Fluid overload and acute kidney injury

Bioimpedance-Guided Fluid Removal in Continuous KRT: The VENUS Randomized Clinical Trial

Key Points

This study, the sole randomized trial of its kind, proposes guidelines for fluid balance management in continuous KRT (CKRT) patients using bioimpedance. Despite this, bioimpedance analysis–guided volume management did not influence the proportion of patients achieving estimated euvolemia at 7 days into CKRT. Further investigation is needed to assess whether bioimpedance analysis guidance can facilitate rapid fluid removal in the early phase of CKRT for patients with AKI.

Background

Ultrafiltration with continuous KRT (CKRT) can be used to manage fluid balance in critically ill patients with AKI. We aimed to assess whether bioimpedance analysis (BIA)–guided volume management was more efficacious than conventional management for achieving estimated euvolemia (e-euvolemia) in CKRT-treated patients.

Methods

In a multicenter randomized controlled trial from July 2017 to July 2020, the patients with AKI requiring CKRT were eligible if the weight at the start of CKRT had increased by ≥5% compared with the weight at the time of admission or total body water (TBW)/height (H)2 ≥13 L/m2. We randomly assigned 208 patients to the control (conventional fluid management; n =103) and intervention groups (BIA-guided fluid management; n =105). The primary outcome was the proportion of attaining e-euvolemia 7 days postrandomization. E-euvolemia was defined as the difference between TBW/H2 D7 and D0 was <−2.1 L/m2, or when TBW/H2 measured on D7 was <13 L/m2. The 28-, 60-, and 90-day mortality rate were secondary outcomes.

Results

The primary outcome occurred in 34 patients in the intervention group and 27 in the control group (47% versus 41%; P = 0.50). The mean value of TBW/H2 measured on D7 was the same at 13.9 L/m2 in both groups. The differences between TBW/H2 D7 and D0 were −1.13 L/m2 in the intervention group and −1.08 L/m2 in the control group (P = 0.84). Patients in the intervention group had a significantly higher proportion of reaching e-euvolemia on D1 than those in the control group (13% versus 4%, P = 0.02). Adverse events did not differ significantly between the groups.

Conclusions

BIA-guided volume management did not affect the proportion of reaching the e-euvolemia at 7 days of the start of CKRT.

Clinical Trial registry name and registration number:

ClinicalTrials.gov , ID: NCT03330626 (Registered on November 6, 2017; seven study participants were retrospectively registered; nonetheless, Institutional Review Board approval of each institution was completed before study participant registration).

Effect of cardiac function in patients with gastrointestinal cancer with or without acute kidney injury assessed using a non-invasive impedance cardiography: a case-control study

OBJECTIVES

This study aimed to analyze the possible causes of changes in cardiac function and investigate the feasibility of clinical assessment of gastrointestinal cancer in patients with or without acute kidney injury (AKI) assessed using a non-invasive impedance cardiography (ICG, Bioz. Cardio Dynamics, USA) to identify independent risk factors.

METHODS

Patients admitted to the Fourth Hospital of Hebei Medical University, China, between May 1, 2019, and February 15, 2022, were included in this study. A total of 51 patients with gastrointestinal cancer (31 men and 20 women, mean age 61.1 ± 10.9 years) with or without AKI were evaluated for ICG. A total of 19 patients underwent ultrasound cardiography (UCG) and ICG evaluations.

RESULT

There was a significant positive correlation between cardiac output (CO), cardiac index (CI), stroke volume (SV), left cardiac work index (LCWI), and ejection fraction (EF) measured using UCG and ICG. The relationship was observed between COICG and COUCG (r = 0.707, P = 0.001), CIICG and CIUCG (r = 0.718, P = 0.001), SVICG and SVUCG (r = 0.837, P < 0.001), and LCWIICG and EFUCG (r = 0.540, P = 0.017). Cardiac function parameters measured using ICG were statistically different between patients with gastrointestinal cancer with or without AKI (P ≤ 0.05). Multivariate analysis revealed that AKI independently affects cardiac function in patients with gastrointestinal cancer.

CONCLUSIONS

UCG and ICG methods are significantly associated with cardiac function in patients with or without AKI, and patients with gastrointestinal cancer with AKI are worse than those without AKI. AKI is an independent risk factor for cardiac function in patients with gastrointestinal cancer.

