Percent of Glottic Opening Clinical Trial
Official title:
Comparison of Laryngoscopy View by Classical Miller, Wis-Hipple and C-MAC Straight Size 1 Blades in Young Children
The purpose of this study is to compare straight blades in obtaining best glottic view in children. The investigators will compare size 1 Classical Miller, size 1 Wis-Hipple, and size 1 C-MAC straight blades in young children.
This will be a prospective, randomized, blinded study. The primary objective is to compare
straight blades in obtaining best glottic view in children. The secondary objectives will be
to determine the subjective ease of laryngoscopy and intubation, desaturation and
complications with each blade and to compare the view of the CMAC with a photo of the direct
view with the CMAC blade.
In this study, the investigators will compare three different straight blades used in
pediatric anesthesia: Miller blade size 1, Wis-Hipple blade size 1, and C-MAC straight blade
size 1.
The sample size was estimated in this equivalence study assuming an alpha two-tailed of
0.05, beta of 0.2, proportion with a POGO score > 80 with the Miller blade (based on the
results of our previous study) of 0.64 and an estimated proportion of 0.74 with the
Wis-Hipple blade in the present study. The hypothesized difference required to reject
equivalence is ≥ 0.2. This requires 29 children per group. To account for un-interpretable
photos, we plan to enroll 10% more or 32 children in each group giving a total of 96
children.
Ninety-six children who are eligible to participate will be randomized and allocated to one
of the three study groups after consent is obtained from the parents/ guardian during
regular anesthesia pre-operative evaluation. According to randomization children will be
assigned to one of three groups:
Group A- Laryngoscopy by classical Miller blade, size 1 Group B- Laryngoscopy by Wis-Hipple
blade, size 1 Group C- Laryngoscopy by C-MAC Miller blade, size 1.
After induction of general anesthesia, the anesthesiologist will perform either direct
laryngoscopy using the Classical Miller, Wis-Hipple or C-MAC blade or indirect laryngoscopy
using the C-MAC video straight blade. Photography of the best glottic view will be taken
during direct laryngoscopy and the image of best glottic view will be saved by C-MAC. At the
conclusion of the study, the photographs from all 96 patients will be converted such that
the quality of the images standardized using Adobe Photoshop will appear similar to two
blinded anesthesiologists who are also unaware of the study hypothesis.
Recruitment Procedure There will not be recruitment in advance. During the pre-anesthesia
assessment of the patients who need to undergo a surgery under general anesthesia they will
be screened for the inclusion and exclusion criteria for the study. The parents/ guardian
will be informed about the study, its objectives, purpose, risks and benefits.
Consenting Procedure The consent to participate in this study will be obtained from parents/
guardian during pre-anesthesia assessment of the child in the holding area. Privacy and
confidentiality will be assured.
Randomization Procedure After obtaining consent each child will be assigned a random serial
number. Randomization will be prepared using random number table by a person not involved in
the study before the study begins. Accordingly the patient will be allocated to a study
group depending upon the matching number.
Research Procedure
1. Induction of General anesthesia ASA standard monitors will be applied prior to
induction of anesthesia. General anesthesia in all children will be induced by face
mask using 70% N20 in O2 and 8% Sevoflurane at fresh gas flow 8 L/min. After loss of
eyelash reflex a peripheral intravenous catheter will be placed. Propofol 2-3 mg/kg and
Rocuronium 0.5 mg/kg will be given. After achievement of adequate anesthesia depth and
preoxygenation laryngoscopy will be performed.
2. Laryngoscopy and Photography The laryngoscopy technique will be chosen according to
randomization. In "group A" anesthesiologist will use size 1 classical Miller blade for
direct laryngoscopy. The blade will be placed under epiglottis and a photo will be
taken by a second anesthesiologist using a high-quality digital camera after obtaining
best glottic view. Then tracheal intubation will be performed. In "group B" size 1
Wis-Hipple blade will be used for direct laryngoscopy in the same manner. In "group C"
a size 1 C-MAC straight blade for indirect videolaryngoscopy will be used. The blade
will also be placed under the epiglottis and a photo of the direct view with the C-MAC
will be taken. In group C the second anesthesiologist will save the images of best
glottic view on a SD card in the C-MAC monitor.
