Impact of Patient Volume on Iodinated Contrast Material Waste with Multidose Contrast Injectors.

Background: Multidose iodinated contrast media (ICM) injectors have shown promise in reducing ICM waste. This study aims to evaluate the impact of patient volume on ICM waste reduction in multidose injectors.

Methods: CT studies performed over one-year period with a multidose injector at our emergency CT unit. We recorded the ICM volume, time, and date for each injection and calculated total annual ICM use, accounting for the 500 mL ICM containers' 8-hour window usage limit. We then calculated the ICM waste for the same patient cohort assuming single-dose vials used with single-dose injectors were used instead, without the 8-hour window for usage. To assess the impact of patient volume, we evaluated six subgroups based on daily injected patient counts: Group 1 (<10 patients/day), Group 2 (10-19 patients/day), Group 3 (20-29 patients/day), Group 4 (30-39 patients/day), Group 5 (40-49 patients/day), Group 6 (≥50 patients/day). Annual and mean per patient ICM waste was calculated for both injector types and compared among all subgroups.

Results: In total, across 12,290 scans, multidose injectors reduced annual ICM waste by 86.1% compared to single-use injectors. Annual ICM waste was zero on days with 50 or more patients and was minimal (253 mL) for days with 40-49 patients. A significant negative correlation between patient volume and ICM waste was observed (r=-0.365, p<0.0001). Mean ICM waste per patient was 2.5 times higher in Group 1 and 71.4% higher in Group 2 with multidose injector compared to single-dose injector. Conversely, in groups with at least 20 patients per day, mean ICM waste per patient was lower with multidose injectors compared to single-dose injectors. Mean ICM waste per patient was reduced by 53.9% in Group 3, 88.9% in Group 4 and 100% in Group 6.

Conclusion: High patient throughput centers with over 40 patients per day can nearly eliminate ICM waste with multidose injectors. However, using multidose injectors in centers with lower patient volumes (<20 patients per day) may lead to increased ICM waste compared to single-dose injectors, underscoring the importance of aligning injector choice with patient volume to optimize resource utilization and minimize waste.