Volume Kinetics of Fluid Resuscitation in Early Sepsis

Adult patients admitted to the intensive care unit (ICU) with sepsis, as defined by the Sepsis-3 criteria, and exhibiting sepsis-induced hypoperfusion prior to receiving adequate volume resuscitation (i.e., 30 ml/kg of crystalloid), are administered Ringer's Lactate at a dose of 30 ml/kg. The initial 20 ml/kg is infused at a constant rate over the first 30 minutes, followed by a 30-minute pause, with an additional 10 ml/kg administered over the subsequent 15 minutes, completing the infusion within 75 minutes. Up to 180 minutes post-infusion, no other fluids (e.g., gelatin, albumin) are administered except for antibiotics, sedatives, or vasoactive substances as needed. Ideally, only one catecholamine (e.g., norepinephrine) is administered. The volume and quantity of these substances are recorded. Arterial blood samples are collected for blood gas analysis, including hemoglobin levels. Urinary output is measured at 30, 60, and 180 minutes, and any blood loss, other than the 1.5 ml per sample collected, is quantified during hemoglobin monitoring. Additionally, urinary creatinine concentration is determined from urine samples collected at baseline. The hemodilution data are utilized as input into a three-compartment model with microconstants for fluid redistribution and excretion.