Cumulative fluid accumulation is associated with the development of acute kidney injury and non-recovery of renal function: a retrospective analysis

How a positive fluid balance develops in acute kidney injury: A binational, observational study

PURPOSE

A positive fluid balance (FB) is associated with harm in intensive care unit (ICU) patients with acute kidney injury (AKI). We aimed to understand how a positive balance develops in such patients.

METHODS

Multinational, retrospective cohort study of critically ill patients with AKI not requiring renal replacement therapy.

RESULTS

AKI occurred at a median of two days after admission in 7894 (17.3%) patients. Cumulative FB became progressively positive, peaking on day three despite only 848 (10.7%) patients receiving fluid resuscitation in the ICU. In those three days, persistent crystalloid use (median:60.0 mL/h; IQR 28.9-89.2), nutritional intake (median:18.2 mL/h; IQR 0.0-45.9) and limited urine output (UO) (median:70.8 mL/h; IQR 49.0-96.7) contributed to a positive FB. Although UO increased each day, it failed to match input, with only 797 (10.1%) patients receiving diuretics in ICU. After adjustment, a positive FB four days after AKI diagnosis was associated with an increased risk of hospital mortality (OR 1.12;95% confidence intervals 1.05-1.19;p-value <0.001).

CONCLUSION

Among ICU patients with AKI, cumulative FB increased after diagnosis and was associated with an increased risk of mortality. Continued crystalloid administration, increased nutritional intake, limited UO, and minimal use of diuretics all contributed to positive FB.

KEY POINTS

Question How does a positive fluid balance develop in critically ill patients with acute kidney injury? Findings Cumulative FB increased after AKI diagnosis and was secondary to persistent crystalloid fluid administration, increasing nutritional fluid intake, and insufficient urine output. Despite the absence of resuscitation fluid and an increasing cumulative FB, there was persistently low diuretics use, ongoing crystalloid use, and a progressive escalation of nutritional fluid therapy. Meaning Current management results in fluid accumulation after diagnosis of AKI, as a result of ongoing crystalloid administration, increasing nutritional fluid, limited urine output and minimal diuretic use.

Impact of renal recovery on in-hospital and post-discharge mortality

OBJECTIVE

To verify the impact of renal recovery on mortality in non-critically ill patients with acute kidney injury.

METHOD

A prospective cohort study was carried out in a public hospital in the Federal District with patients with acute kidney injury admitted to a non-critical care unit. Renal recovery was assessed based on the ratio of serum creatinine to baseline creatinine and the patient was followed up for 6 months. Mortality was assessed during hospitalization and after discharge.

RESULTS

Of the 90 patients with hospital-acquired kidney injury, renal recovery was identified in 34.1% to 75% of cases, depending on the time of assessment, considering a follow-up period of up to 6 months. Recovery of renal function during follow-up had an impact on in-hospital mortality [95% CI 0.15 (0.003 - 0.73; p = 0019).

CONCLUSION

Recovery of renal function has been shown to be a protective factor for mortality in patients admitted to the non-critical care unit. Early identification of kidney damage and monitoring of physiological and laboratory variables proved to be fundamental in identifying the severity of the disease and reducing mortality.

The "CHEOPS" bundle for the management of Left Ventricular Diastolic Dysfunction in critically ill patients: an experts' opinion

The impact of left ventricular (LV) diastolic dysfunction (DD) on the outcome of patients with heart failure was established over three decades ago. Nevertheless, the relevance of LVDD for critically ill patients admitted to the intensive care unit has seen growing interest recently, and LVDD is associated with poor prognosis. Whilst an assessment of LV diastolic function is desirable in critically ill patients, treatment options for LVDD are very limited, and pharmacological possibilities to rapidly optimize diastolic function have not been found yet. Hence, a proactive approach might have a substantial role in improving the outcomes of these patients. Recalling historical Egyptian parallelism suggesting that Doppler echocardiography has been the "Rosetta stone" to decipher the study of LV diastolic function, we developed a potentially useful acronym for physicians at the bedside to optimize the management of critically ill patients with LVDD with the application of the bundle. We summarized the bundle under the acronym of the famous ancient Egyptian pharaoh CHEOPS: Chest Ultrasound, combining information from echocardiography and lung ultrasound; HEmodynamics assessment, with careful evaluation of heart rate and rhythm, as well as afterload and vasoactive drugs; OPtimization of mechanical ventilation and pulmonary circulation, considering the effects of positive end-expiratory pressure on both right and left heart function; Stabilization, with cautious fluid administration and prompt fluid removal whenever judged safe and valuable. Notably, the CHEOPS bundle represents experts' opinion and are not targeted at the initial resuscitation phase but rather for the optimization and subsequent period of critical illness.

Current management of fluid balance in critically ill patients with acute kidney injury: A scoping review

Objective

The overall objective of this scoping review is to assess the extent of the literature related to the fluid management of critically ill patients with acute kidney injury (AKI).

Introduction

AKI is common in critically ill patients where fluid therapy is a mainstay of treatment. An association between fluid balance (FB) and adverse patient-centred outcomes in critically ill patients with AKI regardless of severity has been demonstrated. The evidence for the prospective intervention of FB and its impact on outcomes is unknown.

Inclusion criteria

All studies investigating FB in patients with AKI admitted to an intensive care unit were included. Literature not related to FB in the critically ill patient with AKI population was excluded.

Methods

We searched MEDLINE, EMBASE, and CINAHL from January 1st, 2012, onwards. We included primary research studies, experimental and observational, recruiting adult participants admitted to an intensive care unit who had an AKI. We extracted data on study and patient characteristics, as well as FB, renal-based outcomes, and patient-centred outcomes. Two reviewers independently screened citations for eligible studies and performed data extraction.

Results

Of the 13,767 studies reviewed, 22 met the inclusion criteria. Two studies examined manipulation of fluid input, 18 studies assessed enhancing fluid removal, and two studies applied a restrictive fluid protocol. Sixteen studies examined patients receiving renal replacement therapy, five studies included non-renal replacement therapy patients, and one study included both. Current evidence is broad with varied approaches to managing fluid input and fluid removal. The studies did not demonstrate a consensus approach for any aspect of the fluid management of critically ill patients. There was a limited application of a restrictive fluid protocol with no conclusions possible.

