Contrast-associated acute kidney injury

Assessing the Role of Bioelectrical Impedance Vector Analysis in Prognosis and Prevention of Contrast-Associated Acute Kidney Injury After Percutaneous Coronary Intervention

This study evaluated the impact of Bioelectrical Impedance Vector Analysis (BIVA)-guided hydration therapy on contrast-associated acute kidney injury (CA-AKI) in patients undergoing percutaneous coronary intervention (PCI). From April 2022 to January 2023, this prospective study at the Eastern General Hospital of the Chinese People's Liberation Army involved 902 adults with stable coronary artery disease (CAD) scheduled for PCI. BIVA measurements were performed pre-contrast, followed by a standard hydration regimen. The study focused on the development of CA-AKI and major adverse cardiovascular events (MACE, including all-cause death, nonfatal myocardial infarction, and target vessel revascularization) within 1 year post-PCI. Among the 902 patients (average age: 60.8 years, 65.2% men), CA-AKI post-PCI was observed in 10.8%. Those with CA-AKI had more comorbidities and higher baseline creatinine levels. The contrast volume-to-estimated Glomerular Filtration Rate (eGFR) ratio was higher in CA-AKI patients, with a significantly increased resistance/height ratio (R/H). High R/H values correlated with a greater risk of MACE and all-cause mortality within a year. The study underscores the importance of BIVA-guided hydration therapy and R/H ratio in predicting CA-AKI in PCI patients with stable CAD. Incorporating R/H ratio assessments may enhance pre-procedural risk assessment and improve long-term outcomes (P = .0017).

Acute Kidney Injury in Patients Undergoing Both Right and Left Heart Catheterization with Coronary Angiography Vs Right Heart Catheterization Only

BACKGROUND

Recent studies have challenged the reported causal association between acute kidney injury and iodinated contrast administration, ascribing some cases to changes in renal function that are independent of contrast administration.

METHODS

We studied 1779 consecutive patients undergoing right heart catheterization (RHC) at a Veterans Administration Medical Center. We compared the incidence of acute kidney injury and of nephropathy at 3 months in veterans undergoing right and left heart catheterization and coronary angiography (R&LHC) to the incidence of acute kidney injury and of nephropathy at 3 months in patients undergoing RHC only.

RESULTS

The incidence of acute kidney injury at 3 days was 47 (9.7%) in the R&LHC group and 58 (9.6%) in the RHC group (P = .99). The incidence of nephropathy at 3 months was 115 (17%) in the L&RHC group and 141 (19.2%) in the RHC group (P = 0.31). In a propensity score-paired analysis of 782 patients and after adjustment for baseline characteristics, the odds ratio for acute kidney injury at 3 days among patients undergoing R&LHC was 1.25 (95% confidence interval, 0.65-2.42; P = .50), and the odds ratio for nephropathy at 3 months was 0.69 (95% confidence interval, 0.46-1.04; P = .08).

CONCLUSION

The incidence of changes in creatinine consistent with acute kidney injury at 3 days and of nephropathy at 3 months was not significantly different in patients undergoing R&LHC compared with patients undergoing RHC only. This supports the thesis that not all changes in creatinine after procedures involving administration of contrast are caused by the contrast.

Incidences of and risk factors for clinical and subclinical contrast-associated acute kidney injury in patients who underwent neuroendovascular surgery

BACKGROUND

Contrast-associated acute kidney injury (CA-AKI) can develop after intravascular administration of iodinated contrast media. Neutrophil gelatinase-associated lipocalin (NGAL) is an early marker for AKI that helps to detect subclinical CA-AKI. We investigated the incidence of and risk factors for clinical and subclinical CA-AKI in patients who underwent neuroendovascular surgery.

METHODS

We retrospectively investigated 228 patients who underwent neuroendovascular surgery in 2020. Changes in serum creatinine and urine output were used to detect clinical CA-AKI. Urine NGAL concentration was used to detect subclinical CA-AKI in 67 out of 228 patients.

RESULTS

In 228 patients, serum creatinine, hemoglobin, hematocrit, total protein, and blood urea nitrogen (BUN) decreased significantly (p < 0.001) after surgery. However, serum creatinine decreased less significantly (p < 0.05) than hemoglobin, hematocrit, total protein, and BUN on postoperative Day 3. Two patients out of 228 developed clinical CA-AKI, and seven patients out of 67 with urine NGAL measurements developed subclinical CA-AKI. Multivariate regression analysis revealed that diabetes mellitus and carotid artery stenosis were significantly (p < 0.05) associated with the development of clinical and/or subclinical CA-AKI.

CONCLUSION

There was a large difference between the incidences of clinical CA-AKI (0.88%) and subclinical CA-AKI (10.4%). The difference might have primarily resulted from the different sensitivities between serum creatinine and urine NGAL and possibly from underestimation of the incidence of clinical AKI due to a postoperative decrease in serum creatinine caused by hemodilution. In addition to diabetes mellitus, carotid artery stenosis could also be a risk factor for CA-AKI.

Key Considerations regarding the Renal Risks of Iodinated Contrast Media: The Nephrologist's Role

BACKGROUND

The administration of iodinated contrast medium during diagnostic and therapeutic procedures has always been associated with the fear of causing acute kidney injury (AKI) or an exacerbation of chronic kidney disease. This has led, on the one hand, to the deterrence, when possible, of the use of contrast medium (preferring other imaging methods with the risk of loss of diagnostic power), and on the other hand, to the trialling of multiple prophylaxis protocols in an attempt to reduce the risk of kidney injury.

SUMMARY

A literature review on contrast-induced (CI)-AKI risk mitigation strategies was performed, focussing on the recognition of individual risk factors and on the most recent evidence regarding prophylaxis.

