of Anaesthesia, Cairo University, Egypt
2 Department of Cardiology, Madinah Cardiac Center, Almadinah Almonourah, Saudi Arabia; Department of Cardiology, Sohag University, Egypt
3 Department of Cardiology, Madinah Cardiac Center, Almadinah Almonourah, Saudi Arabia
4 Department of Clinical Pathology, Madinah Cardiac Center, Saudi Arabia

Date of Submission04-Nov-2014
Date of Acceptance01-Dec-2014
Date of Web Publication9-Jul-2015

Correspondence Address:
Rabie Soliman
Department of Anaesthesia, Cairo University, Egypt

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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-9090.160326

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  Abstract 

Context
The GlideScope laryngoscope is a new device for intubation that provides an improved view of the larynx.
Aim
The aim of the study was to compare the hemodynamic effect of Macintosh laryngoscope with GlideScope during intubation in adult cardiac surgery.
Setting and design
This was a prospective, randomized, comparative study conducted in Madinah Cardiac Center, Saudi Arabia.
Materials and methods
The study included 100 patients classified into two groups (n = 50), The patients were intubated either by Macintosh laryngoscope or by GlideScope. The following parameters were monitored: heart rate, mean arterial blood pressure, catecholamine level, intubation time, number of intubation trials, and the complications.
Statistical analysis used
Data were statistically described in terms of mean ΁ SD or frequencies.
Measurements and main results
The intubation time was longer in GlideScope than in Macintosh (P < 0.001), and the number of intubation trials was higher in GlideScope than in Macintosh (P < 0.001). The heart rate increased significantly in patients of the GlideScope group compared with the Macintosh group at first minute (P < 0.001), third minute (P < 0.001), and at fifth minute (P = 0.034). The mean arterial blood pressure increased significantly in patients of the GlideScope group compared with the Macintosh group at first minute (P < 0.001), third minute (P = 0.003), and at fifth minute (P = 0.029). The epinephrine level was higher with GlideScope at first and fifth minute (P = 0.032 and 0.036, respectively). The norepinephrine was higher in the GlideScope group at first and fifth minute (P = 0.043 and 0.033, respectively). The incidence of oral trauma and bleeding was higher with GlideScope than Macintosh (P = 0.003).
Conclusion
The intubation by GlideScope is associated with increased heart rate, blood pressure, catecholamine level, number of intubation trials, and oral complications compared with Macintosh laryngoscope.

Keywords: Bleeding, GlideScope, heart rate, intubation, Macintosh laryngoscope, mean arterial blood pressure, sore throat


How to cite this article:
Soliman R, Mofeed M, Alamoudy O, Farouk A. A prospective randomized comparative study between Macintosh and GlideScope in adult patients undergoing cardiac surgery. Egypt J Cardiothorac Anesth 2015;9:8-13

How to cite this URL:
Soliman R, Mofeed M, Alamoudy O, Farouk A. A prospective randomized comparative study between Macintosh and GlideScope in adult patients undergoing cardiac surgery. Egypt J Cardiothorac Anesth [serial online] 2015 [cited 2019 Nov 20];9:8-13. Available from: http://www.ejca.eg.net/text.asp?2015/9/1/8/160326


  Introduction Top


Tracheal intubation is the standard technique of airway management in cardiac surgery. Transient hypertension and tachycardia occur after endotracheal intubation using laryngoscopy. The peak of elevation in blood pressure and heart rate are within 1-2 min and are usually well tolerated. However, in patients with hypertension, coronary artery disease, or cerebral vascular disease, the hypertension and tachycardia are risky because of the associated increase in myocardial oxygen demand, decrease in oxygen supply, the possibility of cardiac arrhythmia, myocardial ischemia, and cerebral vascular accident [1],[2],[3],[4],[5],[6]. There are many types of laryngoscopes for tracheal intubation, but Macintosh laryngoscope has been the most widely used device for intubation since its design by Robert Macintosh in 1943 [7].

