Ventilatory function during urography: a comparison of iopamidol and sodium iothalamate

The effects on respiratory function during intravenous urography of the ionic contrast medium sodium iothalamate and the non-ionic contrast medium iopamidol were compared. Forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were recorded in 37 non-atopic patients referred for intravenous urography. Nineteen patients received iopamidol and 18 patients received sodium iothalamate. Both the sodium iothalamate and the iopamidol groups showed a significant fall in FEV1 and FVC (P less than 0.001). The reductions in FEV1 and FVC were comparable and were not symptomatic. The differences in the percentage changes of the FEV1 and FVC in the iopamidol and the sodium iothalamate groups were not statistically significant (P greater than 0.5 and P greater than 0.1 respectively). No significant change in the ratio of the FEV1 and the FVC was demonstrated in either the iopamidol or the sodium iothalamate groups. Both the ionic and the non-ionic contrast media produced a measurable but asymptomatic and biologically insignificant fall in static ventilatory function. Bronchospasm does not appear to be an important contrast-induced effect in non-atopic individuals. Iopamidol offers no advantage over sodium iothalamate with respect to ventilatory effects in non-atopic patients undergoing intravenous urography.