Fluid Overload and Precision Net Ultrafiltration in Critically Ill Patients

Abstract

Background: Fluid overload is present in two-thirds of critically ill patients with acute kidney injury and is associated with morbidity, mortality, and increased healthcare resource utilization. Kidney replacement therapy is frequently used for net fluid removal (i.e., net ultrafiltration) in patients with severe oliguric acute kidney injury. However, ultrafiltration has considerable risks associated with it and there is a need for newer technology to perform ultrafiltration safely and to improve outcomes. Summary: Caring for a critically ill patient with oliguric acute kidney injury and fluid overload is one of the most challenging problems. Although diuretics are the first line treatment for management of fluid overload, diuretic resistance is common. Various clinical practice guidelines support fluid removal using ultrafiltration during kidney replacement therapy. Emerging evidence from observational studies in critically ill patients suggests that both slow and fast rates of net fluid removal during continuous kidney replacement therapy are associated with increased mortality compared with moderate UFNET rates. In addition, fast UFNET rates are associated with an increased risk of cardiac arrhythmias. Randomized trials are required to examine whether moderate UFNET rates are associated with a reduced risk of hemodynamic instability, organ injury and improved outcomes in critically ill patients. There is a need for newer technology for fluid removal in patients who do not meet traditional criteria for initiation of KRT. Emerging newer and miniaturized ultrafiltration devices may address an unmet clinical need.

Fluid Balance in Continuous Renal Replacement Therapy: Prescribing, Delivering, and Review

“…Patient actual weight (not ideal body weight) and change are a key in dialysis where this measure is fast, correct, and more reliable than a bed scales weight in ICU patients. The fluid loss decision should be multilayered [18, 23, 29] and may include; a bed scales weight daily, skin and physical assessment for tissue oedema, consideration of osmolality, serum sodium, serum Hct, vasoactive drugs use, urine output, chest X-ray, blood gas oxygen and exchange and current or forecast time off therapy for imaging or possible filter clotting and re-priming time.…”

“…Prescribing for Fluid Balance in ICU Language and terminology are important and the glossary of terms provided (Table 1) can help with prescribing documents or charts (including e-prescribing), discussions between clinicians to ensure the correct outcome is achieved, and for alignment with the literature [16][17][18] and published nomenclature [19]. For example, ultrafiltration (UF) is a mechanism for plasma water removal during CRRT or dialysis, and NUF is the difference between the sum of all dialytic and substitution fluids used during all modes of CRRT and the total volume removed and produced as waste [20,21].…”

Combination Diuretic Therapy to Counter Renal Sodium Avidity in Acute Heart Failure

“…[86][87][88] Marketing of portable or miniaturized devices may further potentiate the interest in this technology. 89,90 Similar to combination diuretic therapy, however, there is no evidence so far for a positive effect on survival.…”

Ultrafiltration Tolerance: A Phenotype That We Need to Recognize

“…The cumulative fluid balance is an independent factor that increases mortality in clinical scenarios such as ARDS, septic shock, AKI and is also associated with prolonged mechanical ventilation, impaired recovery from AKI, impaired wound healing, abdominal compartment syndrome, and discharge to a healthcare facility [2][3][4][5]. One of the strategies when fluid overload is refractory to diuretics is extracorporeal fluid removal (i.e., net ultrafiltration [UF NET ] during kidney replacement therapy).…”