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ORIGINAL ARTICLE
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Hemodynamic Response to Orotracheal Intubation: Comparison between Macintosh, McCoy, and C-MAC Video Laryngoscope


 Department of Anesthesiology and Intensive Care, Guru Gobind Singh Medical College and Hospital, Faridkot, Punjab, India

Correspondence Address:
Sarvjeet Kaur,
C/o Dr. S. S. Ratta, Meet Bikaner Hospital, Sikhanwala Road, Kotkapura - 151 204, Punjab
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/aer.AER_7_19

   Abstract 

Background: The most commonly used devices for direct visualization of the larynx and tracheal intubation are Macintosh and McCoy laryngoscopes. C-MAC video laryngoscope, based on the principles of indirect laryngoscopy, has been introduced into clinical practice in recent years. Video laryngoscope may be useful in difficult tracheal intubation situations. Aim: We aimed at comparing the McCoy and C-MAC video laryngoscope with conventional Macintosh laryngoscope for hemodynamic responses of orotracheal intubation among adults receiving general anesthesia for elective surgeries. Settings and Design: This was a hospital-based randomized, double-blind, comparison, done between June 2015 and October 2016 after permission of institutional ethical committee. Materials and Methods: One hundred and fifty patients with normal airways undergoing elective general anesthesia were randomly allocated to undergo intubation using either Macintosh (Group A), McCoy (Group B), or C-MAC video laryngoscope (Group C). Hemodynamic changes associated with intubation were recorded immediately before and after laryngoscopy and intubation, every minute for 5 min and at 10 min after intubation by an independent observer. The time taken to perform endotracheal intubation and Cormack and Lehane score were also noted in all three groups. Statistical Analysis: Data were compiled, and statistical analysis was performed using SPSS 17.0 version. Results: Hemodynamic response after intubation was least in Group B (McCoy) as compared to Group A (Macintosh) and Group C (C-Mac) (P = 0.001). Ninety-two percentage patients were in Cormack and Lehane score Class I in Group C in comparison to 52% in Group A and 48% in Group B (P = 0.000). Time for intubation taken in Group A, Group B, and Group C was 15.53 ± 1.53 min, 18.65 ± 0.44 min, and 22.82 ± 1.323 min, respectively (P = 0.000). Conclusion: The McCoy laryngoscope provided better attenuation of hemodynamic responses to laryngoscopy and intubation than the Macintosh and C-Mac video laryngoscope whereas more appearance of Cormack and Lehane score Class I was seen with the C-MAC video laryngoscope. Furthermore, the time taken to perform endotracheal intubation was the longest with the C-MAC video laryngoscope.

Keywords: Attenuation, C-MAC laryngoscope, Macintosh laryngoscope, McCoy laryngoscope, tracheal intubation



How to cite this URL:
Aggarwal H, Kaur S, Baghla N, Kaur S. Hemodynamic Response to Orotracheal Intubation: Comparison between Macintosh, McCoy, and C-MAC Video Laryngoscope. Anesth Essays Res [Epub ahead of print] [cited 2019 May 26]. Available from: http://www.aeronline.org/preprintarticle.asp?id=256045


   Introduction Top


Laryngoscopy and tracheal intubation are known to evoke the stress responses, in the form of tachycardia, systemic hypertension, arrhythmias,[1] and increased intracranial pressure exposing the patient to unwanted risk.[2] These responses are more marked in treated and untreated hypertensive patients.[3]

It has been observed that amount of forces exerted during laryngoscopy is the key determinant for mechanical stimulation of supraglottic region and stretch receptors present in the respiratory tract, while endotracheal intubation and cuff inflation contributing little additional stimulation. Thus, use of different types of laryngoscope blades can help decreasing these responses.

The Macintosh laryngoscope (MCL) has been the “gold standard” device for direct laryngoscopy and tracheal intubation since its invention by Foregger and Foregger in 1940s.[4] The McCoy's or Corazelli, London, McCoy laryngoscope is also used for direct laryngoscopy and tracheal intubation.

The C-MAC is an indirect laryngoscope having advantage of abandoning the need to align the optical axis in the pharynx and mouth to visualize the entrance of the larynx and improves laryngeal view.[5]

In past few years, different studies have been conducted successfully to compare Macintosh and McCoy laryngoscopes and Macintosh and video laryngoscopes to assess hemodynamic response to laryngoscopy and intubation; but, few studies have compared these three laryngoscopes together. Hence, our study involves the comparison of Macintosh, McCoy, and C-MAC video laryngoscope to evaluate stress response during intubation.