Conclusions

The current body of evidence for the management of FB in critically ill patients with AKI is limited in nature. The current quality of evidence is unable to guide current clinical practice. The key outcome of this review is to highlight areas for future research.

Association between intrarenal venous flow from Doppler ultrasonography and acute kidney injury in patients with sepsis in critical care: a prospective, exploratory observational study

BACKGROUND

Intrarenal venous flow (IRVF) patterns assessed using Doppler renal ultrasonography are real-time bedside visualizations of renal vein hemodynamics. Although this technique has the potential to detect renal congestion during sepsis resuscitation, there have been few studies on this method. We aimed to examine the relationship between IRVF patterns, clinical parameters, and outcomes in critically ill adult patients with sepsis. We hypothesized that discontinuous IRVF was associated with elevated central venous pressure (CVP) and subsequent acute kidney injury (AKI) or death.

METHODS

We conducted a prospective observational study in two tertiary-care hospitals, enrolling adult patients with sepsis who stayed in the intensive care unit for at least 24 h, had central venous catheters placed, and received invasive mechanical ventilation. Renal ultrasonography was performed at a single time point at the bedside after sepsis resuscitation, and IRVF patterns (discontinuous vs. continuous) were confirmed by a blinded assessor. The primary outcome was CVP obtained at the time of renal ultrasonography. We also repeatedly assessed a composite of Kidney Disease Improving Global Outcomes of Stage 3 AKI or death over the course of a week as a secondary outcome. The association of IRVF patterns with CVP was examined using Student's t-test (primary analysis) and that with composite outcomes was assessed using a generalized estimating equation analysis, to account for intra-individual correlations. A sample size of 32 was set in order to detect a 5-mmHg difference in CVP between IRVF patterns.

RESULTS

Of the 38 patients who met the eligibility criteria, 22 (57.9%) showed discontinuous IRVF patterns that suggested blunted renal venous flow. IRVF patterns were not associated with CVP (discontinuous flow group: mean 9.24 cm H2O [standard deviation: 3.19], continuous flow group: 10.65 cm H2O [standard deviation: 2.53], p = 0.154). By contrast, the composite outcome incidence was significantly higher in the discontinuous IRVF pattern group (odds ratio: 9.67; 95% confidence interval: 2.13-44.03, p = 0.003).

CONCLUSIONS

IRVF patterns were not associated with CVP but were associated with subsequent AKI in critically ill adult patients with sepsis. IRVF may be useful for capturing renal congestion at the bedside that is related to clinical patient outcomes.

Economic Analysis of Renal Replacement Therapy Modality in Acute Kidney Injury Patients With Fluid Overload

Acute kidney injury (AKI) and fluid overload (FO) are among the top reasons to initiate intermittent hemodialysis (IHD) or continuous renal replacement therapy (CRRT). Prior research suggests CRRT provides more precise volume control, but whether CRRT is cost-effective remains unclear. We assessed the cost-effectiveness of CRRT for volume control compared with IHD from a U.S. healthcare payer perspective.

DESIGN

Decision analytical model comparing health outcomes and healthcare costs of CRRT versus IHD initiation for AKI patients with FO. The model had an inpatient phase (over 90-d) followed by post-discharge phase (over lifetime). The 90-day phase had three health states: FO, fluid control, and death. After 90 days, surviving patients entered the lifetime phase with four health states: dialysis independent (DI), dialysis dependent (DD), renal transplantation, and death. Model parameters were informed by current literature. Sensitivity analyses were performed to evaluate results robustness to parametric uncertainty.

SETTING

ICU.

PATIENTS OR SUBJECTS

AKI patients with FO.

INTERVENTIONS

IHD or CRRT.

MEASUREMENTS AND MAIN RESULTS

The 90-day horizon revealed better outcomes for patients initiated on CRRT (survival: CRRT 59.2% vs IHD 57.5% and DD rate among survivors: CRRT 5.5% vs IHD 6.9%). Healthcare cost was 2.7% (+$2,836) higher for CRRT. Over lifetime, initial CRRT was associated with +0.313 life years (LYs) and +0.187 quality-adjusted life years (QALYs) compared with initial IHD. Even though important savings were observed for initial CRRT with a lower rate of DD among survivors (-$13,437), it did not fully offset the incremental cost of CRRT (+$1,956) and DI survival (+$12,830). The incremental cost-per-QALY gained with CRRT over IRRT was +$10,429/QALY. Results were robust to sensitivity analyses.

CONCLUSIONS

Our analysis provides an economic rationale for CRRT as the initial modality of choice in AKI patients with FO who require renal replacement therapy. Our finding needs to be confirmed in future research.

Independent risk factors of acute kidney injury among patients receiving extracorporeal membrane oxygenation

OBJECTIVE

Acute kidney injury (AKI) is one of the most frequent complications in patients treated with extracorporeal membrane oxygenation (ECMO) support. The aim of this study was to investigate the risk factors of AKI in patients undergoing ECMO support.

METHODS

We performed a retrospective cohort study which included 84 patients treated with ECMO support at intensive care unit in the People's Hospital of Guangxi Zhuang Autonomous Region from June 2019 to December 2020. AKI was defined as per the standard definition proposed by the Kidney Disease Improving Global Outcome (KDIGO). Independent risk factors for AKI were evaluated through multivariable logistic regression analysis with stepwise backward approach.

RESULTS

Among the 84 adult patients, 53.6% presented AKI within 48 h after initiation of ECMO support. Three independent risk factors of AKI were identified. The final logistic regression model included: left ventricular ejection fraction (LVEF) before ECMO initiation (OR, 0.80; 95% CI, 0.70-0.90), sequential organ failure assessment (SOFA) score before ECMO initiation (OR, 1.41; 95% CI, 1.16-1.71), and serum lactate at 24 h after ECMO initiation (OR, 1.27; 95% CI, 1.09-1.47). The area under receiver operating characteristics of the model was 0.879.

CONCLUSION

Severity of underlying disease, cardiac dysfunction before ECMO initiation and the blood lactate level at 24 h after ECMO initiation were independent risk factors of AKI in patients who received ECMO support.

