Table 1.
Patient Characteristics by Fluid Balance
| Characteristic | No (%)
|
|||
|---|---|---|---|---|
| Negative FB (N=4,804) |
Even FB (N=5,096) |
Positive FB (N=8,184) |
P value | |
| Age, yrs, median (IQR) | 59 (47–71) | 60 (48–73) | 62 (49–74) | <0.001 |
| Male | 2,705 (56.3) | 2,968 (58.2) | 4,554 (55.7) | 0.0124 |
| Race | ||||
| Caucasian | 3,836 (79.8) | 4,010 (78.7) | 6,368 (77.8) | 0.084 |
| African-American | 335 (7) | 367 (7.2) | 641 (7.8) | |
| Other | 633 (13.2) | 719 (14.1) | 1,175 (14.4) | |
| BMI, kg/m2 median (IQR) | 26.6 (22.4–31.2) | 26.9 (22.8–31.6) | 25.1 (21.1–29.3) | <0.001 |
| Baseline serum creatinine, mg/dl, median (IQR) | 0.86 (0.7 – 1.05) | 0.9 (0.77 – 1.04) | 0.9 (0.7 – 1.06) | 0.0418 |
| History of hypertension | 1,512 (31.5) | 1,550 (30.4) | 2,606 (31.8) | 0.22 |
| History of diabetes | 814 (16.9) | 809 (15.9) | 1,402 (71.1) | 0.15 |
| History of cardiac disease | 979 (20.4) | 834 (16.4) | 1,329 (16.2) | <0.001 |
| History of vascular disease | 443 (9.2) | 450 (8.8) | 810 (9.9) | 0.10 |
| History of heart failure | 778 (16.2) | 617 (12.1) | 1,022 (12.5) | <0.001 |
| History of malignant neoplasms | 139 (2.9) | 177 (3.5) | 376 (4.6) | <0.001 |
| History of chronic liver disease | 352 (7.3) | 485 (9.5) | 1,188 (14.5) | <0.001 |
| History of sequela from liver disease | 283 (5.9) | 381 (7.5) | 999 (12.2) | <0.001 |
| History of liver transplantation | 95 (2) | 109 (2.1) | 285 (3.5) | <0.001 |
| Admission for liver transplantation | 149 (3.1) | 237 (4.7) | 651 (8) | <0.001 |
| Multiple comorbidities | 2,105 (43.8) | 2,139 (42) | 3,904 (47.7) | <0.001 |
| Surgical admission | 2,845 (59.2) | 3,089 (60.6) | 5,447 (66.6) | <0.001 |
| Medical Admission | 1,589 (33.1) | 1,625 (31.9) | 2,216 (27.1) | |
| Vasopressor use* | 1,195 (24.9) | 1,185 (23.3) | 2,616 (32) | <0.001 |
| Mechanical ventilation* | 2,640 (54.9) | 3,021 (59.3) | 5,981 (73.1) | <0.001 |
| Sepsis* | 583 (12.1) | 618 (12.1) | 1,467 (17.9) | <0.001 |
| APACHE III score, median (IQR) | 55 (39–74) | 58 (42–78) | 74 (55–94) | <0.001 |
| Hypotensive index, mmHg-hr, mean (SD)† | 7.27 (0.34) | 6.71 (0.31) | 9.98 (0.3) | <0.001 |
| AKI within 24hrs of ICU admission‡ | 1,322 (27.5) | 1,704 (33.4) | 2,529 (30.9) | <0.001 |
| Fluids administered in the first 24 hrs of ICU admission, L, median (IQR) | 2.71 (1.78 – 3.97) | 3.30 (2.32 – 4.65) | 4.29 (2.97 – 6.42) | <0.001 |
| Mean fluid balance during ICU stay, L, mean (SD) | −0.713 (0.01) | 0.639 (0.01) | 1.729 (0.02) | <0.001 |
| Fluid balance, L/day, median (IQR) | ||||
| At 72 hours | −0.966 (−2.546 – 0.726) | 1.968 (0.78 – 3.435) | 5.781 (3.42–8.903) | <0.001 |
| At 7 days | −1.775 (−3.771 – −0.561) | 1.862 (0.835 – 3.08) | 7.218 (4.711 – 11.147) | <0.001 |
Abbreviations: BMI – Body Mass Index; IQR - interquartile range; SD - standard deviation; APACHE, Acute Physiology and Chronic Health Evaluation; AKI, acute kidney injury
Missing data: Age (n=6); BMI (n=3151); type of admission (n=1273); 72 hour fluid balance (n=34); 7 day fluid balance (n=21); APACHE-III (n=31); reference serum creatinine (n=2); hypotensive index (n=164); fluids administered in first 24 hours (n=50).
At ICU admission
Hypotensive index defined as area under the curve for severity and duration of hypotension. Severity of hypotension was measured using a hypotensive index which integrates the duration and depth of systolic blood pressure (SBP) <90 mmHg in the first 24 hours after ICU admission. mmHg-hr is defined as a lowering of BP below 90 mm Hg over a time interval of 24 hours {i.e., a BP of 80 mmHg for 1 hour and BP ≥90 mmHg for 23 hours will result in 10 mmHg-hr ([90–80]*1=10); a BP of 85 mmHg for 10 hours and a BP ≥90 mmHg for 14 hours will result in 50 mmHg-hr ([90–85]*10=50) (25)}
AKI defined and classified according to the maximum Kidney Disease Improving Global Outcomes (KDIGO) criteria based on serum creatinine, urine output or both(17).