Fluid balance management during continuous renal replacement therapy

Fluid balance neutralization secured by hemodynamic monitoring versus protocolized standard of care in patients with acute circulatory failure requiring continuous renal replacement therapy: results of the GO NEUTRAL randomized controlled trial

PURPOSE

Net ultrafiltration (UFNET) during continuous renal replacement therapy (CRRT) can control fluid balance (FB), but is usually 0 ml·h-1 in patients with vasopressors due to the risk of hemodynamic instability associated with CRRT (HIRRT). We evaluated a UFNET strategy adjusted by functional hemodynamics to control the FB of patients with vasopressors, compared to the standard of care.

METHODS

In this randomized, controlled, open-label, parallel-group, multicenter, proof-of-concept trial, adults receiving vasopressors, CRRT since ≤ 24 h and cardiac output monitoring were randomized (ratio 1:1) to receive during 72 h a UFNET ≥ 100 ml·h-1, adjusted using a functional hemodynamic protocol (intervention), or a UFNET ≤ 25 ml·h-1 (control). The primary outcome was the cumulative FB at 72 h and was analyzed in patients alive at 72 h and in whom monitoring and CRRT were continuously provided (modified intention-to-treat population [mITT]). Secondary outcomes were analyzed in the intention-to-treat (ITT) population.

RESULTS

Between June 2021 and April 2023, 55 patients (age 69 [interquartile range, IQR: 62; 74], 35% female, Sequential Organ Failure Assessment (SOFA) 13 [11; 15]) were randomized (25 interventions, 30 controls). In the mITT population, (21 interventions, 24 controls), the 72 h FB was -2650 [-4574; -309] ml in the intervention arm, and 1841 [821; 5327] ml in controls (difference: 4942 [95% confidence interval: 2736-6902] ml, P < 0.01). Hemodynamics, oxygenation and the number of HIRRT at 72 h, and day-90 mortality did not statistically differ between arms.

CONCLUSION

In patients with vasopressors, a UFNET fluid removal strategy secured by a hemodynamic protocol allowed active fluid balance control, compared to the standard of care.

Relative Blood Volume Monitoring during Continuous Renal Replacement Therapy: A Prospective Observational Study

INTRODUCTION

Hematocrit monitoring during continuous renal replacement therapy (CRRT) allows the continuous estimation of relative blood volume (RBV). This may enable early detection of intravascular volume depletion prior to clinical sequelae. We aimed to investigate the feasibility of extended RBV monitoring and its epidemiology during usual CRRT management by clinicians unaware of RBV. Moreover, we studied the association between changes in RBV and net ultrafiltration (NUF) rates.

METHODS

In a cohort of adult intensive care unit patients receiving CRRT, we continuously monitored hematocrit and RBV using a pre-filter noninvasive optical sensor. We analyzed temporal changes in RBV and investigated the association between RBV change and NUF rates, using the classification of NUF rates into low, moderate, or high based on predefined cut-offs.

RESULTS

We obtained >60,000 minute-by-minute measurements in >1,000 CRRT hours in 36 patients. The median RBV change was negative (decrease) in 69% of patients and the median peak change in RBV was -9.3% (interquartile range: -3.9% to -14.3%). Moreover, the median RBV decreased from baseline by >5% in 40.2% of measurements and by >10% in 20.6% of measurements. Finally, RBV decreased significantly more when patients received a high NUF rate (>1.75 mL/kg/h) compared to low or moderate NUF rates (5.32% vs. 1.93% or 1.97%, p < 0.001).

CONCLUSION

Continuous hematocrit and RBV monitoring during CRRT was feasible. RBV decreased significantly during CRRT, and decreases were greater with higher NUF rates. RBV monitoring may help optimize NUF management and prevent the occurrence of intravascular volume depletion.

Personalized Medicine Transformed: ChatGPT's Contribution to Continuous Renal Replacement Therapy Alarm Management in Intensive Care Units

The accurate interpretation of CRRT machine alarms is crucial in the intensive care setting. ChatGPT, with its advanced natural language processing capabilities, has emerged as a tool that is evolving and advancing in its ability to assist with healthcare information. This study is designed to evaluate the accuracy of the ChatGPT-3.5 and ChatGPT-4 models in addressing queries related to CRRT alarm troubleshooting. This study consisted of two rounds of ChatGPT-3.5 and ChatGPT-4 responses to address 50 CRRT machine alarm questions that were carefully selected by two nephrologists in intensive care. Accuracy was determined by comparing the model responses to predetermined answer keys provided by critical care nephrologists, and consistency was determined by comparing outcomes across the two rounds. The accuracy rate of ChatGPT-3.5 was 86% and 84%, while the accuracy rate of ChatGPT-4 was 90% and 94% in the first and second rounds, respectively. The agreement between the first and second rounds of ChatGPT-3.5 was 84% with a Kappa statistic of 0.78, while the agreement of ChatGPT-4 was 92% with a Kappa statistic of 0.88. Although ChatGPT-4 tended to provide more accurate and consistent responses than ChatGPT-3.5, there was no statistically significant difference between the accuracy and agreement rate between ChatGPT-3.5 and -4. ChatGPT-4 had higher accuracy and consistency but did not achieve statistical significance. While these findings are encouraging, there is still potential for further development to achieve even greater reliability. This advancement is essential for ensuring the highest-quality patient care and safety standards in managing CRRT machine-related issues.

