Wang et al reported 2 nomograms for predicting difficult laryngoscopy.The first predicts the likelihood of difficult laryngoscopy. The authors are from Arhui Medical University and Wannan Medical College in China.
Patient selection: tracheal intubation and general anesthesia
Parameters:
(1) upper lip bite test, Grades I to III
(2) modified Mallampati test, Grades I to IV
(3) sex
(4) temporomandibular joint mobility by mandibular condylar mobility measured by ultrasonography in mm
(5) age in years
(6) body mass index in kg per square meter
(7) thyromental distance in mm
(8) interincisor distance in mm
(9) tongue thickness by ultrasonography in mm
|
Parameter
|
Finding
|
Points
|
|
upper lip bite test
|
Grade I
|
0
|
|
|
Grade II
|
11.2
|
|
|
Grade III
|
45.1
|
|
Mallampati test
|
Grade I
|
0
|
|
|
Grade II
|
0
|
|
|
Grade III
|
0.5
|
|
|
Grade IV
|
28.7
|
|
sex
|
male
|
40.2
|
|
|
female
|
0
|
|
TMJ mobility
|
>= 12 mm
|
0
|
|
|
< 12 mm
|
100
|
|
age in years
|
< 36 years
|
0
|
|
|
36 to 51 years
|
33.9
|
|
|
>= 52 years
|
52.1
|
|
BMI
|
< 18.5 kg per sq meter
|
0
|
|
|
18.5 to 24
|
12.1
|
|
|
25 or 26
|
18.2
|
|
|
27 to 30
|
45.8
|
|
|
>= 30
|
14.7
|
|
thyromental distance
|
>= 78 mm
|
0
|
|
|
65 to 78 mm
|
13.3
|
|
|
< 65 mm
|
43.7
|
|
interincisor distance
|
>= 40 mm
|
0
|
|
|
< 40 mm
|
18.7
|
|
tongue thickness
|
< 60 mm
|
0
|
|
|
60 to 67 mm
|
12.9
|
|
|
> 67 mm
|
48.4
|
total score =
= SUM(points for all of the parameters)
Interpretation:
• minimum score: 0
• maximum score: 422.7
value of X =
= (0.03116 * (score)) - 8.862
probability of difficult laryngoscopy =
= 1 / (1 + EXP((-1) * X))
Performance:
• The area under the ROC curve is 0.93.