Diuretics and Ultrafiltration in Heart Failure

Fluid overload is a risk factor for increased morbidity and mortality, especially in patients with heart disease. The treatment options are limited to diuretics and mechanical fluid removal using ultrafiltration or renal replacement therapy. This paper provides an overview of the challenges of managing fluid overload, outlines the risks and benefits of different pharmacological options and extracorporeal techniques, and provides guidance for clinical practice.

Predicting the risk factors of diabetic ketoacidosis-associated acute kidney injury: A machine learning approach using XGBoost

Objective

The purpose of this study was to develop and validate a predictive model based on a machine learning (ML) approach to identify patients with DKA at increased risk of AKI within 1 week of hospitalization in the intensive care unit (ICU).

Methods

Patients diagnosed with DKA from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database according to the International Classification of Diseases (ICD)-9/10 code were included. The patient's medical history is extracted, along with data on their demographics, vital signs, clinical characteristics, laboratory results, and therapeutic measures. The best-performing model is chosen by contrasting the 8 Ml models. The area under the receiver operating characteristic curve (AUC), sensitivity, accuracy, and specificity were calculated to select the best-performing ML model.

Results

The final study enrolled 1,322 patients with DKA in total, randomly split into training (1,124, 85%) and validation sets (198, 15%). 497 (37.5%) of them experienced AKI within a week of being admitted to the ICU. The eXtreme Gradient Boosting (XGBoost) model performed best of the 8 Ml models, and the AUC of the training and validation sets were 0.835 and 0.800, respectively. According to the result of feature importance, the top 5 main features contributing to the XGBoost model were blood urea nitrogen (BUN), urine output, weight, age, and platelet count (PLT).

Conclusion

An ML-based individual prediction model for DKA-associated AKI (DKA-AKI) was developed and validated. The model performs robustly, identifies high-risk patients early, can assist in clinical decision-making, and can improve the prognosis of DKA patients to some extent.

Changing epidemiology of acute kidney injury in critically ill patients with COVID-19: a prospective cohort

BACKGROUND

Acute kidney injury (AKI) is common in critically ill patients with coronavirus disease-19 (COVID-19). We aimed to explore the changes in AKI epidemiology between the first and the second COVID wave in the United Kingdom (UK).

METHODS

This was an observational study of critically ill adult patients with COVID-19 in an expanded tertiary care intensive care unit (ICU) in London, UK. Baseline characteristics, organ support, COVID-19 treatments, and patient and kidney outcomes up to 90 days after discharge from hospital were compared.

RESULTS

A total of 772 patients were included in the final analysis (68% male, mean age 56 ± 13.6). Compared with wave 1, patients in wave 2 were older, had higher body mass index and clinical frailty score, but lower baseline serum creatinine and C-reactive protein (CRP). The proportion of patients receiving invasive mechanical ventilation (MV) on ICU admission was lower in wave 2 (61% vs 80%; p < 0.001). AKI incidence within 14 days of ICU admission was 76% in wave 1 and 51% in wave 2 (p < 0.001); in wave 1, 32% received KRT compared with 13% in wave 2 (p < 0.001). Patients in wave 2 had significantly lower daily cumulative fluid balance (FB) than in wave 1. Fewer patients were dialysis dependent at 90 days in wave 2 (1% vs. 4%; p < 0.001).

CONCLUSIONS

In critically ill adult patients admitted to ICU with COVID-19, the risk of AKI and receipt of KRT significantly declined in the second wave. The trend was associated with less MV, lower PEEP and lower cumulative FB.

TRIAL REGISTRATION

NCT04445259.

Acute kidney injury-associated delirium: a review of clinical and pathophysiological mechanisms

Acute kidney injury is a known clinical risk factor for delirium, an acute cognitive dysfunction that is commonly encountered in the critically ill population. In this comprehensive review of clinical and basic research studies, we detail the epidemiology, clinical implications, pathogenesis, and management strategies of patients with acute kidney injury-associated delirium. Specifically addressed are the pathological roles of endogenous toxin or drug accumulation, acute kidney injury-mediated neuroinflammation, and acute kidney injury-associated volume overload as discrete potential biological mechanisms of the condition. The optimization of clinical contributors and normalization of renal function are reviewed as pragmatic management strategies in addition to potential and emerging therapeutic approaches.

Fluid accumulation and major adverse kidney events in sepsis: a multicenter observational study

Background

Whether early fluid accumulation is a risk factor for adverse renal outcomes in septic intensive care unit (ICU) patients remains uncertain. We assessed the association between cumulative fluid balance and major adverse kidney events within 30 days (MAKE30), a composite of death, dialysis, or sustained renal dysfunction, in such patients.

Methods

We performed a multicenter, retrospective observational study in 1834 septic patients admitted to five ICUs in three hospitals in Stockholm, Sweden. We used logistic regression analysis to assess the association between cumulative fluid balance during the first two days in ICU and subsequent risk of MAKE30, adjusted for demographic factors, comorbidities, baseline creatinine, illness severity variables, haemodynamic characteristics, chloride exposure and nephrotoxic drug exposure. We assessed the strength of significant exposure variables using a relative importance analysis.

Results

Overall, 519 (28.3%) patients developed MAKE30. Median (IQR) cumulative fluid balance was 5.3 (2.8–8.1) l in the MAKE30 group and 4.1 (1.9–6.8) l in the no MAKE30 group, with non-resuscitation fluids contributing to approximately half of total fluid input in each group. The adjusted odds ratio for MAKE30 was 1.05 (95% CI 1.02–1.09) per litre cumulative fluid balance. On relative importance analysis, the strongest factors regarding MAKE30 were, in decreasing order, baseline creatinine, cumulative fluid balance, and age. In the secondary outcome analysis, the adjusted odds ratio for dialysis or sustained renal dysfunction was 1.06 (95% CI 1.01–1.11) per litre cumulative fluid balance. On separate sensitivity analyses, lower urine output and early acute kidney injury, respectively, were independently associated with MAKE30, whereas higher fluid input was not.

Conclusions

In ICU patients with sepsis, a higher cumulative fluid balance after 2 days in ICU was associated with subsequent development of major adverse kidney events within 30 days, including death, renal replacement requirement, or persistent renal dysfunction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01040-6.

