Vitamin B6 intakes and status of mechanically ventilated critically ill patients in Taiwan

Objective: To assess vitamin B6 intake and status of critically ill patients. The relationship between vitamin B6 status indicators and the severity of illness and outcome in these patients was also examined. Design: Prospective clinical study. Setting: The study was performed at the Taichung Veteran General Hospital, in the central part of Taiwan. Subjects: Ninety-four patients in the intensive care unit (ICU) entered the study and 46 patients successfully completed this study. Interventions: No intervention. Main outcome measures: Vitamin B6 intake was recorded for 14 days. Vitamin B6 status was assessed by direct measures (plasma pyridoxal 5'-phosphate (PLP), pyridoxal (PL), and urinary 4-pyridoxic acid (4-PA)) and indirect measures (erythrocyte alanine (EALT-AC) and aspartate (EAST-AC) aminotransaminase activity coefficient). The severity of illness (APACHE II score), the length of ventilation dependency, and the length of ICU and hospital stay were recorded. Results: Patients had an adequate mean vitamin B6 intake (16.26 +/- 19.39 mg) during the 14 day study. Mean vitamin B6 intake was significantly higher on day 14 than on day 1 (P < 0.001). However, plasma PLP and PL concentrations significantly decreased at the 14th day after admission (P < 0.05). Erythrocyte alanine aminotransaminase activity coefficient and EAST-AC did not change significantly. Urinary 4-PA significantly increased at the 14th day (P < 0.001). No significant relationships were found between APACHE II scores and clinical outcomes (the length of ICU and hospital stay, the length of ventilation dependency) of patients, vitamin B6 intake or status indicators. Conclusions: Critically ill patients received nutritional support in the ICU, and had sufficient mean vitamin B6 intake and adequate vitamin B6 status. Therefore, the severity of illness and the results should not be affected by vitamin B6 status. However, we have noted that plasma PLP and PL concentrations significantly decreased while vitamin B6 intake significantly increased on day 14. Critical clinical conditions and complex metabolism in the critically ill may account for the reduction of plasma PLP and PL. Since vitamin B6 deficiency causes profound effects on immune system function, dietary or supplemented vitamin B6 intake is suggested for hospitalized patients.