Comparison of Classical Miller, Wis-Hipple and C-MAC Size 1 Blades
Condition: Percent of Glottic Opening
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Laryngoscope blade
Intervention type(s): Device
Intervention description(s): The POGO score assesses the percent of the glottic opening that can be seen with each blade
Other intervention name(s): Miller laryngoscope blade; Wis- Hipple laryngoscope blade; C-MAC straight laryngoscope blade
Intervention MeSH terms: Pyrithione zinc
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Other
Keywords: larynx, laryngoscopy; vocal cords, laryngoscopy; airway; pediatric