Model-based Pressure-threshold Flow-rate Estimation for Contrast Injection via Upper-arm Central Venous Ports

To characterize the association between recorded maximum delivered injection rate and peak pressure during contrast-enhanced computed tomography (CT) through upper-arm central venous (CV) ports and estimate port- and viscosity-specific flow-rate thresholds corresponding to 13 kg/cm².

This retrospective study included 205 CT examinations from 102 patients with 103 implanted upper-arm CV ports. Three port systems and eight iodinated contrast media (ICM) formulations grouped by viscosity were evaluated. A no-intercept linear model estimated separate slopes and 13 kg/cm² thresholds for nine port-viscosity combinations using the recorded maximum delivered rate with port-clustered robust inference. Sensitivity analyses excluded pressure-limit activation and flow-reduction cases and examined the 13 kg/cm² preset subgroup.

All subgroup pressure-flow slopes were statistically significant (all p < 0.001), with uncentered R² values ranging from 0.962 to 0.993. Pressure-limit activation and flow reduction occurred in 38 (18.5%) and 26 (12.7%) examinations, respectively. Pressure-flow slopes differed by port and viscosity (both p < 0.001); the port-by-viscosity interaction was not significant in the primary analysis (p = 0.336). Residual formulation-level heterogeneity was detected within viscosity groups (p < 0.001). Thresholds ranged from 2.7 to >5.0 mL/s and changed by at most 5.6% in exclusion analyses. Similar patterns persisted in the 13 kg/cm² preset subgroup despite sparse cells.

Under the evaluated clinical conditions, pressure-flow relationships through upper-arm CV ports differed by port system and ICM viscosity group. Model-based descriptive thresholds provide port- and viscosity-specific pressure-flow reference information for the evaluated combinations.