Asian Journal of Anesthesiology 55 (2017) 41e44
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Asian Journal of Anesthesiology
journal homepage: www.journals.elsevier.com/asianjournal-of-anesthesiology
Research paper
A randomised trial to compare Truview PCD®, C-MAC® and Macintosh
laryngoscopes in paediatric airway management
Ranju Singh, Nishant Kumar*, Aruna Jain
Department of Anaesthesiology & Critical Care, Lady Hardinge Medical College & Associated Shrimati Sucheta Kriplani Hospital, New Delhi, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 13 January 2017
Received in revised form
7 April 2017
Accepted 11 April 2017
Aim: To evaluate and compare the Truview PCD and C-MAC laryngoscopes to the standard Macintosh
laryngoscope in paediatric patients.
Methods: One hundred and fifty ASA I-II patients in the age group of 1e6 years (10e20 kg) scheduled for
elective surgery were randomised into three equal groups for laryngoscopy and intubation with either
Truview PCD (Group T), C-MAC (Group C) or Macintosh (Group M) laryngoscopes under general
anaesthesia. Percentage of glottic opening (POGO) score, application of external laryngeal manoeuvre,
time to intubation, number of attempts at intubation, failed intubations, episodes of desaturation and
trauma caused were recorded and statistically analysed. A p value of <0.05 was taken as significant.
Results: POGO scores were significantly better with Truview PCD as compared with C-MAC and
Macintosh laryngoscopes (94.7 ± 12.9/82 ± 25.0/85.1 ± 17.1; p < 0.01). There were no failed attempts,
episodes of desaturation or trauma in any of the patients. The mean intubation time taken was 19.2 s in
group T, 12.3 s in group C and 10.7 s in group M, respectively. There is a statistically significant difference
among groups (p < 0.01). Eight patients in group T, 21 out of 50 patients in group C and 19 out of 50
patients in group M needed OELM, respectively. There is significant difference among the groups
(p < 0.01)
Conclusion: Using Truview PCD to assist intubation offers excellent view field of glottic opening after
OLEM and the mean time taken is less than 20 s. The Truview PCD tool is suitable for paediatric patients.
© 2017 Taiwan Society of Anesthesiologists. Published by Elsevier Taiwan LLC. This is an open access
article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Keywords:
Laryngoscopes;
Truview PCD;
C-MAC;
Macintosh;
POGO
1. Introduction
Paediatric airway management requires careful clinical evaluation and experienced execution due to anatomical, physiological
and developmental considerations. Prediction of difficult airway is
not always possible in a child as measurement of mentohyoid,
thyromental, mandibular and inter-incisor lengths are not validated.1 A plethora of airway devices have flooded the market to
overcome the inadequacy of difficult airway prediction in children.
The Truview Picture Capture Device (PCD) blade is based on a
combination of an optical system with a specially profiled slim
steel blade. The optical apparatus provides a 48 angled deflection view through a 15-mm eyepiece. The eyepiece can be connected to the Picture Capture Device (PCD). In addition, the
Truview PCD blade has a port that connects to the auxiliary oxygen flow of the anaesthesia machine (flow rate of 4e6 l min 1),
* Corresponding author. A-103, Urja Towers, Sector 47, Gurgaon, Haryana, India.
E-mail:
[email protected] (R. Singh),
[email protected]
(N. Kumar),
[email protected] (A. Jain).
which prevents misting and clears secretions from the lens and
provides continuous oxygen insufflation during intubation. Truview EVO2® has been shown to have distinct advantages over the
conventional Macintosh (M) blade in adults2e7 and provides a
better view of the glottis as compared to the Miller blade in infants and children.8,9
Shaped and handled like the conventional Macintosh blade, the
C-MAC laryngoscope provides an 80 field of view and the image
can be captured electronically in the video or in still format and
displayed on the dedicated monitor.10 The C-MAC laryngoscope has
been proved to provide an equal if not better view of the glottis
with less trauma as compared to the conventional Macintosh blade
in adults.11e14
Although the Truview PCD and C-MAC videolaryngoscopes have
been compared with Macintosh laryngoscope in infants, to the best
of knowledge there are no reports of such a comparison in older
paediatric population. We have therefore designed this study to
evaluate and compare the laryngeal view provided by two videolaryngoscopes to the standard Macintosh laryngoscope in paediatric
patients.