KEY MESSAGES

Nephrologists can contribute significantly in the CI-AKI context, from the early stages of the decision-making process to stratifying patients by risk, individualising prophylaxis measures based on the risk profile, and ensuring appropriate evaluation of kidney function and damage post-procedure to improve care.

Contrast-Induced Acute Kidney Injury: Evidence in Support of Its Existence and a Review of Its Pathogenesis and Management

The role of contrast-induced nephropathy (CIN) remains controversial. Many experts contend that CIN does not exist or is extremely rare. The diagnosis was previously made too frequently and inappropriately in the presence of coexisting and confounding comorbidities and risk factors making it difficult to singularly isolate the etiologic role of intravenous contrast media in acute kidney injury (AKI). It is probable that many patients were denied important diagnostic information from radiocontrast studies for fear of CIN. Recently, a new terminology for CIN was introduced, and the term CIN was replaced by two interrelated new terms: one is contrast-associated acute kidney injury (CA-AKI), and the second one is contrast-induced acute kidney injury (CI-AKI). CA-AKI occurs in association with risk factors or comorbidities, therefore, it is a correlative diagnosis. On the other hand, CI-AKI is a subtype of CA-AKI that results directly from iodinated contrast media. In this review, we present evidence from various studies that argue against CI-AKI and also those that suggest its existence but with much lower frequency. We will also provide the current status of the pathophysiology and management of CA-AKI/CI-AKI.

Capsaicin Prevents Contrast-Associated Acute Kidney Injury through Activation of Nrf2 in Mice

Capsaicin, a transient receptor potential vanilloid 1 channel agonist, possesses antioxidative properties through activating nuclear factor-erythroid 2-related factor 2 (Nrf2). As oxidative stress is a major contributor to the development of contrast-associated acute kidney injury (CA-AKI), we investigated the protective effect of capsaicin against CA-AKI via Nrf2. C57BL/6J mice were treated with dehydration and iodixanol to establish the model of CA-AKI. For pretreatment, capsaicin (0.3 mg/kg) was given via intraperitoneal injection one hour before iodixanol injection. Nrf2-specific siRNA was given through the tail vein to knock down Nrf2. The CA-AKI mouse model had remarkable mitochondrial fragmentation and dysfunction and apoptosis of tubular cells, overproduction of superoxide in renal tubules, increased renal malondialdehyde, tubular epithelial cell injury, and renal dysfunction. Importantly, pretreatment with capsaicin significantly ameliorated tubular cell injury and renal dysfunction with decreased superoxide, renal malondialdehyde, and apoptotic tubular cells and improved mitochondrial morphology and function in the CA-AKI mouse model. The expression of Nrf2 was increased in the kidney from the CA-AKI mouse model and was further enhanced by capsaicin. Administration of siRNA through the tail vein successfully decreased Nrf2 expression in the kidney, and knockdown of Nrf2 by siRNA abolished the beneficial effects of capsaicin on CA-AKI. The present study demonstrated a protective effect of capsaicin pretreatment against CA-AKI via Nrf2.

Reducing contrast medium dose with low photon energy images in renal dual-energy spectral CT angiography and adaptive statistical iterative reconstruction (ASIR)

OBJECTIVE

To evaluate the value of using low energy (keV) images in renal dual-energy spectral CT angiography (CTA) and adaptive statistical iterative reconstruction (ASIR) to reduce contrast medium dose.

METHODS

40 patients with renal CTA on a Discovery CT750HD were randomly divided into two groups: 20 cases (Group A) with 600 mgI kg^-1 and 20 cases (Group B) with 300 mgI kg^-1. The scan protocol for both groups was: dual-energy mode with mA selection for noise index of 10 HU, pitch 1.375:1, rotating speed 0.6 s/r. Images were reconstructed at 0.625 mm thickness with 40%ASIR, Group A used the conventional 70keV monochromatic images, and Group B used monochromatic images from 40 to 70 keV at 5 keV interval for analysis. The CT values and standard deviation (SD) values of the renal artery and erector spine in the plain and arterial phases were measured with the erector spine SD value representing image noise. The enhancement degree of the renal artery (ΔCT = CT(arterial) -CT(plain)), signal-to-noise ratio (SNR=CT_renal-artery/SD_renal-artery) and contrast-to-noise ratio (CNR=(CT_renal-artery-CT_{erector spine})/SD_{erector-spine}) were calculated. The single factor analysis of variance was used to analyze the difference of ΔCT, SNR and CNR among image groups with p < 0.05 being statistically significant. The subjective image scores of the groups were assessed blindly by two experienced physicians using a 5-point system and the score consistency was compared by the κ test.

RESULTS

Contrast medium dose in the 300 mgI kg^-1 group was reduced by 50% compared with the 600 mgI kg^-1 group, while radiation dose was similar between the two groups. The subjective scores were 4.00 ± 0.65, 4.50 ± 0.60 and 3.70 ± 0.80 for images at 70 keV (600 mgI kg^-1 group), 40 keV (300 mgI kg^-1 group) and 45 keV (300 mgI kg^-1 group), respectively with good consistency between the two reviewers (p > 0.05). The 40 keV images in the 300 mgI kg^-1 group had similar ΔCT (469.77 ± 86.95 HU vs 398.54 ± 73.68 HU) and CNR (15.52 ± 3.32 vs 18.78 ± 6.71) values as the 70 keV images in the 600 mgI kg^-1) group but higher SNR values (30.19 ± 4.41 vs 16.91 ± 11.12, p < 0,05).

CONCLUSION

Contrast dose may be reduced by 50% while maintaining image quality by using lower energy images combined with ASIR in renal dual-energy CTA.

ADVANCES IN KNOWLEDGE

Combined with ASIR and energy spectrum, can reduce the amount of contrast dose in renal CTA.