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

BACKGROUND

Historically IV and enteral fluids given during acute kidney injury (AKI) were restricted before the introduction of continuous renal replacement therapies (CRRTs) when more liberal fluids improved nutrition for the critically ill. However, fluid accumulation can occur when higher volumes each day are not considered in the fluid balance prescribing and the NET ultrafiltration (NUF) volume target.

KEY MESSAGES

The delivered hours of CRRT each day are vital for achievement of fluid balance and time off therapy makes the task more challenging. Clinicians inexperienced with CRRT make this aspect of AKI management a focus of rounding with senior oversight, clear communication, and "precision" a clinical target. Sepsis-associated AKI can be a complex patient where resuscitation and admission days are with a positive fluid load and replacement mind set. Subsequent days in ICU requires fluid regulation, removal, with a comprehensive multilayered assessment before prescribing the daily fluid balance target and the required hourly NET plasma water removal rate (NUF rate). Future machines may include advanced software, new alarms - display metrics, messages and association with machine learning and "AKI models" for setting, monitoring, and guaranteeing fluid removal. This could also link to current hardware such as on-line blood volume assessment with continuous haematocrit measurement.

SUMMARY

Fluid balance in the acutely ill is a challenge where forecasting and prediction are necessary. NUF rate and volume each hour should be tracked and adjusted to achieve the daily target. This requires human and machine connections.

Fluid Management during Continuous Renal Replacement Therapy: A Case-Based Approach

Continuous renal replacement therapy (CRRT) is frequently used for fluid management of critically ill patients with acute or chronic kidney failure. There is significant practice variation worldwide in fluid management during CRRT. Multiple clinical studies have suggested that both the magnitude and duration of fluid overload are associated with morbidity and mortality in critically ill patients. Therefore, timely and effective fluid management with CRRT is paramount in managing critically ill patients with fluid overload. While the optimal method of fluid management during CRRT is still unclear and warrants further investigation, observational data have suggested a U-shape relationship between net ultrafiltration rate and mortality. Furthermore, recent clinical data have underpinned a significant gap in prescribed versus achieved fluid balance during CRRT, which is also associated with mortality. This review uses a case-based approach to discuss two fluid management strategies based on net ultrafiltration rate and fluid balance goals during CRRT and harmonizes operational definitions.

Safely correct hyponatremia with continuous renal replacement therapy: A flexible, all-purpose method based on the mixing paradigm

Treating chronic hyponatremia by continuous renal replacement therapy (CRRT) is challenging because the gradient between a replacement fluid's [sodium] and a patient's serum sodium can be steep, risking too rapid of a correction rate with possible consequences. Besides CRRT, other gains and losses of sodium- and potassium-containing solutions, like intravenous fluid and urine output, affect the correction of serum sodium over time, known as osmotherapy. The way these fluids interact and contribute to the sodium/potassium/water balance can be parsed as a mixing problem. As Na/K/H₂ O are added, mixed in the body, and drained via CRRT, the net balance of solutes must be related to the change in serum sodium, expressible as a differential equation. Its solution has many variables, one of which is the sodium correction rate, but all variables can be evaluated by a root-finding technique. The mixing paradigm is proved to replicate the established equations of osmotherapy, as in the special case of a steady volume. The flexibility to solve for any variable broadens our treatment options. If the pre-filter replacement fluid cannot be diluted, then we can compensate by calculating the CRRT blood flow rate needed. Or we can deduce the infusion rate of dextrose 5% water, post-filter, to appropriately slow the rise in serum sodium. In conclusion, the mixing model is a generalizable and practical tool to analyze patient scenarios of greater complexity than before, to help doctors customize a CRRT prescription to safely and effectively reach the serum sodium target.

Perfusion-based deresuscitation during continuous renal replacement therapy: A before-after pilot study (The early dry Cohort)

BACKGROUND

Active fluid removal has been suggested to improve prognosis following the resolution of acute circulatory failure. We have implemented a routine care protocol to guide fluid removal during continuous renal replacement therapy (CRRT). We designed a before-after pilot study to evaluate the impact of this deresuscitation strategy on the fluid balance.

METHODS

Consecutive ICU patients suffering from fluid overload and undergoing CRRT for acute kidney injury underwent a perfusion-based deresuscitation protocol combining a restrictive intake, net ultrafiltration (UFnet) of 2 mL/kg/h, and monitoring of perfusion (early dry group, N = 42) and were compared to a historical group managed according to usual practices (control group, N = 45). The primary outcome was the cumulative fluid balance at day 5 or at discharge.

RESULTS

Adjusted cumulative fluid balance was significantly lower in the early dry group (median [IQR]: -7784 [-11,833 to -2933] mL) compared to the control group (-3492 [-9935 to -1736] mL; p = 0.04). The difference was mainly driven by a greater daily UFnet (31 [22-46] mL/kg/day vs. 24 [15-32] mL/kg/day; p = 0.01). There was no significant difference between both groups regarding hemodynamic tolerance.

CONCLUSION

Our perfusion-based deresuscitation protocol achieved a greater negative cumulative fluid balance compared to standard practices and was hemodynamically well tolerated.