Acute hemodynamic and neurohoromonal effects of furosemide in critically ill pediatrics patients

Association Between Furosemide Exposure and Clinical Outcomes in a Retrospective Cohort of Critically Ill Children

Furosemide is commonly prescribed in critically ill patients to increase the urine output and prevent fluid overload (FO) and acute kidney injury (AKI), but not supported by conclusive evidence. There remain conflicting findings on whether furosemide associates with AKI and adverse outcomes. Information on the impact of furosemide on adverse outcomes in a general population of pediatric intensive care unit (PICU) is limited. The aim of the cohort study was to investigate the associations of furosemide with AKI and clinical outcomes in critically ill children. Study Design: We retrospectively reviewed a cohort of 456 critically ill children consecutively admitted to PICU from January to December 2016. The exposure of interest was the use of furosemide in the first week after admission. FO was defined as ≥5% of daily fluid accumulation, and mean FO was considered significant when mean daily fluid accumulation during the first week was ≥5%. The primary outcomes were AKI in the first week after admission and mortality during PICU stay. AKI diagnosis was based on Kidney Disease: Improving Global Outcomes criteria with both serum creatinine and urine output. Results: Furosemide exposure occurred in 43.4% of all patients (n = 456) and 49.3% of those who developed FO (n = 150) in the first week after admission. Patients who were exposed to furosemide had significantly less degree of mean daily fluid accumulation than those who were not (1.10 [-0.33 to 2.61%] vs. 2.00 [0.54-3.70%], P < 0.001). There was no difference in the occurrence of AKI between patients who did and did not receive furosemide (22 of 198 [11.1%] vs. 36 of 258 [14.0%], P = 0.397). The mortality rate was 15.4% (70 of 456), and death occurred more frequently among patients who received furosemide than among those who did not (21.7 vs. 10.5%, P = 0.002). Furosemide exposure was associated with increased odds for mortality in a multivariate logistic regression model adjusted for body weight, gender, illness severity assessed by PRISM III score, the presence of mean FO, and AKI stage [adjusted odds ratio (AOR) 1.95; 95%CI, 1.08-3.52; P = 0.026]. Conclusion: Exposure to furosemide might be associated with increased risk for mortality, but not AKI, in critically ill children.

Real-time urinary electrolyte monitoring after furosemide administration in surgical ICU patients with normal renal function

Background

Although the loop-diuretic furosemide is widely employed in critically ill patients with known long-term effects on plasma electrolytes, accurate data describing its acute effects on renal electrolyte handling and the generation of plasma electrolyte alterations are lacking. We hypothesized that the long-term effects of furosemide on plasma electrolytes and acid–base depend on its immediate effects on electrolyte excretion rate and patient clinical baseline characteristics. By monitoring urinary electrolytes quasi-continuously, we aimed to verify this hypothesis in a cohort of surgical ICU patients with normal renal function.

Methods

We retrospectively enrolled 39 consecutive patients admitted to a postoperative ICU after major surgery, and receiving single low-dose intravenous administration of furosemide. Urinary output, pH, sodium [Na⁺], potassium [K⁺], chloride [Cl⁻] and ammonium [NH₄⁺] concentrations were measured every 10 min for three to 8 h. Urinary anion gap (AG), electrolyte excretion rate, fractional excretion (Fe) and time constant of urinary [Na⁺] variation (τNa⁺) were calculated.

Results

Ten minutes after furosemide administration (12 ± 5 mg), urinary [Na⁺] and [Cl⁻], and their excretion rates, increased to similar levels (P < 0.001). After the first hour, urinary [Cl⁻] decreased less rapidly than [Na⁺], leading to a reduction in urinary AG and pH and an increment in urinary [NH₄⁺] (P < 0.001). Median urinary [Cl⁻] over the first 3-h period was higher than baseline urinary and plasmatic [Cl⁻] (P < 0.001). During the first 2 h, difference between FeCl⁻ and FeNa⁺ increased (P < 0.05). Baseline higher values of central venous pressure and FeNa⁺ were associated with greater increases in FeNa⁺ after furosemide (P = 0.03 and P = 0.007), whereas higher values of mean arterial and central venous pressures were associated with a longer τNa⁺ (P < 0.05). In patients receiving multiple administrations (n = 11), arterial pH, base excess and strong ion difference increased, due to a decrease in plasmatic [Cl⁻].

Conclusions

Low-dose furosemide administration immediately modifies urinary electrolyte excretion rates, likely in relation to the ongoing proximal tubular activity, unveiled by its inhibitory action on Henle’s loop. Such effects, when cumulative, found the bases for the long-term alterations observed. Real-time urinary electrolyte monitoring may help in tailoring patient diuretic and hemodynamic therapies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0168-y) contains supplementary material, which is available to authorized users.

Diuretics in pediatrics : current knowledge and future prospects

This review summarizes current knowledge on the pharmacology, pharmacokinetics, pharmacodynamics, and clinical application of the most commonly used diuretics in children. Diuretics are frequently prescribed drugs in children. Their main indication is to reduce fluid overload in acute and chronic disease states such as congestive heart failure and renal failure. As with most drugs used in children, optimal dosing schedules are largely unknown and empirical. This is undesirable as it can potentially result in either under- or over-treatment with the possibility of unwanted effects. The pharmacokinetics of diuretics vary in the different pediatric age groups as well as in different disease states. To exert their action, all diuretics, except spironolactone, have to reach the tubular lumen by glomerular filtration and/or proximal tubular secretion. Therefore, renal maturation and function influence drug delivery and consequently pharmacodynamics. Currently advised doses for diuretics are largely based on adult pharmacokinetic and pharmacodynamic studies. Therefore, additional pharmacokinetic and pharmacodynamic studies for the different pediatric age groups are necessary to develop dosing regimens based on pharmacokinetic and pharmacodynamic models for all routes of administration.

