Fluid balance and clinical outcomes in mechanically ventilated children in pediatric intensive care unit : A retrospective observational, analytical study

Abstract

Background : Positive fluid balance is shown to have adverse outcomes in mechanically ventilated children with Acute Respiratory Distress Syndrome (ARDS). Our study attempts to provide an understanding of the threshold of fluid balance requiring intervention in the management of mechanically ventilated children. Methods : This retrospective study was conducted in the Division of Pediatric Critical Care, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER). Medical records from January 2015 to December 2016 were screened. All medical records of children aged 1-month to 13 years admitted to PICU and mechanically ventilated for more than 24 hours with documented input-output balance for at least 48 hours from the start of mechanical ventilation were included. Patients divided into =10% Fluid overload (FO) group and > 10% FO group. Results : Study included 107 children with 84 in =10% FO group and 23 in >10% FO group. The baseline characteristics were similar in terms of age (median 11 months Vs 12 months), sex (M:F = 47:37 Vs 10:13), Pediatric Risk of Mortality (PRISM)- III score (15 Vs 16), inotrope score (20 in both) & vasoactive score (30 in both) and number of patients receiving furosemide [59 (70%) vs 16 (69 %)]. Disordered control of breathing was the most common indication for mechanical ventilation in both groups [37(44%) Vs 12(52%)]. The proportion of children having ARDS [28(35%) Vs 13(56%), p=0.06] and AKI [37(44%) Vs 15(65%), p=0.07] were higher in >10% FO group of which significant number required renal replacement therapy [15(17%) Vs 10(43%), p=0.01]. More children were found to have shock in >10% FO group [58(69%) vs 18(78%), p=0.38] and the proportion of septic shock was significantly higher [27(32%) vs 13(56%), p=0.03]. The >10% FO group had a higher mortality compared to =10% FO group [32(38%) vs 13(57%) RR=1.2, 95%CI 1.0-1.5, p=0.11]. The median (IQR) duration of invasive mechanical ventilation was 6 (4-11) days in =10% FO group and 5 (3-10) days in >10 % FO group (p=0.90). PICU stay was longer in =10% FO group [9 days (6-15) Vs 8 days (6-15) p=0.82]. Ventilator-free days were comparable (23.5 Vs 22.5) and organ dysfunction scores - Pediatric Logistic Organ Dysfunction (PELOD) [12 in both] & Sequential Organ Failure Assessment (SOFA) [8 in both] were similar. The >10% FO group had greater failed extubations (7% Vs 20%) (p=0.23) and higher respiratory morbidity (median Oxygen Saturation Indices 3.55 vs 5.4, p=0.14, Oxygenation Indices calculated for 49 and 12 children respectively were 3.5 Vs 5.15, p=0.59). Conclusion : There was no significant difference in mortality or respiratory morbidity in positive fluid overload >10 % compared to fluid overload =10%. Future prospective studies including a larger number of children are required to obtain more evidence regarding the association of fluid overload with adverse outcomes.