Feasibility of conservative fluid administration and deresuscitation compared with usual care in critical illness: the Role of Active Deresuscitation After Resuscitation-2 (RADAR-2) randomised clinical trial

PURPOSE

Fluid overload is common in critical illness and is associated with mortality. This study investigated the feasibility of a randomised trial comparing conservative fluid administration and deresuscitation (active removal of accumulated fluid using diuretics or ultrafiltration) with usual care in critical illness.

METHODS

Open-label, parallel-group, allocation-concealed randomised clinical feasibility trial. Mechanically ventilated adult patients expected to require critical care beyond the next calendar day were enrolled between 24 and 48 h following admission to the intensive care unit (ICU). Patients were randomised to either a 2-stage fluid strategy comprising conservative fluid administration and, if fluid overload was present, active deresuscitation, or usual care. The primary endpoint was fluid balance in the 24 h up to the start of study day 3. Secondary endpoints included cumulative fluid balance, mortality, and duration of mechanical ventilation.

RESULTS

One hundred and eighty patients were randomised. After withdrawal of 1 patient, 89 patients assigned to the intervention were compared with 90 patients assigned to the usual care group. The mean plus standard deviation (SD) 24-h fluid balance up to study day 3 was lower in the intervention group (- 840 ± 1746 mL) than the usual care group (+ 130 ± 1401 mL; P < 0.01). Cumulative fluid balance was lower in the intervention group at days 3 and 5. Overall, clinical outcomes did not differ significantly between the two groups, although the point estimate for 30-day mortality favoured the usual care group [intervention arm: 19 of 90 (21.6%) versus usual care: 14 of 89 (15.6%), P = 0.32]. Baseline imbalances between groups and lack of statistical power limit interpretation of clinical outcomes.

CONCLUSIONS

A strategy of conservative fluid administration and active deresuscitation is feasible, reduces fluid balance compared with usual care, and may cause benefit or harm. In view of wide variations in contemporary clinical practice, large, adequately powered trials investigating the clinical effectiveness of conservative fluid strategies in critically ill patients are warranted.

Perioperative renal protection

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a common but underestimated syndrome in the perioperative setting. AKI can be induced by different causes and is associated with increased morbidity and mortality. Unfortunately, no specific treatment options are available at the moment.

RECENT FINDINGS

AKI is now understood as being a continuum ranging from normal kidney function over AKI and acute kidney disease to ultimately chronic kidney disease. The KDIGO organization recommend in 2012 implementation of preventive bundles in patients at high risk for AKI. In the perioperative setting, relevant measures include hemodynamic optimization, with careful consideration of blood pressure targets, adequate fluid therapy to maintain organ perfusion and avoidance of hyperglycaemia. These measures are most effective if patients at risk are identified as soon as possible and measures are implemented accordingly. Although current point of care functional biomarkers can detect patients at risk earlier than the established damage biomarkers, some components of the preventive bundle are still under investigation.

SUMMARY

Good evidence exists for the use of biomarkers to identify individual patients at risk for AKI and for the implementation of haemodynamic optimization, abdication of nephrotoxins, adequate fluid administration using balanced crystalloid solutions and glycaemic control. The data for using colloids or the degree of nephrotoxicity of contrast media still remain inconclusive.

[Perioperative management of the brain-dead organ donor : Anesthesia between ethics and evidence]

Hintergrund

Die Anzahl postmortal gespendeter Organe ist in Deutschland weit geringer als der Bedarf. Dies unterstreicht die Wichtigkeit einer optimalen Versorgung während des gesamten Prozesses der Organspende.

Fragestellung

Es existieren internationale Leitlinien und nationale Empfehlungen zu intensivmedizinischen organprotektiven Maßnahmen beim Organspender. Für das anästhesiologische Management fehlen evidenzbasierte Empfehlungen. Ziel dieser Übersichtsarbeit ist es, anhand der vorhandenen Evidenz die pathophysiologischen Veränderungen des irreversiblen Hirnfunktionsausfalls zu rekapitulieren und sich kritisch mit den empfohlenen Behandlungsstrategien und therapeutischen Zielgrößen auseinanderzusetzen. Auch auf ethische Aspekte der Betreuung des postmortalen Organspenders wird eingegangen.

Methode

Diese Übersichtsarbeit basiert auf einer selektiven Literaturrecherche in PubMed (Suchwörter: „brain dead donor“, „organ procurement“, „organ protective therapy“, „donor preconditioning“, „perioperative donor management“, „ethical considerations of brain dead donor“). Internationale Leitlinien und nationale Empfehlungen wurden besonders berücksichtigt.

Ergebnisse

Insgesamt ist die Evidenz für optimale intensivmedizinische und perioperative organprotektive Maßnahmen beim postmortalen Organspender sehr gering. Nationale und internationale Empfehlungen zu Zielwerten und medikamentösen Behandlungsstrategien unterscheiden sich teilweise erheblich: kontrollierte randomisierte Studien fehlen. Der Stellenwert einer Narkose zur Explantation bleibt sowohl unter pathophysiologischen Gesichtspunkten als auch aus ethischer Sicht ungeklärt.

Schlussfolgerungen

Die Kenntnisse über die pathophysiologischen Prozesse im Rahmen des irreversiblen Hirnfunktionsausfalls und die organprotektiven Maßnahmen sind ebenso Grundvoraussetzung wie die ethische Auseinandersetzung mit dem Thema postmortale Organspende. Nur dann kann das Behandlungsteam in dieser herausfordernden Situation sowohl dem Organempfänger als auch dem Organspender und seinen Angehörigen gerecht werden.

Early-Phase Urine Output and Severe-Stage Progression of Oliguric Acute Kidney Injury in Critical Care

Background: The relationship between urine output (UO) and severe-stage progression in the early phase of acute kidney injury (AKI) remains unclear. This study aimed to investigate the relationship between early-phase UO^6−12h [UO within 6 h after diagnosis of stage 1 AKI by Kidney Disease: Improving Global Outcomes (KDIGO) UO criteria] and severe-stage progression of AKI and to identify a reference value of early-phase UO^6−12h for guiding initial therapy in critical care.

