Ge et al reported a nomogram for identifying postoperative hypoxemia in a patient with acute aortic dissection. The authors are from Sir Run Run Shaw Hospital and Zhejiang University in China.
Patient selection: postoperative following repair of an acute aortic dissection
Outcome: postoperative hypoxemia (PaO2 to FIO2 ratio < 200 for the first 2 days after surgery)
Parameters:
(1) pH from 7.0 to 7.5
(2) time on cardiopulmonary bypass from 0 to 400 minutes
(3) hematocrit in percent from 15 to 50 percent
(4) age in years from 20 to 100 years
(5) WBC count in 10^9/L from 0 to 25
(6) Stanford classification of the dissection
(7) PaO2 to FIO2 (PF) ratio from 0 to 800
(8) body mass index (BMI) from 15 to 35 kg per square meter
points for pH =
= (-92 * (age)) + 695
points for cardiopulmonary bypass time =
= (-0.1 * (time)) + 52
points for hematocrit =
= (-1.25714 * (hematocrit)) + 67.8571
points for age =
= (0.35 * (age)) + 37
points for WBC count =
= (2.06 * (WBC)) + 39.5
|
Dissection Type
|
Points
|
|
Stanford A
|
46
|
|
Stanford B
|
30
|
points for PF ratio =
= (-0.0625 * (ratio)) + 50
points for BMI =
= (3 * (BMI)) - 3
total score =
= SUM(points for all 8 parameters)
Interpretation:
• minimum score: 177.5
• maximum score: 513
• The higher the score the greater the risk of hypoxemia.
|
Total Score
|
Percent with Hypoxemia
|
|
< 306.6
|
< 0.5%
|
|
306.6 to 393.6
|
X = (0.0922 * (score)) - 33.26
percent = 1 / (1 + EXP((-1) * X))
|
|
> 393.6
|
> 90%
|
