Assessing redox status in human plasma: experience in critically ill patients

Area of Science:

• Biochemistry
• Critical Care Medicine
• Metabolic Disorders

Background:

• Clinical evaluation of metabolic acidosis traditionally relies on measuring key metabolites.
• Previous research indicated that lactate (L), pyruvate (P), beta-hydroxybutyrate (BOHB), and acetoacetate (AcAc) are not in equilibrium in plasma.
• The degree of disequilibrium can be quantified using the ratio of apparent equilibrium constants (KLP/KBA) for the L-P and BOHB-AcAc redox couplets.

Purpose of the Study:

• To assess the utility of the KLP/KBA ratio in reflecting metabolic disequilibrium in critically ill patients with metabolic acidosis.
• To investigate the correlation between this ratio and patient outcomes, including mortality.

Main Methods:

• Measurements of lactate, pyruvate, beta-hydroxybutyrate, and acetoacetate were performed in 23 critically ill patients.
• The ratio of apparent equilibrium constants (KLP/KBA) was calculated to quantify metabolic disequilibrium.
• Patient outcomes, including mortality during ICU stay, were analyzed in relation to the calculated ratio.

Main Results:

• Metabolic disequilibrium was confirmed, evidenced by an inconstant KLP/KBA ratio (p < .01).
• The ratio demonstrated a positive correlation with clinical improvement.
• Lower KLP/KBA ratios were associated with a higher likelihood of mortality in patients with metabolic acidosis.
• Patients with respiratory acidosis exhibited intermediate ratios and mortality probabilities compared to controls.

Conclusions:

• Changes in the lactate-pyruvate-beta-hydroxybutyrate-acetoacetate cycle reflect the extent of metabolic derangement in critically ill patients.
• The KLP/KBA ratio serves as a valuable indicator of metabolic disequilibrium and a potential prognostic marker for critically ill patients.
• This redox couplet ratio offers insights into patient prognosis, particularly in the context of metabolic acidosis.