The Relationship Between Pressure Drops And Flow

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Background: Hemolysis is a fact in all extracorporeal circuits being used, as investigated and published by many manufacturing companies of commonly utilized capital equipment such as oxygenators and cannulae. Suggested pressure gradients are then established for the protection of blood and hemostasis of the patients undergoing cardiopulmonary bypass. Typically aortic cannulas exert higher flows through a small opening and therefore have been recommended to be limited to a pressure drop of 100 mmHg by manufactures to avoid complement activation and hemolysis to red blood cells (RBC’s).
Methods: The purpose of our study was to quantify the relationship between pressure drops and flow in commonly used extracorporeal circuits specifically to commonly utilized tubing sizes in pediatrics and neonate populations. The more commonly used arterial line tubing sizes for these particular cases studied are 3/8”, 1/4”, 3/16”, and 1/8” inch. Pressure manometers were placed pre- and post- arterial lines of six feet (1.8288 m) in length to accurately collect pressure gradients across them utilizing a roller pump as the driving force. Velocity, diameter, density, and viscosity were also all taken into account when calculating Reynolds number for the all studied tubing sizes, at different temperatures and viscosities.
Results: We propose to collect data, evaluate, and quantify flow rates, pressure drops, and other pertinent variables across different common pediatric cardiopulmonary bypass
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