Contrast Media Administration & Adverse Reaction Management Flashcards
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According to ACR guidelines, at what eGFR threshold is the risk of contrast-induced acute kidney injury MOST significantly elevated?
Answer: eGFR < 30 mL/min/1.73m²
The ACR identifies eGFR < 30 mL/min/1.73m² as the threshold of highest risk for contrast-induced acute kidney injury, warranting careful risk-benefit analysis before contrast use.
How long should metformin be withheld AFTER contrast administration in a patient with renal impairment (eGFR < 45)?
Answer: 48 hours
Metformin must be held for 48 hours after contrast in renally impaired patients to prevent lactic acidosis, which can develop if CIN further reduces metformin clearance.
The Laskey formula for estimating safe contrast volume in renally impaired patients uses which ratio?
Answer: Contrast volume ÷ eGFR (should be < 3.7)
The Laskey formula defines contrast volume (mL) divided by eGFR (mL/min/1.73m²); a ratio below 3.7 is associated with lower CIN risk in patients with renal impairment.
A pregnant patient requires emergency coronary angiography. What is the PRIMARY contrast-related concern for the neonate?
Answer: Transient neonatal hypothyroidism from iodine exposure
Iodinated contrast crosses the placenta and free iodine can suppress neonatal thyroid function, making neonatal thyroid function testing recommended after in-utero exposure.
Which contrast media property is MOST important for minimizing direct cardiac toxicity during intracoronary injection?
Answer: Low ionicity and low osmolality
Low ionicity reduces the direct electrophysiologic effects on myocardium while low osmolality minimizes osmotic stress on red blood cells and endothelium during coronary injections.
How is a delayed contrast reaction defined by timing of onset after contrast administration?
Answer: 1 hour to 7 days after injection
Delayed contrast reactions are defined as adverse events occurring between 1 hour and 7 days after administration, typically presenting as T-cell–mediated skin eruptions such as maculopapular rash.
For an urgent procedure in a patient with a prior severe contrast reaction, which premedication regimen is recommended when full oral preparation is not possible?
Answer: IV methylprednisolone 40 mg and IV diphenhydramine 50 mg administered 1 hour before contrast
When urgent contrast use is required, IV methylprednisolone and IV diphenhydramine given 1 hour before contrast provide a faster-onset alternative to the standard multi-dose oral regimen, though with less efficacy.