http://dx.doi.org/10.1016/j.aja.2017.06.001
2468-824X/© 2017 Taiwan Society of Anesthesiologists. Published by Elsevier Taiwan LLC. This is an open access article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/4.0/).
42
R. Singh et al.
2. Methods
After approval from the Institutional Ethical Committee, 150 ASA
physical status IeII patients in the age group of 1e6 years
(10e20 kg) scheduled for elective surgery at Kalawati Saran Children's Hospital and Srimati Sucheta Kriplani Hospital, New Delhi,
India, requiring general anaesthesia and endotracheal intubation
were recruited for the study between March 2012 and September
2013. The patients were randomised into three equal groups: Group
T e to be intubated using Truview PCD (size 2), Group C e to be
intubated with C-MAC laryngoscope (size 2) and Group M e to be
intubated with the aid of Macintosh (size 2) laryngoscope. The
random numbers were delivered to the operating room in sealed
opaque envelopes and the laryngoscope used was decided at the
time of induction of anaesthesia. Patients with an ASA physical
status grade > II, presence of raised intracranial pressure, high risk
for pulmonary aspiration of gastric contents; coagulopathy and
presence of any pathology of head and neck were excluded.
After a thorough pre-anaesthetic assessment, fasting as per ASA
guidelines and a written informed consent from parents/guardian,
the patient was wheeled inside the operating room and routine
monitors applied. Patients received fentanyl 2 mg kg 1 for analgesia
and anaesthesia was induced by propofol 2 mg kg 1. Ventilation
was maintained by N2O in O2 (60:40) and sevoflurane 1e2% by bag
and mask. Neuromuscular blockade was facilitated by rocuronium
bromide 0.9 mg kg 1 and trachea intubated after 90 s. Patients
allocated to group T were intubated with the aid of the Truview
PCD, those in Group C by an indirect laryngoscopy using the C-MAC
videolaryngoscope, whereas, in group-M patients direct laryngoscopy and intubation was performed with the aid of Macintosh
laryngoscope. The appropriate sized stylet provided with the Truview PCD was used in patients allocated to Group T. All intubations
were performed by the senior anaesthesiologists (Dr. Singh and Dr.
Kumar) with a previous experience of at least twenty intubations
with the Truview PCD and the C-MAC blade. Laryngeal view was
defined as the primary objective of the study. Percentage of glottic
opening (POGO)14 score was used to grade the laryngeal view. The
POGO score is considered to be 100% if the entire glottis is visualized from the anterior commissure to the posterior cartilages, and
the POGO score is 0% if none of the glottic opening is seen. Partial
visualization of the glottis was thus given a subjective score between 0 and 100%. Optimal external laryngeal manoeuvre (OELM)
was applied for best glottic view if the initial POGO was 75%.
POGO after application of OELM was also noted. The time to intubation was measured from the time the laryngoscope entered the
patient's mouth until the time it was taken out after the placement
of endotracheal tube in the trachea. If a tube change was deemed
necessary, the time taken for the placement of only the first tube
inside the trachea was noted. The number of attempts was defined
as withdrawing the tube to the angle of the mouth and reintroducing it. Any fall in oxygen saturation to <95% on the pulse oximeter was noted and the lungs were ventilated with 100% oxygen.
