Acute kidney injury: prevention, detection, and management. Summary of updated NICE guidance for adults receiving iodine-based contrast media

Iodinated contrast media (ICM)-induced thyroid dysfunction: a review of potential mechanisms and clinical management

Iodinated contrast media (ICM) are extensively utilized in medical imaging to enhance tissue contrast, yet their impact on thyroid function has attracted increasing attention in recent years. ICM can induce thyroid dysfunction, with reported prevalence ranging from 1 to 15% and a higher incidence observed in individuals with pre-existing thyroid conditions or other risk factors like age, gender, underlying health issues, and repeated ICM exposure. This review summarized the classification of ICM and the potential mechanisms, risk assessment, and clinical management of ICM-induced thyroid dysfunction, especially in vulnerable populations such as pregnant women and elderly patients. Despite advancements that have enriched our understanding of the pathophysiology and treatment of ICM-induced thyroid dysfunction, critical knowledge gaps remain, such as the long-term effects of ICM on thyroid function, the dose-response relationship between ICM volume and thyroid dysfunction risk, and the ecological impacts of ICM. Therefore, further exploration of the underlying mechanisms of ICM-induced thyroid dysfunction and optimization of the management strategies will be crucial for the safe and effective use of ICM in clinical practice, and collaborative efforts between clinicians and researchers are essential to ensure that the risks of thyroid dysfunction do not outweigh the benefits of imaging.

Incidence of Acute Kidney Injury After Exposure to Intravenous Contrast in Emergency Department Patients Presenting for Stroke

BACKGROUND

Chronic kidney disease (CKD) is to be considered an independent risk factor for developing post-computed tomography (CT) acute kidney injury (AKI); however, current data are limited.

OBJECTIVES

Examine the incidence of AKI after intravenous contrast exposure among patients with and without CKD.

METHODS

A single-center retrospective study examined patients that presented to the Emergency Department and activated the stroke protocol, which involved an immediate CT angiogram. Patients were subdivided into "normal to mild" (glomerular filtration rate [GFR] > 60 mL/min/1.73 m2), CKD III (GFR 30-60 mL/min/1.73 m2), and CKD IV (GFR < 30 mL/min/1.73 m2) groups. The primary outcome was the development of AKI. Patients already on dialysis were excluded.

RESULTS

Among the 794 patients identified, 452 (56.9%) were classified as "normal to mild," 280 (35.3%) were classified as CKD III, and 62 (7.8%) were classified as CKD IV. Patients with normal GFR had a 2.4% incidence of developing AKI, those with CKD III had a 1.4% incidence, and patients with CKD IV had an 8.1% incidence of developing AKI. Overall, 2.5% of patients developed AKI. For CKD III vs. "normal" groups, odds ratio (OR) = 0.58 (95% confidence interval [CI] 0.16-1.72). For CKD IV vs. "normal," OR = 3.52 (95% CI 1.07-10.05). Of those patients with CKD IV who had AKI, all saw improvement in their creatinine prior to discharge and none required renal replacement therapy.

CONCLUSION

This study builds on the evidence demonstrating that patients with CKD III are likely at the same risk of developing post-CT AKI as those with normal renal function. Furthermore, the risk of developing post-CT AKI in CKD IV patients may be far lower than previously thought, was transient, and did not result in renal replacement therapy.

Systematic, Pretransplant Screening by Aortoiliac CT Angiography: Impact on Surgical Decision-making and Clinical Outcomes

Background

Aortoiliac screening before kidney transplantation is suggested by some guidelines to select patients for transplantation and to assist surgical planning. We investigated the clinical outcomes of systematic screening for aortoiliac disease in potential kidney transplant candidates.

Methods

In this observational study, 470 potential kidney transplant candidates underwent aortoiliac computed tomography angiography. Patients were characterized by the presence of peripheral artery disease and calcification of iliac arteries and aortoiliac arteries. The risk of graft loss and graft function at 1 y posttransplant were examined and clinical decisions based on the vascular findings were assessed.

