One hundred nineteen patients were initially reviewed. After excluding 29 based on criteria, 90 were included for analysis. Patients were grouped according to survival. Age, Lac, APACHE II and SOFA scores, adrenaline dose, and length of ICU stay were significantly higher and MAP was significantly lower in patients who died (non-survival group). Patient characteristics are shown in Table 1.
Table 1
| Total (90) | Non-survival group (9) | Survival group (81) | P value |
Sex(male, %) | 65(72.2%) | 6(66.6%) | 57(70.3%) | 0.589 |
Age (years) | 51.82 ± 14.82 | 64.33 ± 5.72 | 50.05 ± 14.89 | 0.000* |
Height (cm) | 168.30 ± 7.32 | 166.78 ± 7.85 | 168.59 ± 7.23 | 0.483 |
Weight (kg) | 66.18 ± 13.07 | 62.05 ± 13.93 | 67.03 ± 12.76 | 0.276 |
HR(bpm) | 98.50 ± 18.41 | 100.88 ± 13.08 | 98.76 ± 19.22 | 0.748 |
MAP(mmHg) | 87 ± 12.71 | 77.56 ± 10.18 | 88.55 ± 12.78 | 0.016* |
P(V−A)CO2(mmHg) | 5.38 ± 2.83 | 6.19 ± 2.38 | 5.21 ± 2.89 | 0.393 |
ScvO2(%) | 77.4 ± 9.10 | 79.97 ± 8.71 | 77.15 ± 9.35 | 0.448 |
Lac (mmol/L) | 3.37 ± 2.08 | 5.01 ± 2.38 | 3.10 ± 1.97 | 0.013* |
APACHE II score | 13.63 ± 4.89 | 18.89 ± 7.07 | 12.80 ± 4.10 | 0.033* |
SOFA score | 8.75 ± 3.43 | 11.56 ± 2.35 | 8.48 ± 3.430 | 0.011* |
sCr(umol/L) | 98.64 ± 21.38 | 84.56 ± 16.54 | 79.37 ± 23.64 | 0.526 |
TBil(umol/L) | 36.56 ± 21.69 | 44.36 ± 37.82 | 34.52 ± 21.73 | 0.244 |
Past medical history(n/%) | | | | |
Hypertension | 8(9.2%) | 2(25%) | 6(75%) | 0.17 |
Diabetes | 13(14.9%) | 3(25%) | 9(75%) | 0.084 |
Cardiovascular disease | 14(16.1%) | 0(0%) | 12(100%) | 0.195 |
COPD | 7(8.0%) | 1(16.7%) | 5(83.3%) | 0.625 |
Diprivan(mg/h) | 46.00 ± 18.89 | 45.55 ± 17.40 | 45.78 ± 19.13 | 0.972 |
Fentanyl(ug/h) | 46.90 ± 44.78 | 41.66 ± 12.50 | 47.64 ± 48.50 | 0.715 |
PEEP(cmH2O) | 5.26 ± 1.03 | 5.12 ± 0.35 | 5.29 ± 1.10 | 0.674 |
Time of mechanical ventilation(h) | 70.81 ± 89.10 | 294.33 ± 125.43 | 56.47 ± 60.72 | 0.085 |
NE (ug/kg/min) | 0.11 ± 0.28 | 0.30 ± 0.58 | 0.09 ± 0.25 | 0.39 |
E (ug/kg/min) | 0.03 ± 0.04 | 0.07 ± 0.03 | 0.03 ± 0.04 | 0.021* |
Length of ICU day(days) | 6.80 ± 5.10 | 17.25 ± 5.67 | 5.86 ± 3.72 | 0.000* |
Values are expressed as means ± standard deviation or numbers (percentage). * indicates significance (P < 0.05).
