Point-of-care measurement of serum creatinine in the intensive care unit

Point of care creatinine derived eGFR measurement in capillary blood for identifying patients at risk

Introduction

The aim of the study was to assess the clinical reliability of eGFR values estimated with a creatinine measurement from a point of care (StatSensor®) compared with measured GFR (mGFR) by a gold standard method.

Methods

We prospectively included 113 patients undergoing renal function assessment. We compared eGFR using creatinine from capillary blood or venous blood measured by StatSensor® and measured GFR (mGFR) by Passing Bablok regression. Performance of eGFR was estimated by biais, precision and accuracy.

Results

A total of 113 subjects were included. Median eGFR values were 59 (10–132), 52 (10–123) and 51 (10–131) ml/min/1.73 m² for enzymatic, capillary and venous measurements, respectively. There was no difference between P30 and P10 for the three eGFR values (p = 0.11 and p = 0.1 respectively). StatSensor® eGFR tended to be underestimated compared to mGFR. For CKD stage 4/5 patients, concordance was 79 and 84% for eGFR with capillary creatinine and venous creatinine respectively. For mGFR< 60 ml/min/1.73 m², concordance was 84 and 88% with capillary creatinine and venous creatinine respectively.

Conclusion

The use of a handheld blood creatinine monitoring system with eGFR calculation provides a good estimation of GFR and allow to identify patients at high risk of acute kidney injury.

Small, short-term, point-of-care creatinine changes as predictors of acute kidney injury in critically ill patients

PURPOSE

To assess short-term creatinine changes as predictors of acute kidney injury (AKI) when used alone and in combination with AKI risk factors.

METHODS

In this prospective cohort study, we identified all creatinine measurements from frequent point-of-care arterial blood gas measurements from ICU admission until AKI. We evaluated the predictive value of small changes between these creatinine measurements for AKI development, alone and with AKI risk factors.

RESULTS

Of 377 patients with 3235 creatinine measurements, generating 15,075 creatinine change episodes, 215 (57%) patients developed AKI, and 68 (18%) developed stage 2 or 3 AKI. In isolation, a creatinine increase over 4.1-7.3 h had a 0.65 area under the curve for predicting stage 2 or 3 AKI within 3-37.7 h. Combining creatinine increases of ≥1 μmol/L/h (≥0.0113 mg/dL/h) over 4-5.8 h with three AKI risk factors (cardiac surgery, use of vasopressors, chronic liver disease) had 83% sensitivity, 79% specificity and 0.87 area under the curve for stage 2 or 3 AKI occurring 8.7-25.6 h later.

CONCLUSION

In combination with key risk factors, frequent point-of-care creatinine assessment on arterial blood gases to detect small, short-term creatinine changes provides a robust, novel, low-cost, and rapid method for predicting AKI in critically ill patients.

Comparison of point-of-care NOVA CCX blood gas analyzer to laboratory analyzer in a population of healthy adult cats

OBJECTIVE

To compare the level of agreement of measurement of analytes (sodium, chloride, potassium, urea nitrogen [UN], creatinine, glucose) in a population of healthy adult cats between the point-of-care (POC) analyzer and laboratory analyzer. To establish reference intervals for the POC analyzer in healthy adult cats.

DESIGN

Prospective observational study.

SETTING

University teaching hospital.

ANIMALS

Fifty-five cats were screened. Seven cats were excluded due to aggression that prohibited phlebotomy, and 1 cat was excluded due to prolonged restraint; 47 cats were enrolled.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

In this patient population, reference intervals for the POC analyzer were calculated: sodium 145-157 mmol/L; chloride 116-124 mmol/L; potassium 3.4-5.5 mmol/L; UN 5.71-13.9 mmol/L (16-39 mg/dl); creatinine 74.3-189.2 mmol/L (0.84-2.14 mg/dl); and glucose 4-11.8 mmol/L (72-213 mg/dl). Comparison between the POC analyzer and laboratory analyzer using the Bland-Altman method was performed. The bias for each analyte is as follows: sodium 1.55 mmol/L; chloride 0.99 mmol/L; potassium 0.21 mmol/L; UN -0.25 mmol/L (-0.7 mg/dl); creatinine 9.73 mmol/L (0.11 mg/dl); and glucose 0.5 mmol/L (9.79 mg/dl).

CONCLUSIONS

Reference intervals for each analyte were similar to other chemistry analyzers. There was no significant difference between the POC and laboratory analyzers in analysis of UN, with a statistically significant difference observed with sodium, potassium, chloride, creatinine, and glucose. However, the values are likely not sufficiently different to alter initial clinical decisions regarding patient care.

