The Intrathoracic Blood Volume Index As An Indicator Of Fluid Management In Critically Ill Patients With Septic Shock

Background Hypoperfusion is the most important feature in the pathogenesis of septic shock. So in the early treatment of septic shock patients, the most important intervention is to restore tissue perfusion. CVP and PAOP are traditionally used to estimate blood volume status, but they are easily affected. Especially in patients with serious lung infection and septic shock, the changes of heart and lung compliance and the use of mechanical ventilation will affect the measurement of CVP and PAOP. It is controversy whether this filling pressure can accurately reflect patient's blood volume status and guide fluid management exactly. Therefore, it is necessary to develop other indicators which can evaluate blood volume status more accurately. In recent years, studies shown that indicators, such as ITBVI and GEDVI derived by transpulmonary thermodilution, can predict fluid responsiveness more accurately than CVP and PAOP. Whether the indicators derived by transpulmonary thermodilution can make up for the lack of pressure indicators, and guide the clinical treatment of septic shock patients in the process of fluid management? There are no related researches.Objective To investigate the effect of fluid management strategy in septic shock patients directed by intrathoracic blood volume index (ITBVI).Methods1.Study design: Prospective clinical observational study. 2.Patients: Septic shock patients in the intensive care unit of our hospital from March 1, 2008 to December 31, 2008. 31 patients were enrolled. 16 patients who received PiCCO monitoring and used ITBVI as indicator of fluid management were enrolled into ITBVI group; 15 patients who received traditional fluid management strategy were enrolled into control group.3.Major outcome: 28-Day mortality, ICU mortality, in-hospital mortality; duration of mechanical ventilation, ICU stay and vasopressor; reversal rate of the first time of shock.4.Parameters for evaluation of treatment: APACHEâ…¡score, SOFA score and vasopressor score were compared between day 1 and day 3. Hemodynamic parameters(heart rate, mean arterial pressure, cardiac index, systemic vascular resistance index).5.Fluid intake, output and fluid balance were recorded in the first 72 hours. The characteristics of rapid fluid challenge occur in the first 72 hours were also recorded.Results1.There was no difference in 28-Day mortality, ICU mortality, in-hospital mortality between two groups. Downward trend in mortality was observed in sub-group patients whose APACHEâ…¡score was higher than 20, but there were no significant difference between two groups. The reversal rate of the first time of shock was higher in ITBVI group(p<0.05), duration of vasopressor was shorter in ITBVI group(p<0.05).2.APACHEâ…¡score, SOFA score and vasopressor score were significantly lower in day 3 compared with day 1 in ITBVI group(p<0.01), whereas there were no changes in control group.3.There was no difference in fluid intake and fluid balance in different time period within 72 hours in two groups. Fluid output was in higher in ITBVI group in 48-72 hours(p<0.01). In sub-group analysis with patients whose APACHEâ…¡score were higher than 20, fluid output was higher(p<0.01) and fluid balance was lower(p<0.05) in ITBVI group in 48-72 hours compared with control group, and fluid balance was lower in ITBVI group in 0-72 hours(p<0.01).4.There was no difference in frequency and type of fluid in fluid challenge cases within 72 hours. Except for fluid challenge with colloid in 0-6 hours, we found more fluid intake in ITBVI group in the first 30 minutes of fluid challenge cases in 0-6 hour, 6-72 hour, 0-72 hour despite crystalloid or colloid.Conclusion1.In this study, ITBVI directed fluid management strategy can elevate reversal rate of the first time of shock and reduce duration of vasopressor.2.Patients'condition were improved in the third day, evaluated by APACHEâ…¡score, SOFA score and vasopressor score.3.Accurately evaluate patient's blood volume status and the quality of fluid challenge(proper infusion rate) may benefit the improvement in the first three days in ITBVI group.