If more than three attempts or >60 s were required after combined
attempts to secure an endotracheal tube, it was considered as failed
intubation. Oesophageal intubation if any was also noted. The
trauma caused during laryngoscopy and need for external
manoeuvres were also noted. Trauma was defined as any bleeding
or abrasion on the lips, gums and angle of mouth of the child or
blood on the laryngoscope blade after intubation. Apart from the
POGO score, all data were noted by an independent observer not
involved in the study. The statistician was also blinded to the
allocation of the groups.
3. Statistical analysis
POGO score was taken as the primary outcome. Sample size was
calculated after a pilot study to detect a difference of at least 25% in
the POGO scores between the three groups using a commercial
statistical software (Medcalc software version 9.2.1.0, Mariakerke,
Belgium) with an a error of 0.05 to achieve a power of 0.8. A p value
of <0.05 was considered to indicate statistical significance. Data is
presented as mean or median with range or standard deviation (SD)
as appropriate.
The ANOVA test was used to compare the time taken to intubate and POGO score. Bonferroni/Tamahane's T2 correction was
applied for intergroup analysis. Number of attempts required for
intubation was analysed using Kruskal Wallis test. The incidence of
failed intubations, number of episodes of desaturation, trauma
caused and need for external manoeuvres was compared using the
Chi square test.
4. Results
Patient characteristics are described in Table 1. Data for all 150
patients was analysed. POGO scores were significantly better with
Truview PCD as compared to C-MAC and Macintosh laryngoscopes
(94.7 ± 12.9%/82 ± 25.0%/85.1 ± 17.1%; p < 0.01). There were no
oesophageal intubations, failed attempts, episodes of desaturation
or trauma in any of the patients. The mean intubation time taken
was 19.2 s in group T, 12.3 s in group C and 10.7 s in group M,
respectively. There is a statistically significant difference among
groups (p < 0.01). Using Truview PCD provided an excellent view of
glottic opening; there is a significant difference of POGO exposure
in the group T and the group C and group M. In addition, 8 patients
in group T (16%), 21 out of 50 patients in group C (42%) and 19 out of
50 patients in group M (38%) needed OELM, respectively. There is
significant difference among the groups (p < 0.01). However, group
T patients may spend more time for intubation than the group C
and group M. The mean POGO scores after OELM were 100% in
group T and M as compared to 97.1% in group C. Laryngoscopy and
intubation parameters are depicted in Table 2.
5. Discussion
We found that the glottic view (POGO score) was clinically and
statistically better with Truview PCD as compared to C-MAC and
Macintosh laryngoscopes and fewer patients in the Truview PCD
group required OELM to improve the view. However the time taken
to intubate the trachea was more as compared to the C-MAC and
Macintosh laryngoscopes, which was statistically significant (7e9 s
more with Truview PCD). The C-MAC and Macintosh laryngoscopes
Table 1
Patient characteristics (values are expressed as mean ± standard deviation).
Sex
Age
Weight
Female
Male
Years
kg
Group T (n ¼ 50)
Group C (n ¼ 50)
Group M (n ¼ 50)
p Value
16 (32%)
34 (68%)
3.8 ± 2.0
14.7 ± 3.9
16 (32%)
34 (68%)
3.5 ± 1.8
13.8 ± 2.7
8 (16%)
42 (84%)
3.9 ± 1.8
15.2 ± 4.2
0.11
0.61
0.13
Comparison of Truview PCD®, C-MAC® and Macintosh laryngoscopes in paediatric patients
43
Table 2
Laryngoscopy and intubation parameters.
POGOa (%)
Time taken (s)
Attempts (1/2/3)
OELMb (n)
POGO after OELM (%)
a
b
Group T (n ¼ 50)
Group C (n ¼ 50)
Group M (n ¼ 50)
p Value
94.7 ± 12.9
19.2 ± 3.5
46/4/0
8 (16%)
100
82 ± 25.0
12.3 ± 4.3
49/1/0
21 (42%)
97.1
85.1 ± 17.1
10.7 ± 2.3
50/0/0
19 (38%)
100
<0.01
<0.01
0.06
0.01
0.27
POGO: Percentage of glottic opening.