Point-of-care testing technologies for the home in chronic kidney disease: a narrative review

Point-of-care testing (POCT) performed by the patient at home, paired with eHealth technologies, offers a wealth of opportunities to develop individualized, empowering clinical pathways. The non-dialysis-dependent chronic kidney disease (CKD) patient who is at risk of or may already be suffering from a number of the associated complications of CKD represents an ideal patient group for the development of such initiatives. The current coronavirus disease 2019 pandemic and drive towards shielding vulnerable individuals have further highlighted the need for home testing pathways. In this narrative review we outline the evidence supporting remote patient management and the various technologies in use in the POCT setting. We then review the devices currently available for use in the home by patients in five key areas of renal medicine: anaemia, biochemical, blood pressure (BP), anticoagulation and diabetes monitoring. Currently there are few devices and little evidence to support the use of home POCT in CKD. While home testing in BP, anticoagulation and diabetes monitoring is relatively well developed, the fields of anaemia and biochemical POCT are still in their infancy. However, patients' attitudes towards eHealth and home POCT are consistently positive and physicians also find this care highly acceptable. The regulatory and translational challenges involved in the development of new home-based care pathways are significant. Pragmatic and adaptable trials of a hybrid effectiveness-implementation design, as well as continued technological POCT device advancement, are required to deliver these innovative new pathways that our patients desire and deserve.

Reduced urinary levels of angiotensin-converting enzyme 2 activity predict acute kidney injury in critically ill patients

Objective: Angiotensin-converting enzyme 2 activity reflects non-classical renin-angiotensin system upregulation. We assessed the association of urinary angiotensin-converting enzyme 2 (uACE2) activity with acute kidney injury (AKI). Design, setting and participants: A prospective observational study in which we measured uACE2 activity in 105 critically ill patients at risk of AKI. We report AKI stage 2 or 3 at 12 hours of urine collection (AKI12h) and AKI stage 2 or 3 at any time during intensive care unit stay in patients free from any stage of AKI at inclusion (AKIICU). AKI prediction was assessed using area under the receiver-operating characteristics curve (AUROC) and net reclassification indices (NRIs). Main outcome measure: AKI stage 2 or 3 at 12 hours of urine collection. Results: Within 12 hours of inclusion, 32 of 105 patients (30%) had developed AKI12h. Corrected uACE2 activity was significantly higher in patients without AKI12h compared with those with AKI12h (median [interquartile range], 13 [6-24] v 7 [4-10] pmol/min/mL per mmol/L of urine creatinine; P < 0.01). A 10-unit increase in uACE2 was associated with a 28% decrease in AKI12h risk (odds ratio [95% CI], 0.72 [0.46-0.97]). During intensive care unit admission, 39 of 76 patients (51%) developed AKIICU. uACE2 had an AUROC for the prediction of AKI12h of 0.68 (95% CI, 0.57-0.79), and correctly reclassified 28% of patients (positive NRI) to AKI12h. Patients with uACE2 > 8.7 pmol/min/mL per mmol/L of urine creatinine had a significantly lower risk of AKIICU on log-rank analysis (52% v 84%; P < 0.01). Conclusions: Higher uACE2 activity was associated with a decreased risk of AKI stage 2 or 3. Our findings support future evaluations of the role of the non-classical renin-angiotensin system during AKI.

Point-of-care creatinine measurements to predict acute kidney injury

BACKGROUND

Plasma creatinine (Cr) is a marker of kidney function and typically measured once daily. We hypothesized that Cr measured by point-of-care technology early after ICU admission would be a good predictor of acute kidney injury (AKI) the next day in critically ill patients.

METHODS

We conducted a retrospective database audit in a single tertiary ICU database. We included patients with normal first admission Cr (Cr_F ) and identified a Cr value (Cr_P ) obtained within 6-12 hours from ICU admission. We used their difference converted into percentage (delta-Cr-%) to predict subsequent AKI (based on Cr and/or need for renal replacement therapy) the next day. We assessed predictive value by calculating area under the receiver characteristic curve (AUC), logistic regression models for AKI with and without delta-Cr-%, and the category-free net reclassifying index (cfNRI).

RESULTS

We studied 780 patients. Overall, 70 (9.0%) fulfilled the Cr AKI definition by Cr_P measurement. On day 2, 148 patients (19.0%) were diagnosed with AKI. AUC (95% CI) for delta-Cr-% to predict AKI on day 2 was 0.82 (95% CI 0.78-0.86), and 0.74 (95% CI 0.69-0.80) when patients with AKI based on the Cr_P were excluded. Using a cut-off of 17% increment, the positive likelihood ratio (95% CI) for delta-Cr-% to predict AKI was 3.5 (2.9-4.2). The cfNRI was 90.0 (74.9-106.1).

