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Table 3 Changes in hydration determined by bioelectrical impedance vector analysis in patients with different magnitude changes in cumulative fluid balance

From: Bioelectrical impedance vector analysis in critically ill patients: a prospective, clinician-blinded investigation

  First measurement Second measurementa Change between first and second measurement P valueb
≥1-L positive fluid balance, n =26     
 Cumulative fluid balance, ml 0 (0) 1385 (1205–2022) 1385 (1205–2022)  
 Study day 0 (0) 1.0 (1.0–2.0) 1.0 (1.0–2.0)  
 Central venous pressure, mmHg 12 (10–13) 12 (8–15) 0 (−3 to 3) 0.84
 Missing observations, n 7 7 7  
 Lactate, mmol/L 2 (1.1–3.3) 1.7 (1.5–2.5) −0.3 (−0.6, 0.4) 0.67
 BIVA hydration, % 73.8 (72.6–82.1) 79.7 (72.9–86.0) 1.5 (−0.8 to 7.0) 0.09
≥2-L positive fluid balance, n =13     
 Cumulative fluid balance, ml 0 (0) 2419 (2196–2696) 2419 (2196–2696)  
 Study day 0 (0) 1.0 (1.0–2.0) 1.0 (1.0–2.0)  
 Central venous pressure, mmHg 12 (10–14) 13 (11–17) 1.5 (0–3) 0.14
 Missing observations, n 5 5 5  
 Lactate, mmol/L 2.2 (1.2–3.7) 2 (1.7–2.4) 0.3 (0.2–0.7) 0.38
 BIVA hydration, % 73.1 (72.6–73.9) 73.8 (73.3–80.3) 0.7 (0–6.4) 0.09
≥1-L negative fluid balance, n =19     
 Cumulative fluid balance, ml 0 (0) −1553 (−2056 to -1297) −1553 (−2056 to −1297)  
 Study day 0 (0) 1.5 (0.5–2.5) 1.5 (0.5–2.5)  
 Central venous pressure, mmHg 11 (10–14) 12 (9–15) 0 (-2.5, 2) 0.72
 Missing observations, n 3 3 3  
 Lactate, mmol/L 1.5 (1.1–2.4) 1.6 (1.2–2.1) 0.1 (−0.4, 0.5) 0.88
 BIVA hydration, % 77.3 (73.0–89.0) 76.5 (73.0–85.2) −0.3 (−4.5 to 0.7) 0.22
≥2-L negative fluid balance, n =15     
 Cumulative fluid balance, ml 0 (0) −2426 (−2606 to −2228) -2426 (−2606 to −2228)  
 Study day 0 (0) 1.5 (1.0–2.5) 1.5 (1.0–2.5)  
 Central venous pressure, mmHg 11 (10–13) 10 (8–12) −2 (−5, 0) 0.11
 Missing observations, n 2 2 2  
 Lactate, mmol/L 2 (1.1–2.4) 1.5 (1.2–2.3) −0.1 (−0.6, 0.3) 0.53
 BIVA hydration, % 77.3 (73.3–88.3) 73.9 (72.7–85.2) −0.8 (−3.4 to −0.1) 0.02
  1. BIVA bioelectrical impedance vector analysis
  2. Continuous variables are presented as median (interquartile range)
  3. aSecond measurement refers to the time when the pre-determined cumulative fluid balance was reached
  4. bChange between the first and second measurement assessed by nonparametric Wilcoxon signed rank test