Flow rates through intravenous access devices: an in vitro study.

STUDY OBJECTIVE: Fluid administration using intravenous (IV) access devices is required in many settings. There are a lack of quantitative data comparing traditional cannulas and modern access devices. We aimed to investigate flow rates through modern intravenous access devices using an in vitro system. DESIGN: This is an experimental study. SETTING AND MEASUREMENTS: Rates of flow of intravenous fluids (crystalloid and colloid) were measured through various access devices using a uroflowmeter. Standardized conditions and repeat measurements ensured validity. Fluid was administered with or without the addition of a pressure bag and needle-free valve. MAIN RESULTS: Increasing the size of cannulas improved flow. Fourteen-gauge cannulas had significantly higher mean flow rates compared to 14G central venous lines in all conditions (136% higher with no pressure bag/valve; 95% CI, +130% to +152%; P < .001). Both the emergency infusion device and rapid infusion catheter produced significantly increased mean flows compared to a 14G cannula (12% higher for emergency infusion catheter; 95% CI, +7% to +15%; P = .008, and 15% higher for rapid infusion catheter; 95% CI, +12% to +21%; P = .004). The needle-free valve significantly impaired flow on 16G and wider IV access devices (36% lower with no pressure bag using 14G cannula; 95% CI, -29% to -46%; P = .003), but flow reductions in narrower IV access were insignificant. Pressure bags significantly improved flow in all devices, in all combinations. CONCLUSIONS: Flow rates in IV devices can be maximized by pressure bag use and removal of needle-free valves. The rapid infusion catheter and emergency infusion catheter allow some increase in flow over a 14G cannula. Familiarity with varying flow rates across IV access devices could better inform clinical decisions.