Micronutrient status during paediatric critical illness: A scoping review

Abstract

Background: No evidence based recommendations for micronutrient requirements during paediatric critical illness are available, other than those arising from recommended nutrient intakes (RNI) for healthy children and expert opinion.

Objectives: The objective of this review is to examine the available evidence from micronutrient status in critically ill children considering studies which describe 1) micronutrient levels, 2) associations between micronutrient levels and clinical outcome, and 3) impact on clinical outcome with micronutrient supplementation during PICU admission.

Design: Scoping review.

Eligibility criteria: Any study which used a qualitative and quantitative design considering causes and consequences of micronutrient levels or micronutrient supplementation during paediatric critical illness.

Sources of evidence: NICE Healthcare Databases Advanced Search website (https://hdas.nice.org.uk/) was used as a tool for multiple searches, with a content analysis and charting of data extracted.

Results: 711 records were identified, 35 were included in the review. Studies evaluated serum micronutrient status was determined on admission day in majority of patients. A content analysis identified (n = 49) initial codes, (n = 14) sub-categories and (n = 5) overarching themes during critical illness, which were identified as: i) low levels of micronutrients, ii) causes of aberrant micronutrient levels, iii) associations between micronutrients levels and outcome, iv) supplementation of micronutrients.

Conclusion: During critical illness, micronutrients should be provided in sufficient amounts to meet reference nutrient intakes for age. Although, there is insufficient data to recommend routine supplementations of micronutrients at higher doses during critical illness, the 'absence of evidence should not imply evidence of absence', and well designed prospective studies are urgently needed to elucidate paediatric micronutrient requirements during critical illness. The absence of reliable biomarkers make it challenging to determine whether low serum levels are reflective of a true deficiency or as a result redistribution, particularly during the acute phase of critical illness. As more children continue to survive a PICU admission, particularly those with complex diseases micronutrient supplementation research should also be inclusive of the recovery phase following critical illness.

Keywords: Critically ill children; Micronutrients; Nutrition; Paediatric intensive care; Vitamins.

Fig. 1

Search results through to inclusion.

Fig. 2

Framework used to characterize concepts of micronutrient status in critically ill children.

Fig. 3

Schematic of factors impacting on micronutrient status during critical illness. In the early phase of critical illness, aberrant serum micronutrient levels may be due to 1) redistribution from central circulation to tissues and organs during the acute phase inflammatory response to critical illness, 2) micronutrient losses due to exudative or stomas losses, 3) reduced stores of enzyme co-factors due to increased requirements during illness and 4) low endogenous levels due to pre-existing diseases. Adapted with permission from Casaer M et al. [8].

Fig. 4

Schematic of World Health Organisation (WHO) recommendations for the management of severe malnutrition. Adapted with permission WHO [86].