Protocol for iv. iodine and gadolinium contrast studies Royal College of Radiologists Standard The individual administering the contrast agent must ensure that the patient understands that it is to be given and agrees to proceed. Renal Function Excretory kidney function is measured as the Glomerular Filtration Rate (GFR) GFR is a measure of the rate at which blood is filtered by the kidneys (ml/min). For day to day use, excretory kidney function is measured by measuring the concentration of Creatinine (Serum Creatinine) High creatinine levels indicate poor excretory kidney function. The simplest way to assess GFR is to use a formula from the serum Cr level with the help of a calculator. egfr = estimated GFR. Can be used only in patients over18 years old! available egfr calculator: ( USE umol/l!) http://www.nkdep.nih.gov/professionals/gfr_calculators/index.htm http://www.kidney.org/professionals/kdoqi/gfr_calculator.cfm http://www.renal.org/egfrcalc/gfr.pl If Cr LEVEL IS MORE THAN 100 ALWAYS USE THE CALCULATOR The stages of CKD (Chronic Kidney Disease) based on GFR level 1 90+ Normal kidney function but urine findings or structural abnormalities or genetic trait point to kidney disease. Observation, control of blood pressure. 2 60-89 Mildly reduced kidney function, and other findings (as for stage 1) point to kidney disease. Observation, control of blood pressure and risk factors. 3 30-59 Moderately reduced kidney function Renal insufficiency Observation, control of blood pressure and risk factors. 4 15-29 Severely reduced kidney function Renal Impairment Planning for endstage renal failure 5 <15 Very severe, or endstage kidney failure (sometimes call established renal failure) Dialysis
Contrast Media Induced Nephrotoxicity / CMN Increase in serum Cr by more than 25% or 44 mmol/l from base line within 3 days following contrast injection. 3rd most frequent cause for acute renal failure - 12% prevalence Risk factors: Pre-existing renal impairment Diabetes High Osmolar CM Large dose of CM (> 100 ml) Dehydration Hypertension Congestive Cardiac Failure In worst cases CMN occurs in 50% of patients In-hospital mortality of CMN patients, who require dialysis can be as high as 35% Protection: Volume expansion, Iv saline 8 12 hours before and after ( 1ml/kg/hour) Infusion starting at the time of injection is not helpful! Alternative combined oral and iv saline infusion Contraindicated in cardiac failure Royal College of Radiologists Standards for Iv. Contrast Agents In the presence of renal impairment all Iodine an high volume Gadolinium contrast agents are nephrotoxic. Nephrotoxicity is related to: the extent of pre-existing renal impairment dose of the contrast agent state of patient hydration Se Cr level should be available for all patients: history of renal disease or diabetes angiographic procedures Recommendations 1. Check for risk factors, especially previous renal disease and diabetes. Questionnaire has to include. 2. Always check if Se Cr level prior to iv. contrast (iodine and gadolinium) is available, especially for inpatients 3. Se Cr always must be measured before iv CM: Intraarterial procedure (catheter angiography) History of renal insufficiency / impairment Diabetes 4. Use of egfr calculator for adults (available on internet)
Recommendations CT/IVU/angiography contrast media (CM) Visipaque is not recommended as a safe contrast! Simplified scoring system: Hypertension: Severe heart failure: Over 75: Diabetes: egfr 30-60 if egfr is < 30 contrast is relative contraindication! Score: 1 - Oral hydration is sufficient iv. contrast can be given 2 - No contrast or alternative imaging or Iv. hydration protocol* 3 - No contrast or alternative imaging or Iv. hydration protocol* 4 - No contrast or alternative imaging 5 - No contrast or alternative imaging *please note that iv. hydration might be contraindicated in severe heart failure or pulmonary oedema. Patients with GFR 60-30 ml/min / Renal Insufficiency CM is relatively contraindicated, alternative imaging advised Check additional risks, use the simplified scoring system If no alternative available: Consultation with requesting doctor Potential additional risk factors (diabetes, hypertension, dehydration, cirrhosis, age) Maintain Iv. hydration as per protocol Use of minimum CM dose (0.5 ml/kg) Use of low osmolar CM Follow up Se Cr level check 24-48 hours Patients with GFR 30-15 ml/min / Renal Impairment Patients with GFR < 15 ml/min / End stage Failure CM not indicated at all, alternative imaging advised. Only CT angiography might be permitted as no other safe alternative is generally available. Smallest dose possible has to be used and 6 hour pre and 12 hours post iv hydration has to be done. Patients on permanent dialysis can get Iodine CM followed by dialysis if contrast study is necessary. Preferably same day dialysis.
