Early restrictive fluid resuscitation has no clinical advantage in experimental severe pediatric acute respiratory distress syndrome

Abstract

Background: Intravenous fluids are widely used to treat circulatory deterioration in pediatric acute respiratory distress syndrome (PARDS). However, the accumulation of fluids in the first days of PARDS is associated with adverse outcome. As such, early fluid restriction may prove beneficial, yet the effects of such a fluid strategy on the cardio-pulmonary physiology in PARDS is unclear. In this study, we compared the effect of a restrictive to a liberal fluid strategy on hemodynamic response and the formation of pulmonary edema in an animal model of PARDS. Methods: Sixteen mechanically ventilated lambs (2-6 weeks) received oleic acid infusion to induce PARDS and were randomized to a restrictive or liberal fluid strategy during a 6-hour period of mechanical ventilation. Transpulmonary thermodilution determined extravascular lung water (EVLW) and cardiac output (CO) Post-mortem lung wet-to-dry weight ratios were obtained by gravimetry. Results: Restricting fluids significantly reduced fluid intake, but increased use of vasopressors among animals with PARDS. Arterial blood pressure was similar between groups, yet CO declined significantly in animals receiving restrictive fluids (p=0.005). There was no difference in EVLW over time (p=0.111) and lung wet-to-dry weight ratio (6.1 IQR 6.0-7.3 vs. 7.1 IQR 6.6-9.4 restrictive vs. liberal, p=0.725) between fluid strategies. Conclusions: Both fluid strategies stabilized blood pressure in this model, yet early fluid restriction abated CO. Early fluid restriction did not limit the formation of pulmonary edema, therefore this study suggests that in the early phase of PARDS a restrictive fluid strategy is not beneficial in terms of immediate cardio-pulmonary effects.

Early Restrictive Fluid Strategy Impairs the Diaphragm Force in Lambs with Acute Respiratory Distress Syndrome

“…The strength of our study was that we performed this experiment under controlled and uniform conditions with standardized, validated, and direct measurements in which we included in vivo function, perfusion, and histology of the diaphragm. Furthermore, as our study was part of a more extensive experiment with the same research design but with different research questions (focused on the cardiopulmonary effects of fluid strategy during pediatric ARDS), 17 we were able to minimize the number of animals used.…”

“…Procedures involving animal data, anesthetics, mechanical ventilation, and surgical techniques were performed in accordance with previously described methods. 17 See appendix in the Supplemental Digital Content 1(http://links.lww.com/ALN/C802) for further details. Experimental details concerning the current study are mentioned separately in this article.…”

“…This study was part of an extensive experiment with the same research design but with different research questions all focused on the cardiopulmonary effects of fluid strategy during experimental pediatric ARDS. 17 The current study focused on the effects of a restrictive fluid strategy versus a liberal fluid strategy on diaphragm structure and function. The effect of a contraction stimulus on the transdiaphragmatic pressures and the formation of diaphragmatic muscle fiber edema were the primary outcomes.…”

“…At the end of the experiment, the cumulative fluid balance in the liberal group (liberal vs. restrictive: 86.0 ml/kg vs. 23.3 ml/kg; P < 0.001) and the cumulative dose of norepinephrine in the restrictive group (restrictive vs. liberal group: 130.7 µg/kg vs. 64.9 µg/kg; P = 0.001) were significantly higher. 17…”

Dysnatremia in children, why is it so hard to stay normal?

“…This is perhaps even more obvious in the pediatric intensive care setting where a slightly elevated plasma sodium sometimes has been highlighted as desirable to prevent tissue swelling, for instance, in traumatic brain injury or in preventing pulmonary tissue edema in ARDS. The physiology behind this reasoning is appealing, logical, and most likely adequate, but the practice currently rests on a partially insufficient scientific basis 3‐5 . Instead, not surprisingly it turns out that variations in sodium homeostasis, often carries a certain risk.…”