HR, heart rate; MAP, mean arterial pressure; P(V−A) CO2, central venous-to-arterial carbon dioxide difference; ScvO2, central venous oxygen saturation; Lac, lactate; APACHE II, Acute Physiology and Chronic Health Evaluation II score; SOFA, Sequential Organ Failure Assessment Score; sCr, serum creatinine; TBil, total bilirubin; COPD, chronic obstructive pulmonary disease; PEEP, positive end-expiratory pressure ventilation; MV, mechanical ventilation; NE, norepinephrine; E, adrenaline
Hemodynamic parameters
Hemodynamic indicators before surgery and in the first 48 hours after are shown in Table 2 and Fig. 1. Pmsf was highest before surgery (20.94 ± 6.48 mmHg), reached its peak at t1 (15.41 ± 2.77 mm Hg), and then declined. Pmsf − CVP reached its peak 24 hours after surgery (6.2 ± 3.60 mmHg). RVr reached its peak at t3 (1.50 ± 0.30 mmHg). Although Pmsf was significantly higher in the non-survival group (F, 6.006; P = 0.016), it did not significantly differ in the groups over time (Table 3). Pmsf was significantly higher in the non-survival group at 0h, t1, t2, t3, and 24h (Table 3, Fig. 2A). Pmsf − CVP was similar between groups and did not significantly differ in them over time (Table 3). Pmsf − CVP was significantly higher in the non-survival group only at 0h (6.21 ± 0.86 vs 5.10 ± 2.73; P = 0.013, Table 3, Fig. 2B). RVr was significantly higher in the non-survival group (F, 5.611; P = 0.022) but did not significantly differ in the groups over time (Table 3). RVr was significantly higher in the non-survival group at t2, t3, and 24h (Table 3; Fig. 2C).
CVP was significantly higher in the non-survival group (F, 5.390; P = 0.024), but did not significantly differ in the groups over time (Table 3). CVP was significantly higher over time in the non-survival group (F, 3.623; P = 0.019; Table 3). CVP was significantly higher in the non-survival group at 24h (Table 3; Fig. 2D). CO did not significantly differ between groups and did not differ over time in either group (Table 3). CO was significantly lower in the non-survival group at t1, t2, and t3 (Table 3; Fig. 2E). MAP did not significantly differ between groups and did not differ over time in either group (Table 2). MAP was significantly lower in the non-survival group at 0h (Table 3; Fig. 2F). Lac did not significantly differ between groups; however, Lac was significantly higher over time in the non-survival group (F, 4.080; P = 0.013; Table 3). Lac was significantly higher in the non-survival group at 0h and t1 (Table 3, Fig. 2G).
Table 2
Hemodynamics factors over time in all patients
| Pmsf (mmHg) | CVP(mmHg) | CO(L/min) | MAP (mmHg) | Pmsf-CVP (mmHg) | RVr (Ω) |
pre | 20.94 ± 6.48 | 17.84 ± 5.82 | 3.26 ± 1.14 | 79.01 ± 10.23 | 3.43 ± 2.08 | 1.34 ± 0.52 |
post | 14.45 ± 6.15 | 9.43 ± 4.45 | 5.11 ± 1.61 | 75.11 ± 6.94 | 4.66 ± 2.46 | 1.23 ± 0.34 |
0h | 15.04 ± 4.93 | 10.06 ± 2.89 | 4.82 ± 1.59 | 87.02 ± 12.71 | 6.02 ± 1.75 | 1.45 ± 0.37 |
t1 | 15.41 ± 2.77 | 9.38 ± 3.01 | 4.51 ± 1.33 | 80.87 ± 10.04 | 6.03 ± 1.50 | 1.42 ± 0.36 |
t2 | 14.85 ± 3.53 | 8.87 ± 3.57 | 4.32 ± 1.58 | 79.45 ± 14.61 | 5.98 ± 1.28 | 1.46 ± 0.34 |
t3 | 14.29 ± 2.91 | 8.09 ± 3.33 | 4.21 ± 1.29 | 81.22 ± 14.03 | 6.10 ± 0.99 | 1.50 ± 0.30 |
24h | 14.17 ± 4.56 | 7.97 ± 3.49 | 4.55 ± 4.35 | 77.73 ± 13.11 | 6.2 ± 3.60 | 1.49 ± 0.33 |
t4 | 14.21 ± 3.03 | 8.07 ± 3.27 | 4.31 ± 1.30 | 80.84 ± 14.64 | 6.13 ± 1.25 | 1.46 ± 0.26 |
t5 | 14.03 ± 3.53 | 8.08 ± 3.29 | 4.23 ± 1.19 | 79.20 ± 14.66 | 5.95 ± 1.14 | 1.46 ± 0.29 |
t6 | 13.64 ± 4.40 | 8.54 ± 3.43 | 4.05 ± 1.07 | 78.35 ± 15.27 | 5.60 ± 1.33 | 1.48 ± 0.32 |
48h | 13.61 ± 4.01 | 8.04 ± 3.24 | 4.17 ± 1.13 | 80.26 ± 15.96 | 5.74 ± 1.43 | 1.46 ± 0.32 |
Values are expressed as mean ± standard deviation. P < 0.05 were considered statistically significant. pre pre-operation, post post-operation, t1-t3 every 4-9h from 0h to 24h after admission to ICU, t4-t6 every 4-9h from 24h to 48h after admission to ICU, Pmsf Mean Systemic Filling Pressure, CVP central venous pressure, CO cardiac output, MAP mean artery pressure, Pmsf-CVP the difference between Mean Systemic Filling Pressure and central venous pressure, RVr the resistance to venous return.