CONCLUSIONS

Among patients admitted with normal Cr, early changes in Cr help predict AKI the following day.

Evaluation of a point-of-care serum creatinine measurement device and the impact on diagnosis of acute kidney injury in pediatric cardiac patients: A retrospective, single center study

Background and aims

Agreement between measurements of creatinine concentrations using point‐of‐care (POC) devices and measurements conducted in a standard central laboratory is unclear for pediatric patients. Our objectives were (a) to assess the agreement for pediatric patients and (b) to compare the incidence of postoperative acute kidney injury (AKI) according to the two methods.

Methods

This retrospective, single‐center study included patients under 18 years of age who underwent cardiac surgery and who were admitted into the pediatric intensive care unit of a tertiary teaching hospital (Okayama University Hospital, Japan) from 2013 to 2017. The primary objective was to assess the correlation and the agreement between measurements of creatinine concentrations by a Radiometer blood gas analyzer (Cre_gas) and those conducted in a central laboratory (Cre_lab). The secondary objective was to compare the incidence of postoperative AKI between the two methods based on Kidney Disease Improving Global Outcomes (KDIGO) criteria.

Results

We analyzed the results of 1404 paired creatinine measurements from 498 patients, whose median age was 14 months old (interquartile range [IQR] 3, 49). The Pearson correlation coefficient of Cre_gas vs Cre_lab was 0.968 (95% confidence interval [CI], 0.965‐0.972, P < 0.001). The median bias between Cre_gas and Cre_lab was 0.02 (IQR ‐0.02, 0.05) mg/dL. While 199 patients (40.0%) were diagnosed as having postoperative AKI based on Cre_lab, 357 patients (71.7%) were diagnosed as having postoperative AKI based on Cre_gas (Kappa = 0.39, 95% CI, 0.33‐0.46). In a subgroup analysis of patients whose Cre_gas and Cre_lab were measured within 1 hour, similar percentage of patients were diagnosed as having postoperative AKI based on Cre_gas and Cre_lab (42.8% vs 46.0%; Kappa = 0.76, 95% CI, 0.68‐0.84).

Conclusion

There was an excellent correlation between Cre_gas and Cre_lab in pediatric patients. Although more patients were diagnosed as having postoperative AKI based on Cre_gas than based on Cre_lab, paired measurements with a short time gap showed good agreement on AKI diagnosis.

The incidence, characteristics, outcomes and associations of small short-term point-of-care creatinine increases in critically ill patients

PURPOSE

We assessed the incidence, characteristics, outcomes and associations of small, short-term point-of-care creatinine increases in critically ill patients.

METHODS

We prospectively identified the first episode of small (>1 μmol/L/h) short-term (3-4 h) point-of-care creatinine increase between two sequential arterial blood gas measurements. We followed patients for the subsequent development of Kidney Disease: Improving Global Outcomes (KDIGO) defined acute kidney injury (AKI) in the intensive care unit (ICU).

RESULTS

Of 387 patients, 279 (72.1%) developed an episode of small short-term point-of-care creatinine increase and 212 (54.8%) developed AKI. Such episodes occurred at a median of 5 (IQR 2-10) hours after ICU admission, while AKI occurred at a median of 15 (IQR 9-28) hours after admission. Patients with such episodes were more likely to be mechanically ventilated on admission (83.9 vs. 44.4%; p < .001) and had higher hospital mortality (10.9 vs. 3.7%, p = .03). Creatinine increase episodes had a sensitivity of 86% (95% CI 78-95) and specificity of 31% (95% CI 26-36) for subsequent AKI stages 2 and 3 in 24 h.

CONCLUSIONS

Small, short-term point-of-care creatinine increase episodes are common. They are associated with illness severity, occur early, precede AKI by 10 h and are sensitive rather than specific markers of AKI.

Acute Kidney Injury Recognition in Low- and Middle-Income Countries

Acute kidney injury (AKI) is increasingly common around the world. Because of the low availability of effective therapies and resource limitations, early preventive and therapeutic measures are essential to decrease morbidity, mortality, and cost. Timely recognition and diagnosis of AKI requires a heightened degree of suspicion in the appropriate clinical and environmental context. In low- and middle-income countries (LMICs), early detection is impaired by limited resources and low awareness. In this article, we report the consensus recommendations of the 18th Acute Dialysis Quality Initiative meeting in Hyderabad, India, on how to improve recognition of AKI. We expect these recommendations will lead to an earlier and more accurate diagnosis of AKI, and improved research to promote a better understanding of the epidemiology, etiology, and histopathology of AKI in LMICs.

