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.

The impact of discussing preoperative fasting with patients.

Patients awaiting surgery are often fasted preoperatively well in excess of the recommended fasting times. Educated perioperative practitioners were asked to discuss preoperative starvation with patients. Preoperative starvation period for clear fluids was significantly reduced from a mean of 8 hours 30 minutes in the original audit, to 6 hours 10 minutes in this study of 113 patients (p < 0.001). Improving patient understanding of preoperative fasting can increase compliance with fasting recommendations.

Preoperative starvation in elective general surgery.

OBJECTIVE: Study preoperative fasting times of adult elective surgical patients. METHODS: Fasting times for food and clear fluids, and the information used by patients to decide when to start fasting were studied. RESULTS: Among 200 patients, median fasting times were 2-4 times the guideline recommendations. Most patients used hospital written instructions but many started fasting substantially earlier than the instructions stipulated. DISCUSSION: Improved communication with patients could improve fasting times.