Continuous Assessment Of Right Ventricular End-diastolic Volume As A Marker Of Cardiac Preload In The Early Goal-directed Therapy In Elderly Septic Shock Patients

1,BackgroundSevere sepsis, septic shock and multiple organ dysfunction syndrome (MODS) are the main cause of death in the intensive care unit (ICU) and have become the main concern and most difficulties of the present critical care medicine. The relevant mortality rate of septic shock was around 28-50%. It remains difficult to diagnosis and treat in daily critical care practice.Monitoring the hemodynamic status of septic shock patients is of crucial importance. Early detection of the abnormal parameters can adopt the appropriate therapeutical result which is known as "early goal-directed therapy (EGDT)". It has been proved that pulmonary artery catheterization was an effective and safe method of hemodynamic monitoring. However, pressure parameters drawn from PA catheter could not always demonstrate the exact change of the cardiac preload accurately. It could be affected with several conditions, such as the position of the catheter, ventricular compliance, thoracic pressure and abdominal cavity pressure, etc. So it is difficult to estimate cardiac preload precisely by this means. Then the result of fluid resuscitation could be impaired. By directly measuring right ventricular end diastolic volume (RVEDV), volumetric pulmonary artery catheter can be treated as an accurate tool to measure the cardiac preload.2,ObjectiveTo investigate the value of the right ventricular end-diastolic volume index (RVEDVI) in elderly patients with septic shock guiding the early goal-directed therapy (EGDT) compare with the traditional pulmonary catheterization.3,Materials and methodsA Investigating object:a) Twenty elderly patients with septic shock who were admitted consecutively to the Intensive Care Unit of Zhejiang Hospital were enrolled.b) Inclusion criteria: Septic shock patients with APACHE II score > 15. The definition of septic shock was accorded to the standard of International Sepsis Definition Conference in 2001:â‘ clinical evidence of infection focus;â‘¡systemic inflammatory response syndrome which manifested by two or more of the following conditions: temperature > 38°C or <36°C; heart rate > 90 beats per minute; respiratory rate >20 breaths per minute or PaCO₂<32 mm hg; white blood cell count > 120000 cells per cubic millimeter, <40000 cells per cubic millimeter, or >10% immature (band) forms;â‘¢systolic pressure lower than 90 mmHg or a reduction >40 mmHg from baseline for at least 1 hour, or maintenance of blood pressure by fluid therapy or vasoactive agents;â‘£evidence of poor tissue perfusion, e.g. oliguria (<30 ml/h) lasting for more than 1 hour.c) Exclusion criteria: Shock sustain for more than 24 hours on admission to ICU or with structural cardiovascular diseases, acute coronary artery syndrome, severe valvular disease of the heart, primary pulmonary hypertension, acute respiratory distress syndrome, acute renal failure, acute hypohepatia, acute renal failure requiring hemodialysis and died within 24 hour of initial post-treatment after admission.B Design:Hemodynamic profile of right ventricular was monitored with Swan-Ganz catheter. Enrolled patients were randomizedly divided into experimental group and control group to process EGDT. The resuscitative destination of experimental group was referred to RVEDVI corrected by RVEF and to RAP in control group. On initial and after EGDT, the RVEDVI, RAP, PAOP, EF, SvO2 and the lactate clearance after 6 hours of both groups of patients were detected and calculated.C Study procedure:Both two groups were given early goal-directed therapy in six hours. The protocol was carried out as follows. Fluid resuscitation was given to achieve a right atrial pressure (RAP) of 12 to 15 mmHg. If the mean arterial pressure (MAP) was less than 65 mm Hg, vasopressors were given to maintain MAP of at least 65 mmHg. If the mixed venous blood oxygen saturation (SvO₂) was less than 70 percent, red cells were transfused to achieve a hematocrit of at least 30 percent. After the right atrial pressure, mean arterial pressure, and hematocrit were thus optimized, if the mixed venous blood oxygen saturation was still less than 70 percent, dobutamine administration was started at a dose of 2.5μg per kilogram of body weight per minute, a dose that was increased until the mixed venous blood oxygen saturation was above 70 percent or until a maximal dose of 10μg per kilogram per minute was given. Parameters including RVEDVI, RAP, PAOP, SvO₂, RVEF, APACHE 11 score, serum lactate and lactate clearance in two groups were recorded and calculated before and after treatment.4,ResultsA The standard-reaching rate of fluid resuscitation was 80% in experimental group and 70% in control group.B Left ventricular end diastolic volume (RVEDVI),right atrial pressure (RAP),PAOP and SvO₂ were significantly increased after EGDT. In goals achieved group, RVEDVI was significantly higher in experimental group than that in control group (124.50±19.32, 95.83±8.81, P<0.05) . Right ventricular ejection fraction (RVEF) (35.88±3.98 vs 31.86±2.34, P<0.05) and RAP (14.38±1.19 vs 12.43±0.53, P<0.05) were significantly increased after EGDT. Lactate clearance rate was significantly higher in experimental group than that in control group (27.70±8.09, 15.70±3.92, P<0.05) . SvO₂ was of no significant difference in both groups.C Correlation analysis showed that RVEDVI in experimental group who reach at standard had no correlation with RAP and PAOP. There was a significant correlation between lactate clearance rate and SvO₂.5,ConclusionRVEDVI is a valuable and effective clinical parameter in evaluation of EGDT effect in elderly patients with septic shock. It is also a good method to improve the success rate of resuscitation.