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Ascorbic Acid in Critical Illness: A Meta-Analysis

1/7/2020 1:30:54 PM
vitamin cPatients who are critically ill have low plasma levels of ascorbic acid. What’s more, low plasma ascorbic acid correlates with a higher risk of multiple organ failure. Therefore, both animal and human studies have explored the effects of ascorbic acid administration during critical illness.
Human studies have shown that above-normal plasma concentrations of ascorbic acid can only be achieved by intravenous (IV) administration because of saturation of intestinal transporters. Studies have also shown that IV administration of 10 grams per day of ascorbic acid leads to above-normal concentrations, whereas administration of 2 grams per day leads only to normal plasma concentrations.

Studies examine intravenous vitamin C for critically patients

To determine whether IV ascorbic acid influences mortality or other clinical parameters in critically ill patients, researchers conducted a comprehensive meta-analysis. The analysis included studies from 1997 to 2018 and was published in 2019 in the Annals of Intensive Care.

Twelve studies were included, of which 8 were randomized controlled trials and 4 were retrospective studies. The studies involved a total of 1210 patients with severe sepsis, septic shock, burn shock, critical injury, post-operation, or trauma. The duration of treatment ranged from 24 hours (in severe burns) to 28 days (in general surgery).

Critically patients can benefit from 3-10 grams IV vitamin C per day

The main finding of the meta-analysis was that IV administration of 3-10 grams per day of ascorbic acid was associated with decreased mortality (OR 0.25; 95% CI (0.14–0.46); p < 0.001; I2 = 0.0%). Lower doses (< 3 g/d) and higher doses (> 10 g/d) were not. Also, the medium-dose administration of ascorbic acid was associated with a shorter duration of vasopressor support and mechanical ventilation.
Ascorbic acid had no effect on any of the other outcomes measured, including resuscitation fluid requirement, urine output, acute kidney injury, length of intensive-care-unit stay, or length of hospital stay.
This meta-analysis was the first to assess whether different doses of IV ascorbic acid contribute to different clinical outcomes. Limitations of the analysis included variations between trials in terms of patient characteristics, duration of therapy, and follow-up period. Although additional studies are needed to clarify the most effective protocols for ascorbic acid, the current analysis demonstrated that daily doses of 3-10 grams of IV ascorbic acid reduced mortality in critically ill patients.   

Wang, Y, H Lin, BW Lin, and JD Lin. “Effects of Different Ascorbic Acid Doses on the Mortality of Critically Ill Patients: A Meta-Analysis.” Ann Intensive Care 9, no. 1 (2019): 58.