A 58-year-old man with type 2 diabetes and stage 3b chronic kidney disease (eGFR 35 mL/min/1.73m²) is scheduled for coronary angiography. Regarding contrast media selection and adverse reaction management, all of the following are appropriate EXCEPT:

Explanation

## Contrast-Induced Nephropathy (CIN) Prevention and Management ### Risk Stratification in This Patient **Key Point:** This patient has multiple risk factors for CIN: - Type 2 diabetes mellitus - Moderate-to-severe renal impairment (eGFR 35) - Age >50 years ### Contrast Media Selection | Agent Type | Osmolality | CIN Risk | Recommendation | |------------|-----------|----------|----------------| | HOCM (ionic) | >1400 | Very high | Avoid | | LOCM (non-ionic) | 600–900 | Moderate–low | **Preferred** | | IOCM (non-ionic) | ~290 | Low | **Optimal** | **High-Yield:** LOCM or IOCM are mandatory in high-risk patients; HOCM are contraindicated. ### CIN Prevention Protocol 1. **Hydration:** Normal saline 0.9% at 1 mL/kg/hr for 12 hours pre-procedure and 6 hours post-procedure (or 600 mL bolus if urgent). 2. **Contrast volume:** Limit to <5 mL/kg body weight. 3. **Medication adjustment:** **Metformin must be held** at the time of contrast administration and for 48 hours post-procedure (or until renal function confirmed stable). 4. **Avoid nephrotoxic drugs:** NSAIDs, ACE inhibitors (relative), diuretics. **Warning:** Metformin + contrast media + renal impairment = **increased risk of contrast-associated lactic acidosis (CALA)**, a rare but life-threatening complication. Metformin is NOT continued during the procedure. ### Acute Allergic Reaction Management | Reaction Type | Severity | Management | |---------------|----------|-------------| | Urticaria, pruritus | Mild | Antihistamines (diphenhydramine 25–50 mg IV) | | Angioedema, bronchospasm | Moderate–severe | Stop contrast, epinephrine 0.3–0.5 mg IM, IV access, oxygen, corticosteroids | | Anaphylaxis | Severe | Epinephrine first, then IV fluids, antihistamines, corticosteroids | **Clinical Pearl:** Allergic reactions to non-ionic contrast are rare (<1%); premedication with corticosteroids and antihistamines is recommended only for prior severe reactions (anaphylaxis, bronchospasm).