Urine Output Monitoring and Acute Kidney Injury in Non-mammalian Exotic Animal Critical Care

Acute kidney injury (AKI) is a sudden, severe decrease in kidney function which can occur in any species. There are various causes of AKI, some of which are seen in domestic species and some that are unique to birds, reptiles, and amphibians. These species present unique challenges with AKI management, such as differences in anatomy and physiology, intravenous and urinary catheterization, repeated blood sampling, and their tendency to present in advanced states of illness. This article will discuss AKI, diagnosis, treatment, and prognosis for non-mammalian exotic species.

Urine Output Monitoring and Acute Kidney Injury in Mammalian Exotic Animal Critical Care

Acute kidney injury (AKI) is a sudden, severe decrease in kidney function which can occur in any species. There are various causes of AKI, some of which are seen in domestic species and some that are unique to exotics. Exotic animals present unique challenges with AKI management such as differences in anatomy and physiology, intravenous and urinary catheterization, repeated blood sampling, and their tendency to present in advanced states of illness. This article will discuss AKI, diagnosis, treatment, and prognosis for exotic companion mammals. The following article will discuss the same in non-mammalian patients.

Role of a fluid-restrictive strategy in flap-surgery: A single center retrospective cohort study

In this study, we evaluated the outcomes of flap surgery and the incidence of acute kidney injury (AKI) in patients who underwent flap surgery using a fluid-restrictive strategy. We retrospectively reviewed the consecutively collected medical records of patients who underwent flap surgery using the fluid-restrictive strategy of our hospital. The patients were divided into 2 groups based on the period of flap surgery: 2011 to 2014 (initiation period of the fluid-restrictive strategy) and 2015 to 2020 (implementation period). Outcomes of flap surgery and the incidence of AKI were evaluated based on percentage changes in cumulative fluid balance to initial body weight (%FO) on post-operative day 7. A total of 140 patients were enrolled in the study; 50 (35.7%) underwent flap surgery in 2011 to 2014 and 90 (64.3%) in 2015 to 2020. In 2015 to 2020, the median %FO significantly decreased from 2.7 (interquartile range [IQR]: 0.8-7.1) to 0.1 (IQR: -2.2 to 3.4%, P < .001), whereas the success rate significantly increased from 53.3% to 70.5% (P = .048) compared to 2011 to 2014. The incidence of AKI remained unchanged. In multivariate analysis, the odds ratio for success was 2.759 (95% confidence interval: 1.140-6.679) in 2015 to 2020 compared to 2011 to 2014. After successfully implementing the fluid-restrictive strategy, the success rate of flap surgery significantly increased without any further increase in the incidence of AKI. Our experience could serve as a model for implementing a fluid-restrictive strategy in flap surgery.

A novel pump-free ultrafiltration rate modulation system for continuous renal replacement therapy applications

Purpose

Extracorporeal ultrafiltration is an attractive alternative to diuretics for removing excess plasma water in critically ill patients suffering from fluid overload. In continuous renal replacement therapy (CRRT), ultrafiltration occurs in isolated form (SCUF) or supplemented by replacement fluid infusion (CVVH) and the net fluid removal rate is controlled by peristaltic pumps. In this work, a pump-free solution for regulating the ultrafiltration rate in CRRT applications is presented.

Methods

The system consists of a motorized clamp on the ultrafiltration line, whose intermittent opening is modulated with a closed-loop control system based on monitoring of ultrafiltrate collected and any replacement fluid infused. The system was tested on two platforms for SCUF and CVVH, with “low-flux” and “high-flux” hemofilter, with various ultrafiltration setpoints and patient net weight loss targets.

Results

In all configurations the set ultrafiltration rate was achieved with a maximum error of 5% and the values recorded were kept within ± 100 ml/h with respect to the setpoint, as recommended by international standard IEC 60601-2-16. The net fluid removal trend was highly correlated with that expected (95%<R2<99%) and the weight loss target was reached in the expected time. For low ultrafiltration rates (60-150 ml/h) the system accuracy was better with the “low-flux” hemofilter.

Conclusion

The developed clamp system represents a valid alternative to state-of-the-art solutions with peristaltic pumps in terms of performance, with potential usability advantages. The compliance with safety requirements given by international standard IEC 60601-2-16 is a prerequisite for clinical use.

