HHE Radiology and imaging supplement 2018 | Page 10

Table 1

Risk factors and prophylaxis for intravenous iodinated contrast 1, 3

eGFR level Risk Prophylaxis

≥45ml / min / 1.73m 2 Nil None

30 – 44ml / min / 1.73m 2 Low Oral or intravenous hydration

eGFR- estimated glomerular filtration rate * Will depend on patient history and known chronic kidney disease or dialysis

Figure 1 Iodinated contrast media utilised in a dual-bolus CT urogram to provide optimal enhancement of the abdominal viscera as vasculature as well as delayed visualisation of the left upper renal tract in a case of haematuria.

Figure 2A Iodinated contrast media being used to guide an interventional angiography stenting procedure of the proximal external iliac artery.

Figure 2B Confirmation of good angiographic result post-stent placement. community settings, PoC blood testing is not used widely within imaging, 7 with limited evaluation of its clinical utility in this environment. Research has shown variation between device performance, 8, 9 although there is strong concordance with laboratory testing and assurance of the performance standards of many different devices.

What has not yet been realised is the opportunity to streamline the imaging pathway and only undertake testing on patients with risk factors. This would remove a significant administrative burden from clinicians and imaging departments as well as reduce inappropriate testing. For many departments, this is a fundamental change in procedures and it will take some convincing of the validity of such a change. Research is ongoing to evaluate the implementation of a screening enabled pathway utilising PoC and this will hopefully provide evidence of the challenges and benefits of the innovation.

Case studies A 75-year-old patient was referred for a CT scan of the abdomen. The referring clinician had arranged a kidney function test, which confirmed a normal level of 70ml / min / 1.73m 2. On the scan day, the patient indicated that she had been unwell in the previous week; therefore a PoC creatinine test was performed. This identified a marked reduction in kidney function to 28ml / min / 1.73m 2, confirmed on laboratory testing. The early indication enabled appropriate action to be taken, including advice regarding proactive oral hydration. On follow up testing three days later, this had improved to 58ml / min / 1.73m 2.

Another 87-year-old patient with chronic kidney disease whose eGFR over the preceding four months varied between 39 and 44ml / min / 1.73m 2 had a PoC test on the day of her CT urogram. This showed a marked improvement with an eGFR of 64ml / min / 1.73m 2 and provided assurance around the administration of contrast. On questioning, the patient had recently been catheterised and had been maintaining her fluid balance.

Both of these case studies confirm the benefit of PoC testing for patients whose kidney function may have altered, both to ensure patient safety and to prevent contrast being withheld inappropriately.

Conclusions In the imaging setting, complications from contrast administration are thankfully rare, with a mild allergic reaction being the most commonly encountered. Contrast carries a small, and controversial, risk of PC-AKI, yet current strategies often rely on blanket testing of all patients as a precaution. The use of a screening tool and PoC testing may provide the greatest opportunity to streamline the imaging pathway and provide assurance of patient safety. International consensus on screening tools is required to enable a step change in pathway redesign underpinned by confidence in PoC device performance standards.

10 HHE 2018 | hospitalhealthcare. com