ABSTRACT
Introduction Mechanical ventilation can increase the rate of free radicals in the systemic circulation due to its effect on the inflammatory system. Previous research has suggested that vitamin D has antioxidant properties. This study aimed to evaluate the effect of vitamin D on total Antioxidant Capacity (TAC) and its relationship with ICU patients' outcomes. Methods In this prospective randomized clinical trial, 36 ventilated ICU patients were randomly allocated to receive either a single intramuscular vitamin D 300,000 IU or its placebo. Serum Vitamin D and TAC were measured before and on day 7 after the intervention. clinical Pulmonary Infection Score (CPIS) and sequential organ failure assessment (SOFA) scores were measured daily for seven days and on days 14 and 28. Results Thirty patients completed the study. The results show that injection of vitamin D leads to a significant increase in the mean changes of vitamin D level on the seventh day of the study (+3.5±1.3 vs -0.4±0.2 P=0.00) and TAC levels (3.2±3.9 vs -2.0±2.6 P=0.00. ICU length of stay was 18.3±8.4 and 25.4±6.6 days in the intervention and placebo arms of the study. Twelve patients in the placebo group and 5 in the vitamin D group died within the 28 day study period. The duration of mechanical ventilation was 15.7± 9.3 vs. 22.6± 9.1 days in vitamin D and placebo arms, respectively. Conclusion : Administration of vitamin D may increase TAC levels and decrease the length of stay and duration of mechanical ventilation in ICU patients