Patients Need Tracheal Intubation Clinical Trial
Official title:
Comparison of the Macintosh, King Vision®, Glidescope® and AirTraq® Laryngoscopes in Routine Airway Management
Failure to successfully intubate the trachea and secure the airway remains a leading cause
of morbidity and mortality, in the operative [1-2] and emergency settings. [3-4]. When the
concept of endotracheal intubation was developed, 100 years ago the procedure was performed
blindly. Shortly thereafter, laryngoscopes were invented, allowing for direct visualization
of the larynx with a viewing angle of 15 degrees [5]. Insufficient laryngoscopic view
constitutes the main reason for difficult intubations [6].
Video laryngoscopes provide an improved view of the glottis, as the camera is a few
millimeters away from the glottis. The use of Glidescope [7-8] and AirTraq [9] laryngoscopes
has superior glottis view and ease of tracheal intubation compared with the traditional
Macintosh laryngoscope. Unfortunately, the use video laryngoscopes is associated with longer
time to tracheal intubation compared with the traditional techniques which be explained with
the variable learning curves of the practitioners. [10]
The King Vision video laryngoscope® (King Systems Company, a division of Consort Medical,
Indianapolis, Indiana, USA) is a relative newcomer to the video laryngoscopes of devices
that claim to provide the "perfect view" for intubation via use of video and digital
technology.
The King Vision Video laryngoscope is a two piece design. It has a reusable monitor that
attaches to disposable blades. Blades are made of high quality poly-carbonate plastic and
house a complementary semi-conductor (CMOS) micro camera offers a 160 degree of view and LED
light source.
Up to best of the authors' knowledge, there is no current published or ongoing randomized
controlled comparative study of the use of King Vision laryngoscope with traditional
laryngoscope and other video laryngoscopes for endotracheal intubation.
Eighty six ASA I-II patients aged 18-65 years scheduled for elective minor surgery under
general anesthesia who need tracheal intubation will be included in this prospective,
randomized, single-blind, controlled study at the author's center after obtaining approval
of the local ethical committee and an informed written consent from all participants.
Patients will be randomly allocated to one of four groups (n=30 for each) namely, Macintosh,
King Vision, Glidescope, or AirTraq groups, by drawing sequentially numbered sealed opaque
envelopes containing a software-generated randomization code (Random Allocation Software,
version 1.0.0, Isfahan University of Medical Sciences, Isfahan, Iran).
Anesthesia:
The Mallampati airway score, thyromental and sternomental distances with neck extension, and
the degree of mouth opening will be evaluated preoperatively as factors predicting difficult
intubation. Patients' monitoring includes pulse oximetry, noninvasive blood pressure
electrocardiography, state and response Entropy (SE and RE) and train of four (TOF) before
induction of anesthesia.
The intubators who will participate in the study received a standardized manikin based
training course followed by 10 successful intubations in clinical practice with the use of
Macintosh, King Vision®, Glidescope®, and the Airtraq® laryngoscopes for endotracheal
intubation.
Anesthetic technique will be standardized in all studied. After breathing 100% oxygen for 3
min through a facemask in a supine "sniffing" position, all patients will receive
intravenous propofol 2-3 mg/kg and remifentanail 0.05-0.25 µg/kg/min for induction of
anesthesia until loss of consciousness defined as decrease of SE less than 50 and the
difference between RE and SE is less than 10. Rocrunium 0.6 mg.kg will be administered and
complete relaxation will be monitored using a nerve stimulator (TOF-GE, Datex-Ohmeda
Division, Instrumentarium Corporation, Helsinki, Finland).
The studied data during intubation will be collected by an independent investigator; the
intubator will not informed about the time taken to achieve any intubations. Tracheal
intubation will be performed with the Macintosh, King Vision, Glidescope, or AirTraq
laryngoscopes, according to the assigned randomization code.
Time to tracheal intubation, defined as the time when the investigated laryngoscope passes
the central incisors to the time when the tip of the tracheal tube passed through the
glottis, will be determined. The duration of laryngoscopy, defined as the time from holding
of the investigated laryngoscope to the appearance of as the first upward deflection on the
capnograph, will be recorded.
Before each procedure, the capnograph gas sample delay time will be measured and then
subtracted from total recorded duration of laryngoscopy, to correct for the different
sampling times between the capnographs used. [11] The best view during laryngoscopy (using
Cormack and Lehane classification) will be recorded. [12]
If intubation is unsuccessful at the first attempt, took longer than 120 seconds, or if
desaturation noted on the pulse oximeter (defined as SpO2 < 92%) [13], the intubation
attempt will be stopped and the lungs will be ventilated with an oxygen-volatile anesthetic
mixture for 3 min. A second attempt will be allowed with the randomly allocated airway
device. If intubation is unsuccessful after two attempts, the protocol allows intubating the
patient with the anesthesiologist's instrument of choice. [14]
The anesthesiologist will be asked to rate the ease of intubation using a 10 cm visual
analog scale (0 for much of ease and 10 for extremely difficult). Hemodynamic parameters
(heart rate, systolic and mean blood pressures) will be recorded at baseline, during the
intubation process, and each 1-min for 5 min and 10 min after tracheal intubation.
A careful examination of the oropharynx will be performed after intubation to determine any
lip, dental or mucosal trauma. Following recovery from anesthesia in the post-anesthesia
care unit, a trained anesthesiologist who will not be involved in the study and who is blind
to the device used will evaluate all patients for a postoperative sore throat to ensure
consistency and severity.
Statistical Analysis
Data will be tested for normality using the Kolmogorov-Smirnov test. Serial changes in the
studied data at intubation will be analyzed with repeated-measures analysis of variance.
Categorical data will be analyzed using Fischer's exact test. Repeated measure analysis of
variance (ANOVA) will be used for continuous parametric variables and the differences will
be then corrected by post-hoc Bonferoni test. The Kruskal-Wallis one-way ANOVA will be
performed for intergroup comparisons for the non-parametric values and post hoc pairwise
comparisons will be done using the Wilcoxon rank sum t test. p value < 0.05 will be
considered statistically significant.
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Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Outcomes Assessor), Primary Purpose: Prevention