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In Vitro Model of Physiological and Pathological Blood Flow with Application to Investigations of Vascular Cell Remodeling
Published on: November 3, 2015
Fluid flow through intravenous cannulae in a clinical model
Duncan McPherson1, Olukorede Adekanye, Antony R Wilkes
1Department of Anaesthesia and Intensive Care Medicine, University Hospital of Wales, Cardiff, UK.
Anesthesia and Analgesia
|March 21, 2009
Summary
Manufacturers' quoted IV cannula flows are unreliable for predicting actual fluid delivery. Actual flow rates are complex and not accurately predicted by standard formulas like Poiseuille's law.
Area of Science:
- Medical Devices
- Fluid Dynamics
- Clinical Engineering
Background:
- Accurate prediction of intravenous (IV) cannula flow is crucial for clinical practice, aiding in flow rate adjustments and device selection.
- Understanding IV cannula flow characteristics is essential for ensuring patient safety and optimizing therapeutic delivery.
Purpose of the Study:
- To evaluate the accuracy of manufacturers' quoted flow rates in predicting actual flow through IV cannulae.
- To characterize the fluid dynamics of flow through various gauges of IV cannulae under different conditions.
Main Methods:
- A simulated vein model was used with IV cannulae ranging from 14 to 20-gauge.
- Experiments involved testing flow with deionized water, Hartmann's solution, and Gelofusine, and varying feeding pressures.
- Flow rates and Reynolds numbers were measured to analyze flow characteristics.
Main Results:
- Actual flow rates deviated significantly from manufacturers' quoted values, even when controlling for fluid type and pressure.
- Flow through IV cannulae exhibited characteristics of both laminar and turbulent flow, with Reynolds numbers often below 2000.
- The relationship between cannula radius and flow was less pronounced than commonly assumed.
Conclusions:
- Poiseuille's law is inadequate for predicting IV cannula flow at clinically relevant flow rates due to non-laminar flow conditions.
- Manufacturers' maximum flow rate specifications are not reliable predictors of actual performance.
- Further research is needed to identify reliable predictors for IV cannula flow dynamics.
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