GlideScope video laryngoscope is a new technique in which a digital camera and a source of light are mounted at the end of the blade. It provides a clear view of the larynx during intubation and is designed to manage difficult intubation [8]. The aim of the study was to assess the hemodynamic effect of GlideScope and Macintosh laryngoscope during orotracheal intubation in adult patients undergoing cardiac surgery.


  Materials and methods Top


After approval of the ethics committee in Madinah Cardiac Center, Saudi Arabia, we studied 100 adult patients who underwent elective cardiac surgery (September 2012-November 2013). Exclusion criteria included patients with renal or hepatic disease, bleeding diathesis, Mallampati score of III or IV, or history of a difficult intubation. All patients received their medications, including diuretics, β-blockers, calcium channel blockers, or angiotensin-converting enzyme inhibitors, ∼2 h before anesthesia induction. The patients were classified randomly (using simple randomization) into two groups (n = 50): group A patients were intubated using Macintosh laryngoscope and group B patients were intubated using GlideScope (GS, Cobalt AVL Monitor; Verathon Medical, Canada).

The patients were premedicated with diazepam 5 mg orally at midnight and 30 min before surgery. Before induction, a peripheral venous cannula 18 or 16 G and radial arterial cannula were inserted under local anesthesia, and the central venous line was inserted after induction. The induction was started with fentanyl 5 μg/kg 5 min before intubation; and then etomidate 0.3 mg/kg and rocuronium 0.8 mg/kg were administered. After loss of response, lidocaine spray 10% (three metered doses) was administered in the oral cavity. The orotracheal intubation was performed when the train-of-four count was zero using peripheral nerve stimulator (Micro Stim; Sun Med Inc., Largo, Florida, USA) and was conducted by the same anesthesiologist. Anesthesia was maintained with sevoflurane 1-3% and fentanyl 1-3 μg/kg/h and cisatracurium 1-2 μg/kg/min, as needed. The increase in heart rate and mean arterial blood pressure during and after intubation was managed with a bolus dose of fentanyl 50-100 μg and by increasing the concentration of sevoflurane.

Monitors of patients

The monitors included: the intubation time, number of intubation trial, rate of stylet using, and the total doses of fentanyl, etomidate, and rocuronium. The heart rate and invasive mean arterial blood pressure were checked before intubation, at first, third, fifth, and 15th minute after intubation. The catecholamine level in blood (epinephrine and norepinephrine, blood samples were drawn from the anticubital vein into an air-tight tube under aseptic condition and was measured using high-performance liquid chromatography) was measured at the first, fifth, and 15th minute. The time was checked with timer built-in ventilator screen (Drδger; Primus, Germany). A continuous ECG with automatic ST-segment analysis (leads II and V) was used according to standard criteria for myocardial ischemia (ST elevations 2 mm from the baseline in leads II and V5, or ST depressions 1 mm from the baseline in leads II and V5, with the elevation or depression lasting for 1 min or more). Moreover, the postoperative complications such as bleeding or trauma to lips, teeth, or tongue were recorded.

The statistical analysis

Data were statistically described in terms of mean (SD), or frequencies (number of cases), confidence intervals (95% CI), and percentages, when appropriate. Comparison of numerical variables between the study groups was made using the Student t-test for independent samples. Within-group comparison of numerical variables was carried out using the repeated measures analysis of variance test using general linear model regression analysis. For comparing categorical data, the χ2 -test was performed. Fisher's exact test was used when the expected frequency was less than 5. P-values less than 0.05 were considered statistically significant. All statistical calculations were performed using computer programs SPSS (Statistical Package for the Social Science; SPSS Inc., Chicago, Illinois, USA), version 15 for Microsoft Windows.