Table 3
Hemodynamics factors over time in the non-survival and survival groups
| | Pmsf (mmHg) | Pmsf-CVP (mmHg) | RVr (Ω) | CVP (mmHg) | CO (L/min) | MAP (mmHg) | Lac (mmol/L) |
Non-survival group | 0h | 15.77 ± 2.97 | 6.21 ± 0.86 | 1.62 ± 0.36 | 9.56 ± 3.12 | 4.07 ± 1.39 | 77.56 ± 10.18 | 5.01 ± 2.38 |
t1 | 16.08 ± 2.77 | 5.30 ± 1.34 | 1.63 ± 0.48 | 10.78 ± 2.68 | 3.48 ± 1.27 | 77.00 ± 11.09 | 6.46 ± 2.25 |
t2 | 16.11 ± 2.74 | 5.44 ± 0.92 | 1.77 ± 0.45 | 10.67 ± 3.04 | 3.33 ± 1.36 | 75.56 ± 8.60 | 4.60 ± 1.57 |
t3 | 15.12 ± 1.56 | 5.45 ± 1.15 | 1.74 ± 0.36 | 9.67 ± 2.17 | 3.32 ± 1.22 | 74.44 ± 11.80 | 3.31 ± 1.80 |
24h | 16.15 ± 3.27 | 5.60 ± 1.08 | 1.75 ± 0.50 | 10.56 ± 4.06 | 3.51 ± 1.39 | 75 ± 8.68 | 4.12 ± 3.90 |
Survival group | 0h | 12.69 ± 7.13 | 5.1 ± 2.73 | 1.41 ± 0.37 | 10.12 ± 2.92 | 4.97 ± 1.61 | 88.55 ± 12.78 | 3.10 ± 1.97 |
t1 | 11.48 ± 7.11 | 6.10 ± 1.52 | 1.37 ± 0.31 | 9.21 ± 3.08 | 4.68 ± 1.26 | 81.45 ± 10.11 | 2.94 ± 1.88 |
t2 | 12.63 ± 6.22 | 6.04 ± 1.33 | 1.39 ± 0.29 | 8.72 ± 3.63 | 4.49 ± 1.57 | 79.83 ± 15.46 | 3.08 ± 2.37 |
t3 | 12.36 ± 5.62 | 6.14 ± 0.95 | 1.45 ± 0.27 | 7.97 ± 3.44 | 4.32 ± 1.28 | 82.03 ± 14.35 | 2.62 ± 1.6 |
24h | 10.6 ± 7.26 | 6.22 ± 3.92 | 1.44 ± 0.27 | 7.67 ± 3.28 | 4.71 ± 4.74 | 77.68 ± 13.69 | 2.17 ± 1.31 |
Total analysis | HF | 0.732 | 0.649 | 0.854 | 0.719 | 0.302 | 0.497 | 0.739 |
group | F, P | 6.006,0.016* | 0.755,0.388 | 5.611,0.022* | 5.390,0.024* | 3.073,0.086 | 2.122,0.151 | 2.489,0.124 |
Time | F, P | 0.195,0.887 | 0.409,0.709 | 2.299,0.078 | 1.914,0.137 | 0.561,0.484 | 2.433,0.096 | 4.080,0.013* |
Time*group | F, P | 0.410,0.731 | 0.249,0.825 | 1.047,0.375 | 3.623,0.019* | 0.084,0.800 | 1.145,0.320 | 1.584,0.204 |
Values are expressed as means ± standard deviation.* indicates significance (P < 0.05).HF, Huynh-Feldt; t1-t3 every 4–9 h from 0h to 24h after admission; Pmsf, mean systemic filling pressure; CVP, central venous pressure; Pmsf − CVP, difference between Pmsf and CVP; RVr, resistance to venous return; CO cardiac output; MAP, mean arterial pressure; Lac, lactate.
