Contrast reaction & safety

Signs

• Wheezing on auscultation
• Cough, chest tightness or shortness of breath
• Falling oxygen saturation
• Accessory muscle use in severe cases

Management

1. 1.Give oxygen 6-10 L/min by mask.
2. 2.Administer albuterol (salbutamol) metered-dose inhaler, 2-3 puffs; repeat as needed.
3. 3.Monitor pulse oximetry and vital signs.
4. 4.If severe, hypoxic or refractory: give IM adrenaline 0.3 mg 1:1000 (0.3 mL) into the lateral thigh and call for help.
5. 5.Escalate to the code team if airway compromise or hypotension develops.

Medications

Signs

• Raised, itchy wheals (hives)
• Localised or diffuse pruritus
• Normal vital signs and no airway or cardiovascular involvement

Management

1. 1.Reassure the patient and observe; most urticaria is self-limited.
2. 2.Monitor for progression to a more serious systemic reaction.
3. 3.If bothersome or widespread, give diphenhydramine 25-50 mg PO, IM or IV.
4. 4.If the patient receives IV diphenhydramine or is drowsy, ensure they do not drive and are observed.

Medications

Signs

• Hypotension with heart rate < 60 bpm
• Pallor, sweating, nausea
• Light-headedness or loss of consciousness

Management

1. 1.Lay the patient flat and elevate the legs.
2. 2.Give oxygen 6-10 L/min by mask.
3. 3.Secure IV access and give rapid IV fluids (normal saline or lactated Ringer’s).
4. 4.If heart rate remains < 60 bpm and the patient is symptomatic, give atropine 0.6-1 mg IV.
5. 5.Repeat atropine if needed to a total of about 3 mg; monitor vitals continuously.

Medications

Signs

• Prior mild-to-moderate allergic-like reaction to iodinated or gadolinium-based contrast
• Elective (non-urgent) imaging that allows a 13-hour lead time

Management

1. 1.Confirm the reaction history and that the study is elective (≥ 13 hours available).
2. 2.Give prednisone 50 mg PO at 13, 7 and 1 hour before contrast administration.
3. 3.Give diphenhydramine 50 mg PO (or IV/IM) 1 hour before contrast.
4. 4.Document the regimen and continue to observe after the injection.

Medications

Signs

• Prior allergic-like contrast reaction
• Urgent / emergent study that cannot wait for the elective regimen

Management

1. 1.Confirm the reaction history and that the study cannot be delayed for the elective regimen.
2. 2.Begin IV corticosteroid as early as possible before contrast (ideally ≥ 4-5 hours where feasible).
3. 3.Give hydrocortisone 200 mg IV OR methylprednisolone 40 mg IV, repeated every 4 hours until contrast is given.
4. 4.Give diphenhydramine 50 mg IV 1 hour before contrast.
5. 5.Weigh urgency of the study against the reduced protection of an accelerated regimen; document the decision.

Medications

Signs

• Swelling, tightness, pain or erythema at the injection site
• Reduced or absent contrast opacification distally
• Skin blistering or tense swelling (severe)
• Paraesthesia, reduced capillary refill or diminished distal pulses (compartment syndrome warning)

Management

1. 1.Stop the injection and disconnect / remove the IV catheter after aspirating if possible.
2. 2.Elevate the affected limb above the level of the heart to promote reabsorption.
3. 3.Apply a cold or warm compress per local policy (either may be used; choose per institutional protocol).
4. 4.Assess neurovascular status and mark / measure the swelling; observe for progression.
5. 5.Monitor closely for compartment syndrome (increasing pain, tense swelling, paraesthesia, reduced perfusion).
6. 6.Obtain urgent surgical / plastics consultation for large-volume extravasation, skin blistering, altered perfusion, or worsening symptoms.
7. 7.Document the estimated volume, site and clinical course; give the patient return-precaution instructions.

Signs

• Patient taking metformin (or a metformin-containing product)
• Planned iodinated contrast administration

Management

1. 1.Check eGFR and the clinical context (stable outpatient vs AKI vs arterial study with possible renal emboli).
2. 2.If eGFR ≥ 30 mL/min/1.73m² and no AKI: no need to routinely stop metformin before or after contrast.
3. 3.If eGFR < 30, or acute kidney injury, or an arterial catheter study with likely renal arterial embolisation: withhold metformin at the time of / after contrast.
4. 4.When withheld, hold metformin for 48 hours and recheck renal function before restarting.
5. 5.Restart metformin only once renal function is confirmed stable / returned to baseline.

Signs

• eGFR < 30 mL/min/1.73m² (highest risk group)
• Acute kidney injury or rapidly changing renal function
• Dehydration; concurrent nephrotoxins

Management

1. 1.Identify at-risk patients (especially eGFR < 30) and confirm the study is indicated.
2. 2.Use the lowest necessary contrast dose and avoid closely repeated contrast injections.
3. 3.Ensure adequate hydration; provide IV volume expansion with isotonic saline in at-risk patients per protocol.
4. 4.Avoid or minimise other nephrotoxic agents around the time of contrast where possible.
5. 5.Recheck renal function after contrast in high-risk patients and manage AKI supportively.

Medications

Signs

• Severe renal impairment (eGFR < 30 mL/min/1.73m²) or dialysis
• Acute kidney injury
• Planned gadolinium-based contrast administration

Management

1. 1.Assess renal function before elective GBCA administration in at-risk patients.
2. 2.Prefer an ACR group II GBCA — these carry a very low risk of NSF even at eGFR < 30.
3. 3.Avoid group I GBCAs in patients with severe renal impairment or AKI.
4. 4.Use the lowest diagnostic dose necessary and document the indication.
5. 5.Exercise caution in pregnancy — give GBCAs only when the benefit clearly outweighs the potential fetal risk.