Iodinated Contrast in Emergency Imaging, Kidney Radiology - 2020 Guideline Update, Part 2

New guidance regarding iodinated contrast in contrast-enhanced emergency imaging of patients with an abnormal renal history.

This is part two of our Guideline Knowledge Check regarding emergency kidney imaging. A just released 2020 National Radiology / Kidney Consensus statement provides new guidance regarding contrast-enhanced emergency imaging of patients with an abnormal renal history. What does this consensus statement recommend?

Today’s Guideline Knowledge Check question comes from the desk of Med-Challenger Emergency Medicine Editor-in-Chief, Andrea Eberly, MD, FAAEM.

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Try this patient case question and find out if you’re following the most current guideline.

A 78-year-old male presents to the hospital after a 30-minute episode of left-sided weakness, which caused him to fall.

He did not sustain any trauma and is now asymptomatic. He has a history of hypertension, poorly controlled congestive heart failure, and atrial fibrillation.

He states that he has some type of kidney problem, but is not receiving dialysis.

His neurological exam is intact, and an initial, unenhanced CT scan is read as normal.

Due to the high risk of stroke after TIA in patients with atrial fibrillation, the patient is admitted and an elective magnetic resonance angiogram (MRA) is ordered.

Question:

According to the 2020 consensus statement from the American College of Radiology and the National Kidney Foundation, how should this patient’s risk for contrast-induced acute kidney injury (CI-AKI) be assessed and managed in the context of a contrast-enhanced imaging study?

Answer Options:

A screening estimated glomerular filtration rate (eGFR) should be obtained in all patients over 75-years-old who have hypertension or diabetes, regardless of kidney history.

Prophylaxis with IV saline hydration is indicated in all patients with an estimated glomerular filtration rate (eGFR) of less than 30 mL/mi/1.73 m².

In patients with compromised kidney function who are not receiving dialysis, a 15% dose reduction of contrast medium decreases the risk of CI-AKI without compromising imaging quality.

Poorly controlled congestive heart failure is a contraindication to giving CI-AKI prophylaxis with IV saline, regardless of the patient’s kidney function.

See the Answer:

The correct answer is:

Poorly controlled congestive heart failure is a contraindication to giving CI-AKI prophylaxis with IV saline, regardless of the patient’s kidney function.

Key Point:

The 2020 consensus guideline advises that CI-AKI prophylaxis with IV normal saline is not indicated for the following 3 groups: (1) the general population of patients with stable eGFR greater than or equal to 30 mL/min/1.73 m², (2) for patients undergoing chronic dialysis, or (3) for patients at risk for heart failure.

Explanation:

The 2020 consensus statement from the American College of Radiology and the National Kidney Foundation provides the following guidance with regards to non-emergent, contrast-enhanced imaging:

Who should be screened for an elevated CI-AKI risk?

A history of kidney disease (eg, CKD, remote AKI, kidney surgery, kidney ablation, albuminuria) is the single highest yield indication for screening for CI-AKI risk.

Diabetes mellitus is an optional screening trigger of lower yield.

Patient age and both treated and untreated hypertension have significant false positive rates for predicting CI-AKI risk and are therefore of uncertain screening value.

How should a patient be screened for an elevated CI-AKI risk?

The eGFR is the single best screening tool to assess CI-AKI risk. Creatinine and blood urea nitrogen levels are a poor indicator of the need for CI-AKI prophylaxis.

Who should receive CI-AKI prophylaxis?

Patients with acute kidney injury and/or an eGFR of less than 30 mL/min/1.73 m²who are NOT undergoing dialysis should receive CI-AKI prophylaxis, which consists of IV saline volume expansion prior to and after intravenous iodinated contrast media administration.

In individual high-risk circumstances, prophylaxis may be considered in patients with an eGFR of 30–44 mL/min/1.73 m²at the discretion of the ordering clinician.

However, the eGFR threshold should NOT be adjusted solely based on concomitant diabetes mellitus.

Who should NOT receive CI-AKI prophylaxis?

Prophylaxis is NOT indicated for patients with stable eGFRs greater than or equal to 30 mL/min/1.73 m², patients undergoing chronic dialysis, or patients at risk for heart failure (the above patient).

However, in patients with congestive heart failure, an eGFR should nonetheless be obtained. If the eGFR of less than 30 mL/min/1.73 m², the risks versus benefits of the contrast-enhanced study should be reassessed.

If a decision is made to proceed, the contrast load should NOT be decreased.

If a smaller contrast load would yield acceptable results, then the contrast load should be lowered for ALL patients, not just those with CI-AKI risk.

Recommended CI-AKI prophylaxis protocol consists of up to 60 minutes of pre-procedure IV volume expansion with normal saline, followed by continued post-procedure hydration for 3 to 12 hours.

Typical regimens range from fixed (eg, 500 mL before and after) to weight-based volumes (1–3 mL/kg per hour).

Other considerations: If possible, nephrotoxic medications should be temporarily withheld in patients at high risk for CI-AKI.

However, dialysis should not be initiated or altered solely based on contrast media administration.

Reference:

Davenport MS, Perazella MA, et al. Use of Intravenous Iodinated Contrast Media in Patients with Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation. Radiology 2020; 294:660–668

American College of Emergency Physicians Clinical Policies Subcommittee (Writing Committee) on Suspected Transient Ischemic Attack; Lo BM, Carpenter CR, Hatten BW, Wright BJ, Brown MD. Clinical policy: critical issues in the evaluation of adult patients with suspected transient ischemic attack in the emergency department. Ann Emerg Med 2016 Sep;68(3):354-70.