  Results Top


There was insignificant difference between the two groups as regards age, weight, sex, preoperative medications and comorbidities, and type of surgery (P > 0.05) [Table 1].
Table 1: Preoperative data of patients

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There was no statistical difference between the two groups as regards the Mallampati class I and II (P = 0.308). The success of first trial of intubation was higher in the Macintosh group than in the GlideScope group patients (P < 0.001). Three patients in the Macintosh group and 10 patients in the GlideScope group needed a second trial (P < 0.001). Moreover, four patients in the GlideScope group needed a third trial and no other trial was needed in the Macintosh group (P = 0.021). The intubation time was longer with GlideScope than with Macintosh laryngoscopy (P < 0.001). There were only five patients in the Macintosh group who needed stylet during intubation, whereas all patients in the GlideScope group were intubated using stylet (P < 0.001). Moreover, the incidence of oral trauma and bleeding related to intubation was higher in the GlideScope group than in the Macintosh laryngoscopy group (P = 0.003) [Table 2].
Table 2: Data of intubation and complications

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[Table 3] shows no statistical difference as regards the dose of etomidate, rocuronium, and fentanyl (P > 0.05); however, after intubation, patients of the GlideScope group needed a higher dose of fentanyl, compared with the Macintosh laryngoscopy group patients, to control the increased heart rate and blood pressure associated with intubation (P < 0.001) [Table 3].
Table 3: Intraoperative data of patients

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There was no statistical difference between the two groups regarding the baseline heart rate(P = 0.936), but after intubation the heart rate increased significantly in patients of GlideScope group more than Macintosh laryngoscopy group at 1st min[P < 0.001 and 95% CI (84.01 to 88.66 and 96.17 to 100.90 respectively)], 3rd min[P < 0.001 and 95% CI (83.29 to 86.46 and 94.00 to 98.07 respectively)]and at 5th min[P = 0.034 and 95% CI (79.51 to 82.04 and 86.11 to 89.84 respectively)], and the comparison at 15th min was insignificant (P = 0.710) [Table 4], [Figure 1]. There was insignificant difference as regards the baseline mean arterial blood pressure between the two groups (P = 0.429); however, after intubation the mean arterial blood pressure increased significantly in patients of the GlideScope group compared with the Macintosh laryngoscopy group at first minute [P < 0.001 and 95% CI (98.25 to 102.26 and 107.35 to 111.72 respectively)], 3rd min [P = 0.003 and 95% CI (96.04 to 99.03 and 104.32 to 113.11 respectively)] and at 5th min [P = 0.029 and 95% CI (91.98 to 96.65 and 98.81 to 106.42) respectively)], and the comparison at 15th minute was insignificant (P = 0.245) [Table 4], [Figure 2].
Figure 1: Heart rate of patients. 1 min: the reading 1 min after intubation; 3 min: the reading 3 min after intubation; 5 min: the reading 5 min after intubation; 15 min: the reading 15 min after in tubation.

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Figure 2: The mean arterial blood pressure of patients. 1 min: the reading 1 min after intubation; 3 min: the reading 3 min after intubation; 5 min: the reading 5 min after intubation; 15 min: the reading 15 min after in tubation.

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Table 4: Hemodynamic data of patients

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Before induction, there was no statistical difference in the catecholamine level between the two groups. The epinephrine level increased significantly at the first minute [P = 0.032 and 95% CI (0.84 to 0.97 and 0.97 to 1.17 respectively) and 5th min(P = 0.036 and 95% CI (0.82 to 1.05 and 1.02 to 1.36 respectively)] in the GlideScope group compared with the Macintosh laryngoscopy group, and the comparison at the 15th minute was insignificant (P = 0.514) [Table 5]. The norepinephrine level increased significantly at the first minute [P = 0.043 and 95% CI (1.39 to 1.62 and 1.74 to 2.15 respectively)] and 5th min [P = 0.033 and 95% CI (1.38 to 1.79 and 1.97 to 2.30 respectively)] in patients of the GlideScope group compared with the Macintosh laryngoscopy group, and the comparison at the 15th minute was insignificant (P = 0.241) [Table 5].
Table 5: Catecholamine levels in blood

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  Discussion Top


The hemodynamic changes typically occur within seconds during laryngscopy (stimuli to oropharynx) and intubation (stimuli to larynx and trachea) and the peak of changes is within one to two minutes and continues for 5 minutes [9].

