S.K. Morcos， Sheffield Teaching Hospital， UK.

<International Circulation>:  In your opinion， how to evaluate the safety of several kinds of iodine contrast medium frequently used in clinic at present?

Prof. SK. Morcos: I think that all contrast media available for clinical use are potentially nephrotoxic in patients with pre-existing reduced renal function.  The choice of the contrast agent is not crucial providing you use a non ionic contrast medium but you have to administer the smallest possible dose that provide the required diagnostic information. There is no consistent evidence in the published scientific literature to suggest that a certain non ionic contrast medium including the iso-osmolar contrast agent is less nephrotoxic in comparison to other non ionic agents. 

<International Circulation>: What is your opinion about how to prevent and cure contrast nephropathy effectively?

Prof. SK. Morcos:  Prevention of contrast nephropathy is very important to avoid morbidity and even mortality associated with this complication. Data in the literature have shown a marked increase in the incidence of non renal complications such as sepsis， respiratory complications and major adverse cardiac events in patients who developed contrast nephropathy. Incidence of mortality amongst these patients is also substantially increased. I think it is crucially important before performing cardiac angiography to identify patients at risk of contrast nephropathy. Appropriate questionnaire about risk factors (renal disease， congestive heart failure， diabetes mellitus， hypertension， gout， treatment with nephrotoxic drugs) and measurement of serum creatinine as a marker of renal function routinely before angiographic examinations is valuable to identify patients at risk of contrast nephropathy. Patients at risk should receive the smallest possible dose of either iso-osmolar or low osmolar non ionic contrast agent and intravenous hydration with normal saline (100 ml/hour) for at least 6 hours before and after the examination. Nephrotoxic drugs should be stopped for at least 24 hours before the examination. The use of nephroprotective drugs including prophylactic administration of acetylcysteine to prevent contrast nephropathy has not been consistently effective in preventing this complication.  Haemofiltration for around 12 hours before and after contrast medium administration has also been recommended in patients with advanced renal impairment (GFR < 30 ml/min) who require interventional angiographic procedures.