Patient selection: cardiac surgery patient in the ICU
Oriignal parameters of the CASUS::
(1) PaO2 to FIO2 ratio
(2) pressure-adjusted heart rate (PAR)
(3) serum creatinine in mg/dL
(4) serum total bilirubin in mg/dL
(5) lactic acid in mmol/L
(6) platelet count in 10^3 per microliter
(7) neurologic status
(8) intra-aortic balloon pump (IABP)
(9) ventricular assist device (VAD)
(10) renal replacement therapy (continuous venovenous hemofiltration, dialysis)
In addition there was addition of a categorical variable for postoperative day (new).
Of these, 3 have 0 beta-coefficients in the logistic model:
(1) PaO2 to FIO2 ratio
(2) pressure-adjusted heart rate
(3) plaletlet count
Of these, 3 multiplied a continuous variable versus the beta-coefficient:
(1) serum creatinine in mg/dL
(2) lactic acid in mmol/L
(3) serum bilirubin in mg/dL
points for serum creatinine =
= (serum creatinine) * 0.3
points for lactic acid =
= (lactic acid) * 0.2
points for serum bilirubin =
= (serum bilirubin) * 0.2
Of these, 4 were categorical variables:
(1) renal replacement therapy
(2) IABP
(3) VAD
(4) neurologic status
|
Categorical Parameters
|
Finding
|
Points
|
|
neurologic status
|
normal
|
0
|
|
|
confused in conversation
|
0.4
|
|
|
sedated
|
0.7
|
|
|
diffuse neuropathy
|
1.4
|
|
intra-aortic balloon pump
|
no
|
0
|
|
|
yes
|
0.6
|
|
ventricular assist device
|
no
|
0
|
|
|
yes
|
2.2
|
|
renal replacement therapy
|
no
|
0
|
|
|
yes
|
0.4
|
|
postoperative day
|
1 or 2
|
0
|
|
|
3
|
0.8
|
|
|
4
|
1.0
|
|
|
5
|
1.2
|
|
|
6
|
1.4
|
|
|
7
|
1.6
|
|
|
8
|
1.9
|
|
|
9
|
2.1
|
|
|
10 or 11
|
2.2
|
|
|
12
|
2.3
|
|
|
>= 13
|
2.5
|
X =
= SUM(points for all of the parameters) – 5.6
probability of ICU mortality =
= 1 / (1 + EXP((-1) * X))
Performance:
• Discrimiinatory power (area under ROC curve): 0.87 to 0.96