Results

Clinically diagnosed peripheral artery disease was present in 66 patients (14%), circular calcifications in 101 patients (21%), and aortoiliac stenosis in 77 patients (16%). In 326 patients undergoing kidney transplantation, circular calcification or aortoiliac stenosis was not associated with an increased risk of graft loss (P = 0.45 and P = 0.28) or estimated glomerular filtration rate (P = 0.23 and P = 0.76) at 1 y posttransplant. When evaluated for transplantability, clinical decision-making based on vascular findings was recorded in 67 of 429 patients (16%), including rejection for transplantation in 7 patients (2%) and laterality for surgical implantation in 52 patients (12%).

Conclusions

Systematic screening by aortoiliac computed tomography angiography may assist in surgical planning but seems of limited clinical value in assessing the risk of future graft loss and graft function in patients undergoing kidney transplantation.

Contrast-associated acute kidney injury in patients with diabetes mellitus following elective percutaneous coronary intervention: Insights from an iodixanol-acute kidney injury registry study

BACKGROUND

Patients with diabetes mellitus (DM) are particularly susceptible to contrast-associated acute kidney injury (CA-AKI). However, few studies have evaluated CA-AKI stages in patients with DM following elective percutaneous coronary intervention (PCI) with iodixanol.

METHODS

Patients with DM who underwent elective PCI in 8 Chinese hospitals from May 2020 to November 2021 were prospectively enrolled in the Iodixanol-Acute Kidney Injury Registry (No. ChiCTR1800016719). According to the European Society of Urogenital Radiation on their CA-AKI diagnosis, and follow-up of major adverse renal and cardiovascular events (MARCE), CA-AKI and prognosis predictors were identified using logistic and Cox multivariable regression, respectively.

RESULTS

There were 1120 patients with DM included and the incidence of CA-AKI was 5.8 % (65/1120). However, most CA-AKI patients were at acute kidney injury stage 1 (96.9 %, 63/65). The dose of iodixanol was not an independent risk factor for CA-AKI, however, a hemoglobin level <110 g/L, a left ventricular ejection fraction (LVEF) <40 %, an estimated glomerular filtration rate <60 mL/min/1.73m2, an N-terminal pro-B-type natriuretic peptide level ≥300 pg/mL, and the use of loop diuretics were independent risk factors. Only 3.5 % (39/1120) of patients experienced MARCE. Hypertension, LVEF <40 %, hemoglobin level <110 g/L, and age >75 years old were independent risk factors for MARCE, while in comparison to indobufen, aspirin is an independent protective factor against MARCE in diabetic patients.

CONCLUSIONS

The incidence of CA-AKI in patients with DM who underwent PCI was low, mostly associated with mild renal impairment, and therefore did not increase the risk of MARCE.

N-acetylcysteine in Kidney Disease: Molecular Mechanisms, Pharmacokinetics, and Clinical Effectiveness

N-acetylcysteine (NAC) has shown beneficial effects in both acute kidney disease and chronic kidney disease (CKD) in preclinical and clinical studies. Different dosage and administration forms of NAC have specific pharmacokinetic properties that determine the temporal pattern of plasma concentrations of NAC and its active metabolites. Especially in acute situations with short-term NAC administration, appropriate NAC and glutathione (GSH) plasma concentrations should be timely ensured. For oral dosage forms, bioavailability needs to be established for the respective NAC formulation. Kidney function influences NAC pharmacokinetics, including a reduction of NAC clearance in advanced CKD. In addition, mechanisms of action underlying beneficial NAC effects depend on kidney function as well as comorbidities, both involving GSH deficiency, alterations in nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent signaling, oxidative stress, mitochondrial dysfunction, and disturbed mitochondrial bioenergetics. This also applies to nonrenal NAC mechanisms. The timing of preventive NAC administration in relation to potential injury is important. NAC administration seems most effective either preceding, or preceding and paralleling conditions that induce tissue damage. Furthermore, studies suggest that very high concentrations of NAC should be avoided because they could exert reductive stress. Delayed administration of NAC might interfere with endogenous repair mechanisms. In conclusion, studies on NAC treatment regimens need to account for both NAC pharmacokinetics and NAC molecular effects. Kidney function of the patient population and pathomechanisms of the kidney disease should guide rational NAC trial design. A targeted trial approach and biomarker-guided protocols could pave the way for the use of NAC in precision medicine.