Correlation between the venous system and clinical indicators
In patients with serum lactate > 2.0 mmol/L at the time of ICU admission, there was a negative correlation between Pmsf-at 24h and lactate clearance rate at 6h (r2=-0.596; P = 0.000; Fig. 3A). The difference in Pmsf − CVP between 48h and 0h was positively correlated with total fluid balance 48h after surgery (r2 = 0.751; P = 0.000; Fig. 3B). In patients with renal insufficiency before surgery, the difference in Pmsf − CVP between 48h and 0h positively correlated with serum creatinine at the time of transfer out of the ICU (r2 = 0.664; P = 0.001; Fig. 3C).
Prediction of 28-day mortality
Pmsf at 0h, Pmsf at 24h, Pmsf − CVP at 0h, RVr before surgery, RVr at 24h, APACHE II, and SOFA were evaluated as predictors of 28-day mortality. Among these, the area under the ROC curve (AUC) was largest for RVr before surgery (AUC, 0.771; 95% confidence interval, 0.583–0.958; P = 0.034; Table 4; Fig. 4A). Pmsf at 24h, Pmsf − CVP at 0h, RVr before surgery, and RVr at 24h, respectively, combined with APACHE II and SOFA were significant predictors of 28-day mortality. SOFA combined with RVr before surgery had the largest AUC (0.883; 95% confidence interval, 0.758–1.000; P = 0.003; Table 4; Fig. 4B).
Table 4
Area under the receiver operating characteristic curve for various indicators
| AUC ± SE | P-value | 95% CI |
APACHE II | 0.769 ± 0.087 | 0.009* | 0.598–0.939 |
SOFA | 0.759 ± 0.071 | 0.011* | 0.620–0.899 |
Pmsf-CVP-0h | 0.557 ± 0.077 | 0.578 | 0.405–0.709 |
Pmsf-0h | 0.567 ± 0.085 | 0.511 | 0.400-0.735 |
Pmsf-24h | 0.760 ± 0.078 | 0.011* | 0.607–0.913 |
RVr-pre | 0.771 ± 0.096 | 0.034* | 0.583–0.958 |
RVr-24h | 0.583 ± 0.121 | 0.514 | 0.346–0.820 |
APACHE II + Pmsf-CVP-0h | 0.793 ± 0.078 | 0.004* | 0.640–0.946 |
SOFA + Pmsf-CVP-0h | 0.784 ± 0.067 | 0.006* | 0.653–0.914 |
APACHE II + Pmsf-0h | 0.809 ± 0.071 | 0.003* | 0.670–0.948 |
SOFA + Pmsf-0h | 0.767 ± 0.070 | 0.009* | 0.630–0.905 |
APACHE II + Pmsf-24h | 0.806 ± 0.069 | 0.003* | 0.671–0.941 |
SOFA + Pmsf-24h | 0.827 ± 0.064 | 0.001* | 0.702–0.952 |
APACHE II + RVr-pre | 0.821 ± 0.088 | 0.012* | 0.648–0.994 |
SOFA + RVr-pre | 0.883 ± 0.064 | 0.003* | 0.758-1.000 |
APACHE II + RVr-24h | 0.692 ± 0.100 | 0.134 | 0.497–0.887 |
SOFA + RVr-24h | 0.813 ± 0.074 | 0.014* | 0.668–0.957 |
Values are expressed as means ± standard deviation.*indicates significance (P < 0.05).AUC, area under the receiver operating characteristic curve; APACHE II, Acute Physiology and Chronic Health Evaluation II score; SOFA Sequential Organ Failure Assessment score; Pmsf, mean systemic filling pressure; Pmsf − CVP, difference between Pmsf and central venous pressure; RVr-pre, resistance to venous return before surgery.