Use of loop diuretics in the critically ill

Diuretic Use in Post-Kidney Transplant Patients: A Retrospective Chart Review

BACKGROUND

The occurrence of delayed graft function (DGF) significantly enhances the possibility of both acute and chronic rejection of the transplanted organ, thereby reducing patient quality of life and survival rates. To prevent and manage oliguria in renal transplant patients, loop diuretics are presently commonly used. In our study, we assessed the possible impact of furosemide on the incidence of DGF among kidney transplant recipients.

METHODS

A review of medical records was conducted to examine demographic characteristics and kidney transplant outcomes in an adult (older than 18 years old) population. The primary objective was to determine the incidence of delayed graft function (DGF), whereas the secondary objective was to compare the creatinine levels and estimated glomerular filtration rate (eGFR) at day 30 and day 90 post-transplantation in patients who were administered furosemide vs those who were not.

RESULTS

This study included 330 patients who underwent kidney transplantation. Furosemide was administered to 169 (51.3%), whereas 161(48.7%) patients did not receive continued dose of diuretic postoperatively. The rate of DGF was significantly higher in patients who received furosemide than in those who did not (furosemide 44% vs 4%; P < .001). The eGFR was lower in the furosemide group compared to the no furosemide group at day 30 (56 ± 24 vs 71 ± 24 mL/min/1.73 m2, P < .001) and day 90 (66 ± 27 vs 78 ± 25 mL/min/1.73 m2, P < .001).

CONCLUSIONS

Our results show that there is no benefit in treating an oliguric AKI with furosemide. Administration of furosemide, especially in high doses, may increase the risk of toxicity, delay dialysis, and increase the length of stay.

Impact of loop diuretics on critically ill patients with a positive fluid balance

The impact of the use of loop diuretics to prevent cumulative fluid balance in non-oliguric patients is uncertain. This is a retrospective study to estimate the association of time-averaging loop diuretic exposure in a large population of non-cardiac, critically ill patients with a positive fluid balance (> 5% of body weight). The exposure was loop diuretic and the main outcomes were 28-day mortality, severe acute kidney injury and successful mechanical ventilation weaning. Time-fixed and daily time-varying variables were evaluated with a marginal structural Cox model, adjusting bias for time-varying exposure and the presence of time-dependent confounders. A total of 14,896 patients were included. Patients receiving loop diuretics had better survival (unadjusted hazard ratio 0.56, 95%CI 0.39-0.81 and baseline variables adjusted hazard ratio 0.53, 95%CI 0.45-0.62); after full adjusting, loop diuretics had no association with 28-day mortality (full adjusted hazard ratio 1.07, 95%CI 0.74-1.54) or with reducing severe acute kidney injury occurrence during intensive care unit stay - hazard ratio 1.05 (95%CI 0.78-1.42). However, we identified an association with prolonged mechanical ventilation (hazard ratio 1.59, 95%CI 1.35-1.89). The main results were consistent in the sub-group analysis for sepsis, oliguria and the study period (2002-2007 vs. 2008-2012). Also, equivalent doses of up to 80 mg per day of furosemide had no significant association with mortality. After adjusting for time-varying variables, the time average of loop diuretic exposure in non-cardiac, critically ill patients has no association with overall mortality or severe acute kidney injury; however, prolonged mechanical ventilation is a concern.

Passive leg raising test with minimally invasive monitoring: the way forward for guiding septic shock resuscitation?

Background

Swift and adequate fluid loading is a cornerstone of septic shock therapy. Yet, careful assessment of volume responsiveness and volume amount during the resuscitation process is a prerequisite. Both overzealous initial fluid administration and late fluid overload are harmful and may be associated with increased mortality.

Main body

Static (i.e., central venous or pulmonary artery occlusion) pressure readings are erroneous for monitoring fluid resuscitation and should be abandoned. Dynamic measurements (i.e., stroke volume and pulse pressure variation) better predict fluid responsiveness than static filling pressures but the conditions necessary for these parameters to correctly evaluate preload dependency are frequently not met. The passive leg raising maneuver as a means to alter biventricular preload in combination with real-time measurement of cardiac output changes is an easy-to-use, fast, relatively unbiased, and accurate bedside test to guide fluid management and to avoid fluid overload during early septic shock treatment. Moreover, PLR may also be particularly useful to assist various treatments that trigger fluid removal during the “de-resuscitation” phase of septic shock.

Conclusions

The passive leg raising maneuver in combination with real-time measurement of cardiac output changes is an easy-to-use, fast, relatively unbiased, and accurate bedside test to guide fluid management during septic shock.

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.

Clinical Factors Associated with Dose of Loop Diuretics After Pediatric Cardiac Surgery: Post Hoc Analysis

A post hoc analysis of a randomized controlled trial comparing the clinical effects of furosemide and ethacrynic acid was conducted. Infants undergoing cardiac surgery with cardiopulmonary bypass were included in order to explore which clinical factors are associated with diuretic dose in infants with congenital heart disease. Overall, 67 patients with median (interquartile range) age of 48 (13-139) days were enrolled. Median diuretic dose was 0.34 (0.25-0.4) mg/kg/h at the end of postoperative day (POD) 0 and it significantly decreased (p = 0.04) over the following PODs; during this period, the ratio between urine output and diuretic dose increased significantly (p = 0.04). Age (r -0.26, p = 0.02), weight (r -0.28, p = 0.01), cross-clamp time (r 0.27, p = 0.03), administration of ethacrynic acid (OR 0.01, p = 0.03), and, at the end of POD0, creatinine levels (r 0.3, p = 0.009), renal near-infrared spectroscopy saturation (-0.44, p = 0.008), whole-blood neutrophil gelatinase-associated lipocalin levels (r 0.30, p = 0.01), pH (r -0.26, p = 0.02), urinary volume (r -0.2755, p = 0.03), and fluid balance (r 0.2577, p = 0.0266) showed a significant association with diuretic dose. At multivariable logistic regression cross-clamp time (OR 1.007, p = 0.04), use of ethacrynic acid (OR 0.2, p = 0.01) and blood pH at the end of POD0 (OR 0.0001, p = 0.03) was independently associated with diuretic dose. Early resistance to loop diuretics continuous infusion is evident in post-cardiac surgery infants: Higher doses are administered to patients with lower urinary output. Independently associated variables with diuretic dose in our population appeared to be cross-clamping time, the administration of ethacrynic acid, and blood pH.