Association between fluid overload and mortality in newborns: a systematic review and meta-analysis

Fluid overload (FO) is associated with higher rates of mortality and morbidity in pediatric and adult populations. The aim of this systematic review and meta-analysis was to investigate the association between FO and mortality in critically ill neonates. Systematic search of Ovid MEDLINE, EMBASE, Cochrane Library, trial registries, and gray literature from inception to January 2021. We included all studies that examined neonates admitted to neonatal intensive care units and described FO and outcomes of interest. We identified 17 observational studies with a total of 4772 critically ill neonates who met the inclusion criteria. FO was associated with higher mortality (OR, 4.95 [95% CI, 2.26-10.87]), and survivors had a lower percentage of FO compared with nonsurvivors (WMD, - 4.33 [95% CI, - 8.34 to - 0.32]). Neonates who did not develop acute kidney injury (AKI) had lower FO compared with AKI patients (WMD, - 2.29 [95% CI, - 4.47 to - 0.10]). Neonates who did not require mechanical ventilation on postnatal day 7 had lower fluid balance (WMD, - 1.54 [95% CI, - 2.21 to - 0.88]). FO is associated with higher mortality, AKI, and need for mechanical ventilation in critically ill neonates in the intensive care unit. Strict control of fluid balance to prevent FO is essential. A higher resolution version of the Graphical abstract is available as Supplementary information.

Effect of furosemide on body composition and urinary proteins that mediate tubular sodium and sodium transport-A randomized controlled trial

Background

Furosemide inhibits the sodium potassium chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle and increases urinary water and sodium excretion. This study investigates the effect of furosemide on body composition estimated with multifrequency bioimpedance spectroscopy (BIS) technique and urinary proteins from NKCC2.

Methods

This study is a randomized, placebo‐controlled, crossover study where healthy subjects received either placebo or 40 mg furosemide on two separate occasions, where body composition with BIS, renal function, proteins from tubular proteins that mediate sodium and water transport, and plasma concentrations of vasoactive hormones were measured before and after intervention.

Results

We observed an expected increased diuresis with a subsequent reduction in bodyweight of (−1.51 ± 0.36 kg, p < .001) and extracellular water (ECW; −1.14 ± 0.23 L, p < .001) after furosemide. We found a positive correlation between the decrease in ECW and a decrease in bodyweight and a negative correlation between the decrease in ECW and the increase in urinary output. Intracellular water (ICW) increased (0.47 ± 0.28 L, p < .001). Urinary excretion of NKCC2 increased after furosemide and the increase in NKCC2 correlated with an increase in urine output and a decrease in ECW.

Conclusion

We found BIS can detect acute changes in body water content but the method may be limited to estimation of ECW. BIS demonstrated that furosemide increases ICW which might be explained by an extracellular sodium loss. Finally, urinary proteins from NKCC2 increases after furosemide with a good correlation with diuresis end the decrease in ECW.

Effect of different hydration doses on renal function in patients with primary osteoporosis treated with zoledronic acid: A hospital-based retrospective cohort study

The objective was to investigate the association of different hydration doses and its effect on renal function in patients with primary osteoporosis treated with zoledronic acid.The subjects with primary osteoporosis treated with zoledronic acid at the First Affiliated Hospital of Chongqing Medical University, China, from January 2015 to December 2018 were included in this study. The subjects were classified according to different hydration doses. Renal function indexes before and after treatment were collected and adverse reactions recorded to analyze the changes in renal function associated with different hydration doses.The choice of the hydration dose treated with zoledronic acid deserves attention. The lower hydration dose is, the greater impact on renal function can be caused.

Effect of fluid balance control in critically ill patients: Design of the stepped wedge trial POINCARE-2

