Fluids in the ICU: which is the right one?

[Recent developments in acute kidney injury : Definition, biomarkers, subphenotypes, and management]

Acute kidney injury (AKI) is a common problem in critically ill patients and is associated with increased morbidity and mortality. Since 2012, AKI has been defined according to the KDIGO (Kidney Disease Improving Global Outcome) guidelines. As some biomarkers are now available that can provide useful clinical information, a new definition including a new stage 1S has been proposed by an expert group of the Acute Disease Quality Initiative (ADQI). At this stage, classic AKI criteria are not yet met, but biomarkers are already positive defining subclinical AKI. This stage 1S is associated with a worse patient outcome, regardless of the biomarker chosen. The PrevAKI and PrevAKI-Multicenter trial also showed that risk stratification with a biomarker and implementation of the KDIGO bundle (in the high-risk group) can reduce the rate of moderate and severe AKI. In the absence of a successful clinical trial, conservative management remains the primary focus of treatment. This mainly involves optimization of hemodynamics and an individualized (restrictive) fluid management. The STARRT-AKI trial has shown that there is no benefit from accelerated initiation of renal replacement therapy. However, delaying too long might be associated with potential harm, as shown in the AKIKI2 study. Prospective studies are needed to determine whether artificial intelligence will play a role in AKI in the future, helping to guide treatment decisions and improve outcomes.

Proceedings of the 2022 UAB CRRT Academy: Non-Invasive Hemodynamic Monitoring to Guide Fluid Removal with CRRT and Proliferation of Extracorporeal Blood Purification Devices

In 2022, we celebrated the 15th anniversary of the University of Alabama at Birmingham (UAB) Continuous Renal Replacement Therapy (CRRT) Academy, a 2-day conference attended yearly by an international audience of over 100 nephrology, critical care, and multidisciplinary trainees and practitioners. This year, we introduce the proceedings of the UAB CRRT Academy, a yearly review of select emerging topics in the field of critical care nephrology that feature prominently in the conference. First, we review the rapidly evolving field of non-invasive hemodynamic monitoring and its potential to guide fluid removal by renal replacement therapy (RRT). We begin by summarizing the accumulating data associating fluid overload with harm in critical illness and the potential for harm from end-organ hypoperfusion caused by excessive fluid removal with RRT, underscoring the importance of accurate, dynamic assessment of volume status. We describe four applications of point-of-care ultrasound used to identify patients in need of urgent fluid removal or likely to tolerate fluid removal: lung ultrasound, inferior vena cava ultrasound, venous excess ultrasonography, and Doppler of the left ventricular outflow track to estimate stroke volume. We briefly introduce other minimally invasive hemodynamic monitoring technologies before concluding that additional prospective data are urgently needed to adapt these technologies to the specific task of fluid removal by RRT and to learn how best to integrate them into practical fluid-management strategies. Second, we focus on the growth of novel extracorporeal blood purification devices, starting with brief reviews of the inflammatory underpinnings of multiorgan dysfunction and the specific applications of pathogen, endotoxin, and/or cytokine removal and immunomodulation. Finally, we review a series of specific adsorptive technologies, several of which have seen substantial clinical use during the COVID-19 pandemic, describing their mechanisms of target removal, the limited existing data supporting their efficacy, ongoing and future studies, and the need for additional prospective trials.

Update on the strategy for intravenous fluid treatment in acute pancreatitis

Fluid therapy/resuscitation is mandatory in acute pancreatitis due to the pathophysiology of fluid loss as a consequence of the inflammatory process. For many years, without clear evidence, early and aggressive fluid resuscitation with crystalloid solutions (normal saline solution or Ringer lactate solution) was recommended. Recently, many randomized control trials and meta-analyses on fluid therapy have revealed that high fluid rate infusion is associated with increased mortality and severe adverse events compared to those resulting from moderate fluid rates, and this has triggered a paradigm shift in fluid management strategies. Meanwhile, there is evidence to show that Ringer lactate solution is superior to normal saline solutions in this context. The purpose of this review is to provide an update on the strategies for intravenous fluid treatment in acute pancreatitis, including the type, optimal amount, rate of infusion, and monitoring guides. Recommendations from recent guidelines are critically evaluated for this review in order to reach the authors' recommendations based on the available evidence.

Normal saline: Past, present, and future

Normal saline (NS) is the most widely used agent in the medical field. However, from its origin to its widespread application, it remains a mystery. Moreover, there is an ongoing debate on whether its existence is reasonable, harmful to the human body, or will still exist in the future. The current review traces back to the origins of NS and provides a brief overview of the current situation of infusion. The purpose may shed some light on the possibility of the existence of NS in the future by elaborating on the origin of NS and the research status of the impact of NS on the human body.

Moderator Effect of Hypoalbuminemia in Volume Resuscitation and Plasma Expansion with Intravenous Albumin Solution

Intravenous administration of crystalloid or colloid solutions is the most common intervention for correcting hypovolemia in intensive care unit patients. In critical illness, especially sepsis and severe trauma, vascular wall permeability increases, and trans-endothelial escape of serum albumin, the major oncotic plasma constituent, contributes to the development of hypoalbuminemia and edema formation. The volume effects of intravenous human albumin solution exceed those of crystalloid solutions. If hypoalbuminemia is an effect moderator, the crystalloid-to-albumin ratio of fluid resuscitation volumes is not well characterized. Randomized controlled trials have confirmed that intravenous administration of human albumin solutions for volume resuscitation results in a lower net fluid balance compared with crystalloids, and smaller infusion volumes may be sufficient for hemodynamic stabilization when human albumin solutions are used. This narrative review summarizes the current evidence and conclusions drawn regarding the role of hypoalbuminemia in volume resuscitation. In the 'Saline versus Albumin Fluid Evaluation' study using 4% human albumin solution or saline, the saline-to-albumin ratio of study fluids was significantly higher in patients with baseline serum albumin concentrations of 25 g/L or less as compared to patients with baseline serum albumin concentrations of more than 25 g/L. In patients receiving renal replacement therapy, intravenous administration of 20-25% human albumin solution reduces intradialytic hypotension and improves fluid removal better than saline if serum albumin levels are similarly reduced. These data suggest that hypoalbuminemia acts as an effect moderator in volume resuscitation and plasma expansion with albumin solution. The volume effectiveness of intravenous human albumin solution in resuscitation appears to be greater when the serum albumin levels are low. In clinical situations, serum albumin concentrations per se may inform when and how to include intravenous albumin in fluid resuscitation if large amounts of crystalloids are needed, which requires further studies.