Table 1.
Baseline Characteristics of Derivation and Validation Cohorts.
| Variables | Derivation Cohort (n = 3132) | Validation Cohort (n = 830) |
|---|---|---|
| Age | ||
| mean ± std (yr) | 53.51 ± 13.80 | 50.1 ± 16.9 |
| <=65 n (%) | 2502 (79.89) | 723 (88.1) |
| >65 n (%) | 630 (20.11) | 107 (12.9) |
| Gender, n (%) | ||
| Male | 1468 (46.87) | 500 (60.2) |
| Female | 1664 (53.13) | 330 (39.8) |
| BMI, mean ± std | 23.60 ± 3.60 | 24.7 ± 7.2 |
| ASA, n (%) | ||
| 1 | 335 (10.70) | 282 (33.8) |
| 2 | 2431 (77.62) | 468 (56.1) |
| 3 | 358 (11.43) | 78 (9.4) |
| 4 | 8 (0.25) | 4 (0.5) |
| Type of Surgery, n (%) | ||
| General Surgery | 1303 (41.60) | 234 (28.2) |
| OB/GYN | 533 (17.02) | 227 (27.4) |
| Peripheral Vascular Surgery | 9 (0.29) | 12 (1.5) |
| Cardiovascular Surgery | 458 (14.62) | 8 (0.9) |
| Thoracic Surgery | 7 (0.22) | 70 (8.4) |
| Orthopedic Surgery | 332 (10.60) | 126 (15.2) |
| Neurosurgery | 1 (0.03) | 22 (2.7) |
| Urology | 431 (13.76) | 72 (8.7) |
| Plastic Surgery | 3 (0.10) | 27 (3.3) |
| Others | 55 (1.75) | 32 (3.9) |
| Magnitude of Surgery, n (%) | ||
| minor | 12 (0.38) | 5 (0.6) |
| intermediate | 243 (7.76) | 169 (20.4) |
| major | 1235 (39.43) | 421 (50.7) |
| major plus | 1642 (52.43) | 235 (23.8) |
| Invasiveness of surgery, n (%) | ||
| endoscopic surgery | 1597 (50.99) | 427 (51.5%) |
| open surgery | 1535 (49.01) | 403 (48.5%) |
| Mode of Anesthesia, n (%) | ||
| general | 2988 (95.40) | 783 (94.3) |
| general + regional | 144 (4.60) | 47 (5.7) |
| Total Anesthesia Time, mean ± std, (h) | 2.97 ± 1.49 | 2.5 ± 1.5 |
| Overall Incidence of Hypothermia (%) | 44.30% | 39.90% |
| Baseline core temperature prior to anesthesia (°C) | ||
| mean ± std | 37.2 ± 0.3 | 37.1 ± 0.4 |
| OR ambient temperature (°C) | ||
| mean ± std | 22.9 ± 1.4 | 23.5 ± 1.7 |
| Patient receiving intraoperative passive warming, n (%) | 3132 (100.0) | 830 (100.0) |
| Patient receiving intraoperative active warming, n (%) | 443 (14.17) | 89 (10.7) |
| Blood transfusion | ||
| autologous | ||
| n (%) | 75 (2.4) | 52 (6.3) |
| mean ± std (ml) | 519.8 ± 372.2 | 429.9 ± 259.3 |
| median (ml) | 447 | 400 |
| min-max (ml) | 0–2250 | 100–1250 |
| allogeneic | ||
| n (%) | 317 (10.1) | 52 (6.3) |
| mean ± std (ml) | 735.2 ± 500.6 | 791.4 ± 777.2 |
| median (ml) | 600 | 800 |
| min-max (ml) | 50–3540 | 150–5800 |
| Perioperative IV fluid | ||
| n (%) | ||
| mean ± std (ml) | 1768.3 ± 819.3 | 1702.5 ± 914.9 |
| patients receiving prewarmed IV fluid, n (%) | 649 (20.7) | 141 (16.9) |
| patients receiving unwarmed IV fluid, n (%) | 2483 (79.3) | 689 (83.0) |
| Intraoperative irrigation fluid | ||
| n (%) | ||
| mean ± std (ml) | 1879.9 ± 8194.5 | 650.4 ± 975.4 |