A high number of recent studies have shown that a positive fluid balance is independently associated with impaired prognosis in specific populations of patients hospitalized in intensive care unit (ICU): acute kidney injury, acute respiratory distress syndrome (ARDS), sepsis, high risk surgery. However, to date, there is no evidence that control of fluid overload reduces mortality in critically ill patients. The main objective is to assess the efficacy of a strategy limiting fluid overload on mortality in unselected critically ill patients hospitalized in ICU. We hypothesized that a strategy based on a weight-driven recommendation of restricted fluid intake, diuretics, and ultrafiltration initiated from 48 h up to 14 days after admission in critically ill patients would reduce all-cause mortality as compared to usual care. We use a stepped wedge cluster randomized controlled trial combined with a quasi-experimental (before-and-after) study. Patients under mechanical ventilation, admitted since >48 h and < 72 h in ICU, and with no discharge planned for the next 24 h are eligible. A total of 1440 patients are expected to be enrolled in 12 ICUs. Sociodemographic and clinical data are collected at inclusion, and outcomes are collected during the follow-up. Primary outcome is all-cause mortality at 60 days after admission. Secondary outcomes are patients weight differences between admission and day7 (or day 14), 28-day, in-hospital, and 1-year mortality, end-organ damages, and unintended harmful events. Analyses will be held in intention-to-treat. If POINCARE-2 strategy proves effective, then guidelines on fluid balance control might be extended to all critically ill patients. Trial registration: ClinicalTrials.govNCT02765009.

Acute kidney injury in cancer patients and impedance cardiography-assisted renal replacement therapy: Experience from the onconephrology unit of a Chinese tertiary hospital

Acute kidney injury (AKI) in cancer patients may disrupt anticarcinogenic treatment and greatly increase associated mortality rates. The present study reported on the management of cancer patients with AKI and, from the nephrologic viewpoint, on the significance of fine volume control during the continuous renal replacement therapy (CRRT). The records of 117 cancer patients with AKI treated over three years were reviewed and their data were compared with those of 120 healthy controls. AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria with serum creatinine levels determined on initial admission and for the diagnosis of AKI. CRRT with concomitant impedance cardiography (ICG) monitoring was performed in 79 patients. On average, AKI manifested as a 1.68±0.38-fold increase in serum creatinine within 10.2±5.7 days. The causes of AKI were diverse, with the major ones being nephrotoxic agents, hypotension and obstructive nephropathy. Renal biopsy confirmed two cases of thrombotic microangiopathy, due to the use of interfon-α and sunitinib malate, respectively, and a third case of cast nephropathy caused by immunoglobulin D multiple myeloma. The patients were generally marantic and had compromised cardiac function compared with the healthy controls. The CRRT prescription was discriminatingly optimized by the ICG parameters effecting discreet fluid balance, as the thoracic fluid content was significantly correlated with the ultrafiltration rate. By considering the causative mechanisms and applying subtle ICG-assisted volume control, the present study may thus help to improve the safety and efficacy of CRRT in cancer patients with AKI. In addition, it provided information to bring advances in onconephrology, a novel nephrological subspecialty field.

Acute Kidney Injury in the Critically Ill

Acute kidney injury (AKI) occurs frequently in the surgical intensive care unit and results in significant morbidity and mortality. AKI needs to be identified early and underlying causes treated or eliminated. Sepsis, major surgery such as coronary artery bypass, and hypovolemia are the most common causes and patients with underlying comorbidities have increased susceptibility. Treatment should begin by ensuring that patients are adequately resuscitated and all contributing causes are replaced or eliminated. After stabilization of hemodynamic status and elimination of contributing causes, treatment becomes largely supportive and may require the use of a renal replacement therapy.

Fluid accumulation threshold measured by acute body weight change after admission in general surgical intensive care units: how much should be concerning?

Background

The objective of this study (ClinicalTrials.gov: NCT01351506) was to identify the threshold level of fluid accumulation measured by acute body weight (BW) change during the first week in a general surgical intensive care unit (ICU), which is associated with ICU mortality and other adverse outcomes.

Methods

Four hundred sixty-five patients were prospectively followed for a 28-day period. The maximum BW change threshold during the first week was evaluated by the maximum percentage change in BW from the ICU admission weight (Max%ΔBW). Daily screening of adverse events in the ICU were recorded. The cutoff point of Max%ΔBW on ICU mortality was defined by considering the area under the receiver operating characteristic (ROC) curve, intersection of the sensitivity and specificity, and the Youden Index. Univariable and multivariable regression analyses were used to demonstrate the associations. Statistical significance was defined as P<0.05.

