Friedman et al developed a respiratory disturbance index (RDI) to help identify patients with obstructive sleep apnea (OSA). A simpler OSA score based on the same parameters was also useful in identifying affected patients. The authors are from Rush-Presbyterian-Saint Luke's Medical Center in Chicago.
Parameters:
(1) grade of body mass index (BMI)
(2) Mallampati score (from 1 to 4, as described in 31.05.01)
(3) tonsillar size grade (from 0 to 4, as described in 09.13.04)
body mass index =
= (body weight in kilograms) / ((body height in meters)^2)
|
BMI |
Grade |
|
< 20 kg per square meter |
0 |
|
20 - 25 |
I |
|
25.01 - 30 |
II |
|
30.01 - 40 |
III |
|
> 40 |
IV |
RDI (from page 1902) =
= (apneic events per hour) + (hyponeic events per hour)
RDI =
= (4.675 * (grade of body mass index)) + (7.816 * (Mallampati score)) + (3.988 * (grade of tonsillar size)) - 7.544
|
RDI |
Interpretation |
|
< 20 |
OSA unlikely |
|
>= 20 |
OSA present |
|
>= 45 |
severe OSA |
based on discussion on page 1904
The authors then described an "OSA score" based on the sum the parameter grades:
OSA score =
= (BMI grade) + (Mallampati score) + (tonsillar size grade)
|
OSA Score |
Findings |
Interpretation |
|
>= 8 |
at least one component grade 4 |
positive for OSA |
|
>= 8 |
2 or 3 components grade 3 |
positive for OSA |
|
<= 4 |
none of the components grade 4 |
negative for OSA |
based on discussion page 1904
Purpose: To evaluate a patient for the risk of obstructive sleep apnea using the scores of Friedman et al.
Specialty: Pulmonology
Objective: risk factors
ICD-10: G47.3,