   Materials and Methods Top


The present study was conducted in a prospective and randomized manner at our institute, from June 2015 to October 2016, in 150 adult patients after being approved by institutional ethics committee. A written informed consent was obtained from all patients.

Inclusion criteria

  1. Patients scheduled for elective surgery
  2. Age between 25 and 60 years of both the sexes
  3. Patients with the American Society of Anesthesiologists (ASA) physical status Classes I and II.


Exclusion criteria

  1. Patients with thyromental distance <6 cm
  2. Mallampati Grade ≥ III
  3. Body mass index (BMI) more than 30
  4. Patients with the ASA physical status Classes ≥ III
  5. Pregnant women.


Due to the nature of the study, true blinding was not possible; however, sealed envelope technique was used for group allocation and persons recording observations was unconnected to the study. All the patients in three groups were successfully intubated. The study population was randomly assigned into three groups, namely:

  • Group A – Laryngoscopy with Macintosh blade number 3 or 4
  • Group B – Laryngoscopy with McCoy blade
  • Group C – Laryngoscopy with C-MAC video blade number 3 or 4.


Laryngoscopy and intubations were performed by an anesthesiologist who was familiar and trained with intubation using Macintosh, McCoy, and C-MAC laryngoscope.

All the patients were given tablet alprazolam 0.25 mg and tablet ranitidine 150 mg orally at night and were kept nil orally for at least 6 h before surgery. All the patients were given – midazolam 1 mg, ondansetron 4 mg, and morphine 0.1 mg/kg intravenously (IV) 15 min before induction. After preoxygenation with 100% oxygen for 3 min, induction was done with propofol (1%) 2 mg/kg, IV and muscle relaxation was achieved with IV atracurium 0.5 mg/kg. After 3 min of controlled ventilation, laryngoscopy was performed with Macintosh, McCoy, and C-MAC Video laryngoscope (according to group allocation) in sniffing position and vocal cord visualization was done using Cormack and Lehane's grading and endotracheal tube was passed through vocal cords under vision. No external pressure was applied in any patient. Failure to intubation was defined as failure after three attempts.

Systolic blood pressure, diastolic blood pressure, mean arterial pressure, pulse rate, SpO2, and electrocardiogram were recorded before induction (preinduction), immediately before (preintubation) and after laryngoscopy and intubation (T0), every minute for 5 min following tracheal intubation, and at 10 min after intubation by an independent observer. Significant hemodynamic response such as heart rate and blood pressure with 20% change from baseline (BL) was also recorded. Any arrhythmia and other complications during intubation such as local injuries, bleeding, laryngospasm, and regurgitation were noted. The time taken to intubation was measured from the time the instrument is inserted in mouth to confirmation by capnography. It was noted using a stopwatch.

Statistical analysis

After completion of the study, all the observations were systematically collected. Statistical test used to draw conclusion were, Chi-square test, one-way ANOVA with post hoc Tukey honestly significant difference. Analysis was done using SPSS 17.0 version (SPSS version 17.0. CHICAGO: SPSS Inc. for Window program).


   Results Top


Demographic data were comparable in all three groups in respect to age, gender, BMI, ASA grade, and MPG grade (P = 0.08) [Table 1]. Induction technique and dosages of drugs were same in all the groups.
Table 1: Distribution of patients in different groups

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On studying each group separately, in Group A (Macintosh), there was a statistically significant increase in heart rate from BL values for up to 2 min (T2) after intubation whereas systolic blood pressure, diastolic blood pressure, and mean blood pressure were significantly raised up to 1-min (T1) postintubation.

In Group B (McCoy), there was a statistically significant increase in all of the study parameters from BL, only up to 1-min postintubation.

In Group C (C-MAC), there was a statistically significant increase in all of the study parameters from BL, up to 5-min postintubation.

On intergroup comparison, the rise in the heart rate compared to BL values was 6.26% in Group B, 14.12% in Group A, and 19.45% in Group C. The difference in heart rate between Group A and Group B remained statistically significant up to 2 min postoperatively. The heart rate response between Group B and Group C was statistically significant up to 5 min postoperatively. No statistically significant changes in heart rate appeared between Group A and Group C [Table 2].
Table 2: Comparison of changes in heart rate

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Attenuation of the rise in systolic blood pressure is statistically significant in Group B. A rise of only 5.18% compared to BL values was observed in Group B (McCoy) when compared with 12.20% in Group A (Macintosh) and 13.40% in Group C (C-MAC) (P > 0.05). Systolic blood pressure, diastolic blood pressure, and mean blood pressure were returned to close to basal values earlier in Group A and Group B (1 min) then in the Group C (5 min) [Table 3].
Table 3: Comparison of changes in systolic blood pressure

