The influence of continuous venovenous hemofiltration on parameter measurement by the transpulmonary thermodilution technique

Abstract

To evaluate the influence of continuous venovenous hemofiltration (CVVH) on measurement of transpulmonary thermodilution parameters. A prospective observational study was conducted. Fifty-six patients who received CVVH and hemodynamic monitoring at the same time admitted to the Department of Critical Care Medicine of Tianjin Third Central Hospital from July 2012 to July 2014 were enrolled. In all the patients, the dialysis catheter was inserted through the femoral vein, and transpulmonary thermodilution measurements were performed by pulse indicator continuous cardiac output (PiCCO) monitoring technology at the same time. Mean arterial pressure (MAP), central blood temperature, cardiac index (CI), global end-diastolic volume index (GEDVI), intrathoracic blood volume index (ITBVI) and extravascular lung water index (EVLWI) were measured before CVVH, immediately after CVVH, and 30 minutes after CVVH, respectively. Results In the 56 patients, there were 36 males and 20 females, (66 ± 16) years of old, height of (172 ± 6) cm, body weight of (68 ± 10) kg. The acute physiology and chronic health evaluation II (APACHE II) scores was 26 ± 6. After CVVH, the central blood temperature was gradually decreased, and blood temperature at 30 minutes after CVVH was significantly lower than that before CVVH (degrees C : 37.17 ± 1.06 vs. 37.57 ± 1.26, P < 0.01). There were no significant changes in MAP and EVLWI before and after CVVH the MAP was (89 ±20), (86 ± 16), (90 ± 17) mmHg ( 1 mmHg = 0.133 kPa) at three time points respectively, and EVLWI was (9.4 ± 3.2, (9.3 ± 3.0), (9.4 ± 2.9) mL/kg, respectively. After CVVH, CI, GEDVI and ITBVI showed a gradual downward tendency. Compared with those before CVVH, the decline of CI, GEDVI, and ITBVI immediately after CVVH was not statistically significant [CI (mL x s (-1) x m(-2): 62.18 ± 24.34 vs 63.85 ± 21.84, GEDVI (mL/m2): 705 ± 103 vs 727 ± 100, ITBVI (mL/m2): 881 ± 129 vs 908 ± 125, all P > 0.05]. CI, GEDVI, ITBVI at 30 minutes after CVVH were significantly decreased [CI mL x s(-1) x m(-2)): 57.84 ± 20.50 vs 63.85 ± 21.84, GEDVI (mL/m2): 681 ± 106 vs. 727 ± 100, ITBVI (mL/m2): 851 ± 133 vs. 908 ± 125, all P < 0.05]. CVVH was associated with a decline of 6.01 mL x s(-1) x m(-2) at 30 minutes after CVVH [95% confidence interval (95% CI)) = -10.67 to -1.50, P = 0.011]. The declines of GEEDVI and ITBVI were observed with 46 mL/m2 (95% CI = -81 to - 11, P = 0.014), 57 mL/m2 (95% CI = -101 to -13, P = 0.014) respectively 30 minutes after CVVH. CVVH had no significant effect on the transpulmonary thermodilution measurement of CI, GEDVI, ITBVI and EVLWI. Thirty minutes after the start of CVVH, CI, GEDVI was decreased significantly, but had no effect on EVLWI.