Rationale and impact
This section briefly explains why the committee made the recommendations and how they might affect practice. It links to details of the evidence and a full description of the committee's discussion.
For adults undergoing procedures with intravenous iodine-based contrast media, the evidence showed that oral fluids were as good as intravenous fluids at preventing contrast-induced acute kidney injury. The evidence did not show that any particular type of oral or intravenous fluids is most effective.
The committee agreed that intravenous fluids are not necessary for outpatients who are usually at a lower risk of contrast-induced acute kidney injury. It also agreed that only inpatients at particularly high risk needed intravenous fluids. Most of the risk factors were taken from recommendation 1.1.6 (developed as part of the 2013 guideline) apart from the level of eGFR which was based on the committee's clinical knowledge and experience. The committee also agreed that, based on their experience and expertise, the risk for intra-arterial administration depends on the site of the injection, and is particularly high with first-pass renal exposure because the contrast medium passes into the kidneys relatively undiluted.
For inpatients at particularly high risk of contrast-induced acute kidney injury, economic modelling showed that intravenous volume expansion with a regimen containing intravenous sodium chloride 0.9% and/or intravenous sodium bicarbonate provides best value.
Based on the evidence, the committee decided that intravenous volume expansion should be used only for inpatients at particularly high risk and that oral hydration should be encouraged in all other adults at increased risk of contrast-induced acute kidney injury.
The committee agreed that more research on estimating the risk of contrast-induced acute kidney injury would help to inform future guidance, so made a research recommendation on the use of eGFR thresholds to stratify risk.
Although the committee agreed that oral hydration regimens were non-inferior to intravenous hydration regimens at preventing contrast-induced acute kidney injury, there was not enough comparative data to enable them to be clear about which oral fluid (if any) was most effective. There was some limited evidence that N-acetylcysteine was not beneficial. However, the committee agreed that, in the absence of evidence of harm, this was not sufficient to make a recommendation to restrict its use. Therefore, it made a research recommendation on different oral fluids and different oral fluid regimens, with and without N-acetylcysteine.
The committee did not consider it necessary for all patients being offered iodine-based contrast media to be routinely discussed with a nephrology team, but concluded that this was important for adults on renal replacement therapy, including people with a kidney transplant. The radiology team responsible for administering the contrast medium or the healthcare professional offering the procedure, such as a cardiologist, would usually do this. For people with other contraindications to intravenous fluids, the committee agreed that the decision to give iodine-based contrast media was better made by individual healthcare professionals.
The recommendations may result in lower resource use for outpatient procedures because people will not need to be admitted to hospital to be given intravenous fluids for volume expansion before they are given a contrast medium.
The recommendation on intravenous volume expansion reflects current practice so there should be no change in practice for inpatients who are at particularly high risk of contrast-induced acute kidney injury. There may be reduced resource use for lower risk inpatients who will not need intravenous fluids.
Full details of the evidence and the committee's discussion are in evidence review A: preventing contrast-induced acute kidney injury.