see also: [[radiation in pregnancy and diagnostic imaging#contrast risk|Pregnancy & lactation contrast risk]] , [[Anaphylaxis]], [[MAC line]] > [!references]- > - [RMH Medical imaging contrast admin procedure](x-devonthink-item://1B3042BA-6894-466B-9C29-7D775E701E08) > - [RMH - PPx contrast-induced AKI](x-devonthink-item://0B4CCEC3-4F60-435B-984C-51EF65957A25) > - [RSNA](https://pubs.rsna.org/doi/full/10.1148/radiol.2019192094) > - [RANZCR](https://www.ranzcr.com/college/document-library/iodinated-contrast-guidelines-2016) > - [radiopedia](https://radiopaedia.org/articles/contrast-induced-acute-kidney-injury) > - [Dunn - IV contrast](x-devonthink-item://CE485235-6238-42FC-A322-B14D9FC578A6) > This is a topic of tremendous debate and misunderstanding. Therefore, in this document we will cover > 1. risks of contrast nephropathy > 2. approach to contrast allergy and desensitisation ## General IV contrast risk factors - previous reaction or allergy to iodinated contrast - renal disease - diabetes, including pts on metformin - [[thyrotoxicosis|hyperthyroidism]] and/or thyroid cancer treatment - hypovolaemia or dehydration - [[Sickle Cell Anaemia]] (can be associated with [↑ sickling of erythrocytes](https://ashpublications.org/blood/article/142/Supplement%201/1138/505333/Impact-of-IV-Contrast-Exposure-during-Vaso)) ### Special note on gadolinium - nephrogenic systemic fibrosis (NSF) is a rare condition in which fibrous plaques develop in the dermis and deeper connective tissues. Has been reported in pts with severe renal disease following use of gadolinum-containing MRI contrast agents ## Contrast nephropathy now called Contrast-induced acute kidney injury > [!quote] >  Increasingly the evidence shows that contrast is not the cause of the renal impairment and that confounding factors such as sepsis are likely to be responsible. >   > A number of case-controlled studies and meta-analyses have been published, with most identifying no difference in the incidence of renal impairment between patients receiving and not receiving intravenous contrast, in patients with baseline normal renal function. One of the major confounding factors of propensity-matched case-controlled studies is that even though baseline renal function may have been similar in the two groups, physicians may have chosen to not prescribe contrast to sicker patients, so the two cohorts may have in fact not been truly matched. There are no randomized controlled trials as yet. > \- [Radiopaedia](https://radiopaedia.org/articles/contrast-induced-acute-kidney-injury) ***RANZCR Guidelines:*** - ==Intravascular iodinated contrast media should be given to any patient regardless of renal function status if the perceived diagnostic benefit to the patient, in the opinion of the radiologist and the referrer, justifies this administration.== - IV contrast related AKI is very rare in patients with eGFR > 30 and oral fluid intake of 2-3 L in preceding 23 hours - Severe renal impairment (eGFR <30 or AKI) is not an absolute contraindication to iodinated contrast media. - Acute emergency imaging procedures requiring contrast media administration eg acute stroke, acute bleeding, trauma, etc should not be delayed to obtain renal funciton tests - eGFR required before giving IV iodinated contrast to pts with known renal disease, diabetes, or taking metformin, except in emergency situations - to reduce the risk fo CIN, where appropriate, patients should eat normally and drink 2-3L/H2) over 24 hours prior to study **There is greatest controversy about the risk of CI-AKI for patients with eGFR less than 30**, with the odds of CI-AKI occurring in this group as a result of a single IV dose of iodinated contrast being either the same or up to 7x greater than in patients with normal renal function. No prospective randomised controlled trials have been conducted to test the hypothesis that there is a difference in the likelihood of AKI developing after iodinated contrast media administration in individuals with various levels of pre-existing renal function impairment at the time of contrast administration. (e) Retrospective studies that concluded that intravenous administration of iodinated contrast media does not cause AKI, or an increased risk of death or dialysis due to AKI, used propensity matching for a series of purported risk factors for CI-AKI, such as age, diabetes, and baseline renal function. In doing so, they retrospectively created a “control” population for the purpose of matching baseline risk of patients who did and did not receive intravenous contrast media. ***management*** - IV 0.9% NaCl or 150mL of NaHCo3 8.4% added to 850mL glucose 5% (withdraw 150mL from a glucose 5% bag then add the bicarb) at 1-3mL/kg/hour starting 1 hour prior to procedure and continuing for 4-6 hours after procedure as volume status allows - use lowest volumes of contrast as possible ## Management of patients with known or suspected allergies ***risk factors:*** - prior anaphylactic reaction - recurrent reaction in 10-60% of patients - severity is *usually similar to previous*; **may be more severe in 10%** - allergy to other medications or foods 2-5x risk - asthma - 6x risk - beta blockers -- may ↑ severity, not incidence > note: seafood/shellfish allergy, cutaneous allergy to iodine-containing skin prep, and allergy to gadolinium or other non-iodinated contrast is ==**not** associated with ↑ risk of contrast allergy== | severity | symptoms | | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------- | | mild | - nausea<br>- mild vomiting<br>- mild urticaria<br>- pruritis<br>- pallor<br>- headache | | Moderate | - laryngeal or facial oedema<br>- dysponea / bronchospasm<br>- rigor<br>- extensive urticaria<br>- severe vomiting<br>- mild hypotension (SBP >80) | | Severe | - pulm oedema<br>- cardiac arrhythmia<br>- severe hypotension (SBP <80)<br>- seizure<br>- arrest | - premedication does not remove the risk; always consider risk/benefit of giving conrast - older studies showed a ↓ risk of anaphylaxis to ionic contrast with steroid premedication, there is no convincing evidence that steroids +/- antihistamines reduce incidence or severity of reactions to non-ionic contrast - premedication should be considered in the setting of previous ==moderate or severe== anaphylaxis ot iodinated contrast. - **previous mild reactions do not require premedication** - if time: oral pred 50mg 13 hours prior and 1 hour before contrast + ceterizine 10mg 1 hour prior - Emergency: hydrocort 200mg IV 4 hours prior to contrast + cetirizine 10mg oral 1 hour before - IV steroids can be administered <4 hours before contrast if clinical urgency demands ; may reduce delayed or rebound reaction ## Running contrast through a MAC line