Table 2.

Patient baseline, intraoperative, and postoperative characteristics within the clusters

VariableNormal Cluster (n=173)Severe Cluster (n=23)P ValueVery Severe Cluster (n=4)P Value
Demographic characteristics
  Age (d)84 (9–163)74 (7.5–119)0.3330 (11.7–72.7)0.61
  <28 d65 (37.6)8 (34.8)0.792 (50)0.63
  <48 h3 (1.7)2 (8.7)0.1000.99
  Weight (kg)4.2 (3.2–10.3)3.4 (3.2–4.6)0.183.4 (3.3–3.9)0.58
Medical history before surgery
  Genetic syndrome8 (4.6)00.5900.99
  Resternotomy15 (8.7)3 (13)0.4500.99
  Cardiopulmonary resuscitation01 (4.3)0.121 (25)0.02
  Mechanical ventilation7 (4)2 (8.7)0.282 (50)0.01
  Inotropic support02 (8.7)0.011 (25)0.02
  Infection15 (8.7)3 (13)0.451 (25)0.32
  Enteropathy3 (1.7)1 (4.3)0.3900.99
Medication before surgery
  Furosemide36 (20.8)6 (26.1)0.3300.58
  Spironolactone9 (5.2)3 (13)0.1500.99
  Angiotensin-converting enzyme inhibitors26 (15)2 (8.7)0.5400.99
β-Blockers10 (5.8)2 (8.7)0.6400.99
  Prostaglandin E237 (21.4)5 (21.7)0.992 (50)0.21
  Aminoglycoside antibiotics24 (13.9)6 (26.1)0.131 (25)0.46
  Vancomycin13 (7.5)4 (17.4)0.121 (25)0.28
Angiography within 1 wk before surgery19 (11)2 (8.7)0.991 (25)0.37
Intraoperative variables
  Aristotle complexity score8 (6–14.5)10 (6.25–11)0.0811 (10.7–11)0.007
  Duration of cardiopulmonary bypass (min)107 (77–133)122 (105–180)0.008259 (192–338)0.007
  Surgery requiring aortic crossclamping163 (94.2)23 (100)0.614 (100)0.99
  Duration of aortic crossclamping (min)61 (37–82)68 (56–78)0.24128 (106–134)0.02
  Ultrafiltration rate (ml/kg per min of bypass)1.3 (0.9–1.8)1.1 (0.9–1.5)0.261.0 (0.8–1.2)0.20
  Surgery requiring deep hypothermic circulatory arrest10 (5.8)7 (30.4)<0.0011 (25)0.23
Blood product transfusions on day 0 and day 1
  Packed red blood cells (ml)511 (314–566)542 (505–567)0.05573 (522–760)0.11
  Fresh frozen plasma (ml)219 (208–246)219 (212–347)0.23425 (371–502)0.03
  Platelets (ml)45 (0–59)44 (25–88)0.21143 (83–202)0.02
Postoperative variables
  Requiring delayed sternal closure27 (15.6)8 (34.8)0.023 (75)0.02
  Requiring extracorporeal membrane oxygenation0013 (75)<0.001
  Left ventricular ejection fraction within 2 h of bypass (%)60 (60–65)60 (45–65)0.4737.5 (30–45)<0.001
  Peak lactatemia within 6 h of surgery (mmol/L)2.9 (2.1–4)3.0 (2.5–5.5)0.215.2 (3.8–7.5)0.02
  Peak lactatemia within 48 h of surgery (mmol/L)3.3 (2.3–4.4)3.6 (2.6–5.8)0.175.2 (3.8–7.5)0.04
  Inotropic support within 48 h of surgery
 Epinephrine (μg/kg per min)0.10 (0.08–0.14)0.14 (0.07–0.20)0.230.15 (0.08–0.21)0.45
 Milrinone (μg/kg per min)0.48 (0.35–0.57)0.44 (0.26–0.54)0.100.46 (0.43–0.51)0.95
 Hydrocortisone for low-cardiac–output syndrome30 (17.3)7 (30.4)0.132 (50)0.15
 Delay to sternal closure (d)2 (1.5–4)5 (2.7–7.2)0.0513 (7.5–14)0.08
Postoperative renal variables
  AKI according to the serum creatinine criteriaa23 (13.3)8 (34.8)0.0083 (75.0)0.01
  AKI according to the urine output criteriaa6 (3.4)3 (13)0.072 (50)0.01
  Negative fluid balance (ml/kg per 24 h)b33.7 (18.9–50.1)14.4 (8.2–24.8)0.019.3 (3.6–21.9)0.09
  Peritoneal dialysis8 (4.6)6 (27.2)<0.0012 (50)0.02
Length of mechanical ventilation (d)1 (0–4)5 (0.7–9.7)0.00613.5 (10.2–19)0.009
Length of intensive care unit stay (d)4 (2–6)8 (4–14.5)0.00216 (11–22.7)0.01
In-hospital death4 (2.3)2 (8.7)0.152 (50)0.006
  • Data are shown as medians (interquartile ranges) or as numbers and percentages. The normal cluster was taken as reference for the calculation of all P values. According to the Bonferroni correction, the significance level was set to 0.025.

  • a According to the Acute Kidney Injury Network classification, with preoperative serum creatinine accounting for baseline.

  • b Within 24 hours of surgery.