Methods: Adult patients with UO < 0.5 ml/kg/h for the first 6 h after intensive care unit (ICU) admission (meeting stage 1 AKI by UO) and UO^6−12h ≥ 0.5 ml/kg/h were identified from the Medical Information Mart for Intensive Care (MIMIC) III database. The primary outcome was progression to stage 2/3 AKI by UO. After other variables were adjusted through multivariate analysis, generalized additive model (GAM) was used to visualize the relationship between early-phase UO^6−12h and progression to stage 2/3 AKI by UO. A two-piecewise linear regression model was employed to identify the inflection point of early-phase UO^6−12h above which progression risk significantly leveled off. Sensitivity and subgroup analyses were performed to assess the robustness of our findings.

Results: Of 2,984 individuals, 1,870 (62.7%) with KDIGO stage 1 UO criteria progressed to stage 2/3 AKI. In the multivariate analysis, early-phase UO^6−12h showed a significant association with progression to stage 2/3 AKI by UO (odds ratio, 0.40; 95% confidence interval, 0.34–0.46; p < 0.001). There was a non-linear relationship between early-phase UO^6−12h and progression of AKI. Early-phase UO^6−12h of 1.1 ml/kg/h was identified as the inflection point, above which progression risk significantly leveled off (p = 0.780). Patients with early-phase UO^6−12h ≥ 1.1 ml/kg/h had significantly shorter length of ICU stay (3.82 vs. 4.17 days, p < 0.001) and hospital stay (9.28 vs. 10.43 days, p < 0.001) and lower 30-day mortality (11.05 vs. 18.42%, p < 0.001). The robustness of our findings was confirmed by sensitivity and subgroup analyses.

Conclusions: Among early-stage AKI patients in critical care, there was a non-linear relationship between early-phase UO^6−12h and progression of AKI. Early-phase UO^6−12h of 1.1 ml/kg/h was the inflection point above which progression risk significantly leveled off.

Lung Ultrasound-Guided Fluid Management versus Standard Care in Surgical ICU Patients: A Randomised Controlled Trial

The value of lung ultrasound (LU) in assessing extravascular lung water (EVLW) was demonstrated by comparing LU with gold-standard methods for EVLW assessment. However, few studies have analysed the value of B-Line score (BLS) in guiding fluid management during critical illness. The purpose of this trial was to evaluate if a BLS-guided fluid management strategy could improve fluid balance and short-term mortality in surgical intensive care unit (ICU) patients. We conducted a randomised, controlled trial within the ICUs of two university hospitals. Critically ill patients were randomised upon ICU admission in a 1:1 ratio to BLS-guided fluid management (active group) or standard care (control group). In the active group, BLS was monitored daily until ICU discharge or day 28 (whichever came first). On the basis of BLS, different targets for daily fluid balance were set with the aim of avoiding or correcting moderate/severe EVLW increase. The primary outcome was 28-day mortality. Over 24 months, 166 ICU patients were enrolled in the trial and included in the final analysis. Trial results showed that daily BLS monitoring did not lead to a different cumulative fluid balance in surgical ICU patients as compared to standard care. Consecutively, no difference in 28-day mortality between groups was found (10.5% vs. 15.6%, p = 0.34). However, at least 400 patients would have been necessary for conclusive results.

Acute kidney injury prevalence, progression and long-term outcomes in critically ill patients with COVID-19: a cohort study

BACKGROUND

There are limited data on acute kidney injury (AKI) progression and long-term outcomes in critically ill patients with coronavirus disease-19 (COVID-19). We aimed to describe the prevalence and risk factors for development of AKI, its subsequent clinical course and AKI progression, as well as renal recovery or dialysis dependence and survival in this group of patients.

METHODS

This was a retrospective observational study in an expanded tertiary care intensive care unit in London, United Kingdom. Critically ill patients admitted to ICU between 1st March 2020 and 31st July 2020 with confirmed SARS-COV2 infection were included. Analysis of baseline characteristics, organ support, COVID-19 associated therapies and their association with mortality and outcomes at 90 days was performed.

RESULTS

Of 313 patients (70% male, mean age 54.5 ± 13.9 years), 240 (76.7%) developed AKI within 14 days after ICU admission: 63 (20.1%) stage 1, 41 (13.1%) stage 2, 136 (43.5%) stage 3. 113 (36.1%) patients presented with AKI on ICU admission. Progression to AKI stage 2/3 occurred in 36%. Risk factors for AKI progression were mechanical ventilation [HR (hazard ratio) 4.11; 95% confidence interval (CI) 1.61-10.49] and positive fluid balance [HR 1.21 (95% CI 1.11-1.31)], while steroid therapy was associated with a reduction in AKI progression (HR 0.73 [95% CI 0.55-0.97]). Kidney replacement therapy (KRT) was initiated in 31.9%. AKI patients had a higher 90-day mortality than non-AKI patients (34% vs. 14%; p < 0.001). Dialysis dependence was 5% at hospital discharge and 4% at 90 days. Renal recovery was identified in 81.6% of survivors at discharge and in 90.9% at 90 days. At 3 months, 16% of all AKI survivors had chronic kidney disease (CKD); among those without renal recovery, the CKD incidence was 44%.

CONCLUSIONS

During the first COVID-19 wave, AKI was highly prevalent among severely ill COVID-19 patients with a third progressing to severe AKI requiring KRT. The risk of developing CKD was high. This study identifies factors modifying AKI progression, including a potentially protective effect of steroid therapy. Recognition of risk factors and monitoring of renal function post-discharge might help guide future practice and follow-up management strategies. Trial registration NCT04445259.

Cumulative Fluid Balance during Extracorporeal Membrane Oxygenation and Mortality in Patients with Acute Respiratory Distress Syndrome

Extracorporeal membrane oxygenation (ECMO) is considered a salvage therapy in cases of severe acute respiratory distress syndrome (ARDS) with profound hypoxemia. However, the need for high-volume fluid resuscitation and blood transfusions after ECMO initiation introduces a risk of fluid overload. Positive fluid balance is associated with mortality in critically ill patients, and conservative fluid management for ARDS patients has been shown to shorten both the duration of mechanical ventilation and time spent in intensive care, albeit without a significant effect on survival. Nonetheless, few studies have addressed the influence of fluid balance on clinical outcomes in severe ARDS patients undergoing ECMO. In the current retrospective study, we examined the impact of cumulative fluid balance (CFB) on hospital mortality in 152 cases of severe ARDS treated using ECMO. Overall hospital mortality was 53.3%, and we observed a stepwise positive correlation between CFB and the risk of death. Cox regression models revealed that CFB during the first 3 days of ECMO was independently associated with higher hospital mortality (adjusted hazard ratio 1.110 [95% CI 1.027–1.201]; p = 0.009). Our findings indicate the benefits of a conservative treatment approach to avoid fluid overload during the early phase of ECMO when dealing with severe ARDS patients.

