Table 2.
Intra- and postoperative variables
| Total (n = 729) | Without postoperative AKI (n = 541) | With postoperative AKI (n = 188) | P value | Preoperative albumin ≥37.5 g/La (n = 456) | Preoperative albumin < 37.5 g/La (n = 273) | P value | |
|---|---|---|---|---|---|---|---|
| Duration of anesthesia (min) | 258 (174, 338) | 253 (169, 337) | 277 (192, 347) | 0.053 | 243 (167, 330) | 272 (201, 364) | 0.002 |
| Duration of surgery (min) | 171 (97, 249) | 165 (92, 245) | 192 (110, 256) | 0.062 | 158 (88, 242) | 189 (121, 272) | 0.002 |
| Emergency surgery | 64 (8.8%) | 37 (6.8%) | 27 (14.4%) | 0.002 | 17 (3.7%) | 47 (17.2%) | < 0.001 |
| Open surgery b | 288 (53.9%) | 193 (50.0%) | 95 (64.2%) | 0.003 | 147 (45.1%) | 141 (67.8%) | < 0.001 |
| Type of surgery | |||||||
| General surgery c | 330 (45.3%) | 229 (42.3%) | 101 (53.7%) | 0.007 | 180 (39.5%) | 150 (54.9%) | < 0.001 |
| Neurosurgery | 18 (2.5%) | 15 (2.8%) | 3 (1.6%) | 0.585 | 10 (2.2%) | 8 (2.9%) | 0.535 |
| Thoracic surgery | 52 (7.1%) | 38 (7.0%) | 14 (7.4%) | 0.846 | 33 (7.2%) | 19 (7.0%) | 0.888 |
| Urologic surgery | 195 (26.7%) | 162 (29.9%) | 33 (17.6%) | 0.001 | 160 (35.1%) | 35 (12.8%) | < 0.001 |
| Gynecological surgery | 25 (3.4%) | 17 (3.1%) | 8 (4.3%) | 0.470 | 6 (1.3%) | 19 (7.0%) | < 0.001 |
| Orthopedic surgery | 52 (7.1%) | 38 (7.0%) | 14 (7.4%) | 0.846 | 29 (6.4%) | 23 (8.4%) | 0.294 |
| Vascular surgery | 15 (2.1%) | 10 (1.8%) | 5 (2.7%) | 0.552 | 11 (2.4%) | 4 (1.5%) | 0.383 |
| ENT surgery | 8 (1.1%) | 6 (1.1%) | 2 (1.1%) | > 0.999 | 3 (0.7%) | 5 (1.8%) | 0.158 |
| Others d | 24 (3.3%) | 18 (3.3%) | 6 (3.2%) | 0.928 | 18 (3.9%) | 6 (2.2%) | 0.200 |
| Intraoperative maximal lactate (mmol/L) e | 1.1 (0.8, 1.5) | 1.1 (0.8, 1.5) | 1.1 (0.8, 1.6) | 0.995 | 1.1 (0.8, 1.5) | 1.1 (0.8, 1.5) | 0.421 |
| Intraoperative minimal Hb (g/L) e | 112 ± 26 | 113 ± 26 | 111 ± 27 | 0.568 | 118 ± 25 | 104 ± 25 | < 0.001 |
| Intraoperative management | |||||||
| Use of vasopressors f | 175 (24.1%) | 116 (21.6%) | 59 (31.4%) | 0.007 | 116 (21.6%) | 59 (31.4%) | 0.007 |
| Volume of artificial colloid infusion (ml) | 500 (500, 1000) | 500 (500, 1000) | 500 (500, 1000) | 0.858 | 500 (500, 1000) | 500 (500, 1000) | 0.618 |
| Estimated blood loss (ml) | 100 (10, 300) | 100 (10, 300) | 100 (10, 300) | 0.138 | 100 (10, 300) | 100 (10, 400) | 0.034 |
| Positive fluid balance (ml) | 2202 ± 1605 | 2201 ± 1579 | 2204 ± 1679 | 0.982 | 2093 ± 1516 | 2382 ± 1731 | 0.023 |
| Postoperative variables before AKI g | |||||||
| Nephrotoxin exposure | |||||||
| Glycopeptides | 46 (6.3%) | 35 (6.5%) | 11 (5.9%) | 0.764 | 17 (3.7%) | 29 (10.6%) | < 0.001 |
| Aminoglycoside | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | – | 0 (0.0%) | 0 (0.0%) | – |
| NSAIDs | 387 (53.1%) | 292 (54.0%) | 95 (50.5%) | 0.415 | 265 (58.1%) | 122 (44.7%) | < 0.001 |
| Hemolysis | 1 (0.1%) | 1 (0.2%) | 0 (0.0%) | > 0.999 | 0 (0.0%) | 1 (0.4%) | 0.374 |
| Rhabdomyolysis | 1 (0.1%) | 1 (0.2%) | 0 (0.0%) | > 0.999 | 0 (0.0%) | 1 (0.4%) | 0.374 |
| Sepsis | 47 (6.4%) | 29 (5.4%) | 18 (9.6%) | 0.043 | 12 (2.6%) | 35 (12.8%) | < 0.001 |
| Use of vasopressors f | 77 (10.6%) | 53 (9.8%) | 24 (12.8%) | 0.254 | 41 (9.0%) | 36 (13.2%) | 0.074 |
| Minimal Hb (g/L) | 103 ± 25 | 105 ± 26 | 99 ± 21 | 0.008 | 109 ± 27 | 94 ± 18 | < 0.001 |
| Maximal BNP (pg/ml) | 247 (130, 456) | 244 (128, 443) | 264 (142, 513) | 0.265 | 209 (115, 373) | 322 (188, 564) | < 0.001 |
| Maximal lactate (mmol/L) | 1.9 (1.3, 2.7) | 1.9 (1.3, 2.7) | 1.8 (1.3, 2.8) | 0.751 | 1.9 (1.4, 2.7) | 1.8 (1.3, 2.7) | 0.377 |
| Perioperative blood transfusion h | 186 (25.5%) | 131 (24.2%) | 55 (29.3%) | 0.172 | 89 (19.5%) | 97 (35.5%) | < 0.001 |
| Non-renal SOFA within 24 h ICU admission | 2 (1, 3) | 2 (1, 3) | 2 (2, 4) | 0.005 | 2 (1, 3) | 3 (1, 4) | 0.001 |
| Postoperative AKI | 188 (25.8%) | – | – | – | 90 (19.7%) | 98 (35.9%) | < 0.001 |
Data are presented as mean ± SD, median (interquartile range), or number of patients (percentage) and compared by independent samples t-test, Mann-Whitney U test or chi-squared test/Fisher’s exact test respectively
BNP B-type natriuretic peptide, ENT ear, nose and throat, Hb hemoglobin, NSAIDs non-steroidal anti-inflammatory drugs, SOFA sequential organ failure assessment score
a The cutoff value of preoperative albumin for postoperative AKI was determined by the Youden index of the ROC curve [see Additional file 3: Figure S1]
b Open or laparoscopic surgery referred to 534 patients
c Abdominal surgery, such as gastrointestinal, hepatobiliary, and pancreatic surgery
d Thyroid or breast surgery
e Measured by arterial blood gas analysis
f Including use of phenylephrine, norepinephrine, epinephrine, and dopamine
g Occurred before start of AKI
h Perioperative blood product transfusion, including packed red blood cell, plasma, and platelet