In the present study, despite the excellent view of the glottis with GlideScope, the intubation time was longer with GlideScope, compared with Macintosh laryngoscope, because of the time needed to direct the endotracheal tube through the vocal cords, or longer time needed for repeated trials of intubation. The heart rate and mean arterial blood pressure increased significantly in the GlideScope group than in the Macintosh laryngoscope group at first, third, and fifth minute after intubation and gradually decreased to be around the baseline values at 15th minute after intubation. The increase in heart rate and mean arterial blood pressure was associated with an increase in epinephrine and norepinephrine, and this explains the stress response produced by a longer intubation time with GlideScope compared with Macintosh laryngoscopy. The total dose of fentanyl needed to control the increase in heart rate and mean arterial blood pressure was higher in the GlideScope group. The incidence of trauma and bleeding from oral cavity was higher in the GlideScope group, compared with the Macintosh laryngoscope group, due to the associated multiple trials and difficulty in directing the endotracheal tube to the glottis during intubation with GlideScope, which exposes the oral mucosa to trauma.

In agreement with our results, many studies showed that the intubation time is prolonged and that the number of intubation trials was higher with GlideScope compared with Macintosh laryngoscopy [10],[11],[12],[13],[14],[15],[16],[17], and other studies documented serious complications associated with GlideScope during intubation [18],[19]. Carassiti et al. [20] reported that the force and pressure used during intubation are localized mainly at the tip of Macintosh blade, whereas distributed homogeneously in the GlideScope blade. This may exaggerate the stimulation produced by the whole blade of GlideScope in comparison with stimulation produced by the tip of Macintosh blade. Xue et al. [21] evaluated the hemodynamic changes with GlideScope and reported a significant increase in heart rate and blood pressure during orotracheal intubation with GlideScope; this can be explained with the study by Jakuπenko and colleagues. They found that the prolonged intubation time with GlideScope leads to a longer contact of the GlideScope blade with the oropharyngolaryngeal zone mucosa receptors, thus producing a greater stress response [22], which potentiates more hemodynamic changes during intubation [16]. Malik and colleagues compared the hemodynamic changes with Macintosh, GlideScope and Airwayscope laryngoscope (AWS) in adult patients undergoing general surgery and reported that heart rate increased significantly with Macintosh and GlideScope and returned to the baseline within 5 min after intubation. The mean arterial blood pressure decreased significantly below the baseline in patients of the Macintosh laryngoscope group [23]. On other hand, a randomized clinical trial done by Bilehjani E and Fakhari S to assess the hemodynamic changes during intubation. The study included 80 patients underwent CABG and the intubation was done either by Macintosh laryngoscopy (n = 40) or GlideScope (n = 40). They found no difference in heart rate and mean arterial blood pressure at the 1st, 5th, 15th min following intubation in comparison to the baseline values (P > 0.05) [11], and the same result was reported by other studies [24],[25],[26],[27].

Contrary to our findings, a randomized double-blind clinical trial included 200 patients underwent elective orthopedic surgery. Heart rate and MAP were measured before, at the time of induction and every minute for 10 minutes following intubation. After intubation, the heart rate and MAP increased significantly in the first two minutes only in direct laryngoscopy group (P < 0.001) but not in GlideScope group [28]. Another clinical trial evaluated the hemodynamic changes in 160 hypertensive patients during intubation. The patients were intubated either with GlideScope or Macintosh laryngoscope. Noninvasive blood pressure and heart rate were recorded before induction, after induction, during laryngoscopy, immediately after intubation, and every minute for the first 5 min after intubation. The blood pressure and heart rate decreased significantly in both groups in comparison with preinduction values [29].


  Conclusion Top


During intubation of adult cardiac surgical patients, the GlideScope is associated with increased heart rate, blood pressure, catecholamine level, intubation time, number of intubation trials, stylet using, oral trauma, and bleeding compared with Macintosh laryngoscope.

Limitations

Our study recognizes some limitations, such as the study being a single center study, the small number of patients, and scarcity of previous studies on GlideScope in cardiac surgery for comparison with our results.


  Acknowledgements Top


The authors thank the anesthesia technicians and anesthesia nurses for their efforts and performance to prepare the instruments and medications during intubation of patients.

All funding was from resources in Madinah Cardiac Center.

Conflicts of interest

There are no conflicts of interest.

 
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    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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