Hidden sources of fluids, sodium and potassium in stabilised Swedish ICU patients: A multicentre retrospective observational study

BACKGROUND

Fluid overload in ICU patients is associated with increased morbidity and mortality. Although studies report on optimisation of resuscitation fluids given to ICU patients, increasing evidence suggests that maintenance fluids and fluids used to administer drugs are important sources of fluid overload.

OBJECTIVES

We aimed to evaluate the volume of maintenance fluids and electrolytes on overall fluid balance and their relation to mortality in stabilised ICU patients.

DESIGN

Multicentre retrospective observational study.

SETTING

Six mixed surgical and medical ICUs in Sweden.

PATIENTS

A total of 241 adult patients who spent at least 7 days in the ICU during 2018.

MAIN OUTCOME MEASURES

The primary endpoint was the volume of maintenance, resuscitation and drug diluent fluids administered on days 3 to 7 in the ICU. Secondary endpoints were to compare dispensed amounts of maintenance fluids and electrolytes with predicted requirements. We also investigated the effects of administered fluids and electrolytes on patient outcomes.

RESULTS

During ICU days 3 to 7, 56.4% of the total fluids given were maintenance fluids, nutritional fluids or both, 25.4% were drug fluids and 18.1% were resuscitation fluids. Patients received fluids 1.29 (95% confidence interval 1.07 to 1.56) times their estimated fluid needs. Despite this, 93% of the cohort was treated with diuretics or renal replacement therapy. Patients were given 2.17 (1.57 to 2.96) times their theoretical sodium needs and 1.22 (0.75 to 1.77) times their potassium needs. The median [IQR] volume of fluid loss during the 5-day study period was 3742 [3156 to 4479] ml day-1, with urine output the main source of fluid loss. Death at 90 days was not associated with fluid or electrolyte balance in this cohort.

CONCLUSION

Maintenance and drug fluids far exceeded resuscitative fluids in ICU patients beyond the resuscitative phase. This excess fluid intake, in conjunction with high urinary output and treatment for fluid offload in almost all patients, suggests that a large volume of the maintenance fluids given was unnecessary.

TRIAL REGISTRATION

ClinicalTrials.org NCT03972475.

Restrictive fluid management versus usual care in acute kidney injury (REVERSE-AKI): a pilot randomized controlled feasibility trial

Purpose

We compared a restrictive fluid management strategy to usual care among critically ill patients with acute kidney injury (AKI) who had received initial fluid resuscitation.

Methods

This multicenter feasibility trial randomized 100 AKI patients 1:1 in seven ICUs in Europe and Australia. Restrictive fluid management included targeting negative or neutral daily fluid balance by minimizing fluid input and/or enhancing urine output with diuretics administered at the discretion of the clinician. Fluid boluses were administered as clinically indicated. The primary endpoint was cumulative fluid balance 72 h from randomization.

Results

Mean (SD) cumulative fluid balance at 72 h from randomization was − 1080 mL (2003 mL) in the restrictive fluid management arm and 61 mL (3131 mL) in the usual care arm, mean difference (95% CI) − 1148 mL (− 2200 to − 96) mL, P = 0.033. Median [IQR] duration of AKI was 2 [1–3] and 3 [2–7] days, respectively (median difference − 1.0 [− 3.0 to 0.0], P = 0.071). Altogether, 6 out of 46 (13%) patients in the restrictive fluid management arm and 15 out of 50 (30%) in the usual care arm received renal replacement therapy (RR 0.42; 95% CI 0.16–0.91), P = 0.043. Cumulative fluid balance at 24 h and 7 days was lower in the restrictive fluid management arm. The dose of diuretics was not different between the groups. Adverse events occurred more frequently in the usual care arm.

Conclusions

In critically ill patients with AKI, a restrictive fluid management regimen resulted in lower cumulative fluid balance and less adverse events compared to usual care. Larger trials of this intervention are justified.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-021-06401-6.

Fluid management in patients with acute kidney injury - A post-hoc analysis of the FINNAKI study

PURPOSE

Whether positive fluid balance among patients with acute kidney injury (AKI) stems from decreased urine output, overzealous fluid administration, or both is poorly characterized.

MATERIALS AND METHODS

This was a post hoc analysis of the prospective multicenter observational Finnish Acute Kidney Injury study including 824 AKI and 1162 non-AKI critically ill patients.

RESULTS

We matched 616 AKI (diagnosed during the three first intensive care unit (ICU) days) and non-AKI patients using propensity score. During the three first ICU days, AKI patients received median [IQR] of 11.4 L [8.0-15.2]L fluids and non-AKI patients 10.2 L [7.5-13.7]L, p < 0.001 while the fluid output among AKI patients was 4.7 L [3.0-7.2]L and among non-AKI patients 5.8 L [4.1-8.0]L, p < 0.001. In AKI patients, the median [IQR] cumulative fluid balance was 2.5 L [-0.2-6.0]L compared to 0.9 L [-1.4-3.6]L among non-AKI patients, p < 0.001. Among the 824 AKI patients, smaller volumes of fluid input with a multivariable OR of 0.90 (0.88-0.93) and better fluid output (multivariable OR 1.12 (1.07-1.18)) associated with enhanced change of resolution of AKI.

CONCLUSIONS

AKI patients received more fluids albeit having lower fluid output compared to matched critically ill non-AKI patients. Smaller volumes of fluid input and higher fluid output were associated with better AKI recovery.

Ratio of Overhydration and Extracellular Water Versus Ratio of Extracellular Water and Body Cell Mass in the Assessment of Fluid Status in Patients With Acute Kidney Injury Requiring Kidney Replacement Therapy: A Cohort Study

OBJECTIVES

The aim of this study is to analyze the association between the ratio of overhydration and extracellular water (OH/ECW) and the ratio of extracellular water and body cell mass (ECW/BCM) measured by bioelectrical impedance and outcomes of patients with acute kidney injury (AKI) requiring kidney replacement therapy (KRT).

