Warming CT Contrast Media May Not Be Necessary

Warming iodinated CT contrast media to body temperature prior to injection may not be necessary, according to newly published research.

In a study published July 30 in the American Journal of Roentgenology, a team of investigators from Valleywise Health in Phoenix revealed that warming contrast agents to body temperature does not necessarily lower the number of adverse reactions in patients.

“The data suggest that maintaining iohexol 350 at room temperature is non-inferior to warming the agent to body temperature before injection,” said first investigator Noor Basharat from Valleywise Health’s radiology department.

Typically, iodinated CT contrast media is warmed to body temperature as a way to reduce viscosity and injection pressure. But, without data that support the overall benefit of warming, hospitals could change their protocols around iohexol 350 prior to injection, they said.

“If warming contrast media were shown to not be advantageous, then institutions would potentially no longer need to expend resources on warming, as well as no longer need to maintain a daily temperature log or provide evidence of device maintenance,” the team said.

Currently, the American College of Radiology has not provided conclusive guidance on warming iodine-based contrast media. But, they do suggest it under certain circumstances, including high-rate power injections, injections with viscous contrast material, arterial injections through small-caliber catheters, or arterial studies where timing and peak enhancement are critical.

To date, though, there has been little investigation into the relationship between contrast media temperature and adverse events. In order to get a better idea, the team conducted a retrospective study of adult patients who underwent CT exams using intravenous iohexol 350 that was either warmed or at room temperature.

Overall, they enrolled 3,939 patients who had scans with warmed contrast media and 3,933 patients who receive it at room temperature. The average patient age was 48, and the group was roughly half male and half female. Based on the team’s analysis, they saw both study groups showed no significant difference in the overall adverse event rate, extravasation rate, or allergic/allergic-like reaction rate.

“Our findings question the utility of pre-warming contrast media, which can be a resource-intensive process,” they said.

Specifically, they determined that the body temperature group experienced 11 adverse events – all extravasations. The group saw a 0-percent allergic or allergic-like reaction rate. Among the room temperature group, there were 17 adverse events – 13 extravasations and four allergic/allergic-like reactions. Their analysis identified an excess of 0.27 adverse events per 100 patients with the room temperature group – a rate below the 0.6-percent non-inferiority margin.

Based on their findings, the team concluded that expending the resources needed to pre-warm iohexol 350 prior to injection may not be warranted.

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