356 
SURGERY AND TRANSPLANTATION 
GAS 
OUTLET 
INLET 
TUBESHEET 
BLOOD 
OUTLET 
HEADER 
PLUG 
FIGURE 1.— Schematic representation of hollow fiber capillary membrane oxygenator. 48,000 fibers with a surface 
area of 4.2M' are used in the 3-liter units. 
oxygenator. Oxygen enters a central manifold 
and is dispersed throughout the fiber bundles 
exiting through ports in the lucite jacket. At each 
end of the fiber bundle is a cone-shaped silicone 
header which directs the blood flow through the 
fibers. Sterilization of these units was accom- 
plished by filling the fiber bundle and the head- 
ers with 0.5% formalin solution. In all experi- 
ments reported, two of the oxygenator units 
were connected in parallel and positioned in the 
vertical position. 
Thirty-five calves ranging in weight from 
65-110 kg were used in these studies. Three 
separate groups of perfusion experiments were 
carried out: (I) membrane oxygenator without 
filters (15 animals) ; (II) membrane oxygena- 
tor with filters (10 animals) ; and (III), bubble 
oxygenator (10 animals) . A diagram of the cir- 
cuitry used in the membrane oxygenator plus 
filter perfusions is illustrated in Figure 2. The 
circuitry consisted essentially of venous drain- 
age into a 1-liter reservoir, a heat exchanger, 
and a roller pump which then pumps the blood 
through a filter and into the oxygenators. Blood 
from the oxygenators returns through the filter 
and into the femoral artery of the experimental 
animal. A similar circuit, but without filters, 
was used in the group I animals. Except for the 
reservoir and venous filters, a similar circuit 
was used in the perfusions with the bubble oxy- 
genator. 
Pressures across the filters were monitored 
continuously in all experiments using Statham 
P23dB transducers. In addition, pressures at 
both blood inlet and outlet of the membrane ox- 
ygenator were continuously monitored. Pres- 
sures were continuously recorded on a Beckman 
Dynograph. 
In all animals, anesthesia was induced and 
maintained with fluothane, nitrous oxide and 
oxygen. Following intubation, the chest was 
opened through a right lateral thoracotomy in 
the fourth interspace. The azygos vein was li- 
gated and the superior and inferior vena cava 
were isolated. The pericardium was opened and 
following intravenous administration of hep- 
arin (4 mg/kg), the inferior vena cava was 
cannulated through the right atrial appendage 
and the superior vena cava through a purse- 
string suture in the lateral wall of the right 
atrium. Arterial return to the animal was ac- 
complished by cannulation of the right femoral 