Renal function after cardiac surgery: adverse effect of furosemide

Renal failure is a frequent event after cardiopulmonary by-pass. Hemodynamic alterations that occur during surgery, as well as factors depending on the host, are the main risk factors for renal dysfunction. To evaluate the frequency and risk factors for renal dysfunction in this setting, a cohort of fifty patients with preoperative serum creatinine under 1.5 mg/dL, submitted to cardiac surgery with cardiopulmonary by-pass was analyzed. Variables related to preoperative patient condition, intraoperative and postoperative periods were recorded. Renal function was assessed by clearances of creatinine, urea and free water, also by fractional excretion of sodium (FENa), at baseline, at anesthetic induction and during postoperative period. Patients were arbitrarily divided in two groups, according to the serum creatinine (S(Cr)) value at the end of the postoperative period: Group 1: S(Cr) < 2 mg/dL (n = 44 patients (88.5%)) and Group II: S(Cr) > 2 mg/dL (n = 6 patients (11.5%)). A decrease of renal function was observed in all patients: creatinemia raised from 1.04 +/- 0.2 to 1.55 +/- 0.4 mg/dL (33%), associated with a rise in FENa. Differences between group I and group II using univariate analysis were: baseline serum creatinine (1.01 +/- 0.23 mg/dL vs. 1.26 +/- 0.19 mg/dL, p = 0.03), FENa (0.99 +/- 0.8 vs. 2.2 +/- 2.1, p = 0.04), furosemide dose during surgery normalized to body surface area (93.2 +/- 23 mg/1.73 m2 BSA vs. 135 +/- 38 mg/1.73 m2 BSA, p < 0.001), and hemodilution index (17.3 +/- 4.3% vs. 22.8 +/- 3.2%, p < 0.01). In the multiple regression model, baseline creatinemia and furosemide dose were associated to renal dysfunction.

Diuretic therapy of heart failure in infants and children

Diuretics are the mainstay of traditional therapy for congestive heart failure. The syndrome of heart failure is now understood to involve complex interactions of neurohumoral substances released in response to poor cardiac function. Developmental changes during infancy and childhood will affect both the activation of systemic neurohumoral responses and the pharmacokinetic and pharmacodynamic actions of diuretics. Few human studies directly evaluate the efficacy of diuretic therapy in heart failure in adults. The pharmacodevelopmental aspects of diuretic therapy in infants and children are also incompletely studied. This review will describe the kidney's role in the pathogenesis of sodium and water retention in heart failure and the developmental changes in the kidney related to fluid retention. Known principles of diuretic therapy in congestive heart failure will be described. All these factors can then be used by the reader to evaluate the role of diuretic therapy in the complex syndrome of heart failure in infants and children.

Aminophylline in the treatment of fluid overload

OBJECTIVE

Aminophylline has not been studied as an adjunct diuretic in critically ill children. Our purpose was to evaluate its use in the treatment of fluid overload in these patients.

DESIGN

Open, controlled clinical trial.

SETTING

Pediatric intensive care unit.

PATIENTS

Study subjects ranged from 2-46 months of age, were fluid overloaded, and were receiving a continuous infusion of furosemide (> or =6 mg/kg/day). Patients with hemodynamic instability or liver dysfunction were excluded.

INTERVENTIONS

A single dose of aminophylline (6 mg/kg) was given after establishing baseline values. There were no additional diuretics or changes in vasoactive agents during the study.

MEASUREMENTS AND MAIN RESULTS

Urine output, creatinine clearance, and sodium and potassium excretion were measured before and after administration of the aminophylline bolus. Heart rate and mean arterial pressure (mm Hg) were recorded hourly. Urine output increased by >80% (p < .01) during the first 2 hrs after administration of the aminophylline bolus and then returned to baseline by 4 to 6 hrs. The change in urine output is consistent with the pharmacokinetics of aminophylline. Heart rate and mean arterial pressure exhibited a change of <10% from baseline.

CONCLUSIONS

These results suggest that aminophylline is an effective adjunct to furosemide in increasing diuresis in critically ill children with fluid overload. The increased diuresis can be accomplished without increased risk if drug levels are adequately monitored.

Pharmacokinetics and renal function in preterm infants

There is an increase in the survival rate of preterm infants due to rapid advances in medical knowledge and technology. However, the research and attention paid to the proper use of pharmacotherapy in these infants is still a relatively underdeveloped field. Effective and safe drug therapy requires a thorough understanding of human developmental biology and of the dynamic ontogeny of drug absorption, drug disposition, drug metabolism, and drug excretion. It is apparent that maturation of organ system function and changes in body composition during gestation and during the neonatal period exert a significant effect on the disposition of drugs. This review focuses on the effects of maturational and drug-induced changes in renal function on clinical pharmacokinetics in the preterm infant.