CECT is one of the most frequently performed radiological investigations in emergency settings. Though, unquestionably, in certain circumstances, the benefit of CECT outweighs the risk of CIN in patients at risk. However, in all patients where CECT may be helpful should not form a basis for routine practice. The nephrology residents often just act to "clear" the patient for contrast study without actually knowing the patients' condition (save S.ur/ S.cr levels!). The standard line written is CECT may be undertaken if clinically indicated.
In order to identify the real exposure to contrast induced nephropathy (CIN) for a patient "risk-scores" basically derived from cardiological procedures can be found in Literature
Among them the Mehran Score (JACC 2004), the Gurm (JACC 2013) and Tziakis ones (Am J Cardiol. 2014) have been proposed to "weight" the risk of CIN using not only the renal function but a lot of other comorbidities or clinical conditions as well:
for example age, presence of diabetes (and metformin use) or peripheral arterial disease, previous percutaneous coronary interventions and so on.
Regardless the value of a single score or its clinical usefulness (in every day clinical practice the contrast can be used for many other clinical purposes than cardiological procedures) i think a notice derived from the studies cited relies in the benefit of a more wide vision of the patient because the CIN is often part of the global cardiovascular risk of the patient.
So i agree with you: the standard line is a simplistic answer to a complex question.
I think that a multidisciplinary approach in which the nephrologists critically use these clinical scores in approaching the CIN problem and the case discussion with other specialists could be a useful resource for the global care of the patient.
In addition to using one of the scores (Mehran, Gurm, or Tziakas), I would strongly recommend to assess the patient's hydration / volume status, as dehydration / volume contraction is one of the major risk factors for CIN.
Do you have an opinion about the type (low- osmolar, e.g. omnipaque, vs. iso-osmolar, e.g. visipaque) of contrast used in patients at risk for CIN?
Current Guideline (both European and US) recommend to use either low-osmolar or iso-osmolar, but not high-osmolar, CM in at-risk patients. These recommendations are based on the fact that metaanalyses of prospective clinical trials found low-osmolar CM equivalent to iso-osmolar CM regarding renal safety. It should be noted, however, that all these clinical trials were done according to protocols that mandated ample (pre-)hydration, whereas, in every-day clinical practice, patients are often not adequately hydrated. In patients who are not sufficiently hydrated, low-osmolar CM probably have an advantage over iso-osmolar CM, based upon the lower viscosity and the stronger diuretic effect of low-osmolar versus iso-osmolar CM.
Please find attached a review on mechanisms, risk factors, and prevention of CIN.
Hi Pankaj,
I view this nephrology "clearance" in two parts, depending on the source of the referral. Firstly and more commonly, is the expectation that nephrologists will identify the relevant risk factors for contrast-induced nephropathy in order to help optimize the patient's condition and minimize the risk of CIN. Others have already provided suggestions as above. Secondly, there is also perhaps a medico-legal aspect to this "clearance" as it relates to procedural informed consent, particular regarding the possibility of AKI requiring renal replacement therapy (particularly in high risk patients and existing CKD). It also means that "clearance" implies that the nephrology team will then provide supportive RRT if the worse case scenario eventuates. In some cases of multi-morbid and elderly/frail patients, RRT may not be tolerated or possible and these issues need to be discussed beforehand.
So, I totally agree with your comments that nephrology residents "clearing" a patient for CECT without due diligence and consideration of the issues, is risky not just for the patient but also potentially from a medico-legal perspective (depending on the environment you work in).
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