Contrast media algogenic potential in peripheral arteriography. Potentiation of bradykinin-induced pain in the rat

Evaluation of the acute adverse reaction of contrast medium with high and moderate iodine concentration in patients undergoing computed tomography

PURPOSE

The aim of this prospective study was to evaluate and compare acute adverse reactions between contrast medium containing moderate and high concentrations of iodine in patients undergoing computed tomography (CT).

MATERIALS AND METHODS

A total of 945 patients undergoing enhanced CT were randomly assigned to receive one of two doses of contrast medium. We then prospectively investigated the incidence of adverse reactions. Iopamidol was used as the contrast medium, with a high concentration of 370 mg I/ml and a moderate concentration of 300 mg I/ml. The frequency of adverse reactions, such as pain at the injection site and heat sensation, were determined.

RESULTS

Acute adverse reactions were observed in 2.4% (11/458) of the moderate-concentration group compared to 3.11% (15/482) of the high-concentration group; there was no significant difference in incidence between the two groups. Most adverse reactions were mild, and there was no significant difference in severity. One patient in the high-concentration group was seen to have a moderate adverse reaction. No correlation existed between the incidence of adverse reactions and patient characteristics such as sex, age, weight, flow amount, and flow rate. The incidence of pain was not significantly different between the two groups. In contrast, the incidence of heat sensation was significantly higher in the high-concentration group.

CONCLUSIONS

The incidence and severity of acute adverse reactions were not significantly different between the two groups, and there were no severe adverse reactions in either group.

Intravenous Injection of High and Medium Concentrations of Computed Tomography Contrast Media and Related Heat Sensation, Local Pain, and Adverse Reactions

OBJECTIVES

To evaluate the incidence of acute adverse reactions and degrees of heat sensation and local pain after intravenous injection of high and medium concentrations of iodinated contrast medium for computed tomography (CT).

METHODS

A prospective study was performed involving 729 patients who underwent contrast CT scans. High-concentration (370 mgI/mL) and medium-concentration (300 mgI/mL) iodinated contrast medium was assigned to 342 patients (group H, aged 20-90 years, mean = 59.8 years) and to 387 patients (group M, aged 20-95 years, mean = 61.7 years), respectively. An injection rate of contrast medium (1, 2, or 4 mL/s) at a base volume of 2 mL/kg of body weight was selected according to the protocols for the evaluated diseases and regions. Each patient was assessed for heat sensation and local pain at the injection site using a visual analog scale (ranging from none for 0 to severe for 10). Acute adverse reactions were recorded when they occurred.

RESULTS

There were no significant differences in patient background factors, including age, sex, history of prior adverse reactions, and allergies, between the 2 groups. The score for heat sensation was significantly higher in group H than in group M (4.46 +/- 2.44 vs. 3.44 +/- 2.45; P < 0.0001 for heat sensation). The data did not show a higher incidence of adverse reactions in group H than in group M (5 [1.46%] of 342 patients vs. 2 [0.52%] of 387 patients; P = 0.26) or a higher score for local pain in group H than in group M (0.98 +/- 1.70 vs. 0.88 +/- 1.49; P = 0.66), respectively.

CONCLUSIONS

High and medium concentrations of iodinated contrast medium can be used for CT study with comparable safety profiles even though heat sensation produced by the high-concentration CM is greater than that produced by the medium-concentration CM.

Evaluation of the acetazolamide test. Vasoreactivity and cerebral blood volume

BACKGROUND AND PURPOSE

We evaluated the potential usefulness of the acetazolamide test by investigating whether acetazolamide vasoreactivity reflected the change in resting cerebral blood volume caused by compensatory vasodilation due to a decline in cerebral perfusion pressure.

METHODS

We measured resting and acetazolamide-activated cerebral blood flow with a stable xenon-enhanced CT system and resting cerebral blood volume with the subtraction technique using contrast-enhanced CT in 30 patients with various diseases. These parameters were measured in the anterior, middle, and posterior cerebral arterial territories of both hemispheres separately. We evaluated the statistical relationships between resting cerebral blood volume and vasoreactivity in these three territories, and the significance of the correlations was tested by ANOVA/ANCOVA to adjust for the double entries.

RESULTS

Significant negative linear relationships were demonstrated between the resting cerebral blood volume and the change in cerebral blood flow, expressed as a percentage induced by acetazolamide activation, for the anterior (r = -.607, P = .0004), middle (r = -.551, P = .0015), and posterior (r = -.523, P = .0078) cerebral arterial territories and between the resting cerebral blood volume and the increase in cerebral blood flow (absolute values) for the anterior (r = -.512, P = .0164) and middle (r = -.523, P = .0001) but not the posterior (r = -.571, P = .0563) cerebral arterial territories.

CONCLUSIONS

The acetazolamide test appears to be useful for the investigation of compensatory vasodilation: the vasoreactivity can be calculated as the increased cerebral blood flow expressed as a percentage or an absolute value, which both reflect cerebral blood volume directly.