B LO O D PUMPS Harvard Apparatus Pulsatile Blood Pumps (continued) Pressure Curves The shape of the output pressure curve is a function of both the pump action and the characteristics of the external system on the output valve side. The following set of curves were obtained with Model 1421, using water as the pumped medium. In the tests, “Sanborn” pressure transducers were inserted in three places, and continuous records obtained under varying conditions. Curve A Curve B Curve C Pressure just beyond the output valve Pressure within the pump chamber Pressure just before the intake valve BLOOD PUMPS Harvard Apparatus Pulsatile Blood Pumps By variation of parameters involved (peripheral resistance, stroke rate, stroke volume and phase ratio), an infinite number of output flow characteristics can be obtained. Hemolysis Test Conditions Models for Dog/Monkey (PC4 55-5321) and Large Animals (PC4 55-3305) Hemolysis ranged from 0.114 mg% to 0.29 mg% per pass through the various pumps, with an error of ±10%. To put these results in perspective, most physiological perfusions are run with flow rates and total blood primes, such that the number of passes through the pump will range from about 1/4 to 3/4 per minute. Assuming one pass in two minutes and no physiological removal of the products of hemolysis, then hemolysis rates would range from 3.4 mg% to 8.7 mg% per hour of pump use. In these studies a reservoir of 500-800 cc of fresh dog blood was used, connected to the pump by 3/8” PVC tubing. Samples at room temperature were taken at 15 and 30 minute intervals for 4 to 5 hours. Samples were spun down and hemolysis measured immediately using the method of Flink and Watson. Since the rate of hemolysis depends on the amount of blood in the system and the flow rate, the results are reported as mg% per pass. The flow rate divided by the volume of blood in the system determines the number of passes through the pump per minute. Pressure and Flow Curves Using Harvard Pulsatile Blood Pump for Dogs/ Monkeys in Isolated Perfusion of Left Lower Lobe of Dog Lung* Pa Pv Qpa Pa Pv Qpa Pulmonary Artery Pressure Pulmonary Venous Pressure Pulmonary Artery Blood Flow Instrumentation: Pressure Flow Recording Statham Biotronex Electromagnetic Flowmeter Electronics for Medicine *Note: The above data is supplied through the courtesy of Cardiorespiratory laboratory Columbia-Presbyterian Medical Center New York, New York, Dr. Alfred P. Fishman, Director. Harvard Apparatus phone 508.893.8999 toll free U.S. 800.272.2775 fax 508.429.5732 www.harvardapparatus.com 85