Comparison of Video Laryngoscope Using Miller or Macintosh Approach During Endotracheal Intubation
Phase: NA
Conditions: Difficult Intubation
Sponsor: Kaohsiung Veterans General Hospital.

 
 
 
Comparison of Video Laryngoscope 
Using Miller or Macintosh Approach 
During Endotracheal Intubation. 
(VGHKS19-CT9-11) 
 
2022/09/06 
 
 
 

Methods 
Patient 
 
The present study was approved by the Ethics Committee of the VGHKS 
(No.VGHKS19-CT9-11). All patients were recruited from the VGHKS between October 
2019 to January 2022. All patient provided informed consent before being enrolled in 
the study.  
 
Inclusion criteria was: [1] Aged>20 [2] Scheduled to received operation that 
required general anesthesia with endotracheal tube [3] ASA I, II. Patient with fallow 
condition would be excluded: [1] Emergent surgery [2] pregnant [3] Limited mouth 
opening [4] Poor dental condition [5] Airway obstruction (oral tumor, 
hypopharyngeal cancer….etc) [6] Deep neck infection [7] Allergic to any anesthetic 
agent. 
Anesthesia protocol 
 
After the patient entered the operating room, monitor would be setup with 
electrocardiogram, non-invasive blood pressure, oxygen saturation, end-tidal carbon 
dioxide (PEtCO2). Intravenous access would then be established. Induction would be 
started right after setting the patient to sniff position and well pre-oxygenated. 
Endotracheal tube selection would fallow rules as below: Inner diameter 7.0mm for 
female patient, 7.5mm for male patient. As nasal endo, Inner diameter 6.5mm for 
female patient, 7.0mm for male patient. As Double lumen endotracheal tube 35 Fr 
for female patient, 37 Fr for male patient. Adjusted by patient’s height as physician’s 
clinical experience. Fentanyl 1-2 ug/kg, propofol 1.5-2mg/kg, rocuronium 0.6-1mg/kg 
or cisatracurium 1-2 mg/kg were administered intravenously as induction agent. 
Intubation was performed 3 minutes after muscle relaxant injection. Mechanical 
ventilation started right after the airway establishment. 
 
During intubation, physician placed the tip of the video conventional Macintosh 

blade at base of epiglottis to achieve glottic opening. Cormack-Lehane grade was 
then record as conventional attempt. Then physician placed the tip of the blade 
under the epiglottis and lift it to achieve glottic opening. Cormack-Lehane grade was 
record as Miller’s attempt. Also, increased lifting force, BURP maneuver would be 
record if applied. If both attempts failed to intubate the patient, the process would 
switch to emergent difficult airway protocol and the patient would drop out the 
research. Three physicians attended this research had experience of anesthesia for 4, 
6, 15 years with success intubation experience> 300+ cases. 
 
Statistics 
The patient data were presented as frequency and percentage for categorical 
variables or mean and standard deviation for continuous variables. The Cormack-
Lehane grading during Miller versus Macintosh approaches was compared using the 
McNemar-Bowker test. The test was 2-tailed and P < 0.05 was considered statistically 
significant. Data analyses were conducted using SPSS 26 (IBM SPSS Inc, Chicago, 
Illinois).