McGrath MAC Videolaryngoscope Versus Optiscope Video Stylet for Tracheal Intubation in Patients With Manual Inline Cervical Stabilization: A Randomized Trial

Abstract

Background:
Manual inline stabilization of the head and neck is a recommended maneuver for tracheal intubation in patients with a suspected cervical injury. However, because applying this maneuver inevitably restricts neck flexion and head extension, indirect intubating devices such as a videolaryngoscope or a video stylet could be required for successful tracheal intubation. In this study, we compared the clinical performance of the McGrath MAC videolaryngoscope versus the Optiscope video stylet in patients with manual inline cervical stabilization during tracheal intubation.

Methods:
In 367 consecutive patients undergoing elective cervical spine surgery, tracheal intubation was randomly performed with manual inline stabilization using either the McGrath MAC videolaryngoscope (group M, n = 183) or the Optiscope video stylet (group O, n = 184) by 2 experienced anesthesiologists in a single institution. The primary outcome was the first-attempt success rate of tracheal intubation. Secondary outcomes were intubation time and the incidence of postoperative airway complications, such as sore throat, hoarseness, blood in the oral cavity, and blood staining on the endotracheal tube.

Results:
The first-attempt success rate of tracheal intubation was significantly higher in group M compared with group O (92.3% vs 81.0%; risk difference [95% confidence interval], 0.11 [0.05-0.18]; P = .002). The intubation time was significantly shorter in group M than in group O (35.7 ± 27.8 vs 49.2 ± 43.8; mean difference [95% confidence interval], 13.50 [5.90-21.10]; P = .001). The incidence of postoperative airway complications was not significantly different between the 2 groups.

Conclusions:
The McGrath MAC videolaryngoscope showed a higher first-attempt success rate for tracheal intubation and a shorter intubation time than the Optiscope video stylet in cervical spine patients with manual inline stabilization during tracheal intubation. These results suggest that the McGrath MAC videolaryngoscope may be a better option for tracheal intubation in such patients.

Full text

Downloaded from http://journals.lww.com/anesthesia-analgesia by BhDMf5ePHKbH4TTImqenVGEOlA4BTqbSawXVGSa82UJQ6eQ+yZjXctCrLCzxy0Uw on 09/22/2020
Downloadedfromhttp://journals.lww.com/anesthesia-analgesia by BhDMf5ePHKbH4TTImqenVGEOlA4BTqbSawXVGSa82UJQ6eQ+yZjXctCrLCzxy0Uw on 09/22/2020
Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
870 www.anesthesia-analgesia.org April 2020 • Volume 130 • Number 4
DOI: 10.1213/ANE.0000000000004442
GLOSSARY
ASA = American Society of Anesthesiologists; CONSORT = Consolidated Standards of Reporting
Trials; IRB = institutional review board
Special attention is required when performing tra-
cheal intubation in patients with a cervical spine
injury, because excessive cervical motion during
tracheal intubation may induce secondary neuro-
logic insult.1 Manual inline stabilization of the head
and neck has been recommended to prevent further
KEY POINTS
• Question: Is the clinical performance of tracheal intubation better when a videolaryngoscope,
rather than a video stylet, is used in patients with manual inline cervical stabilization who
were scheduled for elective cervical spine surgery?
• Findings: The McGrath MAC videolaryngoscope showed a higher first-attempt success rate for
tracheal intubation and a shorter intubation time than the Optiscope video stylet in elective
cervical spine surgery patients with manual inline stabilization.
• Meaning: The McGrath MAC videolaryngoscope may be a better option than the Optiscope
video stylet for tracheal intubation in these patients.
BACKGROUND: Manual inline stabilization of the head and neck is a recommended maneuver
for tracheal intubation in patients with a suspected cervical injury. However, because applying
this maneuver inevitably restricts neck exion and head extension, indirect intubating devices
such as a videolaryngoscope or a video stylet could be required for successful tracheal intuba-
tion. In this study, we compared the clinical performance of the McGrath MAC videolaryngo-
scope versus the Optiscope video stylet in patients with manual inline cervical stabilization
during tracheal intubation.
METHODS: In 367 consecutive patients undergoing elective cervical spine surgery, tracheal
intubation was randomly performed with manual inline stabilization using either the McGrath
MAC videolaryngoscope (group M, n = 183) or the Optiscope video stylet (group O, n = 184)
by 2 experienced anesthesiologists in a single institution. The primary outcome was the rst-
attempt success rate of tracheal intubation. Secondary outcomes were intubation time and the
incidence of postoperative airway complications, such as sore throat, hoarseness, blood in the
oral cavity, and blood staining on the endotracheal tube.
RESULTS: The rst-attempt success rate of tracheal intubation was signicantly higher in group M
compared with group O (92.3% vs 81.0%; risk difference [95% condence interval], 0.11 [0.05–
0.18]; P = .002). The intubation time was signicantly shorter in group M than in group O (35.7 ±
27.8 vs 49.2 ± 43.8; mean difference [95% condence interval], 13.5 [5.9–21.1]; P = .001). The
incidence of postoperative airway complications was not signicantly different between the 2 groups.
CONCLUSIONS: The McGrath MAC videolaryngoscope showed a higher rst-attempt success
rate for tracheal intubation and a shorter intubation time than the Optiscope video stylet in
cervical spine patients with manual inline stabilization during tracheal intubation. These results
suggest that the McGrath MAC videolaryngoscope may be a better option for tracheal intubation
in such patients. (Anesth Analg 2020;130:870–8)
McGrath MAC Videolaryngoscope Versus Optiscope
Video Stylet for Tracheal Intubation in Patients
With Manual Inline Cervical Stabilization:
A Randomized Trial
Hyun-Kyu Yoon, MD, Hyung-Chul Lee, MD, PhD, Jung-Bin Park, MD, Hyongmin Oh, MD,
and Hee-Pyoung Park, MD, PhD
See Article, p 869
From the Department of Anesthesiology and Pain Medicine, Seoul National
University College of Medicine, Seoul National University Hospital, Seoul,
Korea.
Accepted for publication August 14, 2019.
Funding: None.
E ORIGINAL CLINICAL RESEARCH REPORT
The authors declare no conicts of interest.
Clinical trial registration: NCT02769221 (http://clinicaltrials.gov).
Reprints will not be available from the authors.
Address correspondence to Hyung-Chul Lee, MD, PhD, Department of An-
esthesiology and Pain Medicine, Seoul National University Hospital, Seoul
National University College of Medicine, 101 Daehakro, Jongno-gu, Seoul
03080, Korea. Address e-mail to vital@snu.ac.kr.
Copyright © 2019 International Anesthesia Research Society
Respiration and Sleep Medicine

Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
EORIGINAL CLINICAL RESEARCH REPORT
April 2020 • Volume 130 • Number 4 www.anesthesia-analgesia.org 871
neurologic injury in this situation.2 However, apply-
ing manual inline stabilization to patients with an
unstable cervical spine inevitably restricts neck exion
and head extension, resulting in a lower rst-attempt
success rate of tracheal intubation using direct laryn-
goscopy.3,4 Therefore, alternative intubation devices,
such as the videolaryngoscope, video stylet, lighted
stylet, and beroptic bronchoscope have been used for
successful tracheal intubation in patients with manual
inline stabilization.5–11
Videolaryngoscopes can be useful for tracheal intu-
bation in patients with cervical immobilization as they
allow indirect visualization of the larynx even with
restricted neck movements.7 Among various videolar-
yngoscopes, the McGrath MAC videolaryngoscope
(McGrath MAC; Medtronic, Dublin, Ireland), which
has a Macintosh-type blade, provides familiarity to
practitioners with the experience of direct laryngo-
scope (Figure1). In a prior investigation for tracheal
intubation in patients with cervical immobilization,
the McGrath MAC videolaryngoscope showed the
highest rst-attempt success rate of tracheal intuba-
tion among 6 different videolaryngoscopes.12
Video stylets, which are portable and easier to pre-
pare than exible beroptic bronchoscopes, could be
another option for tracheal intubation in patient with
cervical immobilization. Previous studies have shown
the usefulness of video stylets for tracheal intubation
in cervical immobilized patients.13–17 Especially in a
recent study, the Optiscope video stylet (Optiscope;
Clarus Medical LLC, Minneapolis, MN) produced
less cervical spine motion, measured on sagittal radio-
graphic images during tracheal intubation, than the
McGrath MAC videolaryngoscope in patients with
a cervical collar.17 However, the sample size of the
study was not sufcient to compare differences in suc-
cess rate of tracheal intubation, the intubation time, or
severity of sore throat between the techniques.
In patients with a cervical collar, previous stud-
ies have shown similarly high rst-attempt success
rates of tracheal intubation using the McGrath MAC
videolaryngoscope and the Optiscope video stylet.15,17
However, there have been no studies to compare tra-
cheal intubation using these 2 devices in patients with
manual inline stabilization.
In this study, we compared the clinical performance
of the McGrath MAC videolaryngoscope versus the
Optiscope video stylet in terms of the rst-attempt
success rate of tracheal intubation, the intubation
time, and the incidence of postoperative airway com-
plications in patients undergoing cervical spine sur-
gery with manual inline stabilization during tracheal
intubation. Our hypothesis was that the rst-attempt
success rate of tracheal intubation using the McGrath
MAC videolaryngoscope would be higher than that
using the Optiscope video stylet.
METHODS
Patient Population
This study was approved by the institutional review
board (IRB) of Seoul National University Hospital
(IRB No.: 1603-129-751), and the study protocol was
registered before patient enrollment at ClinicalTrials.
gov (NCT02769221, Principal investigator: Hee-
Pyoung Park, Date of registration: May 11, 2016). This
study was conducted under Good Clinical Practice
Figure 1. Study devices used
in this study. A, The McGrath
MAC videolaryngoscope. B, The
Optiscope video stylet.

Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
872 www.anesthesia-analgesia.org ANESTHESIA & ANALGESIA
Intubation in Cervical Spine Immobilization
Guidelines and adhered to the applicable Consolidated
Standards of Reporting Trials (CONSORT) guide-
lines. Written informed consent was obtained from
all patients before enrollment in the study. Adult
patients aged 20–80 years with American Society of
Anesthesiologists (ASA) physical status classication
I–III and who were scheduled for elective cervical
spine surgery from June 1, 2016 to August 31, 2018
at a single tertiary teaching hospital (Seoul National
University Hospital) were recruited into this study
consecutively. Patients who had a history of aspira-
tion pneumonia, gastrointestinal obstruction, coagu-
lopathy, history of gastroesophageal reux disease,
radiation therapy on the neck and airway surgery,
and upper airway lesions (ie, tumor, polyp, inamma-
tion, trauma, abscess, or foreign body) were excluded.
Randomization
Using a computer-generated program, block random-
ization with a mixture of blocks of size 4 and 6 was
performed by an investigator blinded to the study.
The patients were randomly assigned to 2 groups:
McGrath MAC videolaryngoscope group (group
M) or Optiscope video stylet group (group O). All
enrolled patients were evenly allocated to the 2 anes-
thesiologists who performed all tracheal intubation
alternately. The patients did not know which group
they had been assigned to. The allocation order was
concealed in an opaque envelope and was disclosed
by an anesthesia nurse immediately before the induc-
tion of anesthesia.
Study Protocol
Airway evaluation was performed in the operating
room. The modied Mallampati classication,18 which
categorizes patients as 4 classes based on the pharyn-
geal structures seen, and interincisor distance were
measured in the sitting and neutral neck positions.
Thereafter, standard monitors (3-lead electrocardio-
gram, noninvasive blood pressure, and pulse oxim-
etry) were used for all patients, and anesthesia was
induced with target-controlled infusions of propofol
and remifentanil (target effect-site concentrations of 4
µg/mL and 4 ng/mL, respectively). After conrming
the loss of consciousness, 0.6 mg/kg of rocuronium
was administered to facilitate tracheal intubation, and
the patient’s radial artery was cannulated for continu-
ous blood pressure monitoring.
While manual inline stabilization was being per-
formed, the patient’s head was rmly grasped by
an anesthesiology resident to prevent head and
neck movements during the tracheal intubation.
Only mouth opening and jaw lifting were allowed.
Under these conditions, tracheal intubation was per-
formed by 1 of 2 attending anesthesiologists, each of
whom had performed at least 50 successful tracheal
intubations using the McGrath MAC videolaryngo-
scope and the Optiscope video stylet.
In group M, tracheal intubation was performed
using the McGrath MAC videolaryngoscope with a
60°-angled malleable aluminum stylet. In group O, the
Optiscope video stylet with a preloaded endotracheal
tube was inserted into the posterior pharynx at the
midline. Once the epiglottis was identied on the dis-
play, the tip of the Optiscope video stylet was advanced
between the vocal cords and the endotracheal tube was
introduced into the trachea. Mallinckrodt-reinforced
tubes (Medtronic) with an internal diameter of 7.0 mm
for women and 7.5 mm for men were used in both
groups.
The success of tracheal intubation was conrmed
by end-tidal carbon dioxide monitoring with capnog-
raphy. Hemodynamic changes, such as mean arterial
pressure and heart rate, were recorded just before
and 1 minute after tracheal intubation. The intuba-
tion time, which was dened as the interval between
insertion of the device into the oral cavity and with-
drawal of the device from the oral cavity, was also
recorded by an anesthesia nurse who did not know
about this study.
Attempted tracheal intubation taking >180 seconds
was regarded as failed intubation. If the rst attempt
failed, one more chance was given to the same anes-
thesiologist after 1 minute of mask ventilation. In each
case, a maximum of 3 attempts was allowed for the
same anesthesiologist. If all attempts failed, berop-
tic bronchoscopic intubation assisted by direct laryn-
goscopy was performed to complete the procedure.
Rescue mask ventilation was applied whenever the
pulse oximetry was below 90%. After tracheal intuba-
tion, the cuff pressure of the endotracheal tube was
measured and maintained at 25 cm H2O using a Posey
8199 Cufator (Posey Company, Arcadia, CA).
At the end of surgery, the presence of blood in the
oral cavity and blood staining on the endotracheal
tube were evaluated after extubation. In addition,
postoperative sore throat and hoarseness were evalu-
ated at 1 and 24 hours after surgery. The severity of
throat pain was assessed using a numeric rating scale
(0, no pain; 10, the worst pain imaginable). The post-
operative neurologic complications dened as newly
developed or aggravated neurological status (pares-
thesia, paresis, and paralysis) at hospital discharge
were collected from the electronic medical records
by an investigator who was blinded to the group
assignment.
Study Outcomes
The primary outcome of this study was the rst-attempt
success rate for tracheal intubation. Secondary out-
comes were intubation time, hemodynamic variables
(mean arterial pressure and heart rate before and 1

Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
EORIGINAL CLINICAL RESEARCH REPORT
April 2020 • Volume 130 • Number 4 www.anesthesia-analgesia.org 873
minute after intubation), the incidence of postoperative
airway complications (sore throat, hoarseness, blood in
the oral cavity, and blood staining on the endotracheal
tube), and postoperative neurologic complications.
Statistical Analysis
For comparison of discrete variables, including the
rst-attempt success rate of tracheal intubation and
the incidence of postoperative sore throat and hoarse-
ness, blood in the oral cavity, and blood staining
on the endotracheal tube, the χ2 test or Fisher exact
test was performed. For comparison of continuous
variables, the Student t test or the Mann-Whitney U
test was performed depending on the results of the
Kolmogorov–Smirnov test. All statistical analyses
were performed with SPSS software (version 25.0;
IBM Corp, Armonk, NY). In all analyses, P < .05 was
taken to indicate statistical signicance.
Sample Size Determination
In a previous study, the rst-attempt success rate
of tracheal intubation using the McGrath MAC
videolaryngoscope in patients with cervical immo-
bilization was 97.5% and the rst-attempt success
rate of <90% was considered clinically signicant.12
Therefore, we dened a difference of >7.5% in the rst-
attempt success rate of tracheal intubation between the
McGrath MAC videolaryngoscope and the Optiscope
video stylet as clinically signicant. Sample size calcu-
lations using G*Power software (version 3.1.9; Franz
Faul, University of Kiel, Germany) indicated that 163
patients were needed per group for 2-tailed χ2 test to
obtain 80% power and an α value of .05. Considering
a possible dropout rate (10%) and missing data (2%), a
total of 370 patients were enrolled in this study.
RESULTS
Among 435 patients eligible for this study during the
study period, 65 patients were excluded (Figure2).
The remaining 370 patients were randomized, and 3
patients were additionally excluded from data analy-
sis due to the withdrawal of consent (Table1).
The rst-attempt success rate of tracheal intubation
was signicantly higher in group M than in group O
Figure 2. Consolidated Standards of Reporting Trials (CONSORT) ow diagram.

Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
874 www.anesthesia-analgesia.org ANESTHESIA & ANALGESIA
Intubation in Cervical Spine Immobilization
(92.3% vs 81.0%; risk difference [95% condence inter-
val], 0.11 [0.05–0.18]; P = .002; Table2). In addition, the
intubation time was signicantly shorter in group M
than in group O (35.7 ± 27.8 vs 49.2 ± 43.8 seconds;
mean difference [95% condence interval], 13.5 [5.9–
21.1]; P = .001). Group O included 5 patients whose
trachea could not be intubated within 3 attempts.
Each had a long and lax epiglottis that sat toward the
posterior pharynx. In these patients, the trachea was
intubated successfully by beroptic bronchoscopy
with assistance from direct laryngoscopy. There were
no signicant differences in the hemodynamic vari-
ables, including mean arterial pressure and heart rate
measured just before and 1 minute after tracheal intu-
bation, between the 2 groups.
Comparisons of postoperative airway complica-
tions between the 2 groups are presented in Table3.
The incidences of postoperative sore throat and
hoarseness at 1 (20.8% vs 25.0%; P = .400 and 8.7% vs
7.1%; P = .687, respectively) and 24 (10.9% vs 14.7%; P
= .359 and 4.4% vs 3.8%; P = .991, respectively) hours
after surgery were comparable between the 2 groups.
In addition, the incidences of blood in the oral cavity
and blood staining on the endotracheal tube did not
differ signicantly between the 2 groups. The overall
incidence of postoperative neurologic complications
was 6.3% (23/367), and there was no signicant differ-
ence in the incidence of these complications between
the 2 groups (7.7% vs 4.9%; risk difference [95% con-
dence interval], 2.8% [−2.3 to 8.1]; P = .382).
Table 1. Comparisons of Demographics and Airway-Related Variables Between the 2 Groups
Group M
(n = 183) Group O
(n = 184) Mean Difference
(95% CI)
Demographic variables
Age (y) 54.2 ± 14.5 55.3 ± 13.6 1.1 (−1.8 to 4.0)
Male 111 (60.7%) 124 (67.4%) 6.7% (−3.1 to 16.3)
BMI (kg/m2) 24.6 ± 3.5 25.1 ± 3.5 0.5 (−0.2 to 1.2)
ASA physical status
I 84 (45.9%) 78 (42.4%) 3.5% (−6.6 to 13.5)
II 91 (49.7%) 89 (48.4%) 1.3% (−8.8 to 11.4)
III 8 (4.4%) 17 (9.2%) 4.8% (−0.5 to 10.3)
Comorbidities
Hypertension 49 (26.8%) 56 (30.4%) 3.6% (−5.6 to 12.7)
Diabetes mellitus 26 (14.2%) 31 (16.8%) 2.6% (−4.9 to 10.1)
Cardiac disease 4 (2.2%) 7 (3.8%) 1.6% (−2.2 to 5.7)
Respiratory disease 8 (4.4%) 5 (2.7%) 1.7% (−2.4 to 6.0)
Neurologic disease 15 (8.2%) 10 (5.4%) 2.8% (−2.5 to 8.3)
Renal disease 1 (0.5%) 5 (2.7%) 2.2% (−0.7 to 5.7)
Hepatic disease 5 (2.7%) 9 (4.9%) 2.2% (−2.0 to 6.6)
Thyroid disease 3 (1.6%) 2 (1.1%) 0.5% (−2.5 to 3.7)
Malignancy 4 (2.2%) 7 (3.8%) 1.6% (−2.2 to 5.7)
Rheumatoid arthritis 2 (1.1%) 7 (3.8%) 2.7% (−0.7 to 6.6)
Airway-related parameters
Modied Mallampati classication
I 40 (21.9%) 45 (24.5%) 2.6% (−6.0 to 11.2)
II 88 (48.1%) 78 (42.4%) 5.7% (−4.4 to 15.7)
III 50 (27.3%) 52 (28.3%) 1.0% (−8.1 to 10.1)
IV 5 (2.7%) 9 (4.9%) 2.2% (−2.0 to 6.6)
Interincisor distance (mm) 43.9 ± 9.2 42.4 ± 8.1 1.5 (−3.3 to 0.3)
Use of oral airway 6 (3.3%) 9 (4.9%) 1.6% (−2.8 to 6.1)
Surgical variables
Diagnosis
Degenerative 128 (69.9%) 140 (76.1%) 6.2% (−2.9 to 15.2)
Tumorous 47 (25.7%) 36 (19.6%) 6.1% (−2.5 to 14.6)
Trauma 2 (1.1%) 1 (0.5%) 0.6% (−2.0 to 3.4)
Vascular 2 (1.1%) 0 (0.0%) 1.1% (−1.1 to 3.9)
Congenital 4 (2.2%) 7 (3.8%) 1.6% (−2.2 to 5.7)
Site of operation 7.8% (−0.9 to 16.4)
At or above C2 51 (27.9%) 37 (20.1%)
At or below C3 132 (72.1%) 147 (79.9%)
Surgical approach
Anterior 22 (12.0%) 30 (16.3%) 4.3% (−2.9 to 11.5)
Posterior 161 (88.0%) 155 (84.2%) 3.8% (−3.4 to 10.9)
Both 0 (0.0%) 1 (0.5%) 0.5% (−1.6 to 2.9)
Anesthesia time (min) 211.4 ± 105.5 193.8 ± 92.6 17.6 (−2.8 to 38.0)
Operation time (min) 153.8 ± 101.4 137.8 ± 89.2 16.0 (−3.6 to 35.6)
Values are mean ± standard deviation or number (proportion). In the group M and O, tracheal intubations were performed using the McGrath MAC videolaryngoscope
and Optiscope video stylet, respectively.
Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; CI, condence interval.

Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
EORIGINAL CLINICAL RESEARCH REPORT
April 2020 • Volume 130 • Number 4 www.anesthesia-analgesia.org 875
DISCUSSION
In this study, the rst-attempt success rate was sig-
nicantly higher, and the intubation time was sig-
nicantly shorter when tracheal intubation was
performed using the McGrath MAC videolaryngo-
scope than with the Optiscope video stylet in patients
with manual inline stabilization. The incidence of
intubation-related postoperative airway complica-
tions was not signicantly different between the 2
intubation devices.
Both the videolaryngoscope and the video stylet
have been used in clinical practice for tracheal intu-
bation in patients with an unstable cervical spine.
However, in this study, the McGrath MAC videolar-
yngoscope showed signicantly better performance
of tracheal intubation than the Optiscope video sty-
let. The possible mechanisms of these results may be
as follows. First, manual inline stabilization allows
wider mouth opening than cervical collar applica-
tion. Although the blade of the McGrath MAC vide-
olaryngoscope is bulkier than the Optiscope video
stylet, this may not impact the performance of tra-
cheal intubation in patients with manual inline sta-
bilization. This may also explain why our results
were inconsistent with those of a previous study
using a cervical collar, which reported longer intuba-
tion times in patients using the Airway Scope vide-
olaryngoscope (Nihon Kohden, Tokyo, Japan) than
those using the Clarus Video System video stylet
(Clarus Medical LLC).15 Second, intubating devices
with the lens at the tip, such as optical stylet or video
stylet, have been reported to be susceptible to con-
tamination by oral secretions.19,20 In a previous study
using Bonls video stylet (Karl Storz Endoscope,
Table 2. Comparisons of Intubation-Related Variables Between the 2 Groups
Group M
(n = 183) Group O
(n = 184) Mean Difference
(95% CI) P
Successful tracheal intubation
Overall 183 (100.0%) 179 (97.3%) 2.7% (0.1–6.2) .061
At rst attempt 169 (92.3%) 149 (81.0%) 11.3% (4.5–18.3) .002
At second attempt 12 (6.6%) 19 (10.3%) 3.7% (−2.1 to 9.6) .267
At third attempt 2 (1.1%) 11 (6.0%) 4.9% (1.1–9.4) .020
Intubation time (s) 35.7 ± 27.8 49.2 ± 43.8 13.5 (5.9–21.1) .001
Mean arterial pressure (mm Hg)
Before intubation 72.7 ± 18.2 71.8 ± 15.0 0.9 (−4.3 to 2.5) .597
1 min after intubation 87.6 ± 22.1 85.4 ± 21.4 2.2 (−6.7 to 2.3) .326
Heart rate (beats/min)
Before intubation 64.0 ± 11.8 64.8 ± 12.0 0.8 (−1.6 to 3.2) .510
1 min after intubation 80.1 ± 54.4 76.5 ± 13.6 3.6 (−11.7 to 4.5) .398
Values are number (proportion) or mean ± standard deviation. In the group M and O, tracheal intubations were performed using the McGrath MAC videolaryngoscope
and Optiscope video stylet, respectively.
Abbreviation: CI, condence interval.
Table 3. Comparisons of Postoperative Complications Between the 2 Groups
Group M
(n = 183) Group O
(n = 184) Mean Difference
(95% CI) P
Postoperative airway complications
Sore throat
Postoperative 1 h 38 (20.8%) 46 (25.0%) 4.2% (−4.4 to 12.7) .400
Postoperative 24 h 20 (10.9%) 27 (14.7%) 3.8% (−3.1 to 10.7) .359
Throat pain (NRS)
Postoperative 1 h 6.0 (5.0–7.0) 6.3 (5.0–8.0) NA 1.000
Postoperative 24 h 3.0 (2.0–4.5) 3.0 (2.0–4.0) NA .424
Hoarseness
Postoperative 1 h 16 (8.7%) 13 (7.1%) 1.6% (−4.1 to 7.4) .687
Postoperative 24 h 8 (4.4%) 7 (3.8%) 0.6% (−3.8 to 5.1) .991
Blood in the oral cavity 9 (4.9%) 15 (8.2%) 3.3% (−1.9 to 8.7) .297
Blood staining on the endotracheal tube 4 (2.2%) 4 (2.2%) 0.0% (−3.6 to 3.6) 1.000
Postoperative neurologic complications
Overall 14 (7.7%) 9 (4.9%) 2.8% (−2.3 to 8.1) .382
Paresthesia 11 (6.0%) 8 (4.3%) 1.7% (−3.1 to 6.6) .629
Paresis 7 (3.8%) 4 (2.2%) 1.6% (−2.2 to 5.7) .380
Paralysis 0 (0.0%) 0 (0.0%) 0.0% (−2.1 to 2.0) 1.000
Values are number (proportion) or median (interquartile). In the group M and O, tracheal intubations were performed using the McGrath MAC videolaryngoscope
and Optiscope video stylet, respectively. Sore throat was evaluated with numeric rating scale from 0 to 10 (0: no pain, 10: the worst imaginable pain). The
postoperative neurologic complications were dened as newly developed or aggravated neurological status (paresthesia, paresis, and paralysis) at hospital
discharge.
Abbreviations: CI, condence interval; NA, not applicable; NRS, numeric rating scale.

Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
876 www.anesthesia-analgesia.org ANESTHESIA & ANALGESIA
Intubation in Cervical Spine Immobilization
Tuttlingen, Germany), oral secretions reduced the
view during tracheal intubation in 30% (18/60) of the
patients.20 This may also explain why the optical or
video stylets showed excellent performance in man-
nequin studies, but the results could not be repro-
ducible in the living subjects.21–24 In contrast, for the
McGrath MAC videolaryngoscope, the camera lens is
located proximally and covered by the blade, which
can be advantageous in preventing the contamina-
tion by oral secretion (Figure3). Finally, without cer-
vical motion, the hooking or scooping motion below
the epiglottis, which is essential for intubation using
the Optiscope video stylet, was extremely difcult
in some patients with a long and oppy epiglottis.
Meanwhile, the McGrath MAC videolaryngoscope
can lift the epiglottis directly even in patients with a
long and oppy epiglottis.
Increasing the rst-attempt success rate of tracheal
intubation is clinically relevant because repeated
attempts to intubate the trachea can result in intu-
bation-related postoperative airway complications.
However, the McGrath MAC videolaryngoscope and
Optiscope video stylet showed similar and acceptable
proles with regard to postoperative airway com-
plications in this study. The incidence rates of sore
throat measured at 1 hour after surgery were 20.8%
and 25.0% in group M and group O, respectively (risk
difference [95% condence interval], 0.04 [0.04–0.13]).
These results can be ascribed to the following reasons.
First, the force applied to the mucosa, which was
generated by direct contact of the videolaryngoscope
blade, might be minimal. Previous studies reported
that lifting force and soft tissue trauma were sig-
nicantly reduced with the videolaryngoscope than
the direct laryngoscope with a Macintosh blade.25,26
Second, other clinical risk factors affecting the devel-
opment of postoperative sore throat, such as the
duration of anesthesia, size of the endotracheal tube,
endotracheal tube cuff pressure, and sex were ran-
domized or controlled by the study protocol.26–28 In
addition, most tracheas were intubated within second
attempts in both groups.
This study had several limitations. First, the opera-
tors were not blinded to the group assignment, and
this inevitable bias could have affected the results.
Second, as the operators were all skilled in using
both the McGrath MAC videolaryngoscope and the
Optiscope video stylet, the results of this study are not
equally generalizable to practitioners unfamiliar with
either device. However, previous studies revealed that
only 6 and 10 attempts were sufcient for novice users
to achieve high success rate of tracheal intubation
using the McGrath videolaryngoscope and Optiscope
video stylet, respectively.29,30 Third, there may be
some differences in clinical performance of tracheal
intubation with other types of videolaryngoscope and
video stylets. Every airway device has its own distinc-
tive features with regard to the shape and the size of
their blades, body curvature, camera location, and
guidance of the endotracheal tube. Although devices
of the same type usually share similar structures, care
must be taken while generalizing the results. Finally,
the cervical spine motion during tracheal intubation
was not measured in the present study. Therefore, the
Figure 3. Different mecha-
nisms of tracheal intubation.
A, The McGrath MAC videolar-
yngoscope. B, The Optiscope
video stylet. Arrows indicate the
direction of force applied dur-
ing manipulation of the device.
Asterisks indicate the location
of the camera lens.

Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
EORIGINAL CLINICAL RESEARCH REPORT
April 2020 • Volume 130 • Number 4 www.anesthesia-analgesia.org 877
relationship between tracheal intubation and postop-
erative neurologic outcome was uncertain, although
there was no difference in the incidence of postopera-
tive neurologic complications between the 2 groups.
In conclusion, the McGrath MAC videolaryngo-
scope showed better clinical performance in terms of
the rst-attempt success rate of tracheal intubation
and intubation time than the Optiscope video stylet in
patients undergoing cervical spine surgery with man-
ual inline stabilization during tracheal intubation.
In addition, the incidence of postoperative airway
complications was similar between the 2 intubation
devices. These results suggest that the McGrath MAC
videolaryngoscope may be a better option for tracheal
intubation in such patients. E
DISCLOSURES
Name: Hyun-Kyu Yoon, MD.
Contribution: This author helped in the design of the study,
data acquisition, data analysis and interpretation, drafting of
the manuscript, and approval of the submitted version of the
manuscript.
Name: Hyung-Chul Lee, MD, PhD.
Contribution: This author helped in the design of the study,
data acquisition, data analysis and interpretation, drafting
of the manuscript, critical revision of the manuscript, and
approval of the submitted version of the manuscript.
Name: Jung-Bin Park, MD.
Contribution: This author helped in the data acquisition, data
analysis and interpretation, and approval of the submitted ver-
sion of the manuscript.
Name: Hyongmin Oh, MD.
Contribution: This author helped in the data acquisition, data
analysis and interpretation, statistical analysis, and approval of
the submitted version of the manuscript.
Name: Hee-Pyoung Park, MD, PhD.
Contribution: This author helped in the design of the study,
data acquisition, data analysis and interpretation, critical revi-
sion of the manuscript, and approval of the submitted version
of the manuscript.
This manuscript was handled by: David Hillman, MD.
REFERENCES
1. Brimacombe J, Keller C, Künzel KH, Gaber O, Boehler M,
Pühringer F. Cervical spine motion during airway manage-
ment: a cineuoroscopic study of the posteriorly destabi-
lized third cervical vertebrae in human cadavers. Anesth
Analg. 2000;91:1274–1278.
2. National Institute for Health and Care Excellence. NICE
Guideline NG41. Spinal Injury. London, UK: NICE
Guideline; 2016:41.
3. Heath KJ. The effect of laryngoscopy of different cer-
vical spine immobilisation techniques. Anaesthesia.
1994;49:843–845.
4. Thiboutot F, Nicole PC, Trépanier CA, Turgeon AF, Lessard
MR. Effect of manual in-line stabilization of the cervical
spine in adults on the rate of difcult orotracheal intubation
by direct laryngoscopy: a randomized controlled trial. Can J
Anaesth. 2009;56:412–418.
5. Jung JY. Airway management of patients with trau-
matic brain injury/C-spine injury. Korean J Anesthesiol.
2015;68:213–219.
6. Aoi Y, Inagawa G, Hashimoto K, et al. Airway scope laryn-
goscopy under manual inline stabilization and cervical
collar immobilization: a crossover in vivo cineuoroscopic
study. J Trauma. 2011;71:32–36.
7. Enomoto Y, Asai T, Arai T, Kamishima K, Okuda Y. Pentax-
AWS, a new videolaryngoscope, is more effective than the
Macintosh laryngoscope for tracheal intubation in patients
with restricted neck movements: a randomized compara-
tive study. Br J Anaesth. 2008;100:544–548.
8. Kihara S, Yaguchi Y, Taguchi N, Brimacombe JR, Watanabe
S. The StyletScope is a better intubation tool than a conven-
tional stylet during simulated cervical spine immobiliza-
tion. Can J Anaesth. 2005;52:105–110.
9. Seo H, Kim E, Son JD, Ji S, Min SW, Park HP. A prospec-
tive randomised study of a rigid video-stylet vs conven-
tional lightwand intubation in cervical spine-immobilised
patients. Anaesthesia. 2016;71:1341–1346.
10. Houde BJ, Williams SR, Cadrin-Chênevert A, Guilbert F,
Drolet P. A comparison of cervical spine motion during
orotracheal intubation with the trachlight® or the exible
beroptic bronchoscope. Anesth Analg. 2009;108:1638–1643.
11. Holmes MG, Dagal A, Feinstein BA, Joffe AM. Airway man-
agement practice in adults with an unstable cervical spine:
the harborview medical center experience. Anesth Analg.
2018;127:450–454.
12. Kleine-Brueggeney M, Greif R, Schoettker P, Savoldelli GL,
Nabecker S, Theiler LG. Evaluation of six videolaryngoscopes
in 720 patients with a simulated difcult airway: a multicentre
randomized controlled trial. Br J Anaesth. 2016;116:670–679.
13. Byhahn C, Nemetz S, Breitkreutz R, Zwissler B, Kaufmann
M, Meininger D. Brief report: tracheal intubation using the
Bonls intubation brescope or direct laryngoscopy for
patients with a simulated difcult airway. Can J Anaesth.
2008;55:232–237.
14. Komatsu R, Kamata K, Hamada K, Sessler DI, Ozaki M.
Airway scope and StyletScope for tracheal intubation in a
simulated difcult airway. Anesth Analg. 2009;108:273–279.
15. Kim JK, Kim JA, Kim CS, Ahn HJ, Yang MK, Choi SJ.
Comparison of tracheal intubation with the airway scope
or Clarus video system in patients with cervical collars.
Anaesthesia. 2011;66:694–698.
16. Phua DS, Mah CL, Wang CF. The Shikani optical stylet as an
alternative to the GlideScope® videolaryngoscope in simu-
lated difcult intubations–a randomised controlled trial.
Anaesthesia. 2012;67:402–406.
17. Nam K, Lee Y, Park HP, Chung J, Yoon HK, Kim TK. Cervical
spine motion during tracheal intubation using an optiscope
versus the McGrath videolaryngoscope in patients with
simulated cervical immobilization: a prospective random-
ized crossover study. Anesth Analg. 2019;129:1666–1672.
18. Samsoon GL, Young JR. Difcult tracheal intubation: a ret-
rospective study. Anaesthesia. 1987;42:487–490.
19. Liem EB, Bjoraker DG, Gravenstein D. New options for air-
way management: intubating breoptic stylets. Br J Anaesth.
2003;91:408–418.
20. Halligan M, Charters P. A clinical evaluation of the Bonls
intubation brescope. Anaesthesia. 2003;58:1087–1091.
21. Cooney DR, Cooney NL, Wallus H, Wojcik S. Performance
of emergency physicians utilizing a video-assisted semi-
rigid beroptic stylet for intubation of a difcult airway in
a high-delity simulated patient: a pilot study. Int J Emerg
Med. 2012;5:24.
22. Cooney DR, Beaudette C, Clemency BM, Tanski C, Wojcik
S. Endotracheal intubation with a video-assisted semi-rigid
beroptic stylet by prehospital providers. Int J Emerg Med.
2014;7:45.