METHODS

Patients with severe AKI treated with KRT in our hospital between September 2016 and August 2018 were enrolled. These patients were assessed using a body composition monitor before KRT, and on the 3rd day and the 7th day after initiation of KRT. The predictors mainly included OH/ECW and ECW/BCM. The association between all-cause mortality and predictors were analyzed using Cox regression.

RESULTS

A total of 152 patients were included in this study with a median follow-up of 39 (interquartile range 8-742) days. The 28-day mortality, 90-day mortality, and 1-year mortality were 46.7%, 54.6%, and 60.5%, respectively. A high ratio of OH/ECW (adjusted hazard ratio per standard deviation, 1.45; 95% confidence interval = 1.15-1.82, P = .002) and a high ratio of ECW/BCM (adjusted hazard ratio per standard deviation, 1.33, 95% confidence interval = 1.07-1.64, P = .009) before KRT were associated with all-cause mortality during follow-up. Higher ECW/BCM rather than OH/ECW at 7th day was associated with poorer outcomes. Furthermore, a reduction of OH/ECW with an increase of ECW/BCM had higher 1-year mortality as compared to others (85.7% vs. 51.2%, P = .004) in patients who survived 7 days after KRT initiation.

CONCLUSIONS

ECW/BCM performed better than OH/ECW in assessment of fluid status in AKI patients requiring KRT. This study suggested that a simple reduction of OH/ECW without decreasing ECW/BCM may not improve outcomes.

[Therapeutics for acute tubular necrosis in 2020]

Acute kidney injury is a major cause of in-hospital morbidity and mortality because of the serious nature of the underlying illnesses and the high incidence of complications. The two major causes of acute kidney injury that occur in the hospital are prerenal disease and acute tubular necrosis. Acute tubular necrosis has a histological definition, even if a kidney biopsy is rarely performed. Kidney injuries occurring during acute tubular necrosis are underlined by different pathophysiological mechanisms that emphasize the role of hypoxia on the tubular cells such as apoptosis, cytoskeleton disruption, mitochondrial function and the inflammation mediated by innate immune cells. The microcirculation and the endothelial cells are also the targets of hypoxia-mediated impairment. Repair mechanisms are sometimes inadequate because of pro-fibrotic factors that will lead to chronic kidney disease. Despite all the potential therapeutic targets highlighted by the pathophysiological knowledge, further works remain necessary to find a way to prevent these injuries.

Artificial intelligence to guide management of acute kidney injury in the ICU: a narrative review

PURPOSE OF REVIEW

Acute kidney injury (AKI) frequently complicates hospital admission, especially in the ICU or after major surgery, and is associated with high morbidity and mortality. The risk of developing AKI depends on the presence of preexisting comorbidities and the cause of the current disease. Besides, many other parameters affect the kidney function, such as the state of other vital organs, the host response, and the initiated treatment. Advancements in the field of informatics have led to the opportunity to store and utilize the patient-related data to train and validate models to detect specific patterns and, as such, predict disease states or outcomes.

RECENT FINDINGS

Machine-learning techniques have also been applied to predict AKI, as well as the patients' outcomes related to their AKI, such as mortality or the need for kidney replacement therapy. Several models have recently been developed, but only a few of them have been validated in external cohorts.

SUMMARY

In this article, we provide an overview of the machine-learning prediction models for AKI and its outcomes in critically ill patients and individuals undergoing major surgery. We also discuss the pitfalls and the opportunities related to the implementation of these models in clinical practices.

A prediction and interpretation framework of acute kidney injury in critical care

Acute kidney injury (AKI) is a common clinical condition with high mortality and resource consumption. Early identification of high-risk patients to achieve an appropriate allocation of limited clinical resources and timely interventions is of significant importance, which has attracted substantial research to develop prediction models for AKI risk stratification. However, most available AKI prediction models have moderate performance and lack of interpretability, which limits their applicability in supporting care intervention. In this paper, a machine learning-based framework for AKI prediction and interpretation in critical care is presented. First, an ensemble model is developed to predict a patient's risk of AKI within 72 h of admission to the intensive care units. Next, the model is interpreted both globally and locally. For the global interpretation, the important predictors are pinpointed and the detailed relationships between AKI risk and these predictors are illustrated. For the local interpretation, patient-specific analysis is presented to provide a visualized explanation for each individual prediction. Experimental results show that such a prediction and interpretation framework can lead to good prediction and interpretation performance, which has the potential to provide effective clinical decision support.

The Effect of Postoperative Fluid Balance on the Occurrence and Progression of Acute Kidney Injury After Cardiac Surgery

OBJECTIVES

In addition to the association between positive fluid balance (FB) and acute kidney injury (AKI) after cardiac surgery reported by former studies, this study examined the relationship between FB and progressive AKI.

DESIGN

A retrospective, observational study.

SETTING

University teaching, grade A tertiary hospital in Shanghai, China.

PARTICIPANTS

Adult patients after cardiac surgery from July-December 2016.

INTERVENTIONS

Perioperative data relating to postoperative fluid intake and output were collected. AKI progression was defined as a worsening of AKI stage. FB was calculated as (fluid intake [L] - fluid output [L]/body weight [kg] × 100%).

MEASUREMENTS AND MAIN RESULTS

The study comprised 1,522 patients. The incidences of AKI and progressive AKI were 33.1% (n = 504) and 18.1% (n = 91), respectively. There was an exponential increase between 24-hour FB and AKI occurrence, and an approximate "U"-shape association between 48-hour FB and AKI progression. Multivariate logistic regression showed that 24-hour FB ≥5% was an independent risk factor for AKI incidence (odds ratio [OR] 3.976; p < 0.001) and 48-hour FB <-5% or ≥3% was associated with an increase of AKI progression (FB <-5%, OR 7.078 [p = 0.031]; FB 3%-5%, OR 6.598 [p = 0.020]; FB ≥5%, OR 16.453 [p < 0.001]).

CONCLUSIONS

An exponential increase was found between 24-hour FB and AKI occurrence and a "U"-shape association between 48-hour FB and AKI progression. Both excessively negative and positive accumulative 48-hour FB increased the risk of AKI progression, suggesting cautious monitoring and application of fluid load in clinical practice.