Metformin Metformin is not recommended for use in diabetics with renal impairment, because it is exclusively excreted via the kidneys. Accumulation of Metformin may result in the development of the serious complication lactic acidosis. If the serum Cr is normal, the Metformin should be withheld for 48 hours after the procedure. Serum Cr level needs to be checked 24 48 hours after the injection. If the Cr is normal, the patient can safely go back to metformin. If the serum Cr is raised the need for contrast should be re-assessed. If iv contrast is necessary, the Metformin should be withheld 48 hours before and after the procedure. Renal function has to be re-assessed before continuing Metformin. Contribution of seafood and other allergies No evidence of benefit for the prophylactic use of steroids in the prevention of severe reactions to contrast media. It must be noted that suspicion of seafood "allergy", often based more on medical myth than fact, is not a sufficient contraindication to the use of iodinated contrast material. A relationship between iodine levels in seafood and seafood allergy is part of medical lore. While iodine levels in seafood are higher than in non-seafood items, the consumption of the latter exceeds that of the former by far and there is no evidence that the iodine content of seafood is related to reactions to seafood. Available data suggests that seafood allergy increases the risk of a contrast-mediated reaction by approximately the same amount as allergies to fruits or those with asthma. In other words, over 85% of patients with seafood allergies will not have an adverse reaction to iodinated contrast. Finally, there is no evidence that adverse skin reactions to iodine-containing topical antiseptics (e.g., Betadine, Povidine) are of any specific relevance to administration of I.V. contrast material.
GADOLINIUM / MR CONTRAST Creatinine level should be measured in all risk patients before Gd contrast! Recommendations 1. Check for risk factors, especially previous renal disease and diabetes. Questionnaire has to include. 2. Always check if Se Cr level prior to iv. contrast (iodine and gadolinium) is available, especially for inpatients 3. Se Cr always must be measured before iv CM: History of renal insufficiency / impairment Diabetes Use of egfr calculator for adults (available on internet) Nephrogenic Systematic Fibrosis / NSF NSF cases have occurred in patients who had received a gadolinium-based contrast agent for MRI or MRA. Tight, rigid skin that renders bending of the joints difficult, and fibrosis that may lead to multiorgan failure and death. Occurs in patients with impaired renal function and acidosis (3-5%) No known treatment, but improved renal function appears to slow or arrest its development. Most cases, 90% associated with Omniscan, less cases associated with Magnevist and Optimark (US) 250-300 cases worldwide. All of the MRI contrast agents potentially may be linked to a risk for NSF. NSF and Gadolinium contrast agents Medium risk: Ionic linear chelates: Magnevist, Multihance, Primovist, Vasovist Non-ionic cyclic chelates: Prohance, Gadovist Cyclic chelates are considered more stable Should not be used in at-risk patients, unless regarded clinically essential Minimum dose to be used No effective method of removing free Gadolinium ions from the body. Dialysis is not proved to be protective against NSF, although excretory rates of gadolinium during consecutive hemodialysis sessions are 78%, 96%, and 99%, respectively. Patients with GFR lower than 30 ml/min are at higher risk (stage 4-5)
Recommendations MR contrast media (CM) Patients with egfr 60-30 ml/min / Renal Insufficiency Omniscan, Magnevist are not indicated, Primovist and Multihance relatively contraindicated Prohance, Gadovist, can be given 0.2 ml/kg for MR angiography, but max. 15 ml 0.1 ml/kg for other but max 10 ml Oral hydration has to be maintained. Patients with egfr 30 15 ml/min / Renal Impairment Gadolinium CM not indicated, alternative imaging advised If no safe alternative is available (angiography) Gadovist can be used, max 7.5-10 ml. Iv. hydration protocol : 6 hour pre and 6 hours post iv hydration has to be done. Consultation with requesting doctor. Check potential additional risk factors (diabetes, hypertension, dehydration, cirrhosis) Patients with egfr < 15 ml/min / End stage Failure Gadolinium CM not indicated at all. If no safe alternative is available (angiography) CT angiography should be performed. Patients on permanent dialysis should get Iodine CM followed by dialysis if contrast study is necessary. It is generally believed that gadolinium-based contrast media are not nephrotoxic at the approved doses for MR (<0.3 mmol/kg body weight). Recently, a patient with diabetic nephropathy required dialysis because of anuria 6-7 days after MR angiography with 0.14 mmol/kg body weight gadolinium-dtpa-bma to assess renal artery stenosis. No special precautions (e.g., hydration) had been taken. The serum creatinine levels had been within 200 and 300 mol/l for the last 3 years with a very slow increase. This case highlights that gadolinium-based contrast media can cause contrast medium-induced nephropathy in patients with multiple risk factors.