OELM: Optimal external laryngeal maneuver.
were statistically comparable in terms of glottic view and time
taken for laryngoscopy and intubation.
Results similar to ours have been reported by Mutlak et al. They
compared the three laryngoscopes in children weighing <10 kg
with respect to time taken for intubation, while our primary
outcome was laryngeal view as graded by POGO. Time taken was
longest with Truview PCD and similar with C-MAC and Macintosh
laryngoscopes (Truview PCD e 52 s, C-MAC e 28 s, Macintosh e
26 s). However, time taken for intubation was much longer in all
three groups as compared to ours, probably due to visualisation of
the first square wave capnograph on the monitor as the end point.
The user satisfaction score was lowest with the Truview EVO2
because of unfamiliarity with the instrument.15
Riveros et al, however, found that videolaryngoscopes such as
Truview PCD and Glidescope do not improve the view as compared
to conventional laryngoscope in children. Also, the time taken was
more with Truview PCD as compared to conventional laryngoscope
(44 vs 23 s).16
The basic difference in the use of direct and indirect laryngoscopes lies in the fact that although the view of the cords is much
better with the indirect laryngoscopes, intubation is considered
comparatively difficult. While direct laryngoscopy provides a real
image of the cords by actually aligning the laryngeal axis with the
line of the view, indirect laryngoscopes create a virtual image of the
cords that is captured by the camera. Achieving endotracheal
intubation is thus difficult because better hand eye co ordination is
required for the parallax to be countered. The Truview PCD is thus
supplied with an optishape® preformed stylet which is designed to
nullify the parallax created by the laryngoscopic image and directs
the endotracheal tube towards the vocal cords. The use of the stylet
and a learning curve for better hand eye coordination may explain
the longer time required for intubation with the Truview PCD.
The POGO score visualised by both C-MAC and conventional
Macintosh in our study was the same. The time taken for intubation
with C-MAC and Macintosh was also comparable. C-MAC is shaped
like the conventional Macintosh laryngoscope which the anaesthesiologists are already conversant and experienced with.
Although it has a built in camera, the angle of the curvature is same
as that of the conventional Macintosh laryngoscope (22 ). The
camera of C-MAC is advantageous as it provides a clear magnified
and a high resolution image on the monitor and is therefore an
excellent teaching tool.
Since we had included patients with normal airways, there were
no failure attempts and POGO <75% improved to nearly 100% in all
cases after OELM. There were no undesirable effects such as oxygen
desaturation. This was due to oxygen insufflation through the
Truview PCD during a longer time required for intubation and
fogging was also prevented. However in a few cases, the secretions
formed a meniscus on the lens of Truview PCD due to flow of oxygen which did not impair the view of the glottis.
The limitations of our study include absence of blinding, non
inclusion of difficult airways and lack of crossover. Also, POGO is
subjective leading to a certain bias during assessment by the
laryngoscopist.
To conclude, using Truview PCD to assist intubation not only
offers the best laryngeal view over C-MAC and Macintosh blades
but also the time taken is less than 20 s. Truview PCD, provides
better views than the conventional Macintosh laryngoscope, while
the C-MAC provides a good resolution and is a teaching tool.
Ethical approval
Institutional Ethical Committee e IEC Project No. 89 Dated
6.2.12.
Trial registration
Clinical Trial Registry of India (www.ctri.nic.in) Regn. No. CTRI/
2012/09/003011.
Conflicts of interest
None.
Funding source
The Truview Picture Capture Device (PCD)® was provided by
Truphatek India, Mumbai, India for the purpose of the study.
The C-MAC® paediatric blade was provided by Karl Storz
Endoscopy, New Delhi, India for the purpose of this study.
Authors' contribution
RS: Study design, acquisition of data, critical revision, final
approval.
NK: Study design, acquisition of data, analysis and interpretation of data, first draft and critical revision, final approval.
AJ: Study design, critical revision, final approval.
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