Jw. Mulholland et al., Investigation and quantification of the blood trauma caused by the combined dynamic forces experienced during cardiopulmonary bypass, PERFUSION-U, 15(6), 2000, pp. 485-494
Blood is exposed to various dynamic forces during cardiopulmonary bypass (C
PB). Understanding the damaging nature of these forces is paramount for res
earch and development of the CPB circuit. The object of this study was to i
dentify the most damaging dynamic non-physiological forces and then quantif
y this damage.
A series of in vitro experiments simulated the different combinations of dy
namic forces experienced during CPB while damage to the blood was closely m
onitored.
A combination of air-interface (a) and negative pressure (P) caused the gre
atest rate of change in plasma Hb (Deltap (H) over dotb) (4.94 x 10(-3) mg/
dl/s) followed by negative pressure and then an air interface. Shear stress
es, positive pressures, wall impact forces and a blood-nonendothelial surfa
ce caused the least damage (0.26 x 10(-3) mg/dl/s). An air interface showed
no threshold value for blood damage, with the relationship between the siz
e of the interface and the blood damage modelled by a second-order polynomi
al. However, negative pressure did exhibit a threshold value at -120 mmHg,
beyond which point there was a linear relationship.
Investigating the reasons for the increased blood trauma caused by the low-
pressure suction (LPS) system makes it clear how research into minimizing o
r completely avoiding certain forces must be the next step to advancing ext
racorporeal technology.