Permissive hypofiltration

Acute kidney injury (AKI) is a syndrome with a multitude of causes and is associated with high mortality and a permanent loss of renal function. Our current understanding of the most common causes of AKI is limited, and thus a silver bullet therapy remains elusive. A change in the approach to AKI that shifts away from the primary composite endpoint of death/dialysis, and instead focuses on improving survival and mitigating permanent renal damage, is likely to be more fruitful. We suggest that the current approach of augmenting renal function by increasing the renal blood flow or glomerular filtration rate during AKI may actually worsen outcomes. Analogous to the approach towards adult respiratory distress syndrome that limits ventilator-induced lung injury, we propose the concept of permissive hypofiltration. The primary goals of this approach are: resting the kidney by providing early renal replacement therapy, avoiding the potentially injurious adverse events that occur during AKI (for example, fluid overload, hypophosphatemia, hypothermia, and so forth), and initiating therapies focused on improving survival and mitigating permanent loss of kidney function. © 2012 BioMed Central Ltd

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

Subclinical AKI is still AKI

The concept of acute kidney syndromes has shifted in recent years from acute renal failure to acute kidney injury (AKI). AKI implies injury or damage but not necessarily dysfunction. The human kidney has an important glomerular function reserve, and dysfunction becomes evident only when more than 50% of the renal mass is compromised. Recent AKI classifications include even slight changes in serum creatinine, acknowledging that this condition is associated with worse outcomes. This, however, still represents a functional criterion for AKI and implies a glomerular filtration rate alteration that may be a late phenomenon in the time course of the syndrome. An early diagnosis of AKI by using tubular damage biomarkers preceding filtration function loss is possible today. Some studies have shown evidence that there is an additional value of new biomarkers not only because they allow a diagnosis to be made earlier but also because they allow a kidney injury to be diagnosed even in the absence of subsequent dysfunction. Only recently, tubular damage without glomerular function loss was demonstrated to be associated with worse renal and overall outcomes. For this condition, the term 'subclinical' AKI has been introduced, challenging the traditional view that a kidney problem is clinically relevant, only when a loss of filtration function becomes apparent. A new domain of AKI diagnosis could then include functional criteria and damage criteria. This may have an impact on the epidemiology, prevention, and management of AKI. © 2012 BioMed Central Ltd

Should hydroxyethyl starch solutions be totally banned?

The choice of which intravenous solution to prescribe remains a matter of considerable debate in intensive care units around the world. Trends have been moving away from using hydroxyethyl starch solutions following concerns about safety. But are the available data sufficient to clearly assess the risk-benefit balance for all patients, and is there enough evidence of harm to justify removing these drugs completely from our hospitals? © 2013 BioMed Central Ltd