Results

The appropriate cutoff value of Max%ΔBW threshold was 5%. Regarding the multivariable regression model, in overall patients, the occurrence of the following adverse events (expressed as adjusted odds ratio [95% confidence interval]) were significantly associated with a Max%ΔBW of >5%: ICU mortality (2.38 [1.25–4.54]) (P=0.008), ICU mortality in patients without renal replacement therapy (RRT) (2.47 [1.21–5.06]) (P=0.013), reintubation within 72 hours (2.51 [1.04–6.00]) (P=0.039), RRT requirement (2.67 [1.13–6.33]) (P=0.026), and delirium (1.97 [1.08–3.57]) (P=0.025). Regarding the postoperative subgroup, a Max%ΔBW value of more than 5% was significantly associated with: ICU mortality (3.87 [1.38–10.85]) (P=0.010), ICU mortality in patients without RRT (6.32 [1.85–21.64]) (P=0.003), reintubation within 72 hours (4.44 [1.30–15.16]) (P=0.017), and vasopressor requirement (2.04 [1.04–4.01]) (P=0.037).

Conclusion

Fluid accumulation, measured as acute BW change of more than the threshold of 5% during the first week of ICU admission, is associated with adverse outcomes of higher ICU mortality, especially in the patients without RRT, with reintubation within 72 hours, with RRT requirement, with vasopressor requirement, and with delirium. Some of these effects were higher in postoperative patients. This threshold value might be an indicator for caution during fluid management in surgical ICU.

Rhabdomyolysis, compartment syndrome and thermal injury

Rhabdomyolysis (RML) after electrical burns and crush injuries is a well-known clinical entity, but its occurrence following thermal injury has not gained so much attention. Capillary leak syndrome and following polycompartmental syndrome are devastating end results of major thermal injuries. In the current review, polycompartment syndrome within the clinical picture of systemic oedema and its relationship to RML is discussed along with its management and prevention.

Renal replacement therapy in critically ill patients with acute kidney injury--when to start

BACKGROUND

Despite the frequent use of renal replacement therapy (RRT) for patients with acute kidney injury (AKI) in the intensive care unit (ICU), there is no accepted consensus on the optimal indications and timing.

METHODS

The aim of this paper is to identify optimal triggers for RRT in critically ill patients with AKI.

RESULTS

We examined data from 2 randomized controlled trials, 2 prospective studies and 13 retrospective trials and found large variation in the different parameters and cut-offs for initiation of RRT. No single biochemical parameter was adequate to define the optimal indication and time to commence RRT. Degree of fluid overload, oliguria and associated non-renal organ failure appeared to be more appropriate parameters for initiation of RRT. We propose a clinical algorithm based on regular assessment of the patient's condition and trends in these parameters. It is intended to aid the process of deciding when to start RRT in critically ill adult patients with AKI.

CONCLUSION

Available evidence suggests that the decision when to start RRT in critically ill patients with AKI should be based on trends in the patient's severity of illness, presence of oliguria and fluid overload and associated non-renal organ failure rather than specific serum creatinine or urea values.

Fluid overload at initiation of renal replacement therapy is associated with lack of renal recovery in patients with acute kidney injury

BACKGROUND

Patients with acute kidney injury (AKI) requiring initiation of renal replacement therapy (RRT) have poor short- and long-term outcomes, including the development of dialysis dependence. Currently, little is known about what factors may predict renal recovery in this population.

METHODS

We conducted a single-center, retrospective analysis of 170 hospitalized adult patients with AKI attributed to acute tubular necrosis who required inpatient initiation of RRT. Data collection included patient characteristics, laboratory data, details of hospital course and degree of fluid overload at RRT initiation. The primary outcome was recovery of renal function to dialysis independence.

RESULTS

Within 1 year of RRT initiation, 35.9% (61/170) of patients reached the primary end point of renal recovery. The median (interquartile range) duration of RRT was 11 (3-33) days and 83.6% (51/61) recovered prior to hospital discharge. Recovering patients had significantly less fluid overload at the time of RRT initiation compared to non-recovering patients (3.5 versus 9.3%, P = 0.004). In multivariate Cox proportional hazard regression analysis, a rise in percent fluid overload at dialysis initiation remained a significant negative predictor of renal recovery (hazard ratio 0.97, 95% confidence interval 0.95-1.00, P = 0.024).

CONCLUSIONS

In patients with AKI, a higher degree of fluid overload at RRT initiation predicts worse renal recovery at 1 year. Clinical trials are needed to determine whether interventions targeting fluid overload may improve patient and renal outcomes.