302 Radiology: contrast risks Flashcards
What is intravenous contrast media?
Iodinated hydrocarbon ring
Iodine atomic number 53
Increases absorption of x-rays
Injected intravenously
When is contrast media used?
Contrast enhanced plain films –IVU
CT scanning
Angiography / interventional procedures
What is non-iodinated contrast media?
Ferro-magnetic contrast (Gadolinium) used in MRI
What are some side effects of iodinated contrast?
Warmth / Flushing
Headache
Nausea
Itching / rash
Metallic taste
These do NOT indicate allergy to contrast
What are some allergic reactions to contrast?
Urticaria
Bronchospasm
Laryngeal oedema
Hypotension
Generalised anaphylaxis
Incidence of severe reactions: 0.04%
Incidence of major anaphylaxis: 0.004%
What factors put patients at risk of allergic reaction to contrast?
Previous contrast reaction
Asthma (6 times increased risk of reaction)
NOT shellfish allergy or topical Iodine reaction
What is nephrotoxicity defined as?
5% increase in serum creatinine 48-72hrs following contrast injection
A leading cause of hospital acquired AKI, with increased in-hospital/1yr mortality
What puts somebody more at risk of nephrotoxicity caused by contrast?
Renal impairment (raised creatinine)
Diabetes
Metformin therapy
Risk affected by:
-Dose
-Hydration
-Diabetes
-CCF
-Nephrotoxic drugs
eGFR mandated if:
-History of renal disease or DM
-Larger dose of CM than average
-If using IA route that will directly expose the kidneys to a larger/more concentrated dose
How can contrast induced AKI be prevented?
Stop Metformin (48hrs post contrast injection)
Pre- and post-hydration (oral/IV) – intra-vascular volume expansion maintains renal perfusion
Use of contrast is on a risk Vs benefits basis
e.g. Trauma or cancer imaging
What is the first line imaging for AKI?
Ultrasound
What is hydronephrosis?
When the kidneys become stretched and swollen as the result of a build-up of urine inside them
What is a nephrostomy?
A tube is put in to drain the urine directly from your kidney
What is pyelonephritis?
When a UTI travels to the kidney and infects it
What is a Peri-nephric abscess?
The perinephric space is a cone-shaped compartment within the abdomen containing the kidney. The abscess forms somewhere there
They can be drained using ultrasound guidance