Copyright © 2019 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
878 www.anesthesia-analgesia.org ANESTHESIA & ANALGESIA
Intubation in Cervical Spine Immobilization
23. Agrò F, Cataldo R, Carassiti M, Costa F. The seeing sty-
let: a new device for tracheal intubation. Resuscitation.
2000;44:177–180.
24. Webb A, Kolawole H, Leong S, Loughnan TE, Crofts T,
Bowden C. Comparison of the Bonls and Levitan opti-
cal stylets for tracheal intubation: a clinical study. Anaesth
Intensive Care. 2011;39:1093–1097.
25. Russell T, Khan S, Elman J, Katznelson R, Cooper RM.
Measurement of forces applied during Macintosh direct
laryngoscopy compared with GlideScope® videolaryngos-
copy. Anaesthesia. 2012;67:626–631.
26. Aqil M, Khan MU, Mansoor S, Mansoor S, Khokhar RS,
Narejo AS. Incidence and severity of postoperative sore
throat: a randomized comparison of glidescope with
Macintosh laryngoscope. BMC Anesthesiol. 2017;17:127.
27. McHardy FE, Chung F. Postoperative sore throat: cause,
prevention and treatment. Anaesthesia. 1999;54:444–453.
28. El-Boghdadly K, Bailey CR, Wiles MD. Postoperative sore
throat: a systematic review. Anaesthesia. 2016;71:706–717.
29. Ray DC, Billington C, Kearns PK, et al. A comparison of
McGrath and Macintosh laryngoscopes in novice users: a
manikin study. Anaesthesia. 2009;64:1207–1210.
30. Moon YJ, Kim J, Seo DW, et al. Endotracheal intubation
by inexperienced trainees using the Clarus Video System:
learning curve and orodental trauma perspectives. J Dent
Anesth Pain Med. 2015;15:207–212.