Clinical application of the M-numbers of aortic cannulas during hypothermic cardiopulmonary bypass in pediatric patients.
A standardized system to describe the pressure-flow characteristics of a given cannula has recently been proposed and has been termed the M-number system. Using 3 different sizes of aortic cannulas in 50 pediatric cardiac patients on hypothermic cardiopulmonary bypass, we analyzed the correlation between experimentally and clinically derived M-numbers and found it to be positive. Clinical M-numbers were typically 0.35 to 0.55 greater than experimental M-numbers and correlated inversely with a patient's temperature change; this was most probably due to increased blood viscosity arising from hypothermia. This inverse relationship was more marked in higher M-number cannulas. The clinical data obtained in this study suggest that the experimentally derived M-number correlates strongly with the clinical performance of the cannula and that the influence of temperature is significant.
Kim
W G
WG
Department of Thoracic and Cardiovascular Surgery, College of Medicine, Seoul National University Hospital, Korea.
Park
S S
SS
D001011:Aorta; D001809:Blood Viscosity; D002315:Cardiopulmonary Bypass / Q000295:instrumentation*; D002404:Catheterization; D002675:Child, Preschool; D006801:Humans; D007036:Hypothermia, Induced; D007223:Infant; D011312:Pressure; D012212:Rheology