Digital images of oral cavities were analyzed by 7 raters to test inter-rater reliability of measurements. Raters measured areas of the total oral cavity, tongue, teeth, and empty spaces. Low average standard deviations and variances between raters demonstrated high inter-rater reliability for the digital imaging analysis method. This objective analysis technique aims to improve predictions of difficult intubation by eliminating subjectivity compared to prior subjective tests.

1. Objective Airway Assessments Using Digital Imaging
Demonstrates High Inter-rater Reliability
ZD Riley1, PS Santago2, PhD, YF Bryan1, MD
1Department of Anesthesiology, Wake Forest School of Medicine
2Department of Computer Science, Wake Forest University
Introduction
Subjective tests for laryngoscopy and intubation have low
predictive values
The Mallampati classification is used by anesthesiologists by
viewing the anatomic structures in the oral cavity in order to
predict ease of intubation
Inter-rater reliability of this test however have proven to be low
Computer imaging techniques have been used in order predict
difficult intubations
We used digital imaging to test for inter-rated reliability in an
attempt to determine an objective analysis of the anatomic
structures in the oral cavity
References and Further Reading
Year Author Journal Title Findings
1983 SR
Mallampati
Canadian
Anesthetists’
Society
Journal
Clinical Sign to Predict Difficult
Tracheal Intubation
(Hypothesis)
Potential for new airway
analysis based on
tongue/cavity ratio
1985 SR
Mallampati
Canadian
Anesthetists’
Society
Journal
A Clinical Sign to Predict
Difficult Tracheal Intubation: A
Prospective Study5
Testing of 1983
Mallampati airway
hypothesis
2010 M Adamus and
Fritscherova and
S, Hrabalek L. et
al
Biomed Pap Med
Fac Univ Palacky
Olomouc Czech
Repub.
Mallampati Test as a Predictor
of Laryngoscopic View
Mallampati test alone
tested to be inaccurate.
2010 K Gupta and
PK Gupta
Saudi
Journal of
Anesthesia
Assessment of Difficult
Laryngoscopy by Electronically
Measured Maxillo-Pharyngeal
Angle on Lateral Cervical
Radiograph: A Prospective Study
Accurate prediction of
difficult laryngoscopic
view with radiological
imaging method.
2010 Hukins, Craig Journal of
Clinical Sleep
Medicine
Mallampati Class Is Not Useful
in the Clinical Assessment of
Sleep Clinic Patients
Low sensitivity and
specificity with Mallampati
in sleep clinic.
2011 CW Connor
and S Segal
Anesthesia &
Analgesia
Accurate Classification of
Difficult Intubation by
Computerized Facial Analysis
It is possible to use computer
imaging though facial
analysis to predict difficult
intubation.
2014 CW Connor
and S Segal
Anesthesia &
Analgesia
The Importance of Subjective
Facial Appearance on the
Ability of Anesthesiologists to
Predict Difficult Intubation
Facial analysis improves
accuracy of diagnosis of
difficult intubation.
Conclusions
Methods
Digital photographs were taken of research team members
The images consisted of the oral cavity with the mouth open
and the tongue maximally protruded
A total of fourteen images in 7 people were used
Each individual was given a brief in-person tutorial on how to
perform the analyses as well as provided a written guide
Different team members calculated the areas within the image
of each individual for the following: total oral cavity area
including tongue but minus lips, tongue alone, teeth alone,
and unoccupied space by either the tongue or teeth
Ratios were then calculated for each structure to the whole
oral cavity
Means, standard deviations, and variances were then
calculated between each rater’s data in the same fashion that
was done for the intra-rater testing
The Intra-rater reliability was shown in a previous study
(presented in 2014, Riley)
Inter-rater reliability was determined next once the method
was demonstrated to be valid and consistent
Data gathering has begun in patients with anticipated difficult
airways
Figure 1: Images of devices used by anesthesiologists for laryngoscopy and
intubation. From left to right: Laryngoscopes (Macintosh and Miller),
Endotracheal Tube, Image of Airway Anatomy
Figure 2: Sample image used in performing digital imaging analysis
measurements. Image included is of researcher.
Area Average Standard
Deviation
Average
Variance
Total Oral Cavity 1.018 cm2 1.75122
Tongue 0.71% 7.85765x10-5
Teeth 0.44% 2.88495x10-5
Tongue and Teeth 0.97% .000111393
Unoccupied 0.70% 5.73487x10-5
Overall Averaged STDEVA and
VAR.S
0.71% 6.9042x10-5
Results
The inter-rater reliability tested in this study was found to be
high, as represented by the low averages and standard
deviations
All seven members performing the analysis received
comparable results for all fourteen images used in this
particular analysis set
Table 1: Standard deviations and variances were calculated for each
image. Presented are the averages for those values for all images.
Experiment for digital imaging analysis of oral anatomy found
high inter-rater reliability
Data presents low standard deviations and variances to
support method validity
Digital areal analysis is expected to prove beneficial for
predicting intubation and laryngoscopy difficulty in patients
Highly valid method of analysis serves to eliminate subjectivity
Intubation tool recommendation and complication likelihood is
expected to be objectively found through this method