Mechanism of Action of Thiamine and Vitamin C in ARDS Sepsis

Vitamin C Mechanisms in ARDS Sepsis

Vitamin C levels decline rapidly with inflammation in sepsis, with normal values rarely detected when CRP exceeds 40 mg/L, making supplementation necessary 1
Vitamin C primarily acts on the endothelium and microcirculation, preventing microcirculatory flow impairment by preventing thrombin-induced platelet aggregation and P-selectin expression, and reducing micro-thrombi formation 1
Vitamin C restores vascular responsiveness to vasoconstrictors, preserves the endothelial barrier by maintaining cyclic guanylate phosphatase 1
As a powerful antioxidant, vitamin C counteracts the oxidative stress present in ARDS, reducing oxidative damage to proteins and lipids that contribute to organ dysfunction 2, 4
Vitamin C augments antibacterial defenses, potentially reducing infectious complications in sepsis 3

Thiamine serves as an essential cofactor for enzymes involved in cellular energy metabolism, particularly in the context of sepsis where metabolic shifts occur, supporting pyruvate dehydrogenase (PDH) activity, and enabling proper functioning of the Krebs cycle and mitochondrial energy production 1, 3
Thiamine plays a critical role in reducing oxidative stress by supporting the pentose phosphate pathway, and contributing to NADPH production needed for glutathione recycling 1

In ARDS, both nutrients help counteract the hallmark features of alveolar epithelial inflammation, airspace flooding with plasma proteins, surfactant depletion, and loss of normal endothelial reactivity 4, 5

For sepsis and ARDS, current evidence suggests vitamin C dosing of 1.5-2g every 6 hours IV during the acute phase of inflammation 1
During critical illness, a higher vitamin C repletion dose of 2-3g per day should be given intravenously during the acute phase of inflammation 1, 6
The clinical effect of antioxidant combinations may be apparent after just five days of administration 2
Antioxidants as high-dose monotherapy should not be administered without proven deficiency 2, 7
Vitamin C measurement is not recommended during critical illness due to difficulty in interpretation of results 6