V. Bocci et al., Ozonation of blood during extracorporeal circulation. I. Rationale, methodology and preliminary studies, INT J ARTIF, 22(9), 1999, pp. 645-651
We investigated whether exposure of blood ex-vivo to oxygen-ozone (O-2-O-3)
through a gas exchanger is feasible and practical. We first evaluated the
classical dialysis-type technique but we soon realized that semipermeable m
embranes are unsuitable because they are hydrophilic and vulnerable to O-3.
We therefore adopted a system with hydrophobic O-3-resistant hollow fibers
enclosed in a polycarbonate housing with a membrane area of about 0.5 m(2)
. First we tested the system with normal saline, determining the production
of hydrogen peroxide (H2O2) at O-3 concentrations from 5 to 40 mu g/ml. We
then evaluated critical parameters by circulating swine blood in vitro; th
is revealed that heparin is not an ideal anticoagulant for this system. Fin
ally, we performed several experiments in sheep and defined optimal anticoa
gulant dose (sodium citrate, ACD), priming solution, Volume of blood flow p
er min, Volume and concentration of O-2-O-3 mixture flowing counter-current
with respect to blood and the time necessary for perfusion in vivo. The bi
ochemical parameters showed that an O-3 concentration as low as 10 mu g/ml
is effective this means that gas exchange and O-3 reactivity are rapid and
capable of inducing biological effects. The sheep showed no adverse effects
even after 50 min of extracorporeal circulation at higher O-3 concentratio
ns (20 to 40 mu g/ml) but the exchanger became less effective (low pO(2) va
lues) due to progressive clogging with cells.