P0452 - Ascorbic Acid Levels in Critically-Ill Children and the Impact of Nutrition

Background: Critically-ill adults with sepsis and ARDS are known to have low ascorbic acid (AscA) levels. Recent studies suggest improved organ function, decreased vasopressor use, and decreased mortality in adult ICU patients following AscA supplementation. To date there are no studies that describe the impact of pediatric critical illness and nutrition on AscA levels.

Objective: The primary aim of this study was to describe AscA levels in critically-ill pediatric patients. Our secondary aims were to associate AscA levels with disease severity and clinical outcomes as well as explore the influence of nutrition on AscA levels.

Design/

Methods: Single-center prospective observational study in patients aged 1-month to 18-years admitted to a tertiary urban pediatric intensive care unit (PICU) with sepsis and/or respiratory failure requiring mechanical ventilation. Patients with inborn errors of metabolism, ongoing AscA supplementation, or without an indwelling catheter for blood sampling were excluded. Samples were collected within 24 hours of meeting inclusion criteria with repeat samples taken 3-5 days afterward, if available. Plasma AscA levels were analyzed by high performance liquid chromatography.

Results: We have enrolled 31 patients to date. The overall median of initial AscA level was 23.1 [IQR 10.7, 37.5] µM, compared to a physiologic normal range in healthy children of 23-114 µM. Repeat AscA levels obtained in 20 patients were higher (median 43.2 [IQR 14.0, 68.0] µM), with an increase of 11.5 [IQR 6.1, 25.1] µM. Patients who received enteral nutrition had greater increases in their median AscA level compared to those who were not being fed (AscA increase of 23.1 µM vs 8.8 µM; p=0.043). There were 15 patients that had extremely low initial AscA levels (median 10.7 [IQR 6.5, 20.3] µM) compared to the remainder of the group (35.5 [25.5, 54.3] µM). Among this “deficient” cohort, AscA levels remained significantly lower on repeat sampling (13.5 µM vs 54.5 µM; p=0.04). We found no association of AscA with severity of illness or organ dysfunction scores (p not significant). There was no difference in hospital or ICU length of stay (p not significant) between the normal and “deficient” AscA groups; however, our small sample size may have been contributory.

Conclusions: AscA levels in critically-ill children vary on presentation to the ICU. We found roughly half of this population has low initial levels, many of whom remain low on repeat sampling. Enteral nutrition appears to improve AscA levels. Based on these findings, further investigation is warranted to understand the differences between this “deficient” group and the greater PICU population, particularly related to predisposing risk factors and clinical outcomes. Furthermore, this data highlights the need for additional investigation into the role of enteral nutrition in the achievement of normal physiologic levels of AscA and the impact on disease severity.