Pocus Based Fluid Tolerance Score as a Predictor of End Organ Dysfunction and Mortality in Patients with Sepsis – A Prospective Observational Study

INTRODUCTION: Fluids are the first line resuscitation intervention in septic shock. Fluids restore the tissue perfusion and its excessive administration has impact on venous side, leading to venous congestion, organ dysfunction and mortality. Currently bedside test of fluid responsiveness doesn't take into account of the venous congestion. All fluid responders to volume expansion are not fluid tolerant, hence there is underlying tissue edema by fluid overload. Fluid tolerance is defined as degree to which a patient can tolerate fluid administration without causing organ dysfunction. It helps to focus a balance between organ perfusion and venous congestion. POCUS helps in assessing early fluid tolerance, picks up early signs of venous congestion. Clinical signs of fluid intolerance and biomarkers of organ dysfunction may appear later only. Pulmonary congestion assessed by LUS score, cardiovascular fluid intolerance assessed by diastolic dysfunction, right or left systolic dysfunction as well as abnormalities in splanchnic venous pattern (vexus). Aggressive fluid resuscitation can also manifest as abdominal compartment syndrome, increased incidence of AKI. POCUS for assessment of fluid tolerance and to predict organ dysfunction is a novel method which requires research. Robust studies are not there to correlate the relationship of pocus based fluid tolerance and their relation to end organ dysfunction. The study has included some of the pocus parameters (E/e, LV's, RV's, EF, TAPSE, IVC, LUS score, Femoral venous doppler) and proposed a scoring system based on individual parameters values. SOFA score is taken as parameter of end organ dysfunction. Pocus parameters based fluid tolerance score has been constructed and we are analyzing correlation between this fluid tolerance score with end organ dysfunction and mortality in sepsis. This fluid tolerance score may aid clinicians as a rational resuscitation strategy, optimizing the tissue perfusion while avoiding the congestion.(1–10) Aims and Objectives Aim: To predict the impact of fluid to tolerance score on end organ dysfunction and mortality. Primary objective: 1. To correlate pocus based fluid tolerance score with end organ dysfunction and mortality in septic shock patients. Secondary objectives: 1. To evaluate the incidence of organ dysfunction in adult septic patients with systemic venous congestion. MATERIALS AND METHODS: Study area: Medical Intensive Care Unit (MICU), Mazumdar Shaw Medical Centre, Bommasandra, Bengaluru. Study design: Prospective, observational study. Study duration: Study will be conducted for 2 years after obtaining institutional ethics committee approval. STUDY POPULATION: Inclusion Criteria. Patients with age ≥18 years admitted to MICU with sepsis/septic shock: Exclusion. Criteria- Severe MR, AR Pregnancy, CKD Prosthetic, transplant heart Sample size estimation Sample size was calculated using the formula Alpha (α): Type 1 error rate Sens: Expected sensitivity Preb: Prevalence of the outcome (disease) in the population d: Marginal error rate Alpha (α): Type 1 error rate Sens: Expected sensitivity Preb: Prevalence of the outcome (disease) in the population d: Marginal error rate Lu NF et al, evaluated the accuracy of echo parameters to predict outcomes in sepsis patients. The study had a mortality rate of 33% and e’ predicted prognosis in sepsis patients (mortality) with an AUC of 0.65, sensitivity 67.7% and specificity 71%. Since we are proposing a composite score based on POCUS, expecting a higher sensitivity of 85%, with expected mortality rate of 33% and precision 10% the required total sample size is 149 patients (with number of subjects with outcomes needed as 49).(11–15) METHODOLOGY: Sepsis patients admitted to MICU, satisfying inclusion and exclusion criteria are selected for the study. A detailed history, clinical examination was done. Demographic data, comorbidities, vitals on admission, presence/ type of shock, diagnosis on admission, organ site infection, number of organ failure using sequential organ failure assessment (SOFA) score on admission, lab parameters, ionotropic requirement, ventilator settings, arterial blood gas values, RRT. Fluid tolerance score calculated based on pocus parameters values. Data collected at baseline and then on a every 48 hours till icu discharge, Measurements are taken by intensivist who has at least three years of experience in performing ultrasound. USG measurements are performed by single observer to avoid inter- observer variability. To measure LUS score, 10–15 MHz linear array transducer of GE healthcare LOGIQ™ e ultrasound machine is used. The external lung fields are divided into 12 zones: 6 on the right (anterior: upper R1 and lower R2; lateral; upper R3 and lower R4; posterior: upper R5 and lower R6) and 6 on the left side (front: upper L1 and lower L2; lateral: upper L3 and lower L4; rear: upper L5 and lower L6). LUS assigns 0 points to A lines or < 2 separate B lines plus regular sliding; 1 point with lines B ≥ 3 or spaced focal points plus regular sliding; 2 points with coalescing B lines, and 3 points to pulmonary consolidations with a score ranging from 0 (normal lungs) to 36 (worst case scenario). To record the trans-mitral blood flow at the apical four-chamber view, pulsed-wave Doppler was used. The rate E wave was measured. In the septum and the lateral annulus, e’ was measured by tissue Doppler, and the E/e’ ratio was calculated. To measure RV S’ or systolic excursion velocity, RV-focused view is used with tissue Doppler region of interest placed at the lateral corner of the tricuspid annulus acquired at high frame rate. The velocity S’ is read as the highest systolic velocity. TDI imaging with the PWD sample volume placed at the lateral mitral annuls shows characteristic velocity waveforms with two initial negative and two late positive velocity waves which are named S1, S2, E’, and A’ which correspond, respectively, to LV isovolumic contraction velocity, peak systolic contraction velocity, peak early myocardial relaxation velocity, and late diastolic velocity. LVs’ is the peak systolic mitral annular longitudinal velocity. To calculate Ejection fraction, it needs multiple tracings using the apical 4 and 2 chamber views in both diastole and systole. The Simpson Method calculates ejection fraction from the entire volume of the left ventricle during systole and diastole (therefore, it is the definition of ejection fraction.(16–25) It measures actual volumes. Then EF is calculated. To measure IVC, the probe is placed in the subxiphoid area and the liver is used as an acoustic window. Images of the IVC draining into the right atrium are obtained while the probe is in the subxiphoid area The minimum IVC diameter on inspiration and the maximum IVC diameter on expiration are recorded using M-mode just beyond the point where the hepatic veins drain. into the IVC The maximum IVC diameter on inspiration and the minimum IVC diameter on expiration are measured. The IVC collapsibility index is calculated by the following formula: IVC collapsibility index = [maximum diameter on expiration – (minimum diameter on inspiration/maximum diameter on expiration)] In mechanically ventilated patients, the IVC distensibility index is calculated using the formula: IVC distensibility index = [(maximum diameter on inspiration-minimum diameter on expiration)/minimum diameter on expiration] To measure femoral venous doppler of the CFV requires a high frequency (5-13 MHz) linear array vascular probe. Most ultrasound machines will have a venous vascular mode ideally preset for image optimization. The patient should be lying supine in a horizontal position, less than 20°, as changes in intra-abdominal pressure while sitting might alter Doppler patterns of pulsatile flow. The CFV is located inferior to the ileo-inguinal ligament and medial to the common femoral artery. Care should be taken to correctly identify the CFV and not one of its tributaries, such as the saphenous vein. Once identified, 2D and colour flow Doppler allows the examiner to qualitatively assess the presence of a normal or abnormal velocity.(26–37) Combined pocus score is calculated based on below table RESULTS: Final analysis ongoing. DISCUSSIONS/CONLUSION: Final analysis ongoing