Prophylactic hydration measures for Contrast induced nephropathy
What prophylactic hydration measures are recommended?
Beyond supportive measures there are no treatments to reverse CIN once it is established, so prophylactic measures are the only intervention available. Prophylaxis should be used in high-risk individuals, primarily patients with impaired kidney function. Volume expansion is the only consistently effective prophylactic measure to reduce the risk for CIN. Volume expansion may work by:
- • Suppressing the renin-angiotensin system
- • Reducing vasoconstrictive mediators
- • Diluting the contrast media
- • Increasing the transit time of contrast media through the kidney
Pre-procedure hydration has been done with a variety of fluids, including oral hydration, hypotonic solutions (0.45% Normal Saline), and isotonic crystalloids (normal saline, Ringer’s lactate, and isotonic bicarbonate solutions). In a prospective trial, normal saline was superior to 0.45% saline. This is expected because the isotonic fluid provides more effective volume expansion. IV hydration is recommended over oral hydration for the same reason. Until recently, isotonic bicarbonate was suggested to be a better prophylactic solution than normal saline possibly by reducing reactive oxygen species formation. However a large study (4993 patients) comparing isotonic bicarbonate to normal saline has now been completed (PRESERVE Trial) and did not show any benefit of isotonic bicarbonate over normal saline. Thus, the former should not be used due to lack of benefit, increased cost, and risk of compounding errors.
Our recommended infusion rate is:
• Outpatient: 3 mL/kg/hr for 1 hour pre-contrast administration and 1 to 1.5 mL/kg/hr for 4 to 6 hours after contrast
• Inpatients: 1 mL/kg/hr for 6 to 12 hours pre-procedure and intra-procedure, and 6 to 12 hours post-procedure
Infusion rates may need to be reduced in patients at risk for heart failure. The safe administration of prophylactic fluids in these patients may be done by monitoring left ventricular end-diastolic pressures, which was shown to be an effective measure in reducing CIN in the POSEIDON trial.