Drug safety evaluation of oral tenofovir disoproxil fumarate-emtricitabine for pre-exposure prophylaxis for human immunodeficiency virus infection

INTRODUCTION

Tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) are nucleoside reverse transcriptase inhibitors approved as pre-exposure prophylaxis (PrEP) against human immunodeficiency virus (HIV). Prophylactic TDF-based regimens have been shown to reduce the risk of HIV infection by 74 to 92% among participants with detectable drug levels. Adverse events observed in clinical trials include nausea, elevated creatinine and liver enzymes, and decreased bone mineral density.

AREAS COVERED

This article reviews the pharmacology, pharmacokinetics, and the safety profile of TDF and FTC used as PrEP for HIV infection.

EXPERT OPINION

TDF-FTC can have a large impact in preventing HIV infections among high risk individuals when taken daily. Although TDF-FTC is associated with adverse events, they can be minimized with clinician-guided monitoring.

Accuracy of point-of-care serum creatinine devices for detecting patients at risk of contrast-induced nephropathy: a critical overview

Contrast-induced nephropathy (CIN) is a common event in hospitals, with reported incidences ranging from 1 to 30%. Patients with underlying kidney disease have an increased risk of developing CIN. Point-of-care (POC) creatinine devices are handheld devices capable of providing quantitative data on a patient's kidney function that could be useful in stratifying preventive measures. This overview aims to synthesize the current evidence on diagnostic accuracy and clinical utility of POC creatinine devices in detecting patients at risk of CIN. Five databases were searched for diagnostic accuracy studies or clinical trials that evaluated the usefulness of POC devices in detecting patients at risk of CIN. Selected articles were critically appraised to assess their individual risk of bias by the use of standard criteria; 13 studies were found that addressed the diagnostic accuracy or clinical utility of POC creatinine devices. Most studies incurred a moderate to high risk of bias. Overall concordance between POC devices and reference standards (clinical laboratory procedures) was found to be moderate, with 95% limits of agreement often lying between -35.4 and +35.4 µmol/L (-0.4 and +0.4 mg/dL). Concordance was shown to decrease with worsening kidney function. Data on the clinical utility of these devices were limited, but a significant reduction in time to diagnosis was reported in two studies. Overall, POC creatinine devices showed a moderate concordance with standard clinical laboratory creatinine measurements. Several biases could have induced optimism in these estimations. Results obtained from these devices may be unreliable in cases of severe kidney failure. Randomized trials are needed to address the clinical utility of these devices.

The nature and discriminatory value of urinary neutrophil gelatinase-associated lipocalin in critically ill patients at risk of acute kidney injury

BACKGROUND

Different molecular forms of urinary neutrophil gelatinase-associated lipocalin (NGAL) have recently been discovered. We aimed to explore the nature, source and discriminatory value of urinary NGAL in intensive care unit (ICU) patients.

METHODS

We simultaneously measured plasma NGAL (pNGAL), urinary NGAL (uNGAL), and estimated monomeric and homodimeric uNGAL contribution using Western blotting-validated enzyme-linked immunosorbent assays [uNGAL(E1) and uNGAL(E2)] and their calculated ratio in 102 patients with the systemic inflammatory response syndrome and oliguria, and/or a creatinine rise of >25 μmol/L.

MEASUREMENTS AND MAIN RESULTS

Bland-Altman analysis demonstrated that, despite correlating well (r = 0.988), uNGAL and uNGAL(E1) were clinically distinct, lacking both accuracy and precision (bias: 266.23; 95% CI 82.03-450.44 ng/mg creatinine; limits of agreement: -1,573.86 to 2,106.32 ng/mg creatinine). At best, urinary forms of NGAL are fair (area under the receiver operating characteristic [AUROC] ≤0.799) predictors of renal or patient outcome; most perform significantly worse. The 44 patients with a primarily monomeric source of uNGAL had higher pNGAL (118.5 ng/ml vs. 72.5 ng/ml; p < 0.001), remaining significant following Bonferroni correction.

CONCLUSIONS

uNGAL is not a useful predictor of outcome in this ICU population. uNGAL patterns may predict distinct clinical phenotypes. The nature and source of uNGAL are complex and challenge the utility of NGAL as a uniform biomarker.