The oxygen saturation, blood pressure and heart rate will be recorded at the beginning
of laryngoscopy and at the completion of intubation. Time of laryngoscopy and
intubation will be recorded using a stopwatch. These data will be recorded by a second
anesthesiologist who will also be taking the photograph of the glottic opening. With
this technique the time to intubation will not be prolonged as a result of
participating in this study.
Even though taking a photo of glottic opening during laryngoscopy is not a routine
practice we expect no significant delays in intubation or laryngoscopy.
3. Computer Editing Adobe Photoshop editing of images will be performed after collecting
all data at conclusion of the study. The images will be cropped to present only the
glottic view without the blade. The image quality and color will be approximated to
ensure the images from the two different cameras (digital camera and C-MAC camera) will
be similar.
4. Image grading by POGO and Cormack- Lehane scale Two anesthesiologists who are not
involved in the study will be blinded to the study all together. They will review all
images after they are randomized and de-identified and grade the POGO score.
5. Subjective evaluation of each blade There will be 4 anesthesiologists performing the
laryngoscopies. Each patient will undergo only one laryngoscopy and tracheal intubation
by one of the anesthesiologist. After the intubation, the anesthesiologist who
performed the laryngoscopy and intubation will rate the difficulty of laryngoscopy and
intubation on visual analogue scale 0-10 (0 representing very easy & 10 very difficult
laryngoscopy/ intubation). This evaluation can be done at any time before the
electronic record is completed and will not interfere with patient care.
Data Collection and Storage The investigator will use a specially designed data collection
sheet. General information, demographic data, vital signs and procedure data will be
recorded on this. The general information will include patient's hospital ID label, subject
serial number, subject randomization group, procedure date and time. The demographic data
will include gender, age, weight, height, ASA class, type of surgery. The procedure data
section will include the time from mask induction to IV medication administration, ease of
laryngoscopy, ease of intubation and complications.
The investigators will use either a C-MAC monitor or a free standing high definition photo
camera depending on the randomization group. Each photo will be saved on a SD memory card
and after procedure will be transferred to Principal Investigator's computer where it will
be saved under subjects serial number. At the completion of data collection of all 96
subjects the images will be edited and presented to a blinded anesthesiologist who will
score each image by POGO and Cormack Lehane classification.
The data collection sheets will be kept by the principal investigator in a locked file in a
locked anesthesia office. The images will be stored in principal investigator's computer
that is password secured.
The data will be stored for 3 years after completion of the study by the primary
investigator alone.
All data will be treated according to HIPAA practice. All collected data for this study will
be de-identified for privacy protection. It will be stored using the unique study case
number only, with no direct patient identifiers.
Data Analysis For the primary hypothesis of the study, the POGO scores from the Miller,
Wis-Hipple size 1 blades and the C-MAC lifting the epiglottis, will be compared using the
Kruskall Wallis test. For the secondary hypothesis, the POGO scores for the C-MAC 1 Miller
blade lifting the epiglottis will be compared with the photos of the larynx taken at the
lips using the Wilcoxon paired rank sum test. Data whose distribution deviate from normality
(based on the Kolmogorov Smirnov test) will be presented as medians and ranges and analyzed
using the above tests. Data that will be normally distributed will be presented as means and
standard deviations, and analyzed using Student's t test and one-way ANOVA (with the Scheffe
test) as appropriate. P < 0.05 for two tails was accepted. Data will be analyzed on an
intention to treat basis.
Data Safety Monitoring Plan The safety of research participants and integrity of the data
will be carefully monitored at multiple levels. The PI will be highly involved with all
aspects of the protocol and will assume ultimate responsibility for the safety and
well-being of research participants and the integrity of data collected. The PI will meet
with each member of the study staff to ensure that they are aware of all procedures and
clarify any questions they have about the protocol before initiation of the study. A record
of the training sessions will be kept in the study repository. Quality control and
participant safety will also be ensured via monthly supervision of research and clinical
staff by PI. During these meetings the research staff will discuss the status of the
research project and review the protocol, consents, any safety issues that have risen, and
any additional issues to ensure that any reportable information will receive immediate and
appropriate action. Each of these meetings will be documented in a log that is stored in the
study repository.
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