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Suppression of maximum rise in diastolic blood pressure was also seen in Group B which was statistically significant. The minimum rise in the diastolic blood pressure compared to BL was only 6.88% in Group B (McCoy) compared to 14.55% in Group C (C-MAC) and 13.66% in Group A (Macintosh) [Table 4].
Table 4: Comparison of changes in diastolic blood pressure

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Similarly, mean arterial pressure was increased 6.12% in Group B, 12.94% in Group A, and 14.01% in Group C compared to BL values [Table 5]. The effect of laryngoscopy and intubation on hemodynamic profiles remained for shortest duration in Group B (McCoy) and for longest duration in Group C (C-MAC).
Table 5: Comparison of changes in mean blood pressure

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Ninety-two percentage patients were in Class I (Cormack and Lehane score) in Group C in comparison to 52% in Group A and 48% in Group B (P = 0.000) [Table 6].
Table 6: Comparison of Cormack and Lehane grade

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Time for intubation taken in Group A, Group B, and Group C was 15.53 ± 1.53 min, 18.64 ± 0.44 min, and 22.82 ± 1.323 min, respectively, which was statistically significant in-between the groups (P > 0.05) [Figure 1].
Figure 1: Comparison of time for intubation

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Spo2 changes at postintubation in all three groups were nonsignificant. There was no incidence of failed intubation in either of the group. No incidence of cyanosis, laryngospasm, arrhythmia, regurgitation, local injury, and bleeding was found in all three groups.


   Discussion Top


Obtunding the hemodynamic responses during laryngoscopy and intubation remains a major concern for the anesthesiologists. Deep anesthesia, topical anesthesia, opioids, calcium channel blockers, beta blockers, and laryngeal mask airway have been tried with varying success.[6],[7],[8]

In our study, we found that our primary outcome of hemodynamic responses to laryngoscopy and intubation was least in Group B (McCoy) as compared to Group A (Macintosh) and Group C (C-MAC), which was contrary to previous study by Buhari and Selvaraj.[9] This can be attributed to differences in inclusion criteria, as they studied only ASA 1 patients and found no statistically significant increase of hemodynamic parameters at any time interval while using MCL compared to McCoy and C-MAC laryngoscopes. Han et al. also did not find any statistically significant difference between Macintosh and McCoy laryngoscopes in terms of hemodynamic responses after laryngoscopy and intubation. It could be due to use of fentanyl in their study.[10]

Previous studies had shown that hemodynamic responses to laryngoscopy and intubation were less with McCoy laryngoscope compared with different types of laryngoscopes used in their studies.[1],[11],[12] It may be due to function of the McCoy blade through a lever attached to its proximal end and decreases the force on glossoepiglottic fold.

The C-MAC has higher hemodynamic response to intubation compared to McCoy laryngoscope while no statistically significant differences were seen between Macintosh and C-MAC laryngoscopes. Similarly, Sarkilar et al. did not find any significant change in terms of hemodynamic response to intubation between Macintosh and C-MAC laryngoscopes.[13]

There was a statistically significant reduction of the Cormack–Lehane score in our study while using the C-MAC video laryngoscope. Similar results were found with use of another video laryngoscope called Airtraq in different studies.[14],[15],[16] Hence, the Cormack–Lehane score may be applied to predict the outcome of both direct and indirect laryngoscopy.

Similar to our study, previous authors also observed longer intubation time with video laryngoscope compared to MCL.[4],[17]

In our study, longer duration of intubation was found in C-MAC group compared to Macintosh and McCoy group. The experience of a person who performed the laryngoscopy and inclusion criteria of studies are the influencing factors to determine intubation time.

There were some limitations with regard to our study. First, we could not blind the anesthetist to the laryngoscope being used. Second, results of the study may be differed in the hands of inexperienced or less experienced anesthetist. Third, the Cormack–Lehane score was initially validated for use with direct laryngoscopy whereas we used this score for indirect laryngoscopy. Finally, more studies are required to determine advantages of C-MAC over other devices.