Iodinated Contrast Guideline Update for Emergency Kidney Imaging - National Radiology Kidney Consensus statement provides new guidance regarding contrast-enhanced emergency imaging of patients with an abnormal renal history

About Guideline Knowledge Checks:

With each update of national clinical practice guidelines, some recommendations change and many remain unchanged. Med-Challenger Guideline Knowledge Checks help you know both what is new and what has stayed the same in the most recent guidelines pertinent to each medical specialty.

About the Author:

Andrea Eberly, MD, FAAEM graduated from the David Geffen Medical School of Los Angeles (UCLA) and completed her residency in Emergency Medicine at the University Medical Center, Tucson, Arizona. After working as an attending physician in Tucson, she followed a recruiting call to the island of Guam, where she served in various roles, including as the director of the emergency department, the EMS Medical Director of Guam, and the Director of the 911 Call System. She has maintained her emergency medicine board certification through three cycles of American Board of Emergency Medicine Board Exams (last in 2014), all three with the help of Med-Challenger.

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The correct answer is:

After resolution of symptoms, observe the asymptomatic patient for at least 6 hours; antihistamines and glucocorticoids do not reliably decrease risk of biphasic anaphylaxis and are not recommended for this purpose.

Key Point:

The AAAAI and ACAAI jointly emphasize that importance of:

1. identifying patients at increased risk for a recurrence of anaphylaxis within 1-72 hours (biphasic anaphylaxis), and secondly

2. understanding that neither antihistamines nor glucocorticoids ameliorate that risk.
They recommend an extended observation period for those at risk for biphasic anaphylaxis, with a suggestion that 6 hours observation of the asymptomatic patient may be sufficient, depending on the patient’s co-morbidities. The threshold for admission should be low in older patients and those with cardiovascular or other chronic disease (increased risk of fatal anaphylaxis also during the recurrence).

Explanation:

The AAAAI and ACAAI endorse a 3-category definition of anaphylaxis from 2006 that captures the full range of anaphylaxis presentations - from milder cases to those that lack classic features such as skin manifestations or hypotension. They state:

Anaphylaxis is likely when 1 of the following 3 categories applies:

a) Assumes rash, but not hypotension; 2 symptoms required: acute onset of an illness (minutes to hours) with involvement of the skin, mucosal tissue, or both with either respiratory involvement or reduced blood pressure and/or associated symptoms of end-organ dysfunction; or

b) Most flexible definition designed to capture milder cases, eg urticaria plus GI symptoms – 2 symptoms required: two or more of the following that occur rapidly after exposure to a likely allergen for the patient, including:

i. involvement of skin-mucosal tissue,
ii. respiratory involvement,
iii. reduced blood pressure or associated symptoms, or
iv. gastrointestinal symptoms; or i. involvement of skin-mucosal tissue,

c) Assumes hypotension, but not rash - 1 symptom required: reduced blood pressure as a result of exposure to a known allergen trigger.

In a patient who falls into one of the above categories for anaphylaxis, epinephrine is the first drug to be given, something that one study found to only occurs in 8% of patients due to the administration of antihistamines and glucocorticoids prior to epinephrine. Studies show that the delay of epinephrine is associated with increased fatality.

Antihistamines and glucocorticoids also do not reliably decrease the risk of biphasic anaphylaxis. It is estimated that at a 5% incidence rate of biphasic anaphylaxis, 72 patients would need to be treated with antihistamine and 161 patients with glucocorticoids, respectively, to possibly prevent one case of biphasic anaphylaxis. However, both agents can be given as secondary treatment to increase patient comfort. This is not to be confused with patients who have an allergic reaction without anaphylaxis, who do not require epinephrine and are routinely treated with antihistamines and glucocorticoids.

Finally, a 1-hour observation period of the ASYMPTOMATIC patient after resolution of anaphylaxis is sufficient in most non-severe cases of anaphylaxis (negative predictive value of 95% for occurrence of biphasic anaphylaxis) as long as the patient also does not have co-morbidities that increase the risk of a fatal outcome.

In patients with either a severe case of anaphylaxis or e.g. cardiovascular or other chronic morbidities, the optimal observation period is unknown. The authors suggest a minimum of a 6-hour observation period of the asymptomatic patient AFTER resolution of anaphylaxis (97.3% negative predictive value for occurrence of biphasic anaphylaxis). This extended observation period has been calculated to be cost-effective, based on an estimate that the extended observation period leads to an estimated 76% reduction in mortality.

Signs of increased risk of biphasic anaphylaxis (requires extended observation:

1. Severe symptoms at presentation (no odds ratio provided)

2 doses of epinephrine are necessary (odds ratio 4.82)

3. cutaneous signs and symptoms (odds ratio 2.54)

4. drug trigger in children (odds ratio 2.35)

5. wide pulse pressure (odds ratio 2.11)

6. unknown trigger (odds ratio 1.63)

Iodinated Contrast Guidelines 2020 Update for Emergency Imaging, Part 2 – Guideline Knowledge Check

Iodinated Contrast in Emergency Imaging, Kidney Radiology - 2020 Guideline Update, Part 2

Subscribe for More

Try this patient case question and find out if you’re following the most current guideline.

A 78-year-old male presents to the hospital after a 30-minute episode of left-sided weakness, which caused him to fall.