An acid-base imbalance, called metabolic acidosis (acid-base disorder lasting from several minutes to several days, caused by a decrease in serum bicarbonate ion (HCO3) concentration), is often observed in critically ill patients with various underlying diseases. Metabolic acidosis has a negative impact on the cardiovascular, respiratory, digestive, nervous, excretory, hematological, endocrine, musculoskeletal and immune systems and is associated with unfavourable outcomes. Reamberin® is a solution of disubstituted sodium salt of succinic acid, which has an alkaline reaction and succinate is capable to integrate into the Krebs cycle and restore energy metabolism in the cell. The aim of the present study is to evaluate the efficacy and safety of meglumine sodium succinate at a dose of 500 to 3000 ml in critically ill patients with metabolic acidosis and choose the optimal volume of its solution for the correction of metabolic acidosis in critically ill patients.

Inclusion Criteria:

1. Signed and dated written Informed Consent (if unconscious due to a critical condition, the decision is made by a Council consisting of 3 physicians)
2. Male and female patients aged 18-70
3. Critical illness ((shock (including traumatic, hypovolemic), major trauma, acute massive blood loss, acute complicated surgical diseases of the abdominal organs) accompanied by metabolic acidosis, defined as serum bicarbonate <22mmol/L
4. pH of arterial blood 7.20-7.35, inclusive
5. Planned volume of infusion >= 1500 ml per day
6. Interval between admission to the ICU and randomization <24 hours

Exclusion Criteria:

1. Pregnant and lactating women
2. Known hypersensitivity to any component of the study drug / placebo
3. Chronic kidney disease stage C5 (end-stage renal failure)
4. Acute hepatic failure (ALT > 15 upper normal limits) or liver cirrhosis
5. Traumatic brain injury accompanied by cerebral edema
6. Previously diagnosed mental illness
7. Any chronic disease in the terminal stage with a life expectancy of < 3 months
8. HIV infection
9. Clinically significant cardiovascular disease (unstable angina pectoris or angina pectoris of functional class III or higher; chronic heart failure III - IV class according to NYHA; acute myocardial infarction within 6 months before screening)
10. Extremely low or extremely high body fat
11. Infusion sodium bicarbonate, sodium bicarbonate, trometamol, Sterofundin, Quintasol, Ringer's lactate (Hartmann's solution) within 6 hours before screening
12. Acute respiratory acidosis
13. Poisoning with chemical compounds causing metabolic acidosis
14. Alcohol in saliva at screening >= 0.5 pro mille
15. Previously diagnosed chronic obstructive pulmonary disease