Table 1.
Characteristics of patients undergoing cardiac surgery.
| Characteristic | All patients (N = 8186) | Preoperative anemiaa |
|||||
|---|---|---|---|---|---|---|---|
| No |
Yes |
||||||
| ΔHbb < 50 % (n = 5447) | ΔHb ≥50 % (n = 869) | P | ΔHb <30 % (n = 851) | ΔHb ≥30 % (n = 1019) | P | ||
| Preoperative factors | |||||||
| Age, year | 52.0 (45.0–61.0) | 51.0 (44.0–60.0) | 56.0 (48.0–63.0) | <0.001 | 49.0 (42.0–60.0) | 57.0 (48.0–65.0) | <0.001 |
| Female | 4720 (57.7) | 3174 (58.3) | 435 (50.1) | <0.001 | 576 (67.7) | 535 (52.5) | <0.001 |
| BMI, kg/m2 | 22.7 (20.8–24.7) | 22.7 (21.1–25.0) | 22.7 (21.0–24.5) | 0.034 | 22.3 (20.2–23.7) | 22.5 (20.3–24.0) | 0.446 |
| Current smoking | 2291 (28.0) | 1498 (27.5) | 289 (33.3) | <0.001 | 188 (22.1) | 316 (31.0) | <0.001 |
| ASA classification | 0.027 | 0.502 | |||||
| II-III | 7696 (94.0) | 5165 (94.8) | 808 (93.0) | 788 (92.6) | 935 (91.8) | ||
| IV-V | 490 (6.0) | 282 (5.2) | 61 (7.0) | 63 (7.4) | 84 (8.2) | ||
| NYHA classification | 0.264 | 0.807 | |||||
| I | 144 (1.8) | 91 (1.7) | 17 (2.0) | 18 (2.1) | 18 (1.8) | ||
| II | 2006 (24.5) | 1348 (24.7) | 214 (24.6) | 202 (23.7) | 242 (23.7) | ||
| III | 5765 (70.4) | 3879 (71.2) | 608 (70.0) | 576 (67.7) | 702 (68.9) | ||
| IV | 271 (3.3) | 129 (2.4) | 30 (3.5) | 55 (6.5) | 57 (5.6) | ||
| Comorbidities | |||||||
| Chronic obstructive pulmonary disease | 67 (0.8) | 38 (0.7) | 10 (1.2) | 0.158 | 7 (0.8) | 12 (1.2) | 0.448 |
| Hypertension | 1341 (16.4) | 788 (14.5) | 179 (20.6) | <0.001 | 148 (17.4) | 226 (22.2) | 0.010 |
| Coronary heart disease | 1060 (12.9) | 567 (10.4) | 151 (17.4) | <0.001 | 117 (13.7) | 225 (22.1) | <0.001 |
| One diseased vessel | 231 (2.8) | 138 (2.5) | 30 (3.5) | 31 (3.6) | 32 (3.1) | ||
| Two diseased vessels | 193 (2.4) | 99 (1.8) | 29 (3.3) | 19 (2.2) | 46 (4.5) | ||
| Three diseased vessels | 519 (6.3) | 273 (5.0) | 82 (9.4) | 56 (6.6) | 108 (10.6) | ||
| Not investigated | 117 (1.4) | 57 (1.0) | 10 (1.2) | 11 (1.3) | 39 (3.8) | ||
| Previous myocardial infarction | 229 (2.8) | 119 (2.2) | 30 (3.5) | 0.023 | 27 (3.2) | 53 (5.2) | 0.033 |
| Infective endocarditis | 190 (2.3) | 44 (0.8) | 8 (0.9) | 0.733 | 76 (8.9) | 62 (6.1) | 0.020 |
| Atrial fibrillation | 3723 (45.5) | 2567 (47.1) | 462 (53.2) | 0.001 | 306 (36.0) | 388 (38.1) | 0.345 |
| Previous congestive heart failure | 1511 (18.5) | 993 (18.2) | 171 (19.7) | 0.307 | 174 (20.4) | 173 (17.0) | 0.055 |
| Peripheral arterial disease | 112 (1.4) | 62 (1.1) | 12 (1.4) | 0.538 | 13 (1.5) | 25 (2.5) | 0.162 |
| Previous cardiovascular surgery | 1825 (22.3) | 1081 (19.8) | 237 (27.3) | <0.001 | 186 (21.9) | 321 (31.5) | <0.001 |
| Previous transient ischemic attack | 36 (0.4) | 28 (0.5) | 3 (0.3) | 0.511 | 3 (0.4) | 2 (0.2) | 0.521 |
| Previous stroke | 336 (4.1) | 203 (3.7) | 36 (4.1) | 0.551 | 50 (5.9) | 47 (4.6) | 0.221 |
| Liver injury | 412 (5.0) | 263 (4.8) | 53 (6.1) | 0.111 | 46 (5.4) | 50 (4.9) | 0.627 |
| Renal dysfunction | 364 (4.4) | 161 (3.0) | 44 (5.1) | 0.001 | 67 (7.9) | 92 (9.0) | 0.373 |
| Diabetes mellitus | 528 (6.5) | 290 (5.3) | 67 (7.7) | 0.005 | 61 (7.2) | 110 (10.8) | 0.007 |
| Echocardiography | |||||||
| Left ventricular functionc, % | 0.514 | 0.091 | |||||
| Good | 7109 (86.8) | 4704 (86.4) | 755 (86.9) | 766 (90.0) | 884 (86.8) | ||
| Moderate | 1041 (12.7) | 719 (13.2) | 108 (12.4) | 83 (9.8) | 131 (12.9) | ||
| Poor | 36 (0.4) | 24 (0.4) | 6 (0.7) | 2 (0.2) | 4 (0.4) | ||
| Pulmonary hypertensiond, mmHg | 0.288 | 0.010 | |||||
| Normal | 6728 (82.2) | 4526 (83.1) | 725 (83.4) | 646 (75.9) | 831 (81.6) | ||
