In Vitro Analysis of Flow Rates in Peripheral Catheter Devices: Implications for Emergency Fluid Resuscitation

Rapid, intravenous (IV) infusion is critical for resuscitation in emergency medicine. Needleless connectors improve safety by reducing the risk of bloodstream infection transmission and air embolism; however, needleless connectors also significantly limit flow rates. Although prior studies demonstrated that 3-way and 4-way "high-flow" stopcocks have flow rates noninferior to uninterrupted catheter tubing, the performance of 1- and 2-way high-flow stopcocks remains poorly understood. This study evaluated flow rates across various catheter connection adjuncts to identify optimal devices for resuscitation efficacy.

A 500-mL infusion circuit of 0.9% normal saline was tested with needleless connectors, standard and high-flow stopcocks under gravity (0 mm Hg) and pressurized (300 mm Hg) conditions. A 16-gauge IV catheter connected directly to IV tubing served as the control. Fluid volume was measured gravimetrically over 120 seconds, and flow rate was calculated. Each condition was repeated in quadruplicate. Data were analyzed via 2-way analysis of variance and follow-on Tukey's post hoc testing, with multiplicity-adjusted statistical significance defined as P < .05.

The use of needleless connectors significantly decreased flow compared to control in both the gravity cohort (0.95 ± 0.018 mL/second vs. 1.19 ± 0.05 mL/second, P < .0001) and the pressurized cohort (3.10 ± 0.048 mL/second vs. 3.46 ± 0.072 mL/second, P < .0001). The use of high-flow 2-way stopcocks did not significantly reduce flow in either gravity (1.21 ± 0.05 mL/second, P = .932) or pressurized cohorts (3.42 ± 0.048 mL/second, P = .957) compared to control. In addition, the use of high-flow 3-way stopcocks did not significantly reduce flow in gravity (1.240 ± 0.02 mL/second, P = .368) or pressurized cohorts (3.43 ± 0.064 mL/second, P = .986) compared to control.

In an idealized system, the use of high-flow stopcocks allows for an 8%-10% increase in flow rate compared to needleless connectors, correlating to an additional 400 mL of fluid delivered over a 20-minute period. The 2-way high-flow stopcock could provide a significant advantage by delivering increased flow rates while offering a compact design that maintains a low operational footprint. Given the impact of rapid fluid administration in trauma and resuscitation, high-flow stopcocks may enhance emergency care efficiency in austere combat environments.