Fluid Overload in Children With Bronchiolitis.

Unauthorized reproduction of this article is prohibited Pediatric Critical Care Medicine www.pccmjournal. org 301 Fluid overload is common among critically ill children. Over the last decades, pediatric intensivists learned to administer fluids generously. Early and “aggressive” fluid administration became the treatment cornerstone for children with hemodynamic instability (1). This was reinforced by a number of studies showing resuscitation strategies that involved large amounts of IV fluid (e.g., Pediatric Advanced Life Support guidelines, goal-directed therapy) being effective in reducing morbidity and mortality in hemodynamically unstable children (2). A clear physiologic basis existed—that is, to restore circulating volume and improve cardiovascular status—so pediatric intensivist learned to accept IV fluids as a safe and effective therapy in emergency and PICUs. Fluid resuscitation was—and continues to be—a great success story. However, as intensive care science moves forward, we ask ourselves how much fluid is too much? There is now growing evidence that fluid accumulation is also linked to worsened clinical outcomes (3, 4). This does not undermine the importance of adequate fluid resuscitation but highlights the importance of continuously assessing fluid status. Studies are now showing that a more restrictive approach to fluid management can improve clinical outcomes of populations that often require large amounts of fluid resuscitation such as sepsis and acute respiratory distress syndrome (5), but restricting fluid in other populations such as patients undergoing major abdominal surgery may be harmful (6). In this issue of Pediatric Critical Care Medicine, Flores-González et al (7) report their findings of a prospective multicenter study looking at the effect of fluid overload in children with severe acute bronchiolitis. This population is interesting because it comprises one of the largest groups of children requiring intensive care, carrying a significant volume burden to PICUs despite having a very low mortality rate. This population is also interesting because it has a pathology with primary pulmonary involvement and little hemodynamic effect. The high capillary density of the lungs and the propensity for lung capillary leak in response to inflammation potentiates the possible impact of fluid accumulation on clinical outcomes. Furthermore, the low hemodynamic impact of this illness naturally limits the confounding effect of fluid resuscitation for shock. In their analysis, the authors found that a positive fluid balance 24 hours after PICU admission was associated with longer duration of mechanical ventilation, as well as longer PICU and hospital stay. Some of these effects were also observed at 48 and 72 hours. These findings are in keeping with fluid management studies in other pediatric populations (8, 9). Although these results only show an association and do not imply causation, it is hard to ignore the vast amount of literature that is currently emerging point in the same direction: we need to improve our patient’s fluid management! We already recognize fluid overload as deleterious to our patients (10, 11), maybe it is time to recognize that our patient’s fluid “maintenance” requirements may be lower than our usual estimate for healthy children. We should also consider that critically ill children often have a hormonal response that will retain fluid, so diuresis may need to be stimulated when it is safe to do so. Perhaps we should look at fluid balances with as much attention as we look at vasoactive drug infusions or blood pressure targets and act on fluid overload with the same emphasis that we learned to treat hemodynamic instability. An interesting aspect of the population studied was that even on the first day of admission most patients were receiving enteral feeding. It would be acceptable to think that as clinical status improve, patients may tolerate larger amounts of enteral feeding and a positive balance in this setting could be not so clinically relevant. However, the authors found that the effect of fluid overload in clinical outcome seems to be independent of route of fluid administration. This again emphasizes the importance of constant patient fluid assessment and that provision of adequate caloric intake should not be an excuse to tolerate a patient positive fluid balance. Besides the fluid management data, the current study by Flores-González et al (7) also exposes other features of the reallife management of severe bronchiolitis in children. Despite extensive research, treatment of severe bronchiolitis remains mainly supportive, and this can be frustrating for both parents and attending physicians (12, 13). Parents often see their child deteriorating and “no one doing anything about it. ” Physicians, especially intensivist, may feel powerless and struggle with the lack of treatment options. This often leads to attempts to use therapies that have been shown not to be effective in this population. Salbutamol, nebulized adrenaline, nebulized hypertonic saline, corticosteroids were very frequently used (either alone or in combination) in this population (7). It is clear that physicians wanted to do something and sometimes may have done too much. Used too many unproven therapies and too much fluid. Flores-González et al (7) from the BRUCIP study showed us that moderation is very much needed in the management of children with severe bronchiolitis.