The Diagnostic Yield and Clinical Impact of Systematic Screening of Kidney Transplant Candidates by Cardiac Computed Tomography: A Cohort Study

BACKGROUND

Although cardiovascular screening of kidney transplant candidates is recommended, the optimal approach is debated. Previous studies show that noninvasive imaging provides prognostic information, but systematic screening may have less recognized effects, such as additional investigations, incidental findings, procedural complications, and delay of transplantation. To address this, we characterized the diagnostic yield and clinical implications of systematic screening for cardiovascular disease using cardiac computed tomography (CT) in potential kidney transplant candidates.

METHODS

This was a single-center, observational cohort study including all potential kidney transplant candidates >40 years of age or with diabetes or on dialysis treatment for >5 years, systematically referred to cardiac computed tomography (CT; non-contrast CT and coronary CT angiography) between 2014 and 2019 before evaluation for kidney transplantation at Aarhus University Hospital. Patient records were examined for data on baseline characteristics, additional investigations and complications, plasma creatinine, dialysis initiation, time until wait-listing, and incidental findings.

RESULTS

Of 473 patients who underwent cardiac CT, additional cardiac investigations were performed in 156 (33%), and 32 (7%) were revascularized. Twenty-two patients had significant incidental nonvascular findings on cardiac CT. No patient was rejected for transplantation based on cardiac CT. In patients not yet on dialysis, the slope in the estimated glomerular filtration rate decline did not change significantly after coronary CT angiography.

CONCLUSION

Screening by cardiac CT led to additional cardiac investigations in one-third of patients; only a few patients were revascularized, with unknown benefits in asymptomatic patients. Cardiac CT was safe in this population; however, the clinical consequences of the screening were limited.

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.

Effectiveness of Oral Hydration in Preventing Contrast-Induced Nephropathy in Individuals Undergoing Elective Coronary Interventions

BACKGROUND

Contrast-induced nephropathy (CIN) is defined as worsening renal function, represented by an increase in serum creatinine of ≥ 25% or ≥ 0.5 mg/dL up to 72 h after exposure to iodinated contrast medium (ICM). The most effective preventive measure to date is intravenous hydration (IVH). Little is known about the effectiveness of outpatient oral hydration (OH).

OBJETIVE

To investigate whether outpatient OH with water is as effective as IVH with 0.9% saline solution in preventing CIN in elective coronary procedures.

METHODS

In this retrospective observational study, we analyzed the medical records and laboratory data of individuals undergoing percutaneous coronary procedures with ICM. Data collected between 2012 and 2015 refer to individuals who underwent IVH and those collected between 2016 and 2020 (after implementation of an OH protocol) correspond to individuals who underwent OH at home before and after coronary procedures as instructed by the nursing team. Statistical significance was established at α = 0.05.

RESULTS

In total, 116 patients were included in this study: 58 in the IVH group and 58 in the OH group. An incidence of CIN of 15% (9/58) was observed in the group that received IVH and an incidence of 12% (7/58) was seen in the group that received OH (p = 0.68).

CONCLUSION

The OH protocol, performed by the patient, appears to be as effective as the in-hospital IVH protocol for the renal protection of individuals susceptible to CIN in elective coronary interventions. These findings should be put to test in larger trials.

Perioperative acute kidney injury: impact and recent update

PURPOSE OF REVIEW

Acute kidney injury (AKI) is common in hospitalized patients and is a major risk factor for increased length of stay, morbidity, and mortality in postoperative patients. There are multiple barriers to reducing perioperative AKI - the etiology is multi-factorial and the diagnosis is fraught with issues. We review the recent literature on perioperative AKI and some considerations for anesthesiologists that examine the far-reaching effects of AKI on multiple organ systems.

RECENT FINDINGS

This review will discuss recent literature that addresses the epidemiology, use of novel biomarkers in risk stratification, and therapeutic modalities for AKI in burn, pediatrics, sepsis, trauma, cardiac, and liver disease, contrast-induced AKI, as well as the evidence assessing goal-directed fluid therapy.

SUMMARY

Recent studies address the use of risk stratification models and biomarkers, more sensitive than creatinine, in the preoperative identification of patients at risk for AKI. Although exciting, these scores and models need validation. There is a need for research assessing whether early AKI detection improves outcomes. Enhanced recovery after surgery utilizing goal-directed fluid therapy has not been shown to make an appreciable difference in the incidence of AKI. Reducing perioperative AKI requires a multi-pronged and possibly disease-specific approach.