Fluid resuscitation is a critical component of sepsis treatment. Research has shown that intravenous (IV) fluid therapy in sepsis positively impacts cardiac output and thereby oxygen (O2) delivery through a complex interaction of central venous pressure, right atrial pressure, venous resistance, ventricular compliance, cardiac contractility, and systemic vascular resistance. The 2021 sepsis prevention guidelines recommend balanced crystalloids as first-line therapy. However, no studies in the literature have evaluated the effect of albumin on O2 delivery. In our study, the investigators aim to assess the impact of albumin replacement on O2 delivery in sepsis patients in the intensive care unit.

Patients will be admitted from the emergency room, operating room or medical wards. After obtaining written consent from the patients or their guardians, patients who are followed up in the intensive care unit with a diagnosis of sepsis, patients over the age of 18, who are diagnosed with hypo-albuminemia after more than 4 L/day fluid resuscitation and who undergo albumin replacement will be included in the study. Treatment support for sepsis patients will be organized according to international guidelines and our local protocol, with appropriate antibiotic therapy, fluid infusion (Crystalloids 20 mL/Kg), norepinephrine infusion to keep mean arterial pressure (MAP)>65 mmHg, and infection source control. Demographic information of the patients, sepsis cause, systemic diseases, surgical history, Sequential Organ Failure Assessment (SOFA) score, which shows the severity of the disease, Acute Physiology and Chronic Health Evaluation (APACHE II) score, hemodynamic variables, blood gas parameters, complete blood count and blood biochemistry. values, total daily fluid intake and excretion, and daily fluid balance will be recorded.

For patients with a plasma albumin value below 2.5 d/dL who require 4 L or more of crystalloid per day, 20% Albumin (100 mL) will be administered as an intravenous infusion over a minimum of 15 minutes once a day for 3 days.The effect of albumin replacement on the measurements will be evaluated by calculating the ECHO findings, blood gas parameters and SOFA score of the study patients before and after albumin replacement. Oxygen delivery will be calculated 6 times in total for 3 days and the SOFA score will be calculated 3 times in total once a day.

Inclusion Criteria:

• Followed up with a diagnosis of sepsis,
• over 18 years old
• Patients who were diagnosed with hypo-albuminemia after more than 4L/day fluid resuscitation and underwent albumin replacement

Exclusion Criteria:

• Consent is not given by the patient or his/her guardian,
• The initial cause of shock was hypovolemic, cardiogenic or obstructive shock.
• Pregnancy or suspected pregnancy
• Peripheral limb or severe organ ischemia with peripheral artery disease
• Cardiac functions cannot be evaluated optimally by transthoracic echocardiography
• Patients who died within the first 24 hours after intensive care admission

Arterial oxygen saturation (SaO2), hemoglobin (Hb), partial pressure of oxygen in the arterial blood (PaO2) values will be obtained by blood gas measurements.

Cardiac output will be calculated from the parasternal long axis window by transthoracic echocardiography and left ventricular outflow tract (LVOT) measurement. LVOT peak velocity measurement (VTI) will be displayed in PulseWave mode through the apical 5-window window. During measurement, the image will be frozen and VTI will be measured from the widest wave.

The effect of albumin replacement on the measurements will be evaluated by calculating the ECHO findings, blood gas parameters and SOFA score of the study patients before and after albumin replacement.