To our knowledge, this is the first European survey that has described multiple aspects of IV-MFT in acute pediatric and intensive care. Our results show a wide variation in practice in IV-MFT in children across Europe. IV-MFT should be considered like any other drug, with side effects and consequences (1). The indications for IV-MFT are varied. The Enhanced Recovery After Surgery (ERAS) protocol recommends avoiding prolonged IV-MFT by starting enteral nutrition/fluids early (11). Whenever it is possible, the IV-MFT should not be the first line of hydration as it is associated with greater potential for loss of nutritional status and iatrogenic electrolyte disturbances. (12)
In 1957, Holliday and Segar published a formula to guide the prescribing of pediatric IV-MFT volume. We found that this formula still dominates practice, despite the limitations of this original paper, which was based on the energy requirements of healthy, well hydrated children (14). We still have little definitive evidence that Holliday and Segar is the optimum formula (15). Indeed, there are many situations where it was felt prudent to restrict fluids beyond this standard calculation. Our survey showed that IV-MFT fluid was commonly restricted in children with cardiac conditions, renal failure, invasive mechanical ventilation and often in
children following cardiac surgery, with no respondents reporting exceeding the standard maintenance fluid volumes.
The majority of the respondents reported that they included most of the fluids received by the patients while calculating the total fluid intake and daily fluid balance (enteral & parenteral fluids).
Underhydration has rarely been reported in the literature, in contrast to the impact of overhydration. The frequency and adverse effects of fluid overload is increasingly reported in critically ill children leading to longer duration of mechanical ventilation, the need for renal replacement therapy and longer duration of ICU stay. (16) This is due to multiple factors, one being that critically ill children may have increased levels of secreted anti-diuretic hormone (ADH) to compensate for the initial hypovolemia, which predisposes them to fluid retention and hyponatremia (17).
This study highlighted that most respondents have chosen to prescribe the isotonic solution for maintenance intravenous fluid for the critically and acutely ill children. This finding is aligned with the latest recommendation of the American Academy of Pediatrics (AAP) Clinical Practice Guideline which recommend the use of isotonic fluid therapy instead of hypotonic fluid therapy. (18)
This recommendation has markedly changed the prescribing of IV-MFT practices in children toward isotonic fluid therapy (19). The aim of this recommendation was to prevent adverse events associated with iatrogenic hyponatremia and acute or permanent neurological impairment associated with the administration of hypotonic solutions in contrast to isotonic solutions. (18). Moreover, fatal hyponatremia has been reported in children receiving hypotonic fluid therapy. (20,21). On the other hand, children receiving isotonic fluid therapy have an increased risk for hypernatremia, which has previously been associated with increased risk of mortality if left untreated. (19)
The results of our study are consistent with recent observational studies, indicating that the unbalanced crystalloids are the most used maintenance fluids, whereas factors contributing to the decision of prescribing balanced salt solutions were mainly related to the serum chloride level, presence of metabolic acidosis and patient’s clinical condition respectively. (5,22,23)
Debates have focused on whether chloride rich solutions worsen patient’s outcome through the increased risk of hyperchloremic acidosis and whether the physiologically balanced solutions may improve or ameliorate these outcomes. Notably, potential side effects related to saline-chloride use have been identified, including hyperchloremic acidosis, nephrotoxicity, coagulopathy, gastrointestinal dysfunction and increased mortality. studies have shown that hyperchloremia produces consequent risks of coagulopathy, renal vasoconstriction, heightened inflammatory response in the kidneys through the release of eicosanoids and results in reduced renal cortical tissue perfusion and has been associated with higher incidence of acute kidney injury. (23-26) In adults, several studies have reported a higher incidence of metabolic acidosis and hyperchloremia in patients who received saline compared with balanced solutions. (27,28)
Whereas for the physiologically balanced salt solutions such as RL, the lactate in RL gets converted to bicarbonate via gluconeogenesis and oxidation not only in the liver but also in the kidneys and can improve pH and may ameliorate this harm associated with the chloride-rich solutions. (29)
However, there is a lack of robust evidence to be able to recommend the use of one isotonic crystalloid over another one in children. Although some societies/organizations such as the North American Society for Pediatric Gastroenterology (2018), Hepatology and Nutrition and the WHO advocates Ringer lactate as preferred fluid for fluid therapy in cases of acute pancreatitis and for correction of severe diarrheal dehydration respectively. (29,30)
Although the understanding of metabolic response to critical illness has evolved over the last decade, there is still huge variability in daily practice around the ideal composition of IV-MFT. (31,32). Glucose is the preferential energy substrate during critical illness and a lack of glucose supply leads to ketogenesis and neurological effects (33), and most respondents still prescribed glucose in IV-MFT in young children. However, the age at which glucose was no longer prescribed in fluids was very heterogeneous.
The addition of electrolytes to IV-MFT was highly variable, probably due to the lack of recommendations to guide the clinicians. The AAP recommends using solutions with appropriate levels of potassium chloride, most commonly 2 mmol of potassium per 100 kcal metabolized (34). However, despite this recommendation most ready to use maintenance IV fluid solutions do not meet these recommendations, (e.g., Ringers Lactate contains 0.4 mmol/kg/L). The practice of adding micronutrients to IV-MFT was also rare. A recent systematic review of micronutrients studies in critically ill children revealed that micronutrients should be provided in sufficient amount to the critically ill pediatric patients, but there was insufficient data to recommend routine supplementation of micronutrients at higher doses during the critical illness. (34)
Limitations of the Study
This study has some limitations, inherent to its design. The self-report nature of the survey risks bias, and may reflect individual views rather than actual practice, and selection bias, caused by the voluntary nature of the survey, may have resulted in clinicians with a greater interest in the topic answering. Moreover, as PICU intensivist or anesthetists were surveyed, the accuracy of the practice on general pediatric wards may be less reliable. However, our response rate is good, improving the reliability of the survey and it is the first survey to engage with clinicians across Europe and the middle east around broader practices around IV-MFT in children.