Coronary Artery Bypass Prognosis of Mortality - Medical Algorithm

Description

Higgins et al developed a risk stratification score calculated at the time of ICU admission following coronary artery bypass grafting. It can be used to evaluate the outcomes of ICU care. It is complementary with the author's previously reported Preoperative Severity Score (see above). The authors are from the Cleveland Clinic.

Morbidity events (page 1051):

(1) cardiac complications

(2) prolonged ventilatory support

(3) central nervous system complications

(4) renal failure

(5) serious infection

(6) death

Preoperative factors used in ICU Admission Score:

(1) small body size

(2) history of prior heart operation

(3) history of operation or angioplasty for peripheral vascular disease

(4) age

(5) serum creatinine

(6) serum albumin

Intraoperative factors used in ICU Admission Score:

(7) cardiopulmonary bypass time

(8) use of intra-aortic balloon mump after coronary bypass

ICU admission physiology used in ICU Admission Score:

(9) A-a oxygen gradient

(10) heart rate

(11) cardiac index

(12) central venous pressure

(13) arterial bicarbonate

Parameter	Finding	Points
body size	BSA < 1.72 square meters (small)	1
	BSA >= 1.72 square meters	0
history of prior cardiac operation	0	0
	1	1
	>= 2	2
history of operation or angioplasty for peripheral vascular disease	present	3
	absent	0
age	>= 70	3
	< 69	0
preoperative serum creatinine	>= 1.9 mg/dL	4
	< 1.9 mg/dL	0
preoperative serum albumin	>= 3.6 g/dL	0
	< 3.5 g/dL	5
cardiopulmonary bypass time	>= 160 minutes	3
	< 160 minutes	0
intra-aortic balloon pump used after cardiopulmonary bypass	used	7
	not used	0
A-a oxygen gradient	>= 250 mm Hg	2
	< 250 mm Hg	0
heart rate	>= 100 beats/minute	3
	< 100 beats/minute	0
cardiac index	>= 2.1 L per min per meter squared	0
	< 2.1 L/min/(meter squared)	3
central venous pressure	>= 17 mm Hg	4
	< 17 mm Hg	0
arterial bicarbonate	>= 21 mmol/L	0
	< 21 mmol/L	4

ICU risk stratification score =

= SUM(points for all 13 parameters)

Interpretation:

• minimum score: 0

• maximum score: 44

ICU Risk Stratification Score	Observed Mortality in 1994-1995	Observed Morbidity in 1994-1995
0 - 5	1%	3%
6 - 9	2%	10%
10 - 13	4%	20%
14 - 20	10%	35%
>= 21	40%	90%

percents estimated from Figures 1 and 2, page 1055

Preoperative Severity Score	ICU Risk Stratification Score	Mortality
<= 6	<= 14	1.66%
	> 14	19.4%
>= 7	<= 14	4.33%
	> 14	27.9%

Multivariate Model

Parameter	Mortality Model	Morbidity Model
intercept	4.12	2.57
use of intra-aortic balloon pump after cardio-pulmonary bypass	1.49	1.96
cardiac index at ICU admission in liters per minute per square meter	-0.64	-0.47
age per decade	0.39	0.21
preoperative serum albumin (in g/dL)	-1.74	-0.90
history of peripheral vascular disease or intervention	1.07	0.72
cardiopulmonary bypass time per 10 minutes	0.10	0.07
heart rate > 100 beats/minute at ICU admission	0.82	0.49
arterial bicarbonate at ICU admission in mmol/L	-0.17	-0.13
central venous pressure at ICU admission in mm Hg		0.10
body surface area in square meters		-0.90
>= 2 prior heart operations		0.80
preoperative serum creatinine in mg/dL		0.21
A-a gradient at ICU admission per 10 mm Hg		0.04

from Tables 3 and 4, pages 1053-1054

where:

• The table says serum albumin is in "mg/dL" which may be an error, since the data in Table 2 records this as having a mean value of 4.4

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ICD-10

ICU Admission Score of Higgins et al For Prediction of Morbidity and Mortality After Coronary Artery Bypass Grafting

Purpose: To calculate the ICU Admission Score of Higgins et al for evaluating a patient's risk after coronary artery bypass surgery.

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Objective

ICD-10