Nausea and vomiting after exposure to non-ionic contrast media: incidence and risk factors focusing on preparatory fasting.

OBJECTIVE: To prospectively evaluate the incidence of nausea and vomiting after exposure to non-ionic iodinated contrast media (ICM), and to identify potential risk factors, with a focus on fasting duration for solid food and fluids, separately.

METHODS: From January to March 2017, 1175 patients (605 males, 570 females; median age, 60 years; range, 20-91 years) undergoing ICM-enhanced CT were included in this study. Patients received instructions for a 6 h preparatory fast from solid food. Nausea and vomiting after ICM exposure were assessed on a 3-point scale (mild, moderate, severe). Patients' characteristics and the fasting duration were evaluated to identify risk factors using logistic regression analysis.

RESULTS: Of the 1175 patients, 34 [2.9%; 95% confidence interval (CI) (2.0-4.0)] experienced mild nausea. No patients experienced vomiting [95% CI (0.0000-0.0005)]. 1173 (99.8%) carried out a 6 h fast, and the median fasting durations were 14 h for solid food (interquartile range, 12.5-15.5 h) and 11 h for fluid (interquartile range, 0-13.5 h), respectively. Fasting durations for solid food and fluids were not associated with nausea on univariate regression analyses (p = 0.282-1.000 and  0.146-1.000, respectively). Multivariate regression analysis revealed that a history of drug hypersensitivity [odds ratio = 4.33; 95% CI (1.85-17.52); p = 0.039] was independent risk factors for nausea, whereas iobitridol was less nauseous [odds ratio = 0.32; 95% CI (0.11-0.90); p = 0.032].

CONCLUSION: Mild nausea occurred in 2.9% of patients and none vomited in our study population with a 6 h preparatory fast from solid food. Many patients underwent excessive fasting for fluids as well as solid food and their fasting durations were not associated with nausea. Advances in knowledge: We firstly evaluated fasting durations for solid food and fluids, and their impacts on vomiting or nausea after ICM exposure with an instruction of 6 h preparatory fast for solid food: many patients underwent excessive fasting for fluids and the fasting duration was unrelated to nausea.