Estimation of renal function immediately after cessation of continuous renal replacement therapy at the ICU.

Estimating glomerular filtration (eGFR) after Continuous Renal Replacement Therapy (CRRT) is important to guide drug dosing and to assess the need to re-initiate CRRT. Standard eGFR equations cannot be applied as these patients neither have steady-state serum creatinine concentration nor average muscle mass. In this study we evaluate the combination of dynamic renal function with CT-scan based correction for aberrant muscle mass to estimate renal function immediately after CRRT cessation. We prospectively included 31 patients admitted to an academic intensive care unit (ICU) with a total of 37 CRRT cessations and measured serum creatinine before cessation (T1), directly (T2) and 5 h (T3) after cessation and the following two days when eGFR stabilized (T4, T5). We used the dynamic creatinine clearance calculation (D3C) equation to calculate eGFR (D3CGFR) and creatinine clearance (D3Ccreat) between T2-T3. D3Ccreat was corrected for aberrant muscle mass when a CT-scan was available using the CRAFT equation. We compared D3CGFR to stabilized CKD-EPI at T5 and D3CCreat to 4-h urinary creatinine clearance (4-h uCrCl) between T2-T3. We retrospectively validated these results in a larger retrospective cohort (NICE database; 1856 patients, 2064 cessations). The D3CGFR was comparable to observed stabilized CKD-EPI at T5 in the prospective cohort (MPE = - 1.6 ml/min/1.73 m2, p30 = 76%) and in the retrospective NICE-database (MPE = 3.2 ml/min/1.73 m2, p30 = 80%). In the prospective cohort, the D3CCreat had poor accuracy compared to 4-h uCrCl (MPE = 17 ml/min/1.73 m2, p30 = 24%). In a subset of patients (n = 13) where CT-scans were available, combination of CRAFT and D3CCreat improved bias and accuracy (MPE = 8 ml/min/1.73 m2, RMSE = 18 ml/min/1.73 m2) versus D3CCreat alone (MPE = 18 ml/min/1.73 m2, RMSE = 32 ml/min/1.73 m2). The D3CGFR improves assessment of eGFR in ICU patients immediately after CRRT cessation. Although the D3CCreat had poor association with underlying creatinine clearance, inclusion of CT derived biometric parameters in the dynamic renal function algorithm further improved the performance, stressing the role of muscle mass integration into renal function equations in critically ill patients.

GFR estimation is complicated by a high incidence of non-steady-state serum creatinine concentrations at the emergency department.

BACKGROUND: Acquiring a reliable estimate of glomerular filtration rate (eGFR) at the emergency department (ED) is important for clinical management and for dosing renally excreted drugs. However, renal function formulas such as CKD-EPI can give biased results when serum creatinine (SCr) is not in steady-state because the assumption that urinary creatinine excretion is constant is then invalid. We assessed the extent of this by analysing variability in SCr in patients who visited the ED of a tertiary care centre. METHODS: Data from ED visits at the University Medical Centre Utrecht, the Netherlands between 2012 and 2019 were extracted from the Utrecht Patient Oriented Database. Three measurement time points were defined for each visit: last SCr measurement before visit as baseline (SCr-BL), first measurement during visit (SCr-ED) and a subsequent measurement between 6 and 24 hours during admission (SCr-H1). Non-steady-state SCr was defined as exceeding the Reference Change Value (RCV), with 15% decrease or 18% increase between successive SCr measurements. Exceeding the RCV was deemed as a significant change. RESULTS: Of visits where SCr-BL and SCr-ED were measured (N = 47,540), 28.0% showed significant change in SCr. Of 17,928 visits admitted to the hospital with a SCr-H1 after SCr-ED, 27,7% showed significant change. More than half (55%) of the patients with SCr values available at all three timepoints (11,054) showed at least one significant change in SCr over time. CONCLUSION: One third of ED visits preceded and/or followed by creatinine measurement show non-stable serum creatinine concentration. At the ED automatically calculated eGFR should therefore be interpreted with great caution when assessing kidney function.

[Pharmacotherapy in patients with loss of renal function]. / Farmacotherapie bij nierfunctieverlies.

When dosing renally excreted drugs in patients with kidney disease, it is important to have a reliable estimate of renal function. The estimated glomerular filtration rate (eGFR) is often used in the clinic, although this measure can be inaccurate in certain situations. Choosing the appropriate drug and dosage should therefore not be solely based on the eGFR. In this review, we discuss the physiology behind renal function estimation and drug dosing and propose a step by step approach to dosing renally excreted drugs in patients with kidney disease.