[Assessment of fluid volume in critically ill patients with extravascular lung water index]

To examine the effect of rapid infusion test guided by extravascular lung water index ( EVLWI ) on hemodynamics in critically ill patients at different states in order to guide volume resuscitation.

A prospective observation was conducted. Forty critically ill patients admitted to Department of Critical Care Medicine of Tianjin Third Central Hospital from June 2012 to April 2014 were enrolled. Based on the levels of EVLWI and pulmonary vascular permeability index ( PVPI ) and the cardiac function, the patients were divided into four groups: septic patients with normal EVLWI and PVPI ( n = 17 ), septic patients with increased EVLWI and PVPI ( n = 3 ), septic patients with increased EVLWI and normal PVPI ( n = 4 ), and coronary heart disease and heart failure patients with normal EVLWI and PVPI ( n = 16 ). The rapid infusion test was conducted in all patients using lactated Ringer solution 250 mL, followed by infusion of crystalloid with rate of 150 mL/h. The conditions of mechanical ventilation and vasoactive drugs were not changed during study. The changes in EVLWI, intrathoracic blood volume index ( ITBVI ), and cardiac index ( CI ) before capacity load, at immediate capacity load, and 15, 45, 105 minutes after load were determined by pulse indicator continuous cardiac output ( PiCCO ). On the base of volume status before and after the liquid infusion, the standard for the changes were: stroke volume ( SV ) increased by 12%-15%, central venous pressure ( CVP ) greater ≥ 2 mmHg ( 1 mmHg = 0.133 kPa ), CI>15%, and ITBVI change greater than 10%.

There were no statistically significant differences in the observed indicators at the each time point before and after rapid infusion test among the four groups ( all P>0.05 ). In septic patients with normal EVLWI and PVPI group, ITBVI was slightly increased by 5.4%-9.7% from 15 minutes to 45 minutes after rapid infusion test. In coronary heart disease and heart failure patients with normal EVLWI and PVPI group, the EVLWI was increased by 11.9%, 5.9%, and 14.7% respectirely at 15, 45, and 105 minutes, ITBVI was slightly increased by 6.4% at 45 minutes, CI was increased by 29.5% immediately after rapid infusion. In septic patients with increased EVLWI and PVPI group, CVP was increased by 8 mmHg immediately, EVLWI was increased significantly by 15.8% at 45 minutes, ITBVI was slightly decreased by 10.0% at 45 minutes, CI was increased by 24.7% immediately, and increased by 17.0% at 105 minutes, and PVPI was increased by 15.6%-28.1% at 15-105 minutes after rapid infusion. In septic patients with increased EVLWI and normal PVPI group, CVP was increased by 1.5 mmHg at 15 minutes, EVLWI was increased immediately, which was increased by 17.4%, 24.0%, and 31.4% respectively at 15, 45, and 105 minutes, ITBVI was increased by 13.9% at 15 minutes, CI was increased by 16.1% at 15 minutes after rapid fluid infusion.

Rapid fluid replacement in critically ill patients with crystalloid, regardless of whether the EVLWI was normal or increased, the short-term response was affected by the volume and cardiac function of patients. Different status of patients showed different volume effect curve: no significant changes in hemodynamic parameters were found in patients with normal EVLWI and volume parameters. In patients with potential cardiac dysfunction, CI and EVLWI increased significantly; regardless of PVPI increased or normal, EVLWI and CI were increased in patients with elevated EVLWI; two different changes could be found in the two types of pulmonary edema while ITBVI was increased.