Extracorporeal circulation combined with hypothermia and hemodilution technique utilizing 5% dextrose in water
A hypothermic, low flow perfusion, utilising 5% dextrose in water as the priming
fluid in the pump-oxygenater, was carried out to observe changes in oxygen
consumption, blood pH and CO^^2 tension during the bypass period.
The heat transfer efficiency of our own device was fairly satisfactory as
compared which that of the other authors.
A low oxygen consumption which was approximately one third of the preperfusion
value, was observed during the total bypass period. This is believed to be due to
the effect of low flow rates employed, hypothermia and low CO^^2 tension observed
in these animals. In two animals, it was observed that the oxygen consumption
increased with the increase of perfusion flow rates. In principle, the oxygen
uptake of an organism may be expected to remain constant over a wide range of
perfusion flow rates, as long as the tissuessean extract whatever oxygen they need.
However, many experimental findings indicate a decrease in oxygen uptake with
decreasing perfusion rates. It appears that during periods of decreased oxygen
supply the perfused organism lives partly under anaerobic conditions and incurs an
oxygen debt which must be paid back at a later time. This was observed in these
animal showing markedly increased oxygen consumption at the postperfusion period
which reached about 150% of preperfusion value.
The pH of the arterial blood and the partition of the total CO^^2 remained within
a fairly normal range. There was marked reduction in CO^^2 tension during the
bypass period which was mainly due to the hyperventilation at the preperfusion
period. Its harmful effect on the oxyhemoglobin dissociation curve and cerebral was
The hemodilution by the use of 5% dextrose in water as the priming fluid is
considered not only insignificant as far as the oxygen carrying capacity of the
blood is concerned but also has many advantages. The hemoglobin value which was
moderately low during bypass returned to 92% of the preperfusion figure after the
bypass, indicating that most of the added fluid was not available to the
circulation oxygenater was returned to the animal.