Table 1.
Comparison of demographic and perioperative variables in patients who did and did not develop AKI (Cr >50%) within 72 hours of operation (n = 338)
| Variable | Overall (n = 338) | No AKI (n = 310) | AKI (n = 28) | P |
|---|---|---|---|---|
| Age (years) | 63 ± 10 | 63 ± 10 | 66 ± 8 | 0.10 |
| Gender (women %) | 22 | 22 | 14 | 0.30 |
| Race (%) | 0.60 | |||
| white | 90 | 90 | 85 | |
| first nation | 5 | 5 | 9 | |
| other | 5 | 5 | 6 | |
| Comorbid conditions (%) | ||||
| diabetes mellitus | 27 | 27 | 28 | 0.90 |
| chronic obstructive pulmonary disease | 5 | 5 | 4 | 0.80 |
| angina | 88 | 89 | 86 | 0.70 |
| heart failure | 6 | 6 | 3 | 0.50 |
| myocardial infarction | 51 | 51 | 50 | 0.50 |
| prior revascularization | 8 | 8 | 7 | 0.60 |
| peripheral artery disease | 7 | 6 | 17 | 0.04 |
| cerebrovascular disease | 11 | 10 | 21 | 0.09 |
| ejection fraction (%) | 56 ± 16 | 56 ± 16 | 56 ± 16 | 0.30 |
| ejection fraction <30% (%) | 4 | 4 | 5 | 0.60 |
| APACHE | 3.6 ± 0.5 | 3.6 ± 0.5 | 3.7 ± 0.5 | 0.70 |
| EURO | 2.1 [1.3, 4.0] | 2.1 [1.2, 3.6] | 2.7 [1.5, 4.7] | 0.10 |
| Preoperative renal function | ||||
| baseline preoperative creatinine (μmol/L) | 87 ± 20 | 86 ± 19 | 95 ± 30 | 0.02 |
| GFR (ml/min per 1.73 m2) | 82 ± 20 | 82 ± 19 | 78 ± 28 | 0.30 |
| MDRD eGFR <60 ml/min per 1.73 m2 (%) | 14 | 13 | 24 | 0.08 |
| Type of surgery (%) | ||||
| coronary artery bypass graft (%) | 87 | 87 | 72 | |
| valve (%) | 13 | 13 | 28 | |
| Intraoperative variables | ||||
| pump time (minutes) | 102 ± 46 | 100 ± 46 | 118 ± 42 | 0.01 |
| cross-clamp time (minutes) | 66 ± 35 | 65 ± 36 | 76 ± 35 | 0.02 |
| total operating room time (minutes) | 229 ± 85 | 228 ± 83 | 255 ± 89 | 0.04 |
| urinary output (ml/h) | 209 [154, 289] | 223 [160, 298] | 172 [118, 233] | 0.02 |
| MAP at start of OR (mmHg) | 98 ± 15 | 97 ± 14 | 99 ± 16 | 0.01 |
| MAP at end of OR (mmHg) | 73 ± 11 | 73 ± 10 | 71 ± 11 | 0.40 |
| Postoperative variables | ||||
| percentage change in creatinine on exit from OR (%) | −10 ± 14 | −11 ± 14 | −1 ± 19 | <0.01 |
| postoperative day 1 hepcidin-25 | 2782 [1153, 4705] | 2912 [1371, 4799] | 849 [312, 3074] | <0.01 |
| postoperative day 1 hepcidin-25/creatinine | 198 [92, 303] | 201 [98, 319] | 68 [19, 206] | <0.01 |
| RBC transfusion in first 24 hours (% patients) | 28 | 28 | 31 | 0.40 |
| vasopressor requirement in first 24 hours (%) | 7 | 6 | 14 | 0.10 |
Continuous variables are expressed as mean ± SD or median [interquartile range] as appropriate depending on the distribution. Categorical values are expressed as %. Independent samples T test was used for Gaussian variables, Mann–Whitney U-test was used for non-Gaussian distributions, and chi-squared test for categorical variables. AKI, acute kidney injury; APACHE, Acute Physiology and Chronic Health Evaluation; EURO, European System for Cardiac Operative Risk Evaluation; MDRD, modification of diet in renal disease; eGFR, estimated GFR; OR, operating room; RBC, red blood cell MAP, mean arterial pressure.