Incidence and peri-operative risk factors for development of acute kidney injury in patients after cardiac surgery: A prospective observational study

Table 1 Baseline demographic and clinical characteristics in all patients and according to acute kidney injury status

Total population (%)	N = 206	AKI	No AKI	P value
	206 (100)	55 (26.7)	151 (73.3)
Baseline pre-operative characteristics
Gender, female	62 (30.1)	13 (23.6)	49 (32.5)	0.236
Age (yr)	70 (59-76)	74 (59–79)	68.5 (59–74)	0.039
BMI (kg/m2)	27.8 (25.2-31.3)	27.0 (24.8–30.0)	28.1 (25.4–31.5)	0.308
EuroScore II (%)	1.7 (1.09-2.9)	2.54 (1.52–4.4)	1.54 (0.94–2.4)	0.0001
Hb (gr/dL)	10.3 (9.6-11)	10.3 (9.8–10.9)	10.2 (9.5–11.0)	0.603
WBC (×103/μL)	10.3 (7.9-13.1)	11.4 (8.9–13.7)	9.5 (7.5–12.8)	0.015
Creatinine (mg/dL)	0.9 (0.8-1.1)	1.0 (0.9–1.3)	0.9 (0.8–1.1)	0.009
CKD	50 (24.3)	22 (40)	28 (18.5)	0.003
eGFR (mL/min/1.73 m2)	79.1 (60.2-89.9)	69.1 (52.3-84.2)	81.3 (63.1-90.8)	0.007
PPC	5 (2.4)	1 (1.8)	4 (2.6)	1.0
ICD	5 (2.4)	4 (7.3)	1 (0.7)	0.019
PAD	10 (4.9)	4 (7.3)	6 (4)	0.462
Thyroid disease	36 (17.5)	7 (12.7)	29 (19.2)	0.309
Stroke	3 (1.5)	1 (1.8)	2 (1.3)	1.0
Intraoperative characteristics
CPB (Extracorporeal circulation)	198 (96.1)	51 (92.7)	147 (97.4)	0.214
Duration of CPB (min), Ν = 198	112 (84-145)	121 (104–171)	106 (80–141)	0.009
Aortic cross-clamp time (min), Ν = 193	89 (59-108)	87 (67–111)	77 (56–107)	0.067
Duration of general anesthesia in surgery (min)	240 (190-300)	273 (213–350)	229 (183–300)	0.016
CABG	116 (56.3)	29 (52.7)	87 (57.6)	0.634
Heart valve repair	7 (3.4)	1 (1.8)	6 (4)	0.678
Aortic valve replacement	71 (34.5)	20 (36.4)	51 (33.8)	0.743
Mitral valve replacement	15 (7.3)	4 (7.3)	11 (7.3)	1.0
Tricuspid valve replacement	7 (3.4)	2 (3.6)	5 (3.3)	1.0
Mixed valve replacement	10 (4.9)	2 (3.6)	8 (5.3)	1.0
Aneurysm repair	23 (11.2)	5 (9.1)	18 (11.9)	0.803
Acute aortic dissection	4 (1.9)	3 (5.5)	1 (0.7)	0.059
Heart transplant	4 (1.9)	3 (5.5)	1 (0.7)	0.059
Post-operative characteristics
Duration of mechanical ventilation (min)	780 (591-1198)	1113 (777–2195)	714 (511–1020)	0.0001
Duration of sedation in ICU (min)	360 (250-600)	540 (300–810)	300 (240–480)	0.0001
Duration of sedation during and post surgery (min)	593 (480-842)	754 (540–1245)	570 (476–740)	0.0001
Fluid balance 24 h post surgery (mL)	722 (70-1418)	1090 (330–1862)	501 (11–1150)	0.001
Fluid balance 48 h post surgery (mL), (N = 146)	N (%); 146 (70.9)	46 (31.5)	100 (68.5)	0.526
	-202 [(-1146) - 377]	-163 [(-1186) – 531]	-248 [(-1099) – 296]
Systolic blood pressure (mmHg)	119 (105-135)	116 (103 – 134)	120 (108–135)	0.162
Diastolic blood pressure (mmHg)	61 (55-70)	58 (54–65)	63 (55–70)	0.015
Mean arterial blood pressure (mmHg)	80 (71-88)	75 (68–84)	80 (74–89)	0.005
Vasopressors	65 (31.6)	27 (49.1)	38 (25.2)	0.002
Inotropes	130 (63.1)	41 (74.5)	89 (58.9)	0.05

AKI: Acute kidney injury; BMI: Body mass index, Hb: Hemoglobin, WBC: White blood cells; sCr: Serum creatinine, HTN: Hypertension; CKD: Chronic kidney disease defined as eGFR ≤ 60 mL/min/173 m²; PPC: Permanent pacemaker; ICD: Implantable cardioverter defibrillator; PAD: Peripheral artery disease; CPB: Cardiopulmonary bypass, ICU: Intensive care unit. All continuous variables are presented as median (interquartile range) and categorical variables as absolute values (%). Statistical significance was set at P value less than 0.05.