Appendicitis
Contrast Induced Nephropathy
- Overview:
- Usually the result of obstruction of the lumen of the appendix which results in bacterial overgrowth and increased pressure, ultimately leading to perforation
- Luminal obstruction can occur secondary to fecoliths, malignancy, and lymphoid proliferation
- Diagnosis by CT scan
- Normal luminal size is ~6mm, however an inflamed appendix is usually >10mm
- On contrasted CT, the inflamed appendix wall is thick with contrast enhancement
- Fat stranding & fluid may be noted surrounding the appendix
- Concurrent findings may include a small bowel obstruction, mesenteric lymphadenopathy & free fluid
- Perforation
- Free Perforation
- The perforation does not get walled off, but spreads throughout the abdomen and often results in SIRS response and sepsis
- Treatment is emergent surgical intervention with washout
- Loculated Perforation
- The perforation is walled off, usually by the omentum and forms a periappendiceal abscess
- This commonly requires drainage with CT or U/S guidance, and interval appendectomy in 6-8 weeks
- Free Perforation
Contrast Induced Nephropathy
- Proposed Mechanism of Injury
- Evidence in animal models suggest hypoxia and mitochondrial dysfunction are a result of contrast administration
- Increased viscosity in the blood following contrast administration results in decreased oxygen delivery to tissues
- Increasing concentrations of contrast in the blood result in mitochondrial dysfunction
- Patients At Risk
- Patients with a history of CHF and CKD are more likely to develop AKI following contrast administration
- In our shop, GFR<30 or Cr>2.0 is a soft cutoff due to prior studies demonstrating increased odds ratio of AKI in these patients
- Questioning the Status Quo
- A recent study by Hinson et al. examined >17K patients in a single center retrospective cohort fashion
- Primary outcome was AKI and secondary outcomes were the development of CKD or need for dialysis within 6 months
- They found no association of AKI with contrast administration (primary outcome), and no association of CKD or need for dialysis (secondary outcome)
- Limitations limit applicability, as patients in the contrast group received IVF administration at more than twice the rate of the noncontrast group