Fluid overload is common in children in the pediatric intensive care unit (PICU) and is associated with worse outcomes, according to systematic review and meta-analysis published online in JAMA Pediatrics.

Fluid overload has shown consistent and robust negative association with mortality and greater risk of significant morbidity in the form of worsening organ dysfunction and longer duration of organ support, particularly mechanical ventilation,” corresponding author Dr. Sean Bagshaw from the University of Alberta, Edmonton, Canada, told Reuters Health.

“The findings of this evidence synthesis should draw attention for clinicians to review and follow fluid balance among PICU patients,” Dr. Bagshaw said by email.

Along with the colleagues he synthesized evidence from 44 studies that correlated fluid balance or fluid overload with outcomes in a total of 7,507 critically ill children. Most of the studies were retrospective (61%) or prospective (30%) cohort studies.

There currently is no consensus on how best to define fluid overload, the authors point out in their article, and available evidence largely consists of “small observational studies applying heterogeneous metrics to assess fluid balance and define fluid overload.”

In the current analysis, the number of children with fluid overload varied by case mix and fluid overload definition, ranging from 10% to 83% (median, 33%).

In 17 studies, fluid overload, regardless of how it was defined, was associated with about a fourfold greater likelihood of dying in the hospital (odds ratio, 4.34). In 22 studies, children who survived had a lower percentage of fluid overload than those who did not survive (mean difference, -5.62).

In 11 studies, after adjustment for severity of illness, there was a 6% increase in odds of mortality for every 1% increase in percentage fluid overload (adjusted odds ratio, 1.06). The findings “support the hypothesis that a threshold may exist beyond which fluid accumulation becomes unhelpful or frankly harmful,” write the researchers.

In addition, fluid overload was associated with more than a greater than the twofold increased risk for prolonged mechanical ventilation (3 studies; OR, 2.14) and acute kidney injury (7 studies; OR, 2.36).“Our findings also suggest that fluid balance may represent an identifiable and modifiable target for intervention,” the authors note.

The researchers say their findings in PICU patients align with mounting evidence on the negative association between fluid accumulation and outcomes in critically ill adults, including acute respiratory distress syndrome, sepsis, and acute kidney injury – and in perioperative settings.

“While our review does not provide clear evidence for how to optimally address fluid accumulation/overload in PICU, it provides a foundation for additional research in this area and it should focus clinicians to ask whether all the fluid given to critically ill children is needed, whether some may be avoidable or unnecessary, and to consider clinical measures to mitigate excessive accumulation,” Dr. Bagshaw told Reuters Health.