The critical care literature 2019

An emergency physician (EP) is often the first health care provider to evaluate, resuscitate, and manage a critically ill patient. In recent years, the annual hours of critical care delivered in emergency departments across the United States has steadily increased. From 2006 to 2014, emergency department (ED) visits for critically ill patients increased approximately 80%. In addition to seeing more critically ill patients, EPs are often tasked with providing critical care long beyond the initial resuscitation period. In fact, more than 50% of ED patients that require admission to the ICU remain in the ED for more than 6 h. Prolonged ED wait times for critically ill patients to be transferred to the ICU is associated with increased hospital, 30-day, and 90-day mortality. It is during these early hours of critical illness, while the patient is in the ED, where lives can be saved or lost. Therefore, it is important for the EP to be knowledgeable about recent developments in resuscitation and critical care medicine. This review summarizes important articles published in 2019 pertaining to the resuscitation and care of select critically ill patients. We chose these articles based on our opinion of the importance of the study findings and their application to emergency medicine. The following topics are covered: sepsis, rapid sequence intubation, mechanical ventilation, neurocritical care, post-cardiac arrest care, and ED-based ICUs.

Incidence, Risk Factors, and Outcome of Acute Kidney Injury in the Intensive Care Unit: A Single-Center Study from Jordan

Background

Acute kidney injury (AKI) is a common serious problem affecting critically ill patients in intensive care unit (ICU). It increases their morbidity, mortality, length of ICU stay, and long-term risk of chronic kidney disease (CKD).

Methods

A retrospective study was carried out in a tertiary hospital in Jordan. Medical records of patients admitted to the medical ICU between 2013 and 2015 were reviewed. We aimed to identify the incidence, risk factors, and outcomes of AKI. Acute kidney injury network (AKIN) classification was used to define and stage AKI.

Results

2530 patients were admitted to medical ICU, and the incidence of AKI was 31.6%, mainly in stage 1 (59.4%). In multivariate analysis, increasing age (odds ratio (OR) = 1.2 (95% CI 1.1–1.3), P = 0.0001) and higher APACHE II score (OR = 1.5 (95% CI 1.2–1.7), P = 0.001) were predictors of AKI, with 20.4% of patients started on hemodialysis. At the time of discharge, 58% of patients with AKI died compared to 51.3% of patients without AKI (P = 0.05). 88% of patients with AKIN 3 died by the time of discharge compared to patients with AKIN 2 and 1 (75.3% and 61.2% respectively, P = 0.001).

Conclusion

AKI is common in ICU patients, and it increases mortality and morbidity. Close attention for earlier detection and addressing risk factors for AKI is needed to decrease incidence, complications, and mortality.

Protocol and statistical analysis plan for the REstricted fluid therapy VERsus Standard trEatment in Acute Kidney Injury-REVERSE-AKI randomized controlled pilot trial

Background

Fluid accumulation frequently coexists with acute kidney injury (AKI) and is associated with increased risk for AKI progression and mortality. Among septic shock patients, restricted use of resuscitation fluid has been reported to reduce the risk of worsening of AKI. Restrictive fluid therapy, however, has not been studied in the setting of established AKI. Here, we present the protocol and statistical analysis plan of the REstricted fluid therapy VERsus Standard trEatment in Acute Kidney Injury—the REVERSE‐AKI trial that compares a restrictive fluid therapy regimen to standard therapy in critically ill patients with AKI.

Methods

REVERSE‐AKI is an investigator‐initiated, multinational, open‐label, randomized, controlled, feasibility pilot trial conducted in seven ICUs in five countries. We aim to randomize 100 critically ill patients with AKI to a restrictive fluid treatment regimen vs standard management. In the restrictive fluid therapy regimen, the daily fluid balance target is neutral or negative. The primary outcome is the cumulative fluid balance assessed after 72 hours from randomization. Secondary outcomes include safety, feasibility, duration, and severity of AKI, and outcome at 90 days (mortality and dialysis dependence).

Conclusions

This is the first multinational trial investigating the feasibility and safety of a restrictive fluid therapy regimen in critically ill patients with AKI.

Trial registration

clinical.trials.gov NCT03251131.

Fluid removal associates with better outcomes in critically ill patients receiving continuous renal replacement therapy: a cohort study

BACKGROUND

Fluid overload is associated with morbidity and mortality in patients receiving renal replacement therapy (RRT). We aimed to explore whether fluid overload at initiation of RRT was independently associated with mortality and whether changes in cumulative fluid balance during RRT were associated with outcome.

METHODS

We retrospectively analysed the data of patients who were admitted to the multidisciplinary adult intensive care unit (ICU) in a tertiary care centre in the UK between 2012 and 2015 and received continuous RRT (CRRT) for acute kidney injury for at least 24 h. We collected baseline demographics, body mass index (BMI), comorbidities, severity of illness, laboratory parameters at CRRT initiation, daily cumulative fluid balance (FB), daily prescribed FB target, fluid bolus and diuretic administration and outcomes. The day of the lowest cumulative FB during CRRT was identified as nadir FB.

RESULTS

Eight hundred twenty patients were analysed (median age 65 years; 49% female). At CRRT initiation, the median cumulative FB was + 1772 ml; 89 patients (10.9%) had a cumulative FB > 10% body weight (BW). Hospital survivors had a significantly lower cumulative FB at CRRT initiation compared to patients who died (1495 versus 2184 ml; p < 0.001). In the 7 days after CRRT initiation, hospital survivors had a significant decline in cumulative FB (mean decrease 473 ml per day, p < 0.001) whilst there was no significant change in cumulative FB in non-survivors (mean decrease 112 ml per day, p = 0.188). Higher severity of illness at CRRT initiation, shorter duration of CRRT, the number of days without a prescribed FB target and need for higher doses of noradrenaline were independent risk factors for not reaching a FB nadir during CRRT. Multivariable analysis showed that older age, lower BMI, higher severity of illness, need for higher doses of noradrenaline and smaller reductions in cumulative FB during CRRT were independent risk factors for ICU and hospital mortality. Cumulative FB at CRRT initiation was not independently associated with mortality.

CONCLUSION

In adult patients receiving CRRT, a decrease in cumulative FB was independently associated with lower mortality. Fluid overload and need for vasopressor support at CRRT initiation were not independently associated with mortality after correction for severity of illness.