CARDIOVASCULAR ENGINEERING Journal for Extracorporeal Circulation, Assist Devices,Transplantation and Artificial Organs
	Volume 2, 1997, No 4

Flow Gradients of Venous Cannulae During Extracorporeal Circulation

H. R. Shah, M. Vaynblat, C. Bertuglia, M. Chiavarelli

Abstract:
Background: The introduction of metal-tip (DLP) and plastic-tip (RM) right angle venous cannulae for cardiopulmonary bypass offers several advantages. Unfortunately, flow characteristics of both sets of cannulae have been tested with water. The purpose of this study was to use human blood to test venous cannulae at various degree of hemodilution and hypothermia. Methods: An extracorporeal circuit was assembled to test DLP and RM right angle cannulae. The study was designed to include five groups: (1) 37 °C, hematocrit 0%; (2) 15 °C, hematocrit 15%; (3) 37 °C, hematocrit 15%; (4) 30 °C, hematocrit 20%; (5) 37 °C, hematocrit 30%. The maximum acceptable flow was determined for each individual cannula size and type. Results: The maximum flows of both DLP and RM cannulae as a group were lower at a hematocrit of 30% than at a hematocrit of 15% and 0% (F = 18.40, p <0.0001). a significant difference was obtained for each type of cannulae (dlp: f="12.22," p="0.0009;" rm: f="12.66," p="0.0007)." as the temperature was decreased from 37 °c to 15 °c the maximum flow decreased by 7.7 ± 1.9 per cent from 2.45 ± 0.36 l/min to 2.28 ± 0.35 l/min (f="12.99," p="0.0026)." rm cannulae in comparison to dlp cannulae achieved a higher maximum flow. conclusions: hematocrit has a more pronounced influence on maximum flow then temperature. venous cannulae for cardiopulmonary bypass should be selected on the basis of their performance in an extracorporeal circuit primed with human blood. testing the cannulae with water will overestimate their conductance.

Keywords:
Flow gradients, extracorporeal circulation, DLP venous cannulae, RM venous cannulae

Address for Correspondence:

Reference:
(CVE. 1997; 2 (4): 260-263)

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