   Conclusion Top


McCoy laryngoscope provides better attenuation of hemodynamic responses to laryngoscopy and intubation as compared to MCL and C-MAC laryngoscope. However, C-MAC laryngoscope can be used in cases of predicted difficult intubation because of the better laryngoscopic view despite maximum time taken for intubation.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

1.
Singhal S, Neha. Haemodynamic response to laryngoscopy and intubation: Comparison of McCoy and Macintosh laryngoscope. Internet J Anesth 2007;17:724-7.  Back to cited text no. 1
    
2.
Prys-Roberts C, Greene LT, Meloche R, Foëx P. Studies of anaesthesia in relation to hypertension. II. Haemodynamic consequences of induction and endotracheal intubation. Br J Anaesth 1971;43:531-47.  Back to cited text no. 2
    
3.
Low JM, Harvey JT, Prys-Roberts C, Dagnino J. Studies of anaesthesia in relation to hypertension. VII: Adrenergic responses to laryngoscopy. Br J Anaesth 1986;58:471-7.  Back to cited text no. 3
    
4.
Foregger R, Foregger RV. Manufacturer of anesthesia equipment. Anesthesiology 1996;84:190-200.  Back to cited text no. 4
    
5.
Jungbauer A, Schumann M, Brunkhorst V, Börgers A, Groeben H. Expected difficult tracheal intubation: A prospective comparison of direct laryngoscopy and video laryngoscopy in 200 patients. Br J Anaesth 2009;102:546-50.  Back to cited text no. 5
    
6.
Kautto UM, Heinonen J. Attenuation of circulatory response to laryngoscopy and tracheal intubation: A comparison of two methods of topical anaesthesia. Acta Anaesthesiol Scand 1982;26:599-602.  Back to cited text no. 6
    
7.
Wig J, Sharma M, Baichoo N, Agarwal A. Nicardipine and verapamil attenuate the pressor response to laryngoscopy and intubation. Can J Anaesth 1994;41:1185-8.  Back to cited text no. 7
    
8.
Casati A, Fanelli G, Albertin A, Deni F, Danelli G, Grifoni F, et al. Small doses of remifentanil or sufentanil for blunting cardiovascular changes induced by tracheal intubation: A double-blind comparison. Eur J Anaesthesiol 2001;18:108-12.  Back to cited text no. 8
    
9.
Buhari FS, Selvaraj V. Randomized controlled study comparing the hemodynamic response to laryngoscopy and endotracheal intubation with McCoy, Macintosh, and C-MAC laryngoscopes in adult patients. J Anaesthesiol Clin Pharmacol 2016;32:505-9.  Back to cited text no. 9
[PUBMED]  [Full text]  
10.
Han TS, Kin JA, Park NG, Lee SM, Cho HS, Chung IS. A comparison of the effects of different type of laryngoscope on hemodynamics. McCoy versus the Macintosh blade. Korean J Anasthesiol 1999;37:398-401.  Back to cited text no. 10
    
11.
Haidry MA, Khan FA. Comparison of hemodynamic response to tracheal intubation with Macintosh and McCoy laryngoscopes. J Anaesthesiol Clin Pharmacol 2013;29:196-9.  Back to cited text no. 11
[PUBMED]  [Full text]  
12.
Gill N, Purohit S, Kalra P, Lall T, Khare A. Comparison of hemodynamic responses to intubation: Flexible fiberoptic bronchoscope versus McCoy laryngoscope in presence of rigid cervical collar simulating cervical immobilization for traumatic cervical spine. Anesth Essays Res 2015;9:337-42.  Back to cited text no. 12
[PUBMED]  [Full text]  
13.
Sarkılar G, Sargın M, Sarıtaş TB, Borazan H, Gök F, Kılıçaslan A, et al. Hemodynamic responses to endotracheal intubation performed with video and direct laryngoscopy in patients scheduled for major cardiac surgery. Int J Clin Exp Med 2015;8:11477-83.  Back to cited text no. 13
    
14.
Maharaj CH, O'Croinin D, Curley G, Harte BH, Laffey JG. A comparison of tracheal intubation using the Airtraq or the Macintosh laryngoscope in routine airway management: A randomised, controlled clinical trial. Anaesthesia 2006;61:1093-9.  Back to cited text no. 14
    
15.
Maharaj CH, Costello JF, Higgins BD, Harte BH, Laffey JG. Learning and performance of tracheal intubation by novice personnel: A comparison of the Airtraq and Macintosh laryngoscope. Anaesthesia 2006;61:671-7.  Back to cited text no. 15
    
16.
Maharaj CH, Costello JF, Harte BH, Laffey JG. Evaluation of the Airtraq and Macintosh laryngoscopes in patients at increased risk for difficult tracheal intubation. Anaesthesia 2008;63:182-8.  Back to cited text no. 16
    
17.
Sun DA, Warriner CB, Parsons DG, Klein R, Umedaly HS, Moult M. The GlideScope video laryngoscope: Randomized clinical trial in 200 patients. Br J Anaesth 2005;94:381-4.  Back to cited text no. 17
    


    Figures

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

 
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