| Mild | 427 (5.2) | 259 (4.8) | 51 (5.9) | 54 (6.3) | 63 (6.2) | ||
| Moderate | 705 (8.6) | 465 (8.5) | 69 (7.9) | 92 (10.8) | 79 (7.8) | ||
| Severe | 326 (4.0) | 197 (3.6) | 24 (2.8) | 59 (6.9) | 46 (4.5) | ||
| Intraoperative factors | |||||||
| Type of surgery | <0.001 | <0.001 | |||||
| Valve | 7241 (88.5) | 4692 (91.1) | 721 (83.0) | 750 (88.1) | 808 (79.3) | ||
| Coronary artery bypass grafting | 794 (9.7) | 401 (7.4) | 116 (13.3) | 91 (10.7) | 186 (18.3) | ||
| Both | 151 (1.8) | 84 (1.5) | 32 (3.7) | 10 (1.2) | 25 (2.5) | ||
| Time on bypass, min | 114.0 (89.0–142.0) | 112.0 (88.0–138.0) | 126.0 (100.0–158.0) | <0.001 | 108.0 (85.0–137.0) | 121.0 (94.0–149.0) | <0.001 |
| Cross-clamp time, min | 75.0 (57.0–100.0) | 73.0 (56.0–98.0) | 82.0 (63.0–110.0) | <0.001 | 71.0 (53.0–95.0) | 81.0 (60.0–106.0) | <0.001 |
| Duration of surgery, h | 4.8 (4.0–5.5) | 4.7 (4.0–5.4) | 5.3 (4.3–6.1) | <0.001 | 4.6 (4.0–5.3) | 5.0 (4.2–5.9) | <0.001 |
| Perioperative hemoglobin | |||||||
| Preoperative hemoglobine, g/dL | 13.5 (12.3–14.6) | 13.9 (13.1–14.8) | 14.5 (13.7–15.4) | <0.001 | 10.7 (9.6–11.5) | 11.7 (11.1–12.1) | <0.001 |
| Postoperative nadir hemoglobinf g/dL | 8.2 (7.3–9.0) | 8.5 (7.8–9.4) | 6.8 (6.1–7.1) | <0.001 | 8.3 (7.7–8.8) | 7.1 (6.6–7.7) | <0.001 |
| ΔHbb, % | 38.5 (32.0–44.8) | 38.7 (33.5–43.4) | 53.5 (51.4–56.7) | <0.001 | 22.4 (15.9–26.4) | 37.4 (33.6–42.5) | <0.001 |
| Blood transfusion | |||||||
| Perioperative RBC transfusion | 3915 (47.8) | 1872 (34.4) | 639 (73.5) | <0.001 | 633 (74.4) | 771 (75.7) | 0.524 |
| Total RBC, units | 3.0 (2.0–5.0) | 2.0 (2.0–4.0) | 4.0 (2.0–7.5) | <0.001 | 4.0 (2.0–5.0) | 4.0 (2.0–6.0) | 0.130 |
| Intraoperative RBC transfusion | 1957 (23.9) | 891 (16.4) | 196 (22.6) | <0.001 | 427 (50.2) | 443 (43.5) | 0.004 |
| Volume of intraoperative RBC transfusion, units | 2.0 (2.0–4.0) | 2.0 (2.0–3.0) | 3.0 (2.0–6.0) | <0.001 | 3.0 (2.0–4.0) | 3.0 (2.0–4.0) | 0.041 |
| Postoperative RBC transfusion | 2584 (31.6) | 1222 (22.4) | 501 (57.7) | <0.001 | 384 (45.1) | 477 (46.8) | 0.466 |
| Volume of postoperative RBC transfusion, units | 3.0 (2.0–4.0) | 2.0 (2.0–3.5) | 4.0 (2.0–7.0) | <0.001 | 3.0 (2.0–4.0) | 3.5 (2.0–5.0) | 0.047 |
| Perioperative PLT transfusion | 1078 (13.2) | 601 (11.0) | 156 (18.0) | <0.001 | 130 (15.3) | 191 (18.7) | 0.048 |
| Perioperative FFP transfusion | 2462 (30.1) | 1288 (23.6) | 481 (55.4) | <0.001 | 228 (26.8) | 465 (45.6) | <0.001 |
Values are presented as n (%) or median (interquartile range) unless otherwise noted. Continuous variables were compared using Student's t-test or Mann-Whitney U test, and categorical variables were compared using the chi-squared or Fisher's exact test.
a
Preoperative anemia was defined as preoperative hemoglobin <12 g/dL for women or <13 g/dL for men.
b
ΔHb (%) was defined as (Preoperative hemoglobin – Postoperative nadir hemoglobin)/Preoperative hemoglobin × 100.
c
Categorized as good when the left ventricular ejection fraction ≥51 %, as moderately reduced when the fraction was 31–50 %, or as poor when the fraction ≤30 %.
d
Classified as mild when pulmonary arterial pressure was 25–34 mmHg, as moderate when pressure was 35–44 mmHg, or as severe when ≥45 mmHg.
e
Preoperative hemoglobin was defined as the last available measurement before surgery.
f
Postoperative nadir hemoglobin was defined as the lowest level measured from ICU admission until day 3 after cardiac surgery.BMI, body mass index; ASA, American Society of Anesthesiologists; NYHA, New York Heart Association; RBC, red blood cell; PLT, platelet; FFP, fresh frozen plasma.