M. P. KAYE AND J. B. PACE 
363 
2. Button, R. C, Mather, F. W., Ill, Walkkr, S. N., 
Lipps, B. J., Jr., Rudy, L. W., Severinghaus, J. W., 
and Edmunds, L. H., Jr. Development and Evalua- 
tion of a New Hollow Fiber Membrane Oxygenator. 
Trans. Amer. Soc Artif. Int. Organs 27:331, 1971. 
DISCUSSION 
Chairman Veith: Dr. Kaye's interesting 
j paper is now open for discussion. 
Richard E. Clark, Washington University, 
St. Louis: What was the priming solution for 
both the circuits and were the volumes de- 
creased ? 
Dr. Kaye; The priming solutions were the 
same for both circuits. We used 2 units of 
freshly drawn calf blood and filled the remain- 
der of the circuit with lactated ringers in all in- 
stances. 
Dr. Clark : What was the volume ? 
Dr. Kaye: The volume was approximately 
2,500 cc, for both circuits. 
Jack Block, Cornell University Medical 
College, New York: I think everybody should 
know that Dr. Kaye has accomplished all this 
research after having this oxygenator at his 
disposal for less than 6 months. We took 2 years 
with our Landei-Edwards membrane oxygena- 
tor to get to the same point. I think a couple of 
things that we've learned might be of some 
help. The first point concerns the outflow filter 
in front of the membrane. We've had difficulty 
on long pump runs with the filter plugging up, 
and we now put two parallel filters in front of 
the unit (using only one at a time). If debris 
accumulates in one filter, we switch to the other 
without the hectic period of trying to change 
the single filter. Second, this unit was devel- 
oped, given to the National Institutes of Health 
; for testing, and then given to Dr. Kaye. There 
are groups of investigators around the country 
who have developed membrane oxygenators and 
similar devices who have been somewhat reluc- 
tant to follow this procedure, which I think is 
presently required of anybody with an NIH 
contract. I would ask that in the future, we set 
up some mechanism for the investigator who 
I doesn't want to release his tool to the National 
1 Institutes of Health for independent testing. If 
the investigator has the facilities and the tech- 
nical ability to do the testing himself, perhaps 
he should be allowed to do so. 
Dr. Kaye : Jack, thank you very much. I like 
to point out that we received these three liter 
units from the Dow Chemical Company after 
much of the preliminary work had been done at 
the CVRI. But the three liter units were not 
produced in this mold until June or July of this 
past year, and the 6 months from initiation of 
studies to our clinical trials is a very short 
period. 
Although I did not mention it, our diagram 
shows two filters in the line, on the front and 
back end. Only one of these filters is used at any 
given time, and there is a clamp across the 
other. It's a safety device because filters do 
plug. During the course of these runs, we've 
had three of the filters plug up. 
We currently have a series of investigations 
on the prolonged use of these oxygenators un- 
derway, and we have now pumped calves for pe- 
riods of 4 and 5 days with one of these units 
doing partial bypass at rates up to 2,700 cc. 
Chairman: You indicated that the reason 
you had the bad results with your bubble oxy- 
genator bypasses was air embolism. But did you 
do a control where you used a filter and a bubble 
oxygenator? 
Dr. Kaye : Yes, we had filters in the arterial 
line with the bubble. But the foaming that we 
got from calf blood was so overwhe- ning that 
we couldn't defoam adequately through the oxy- 
genator and it went right through the filters 
into the animal. 
Chairman : Why did you use such high doses 
of heparin, 4 mg per kilogram? 
Dr. Kaye : We used this dose for a very poor 
but honest reason. Our clinical affiliate, the 
Rush Presbyterian St. Luke's Medical in Chi- 
cago, uses this dose routinely on its patients. 
Since we were going to do our clinical trials at 
their hospital, we thought we would use their 
protocol for bypass. 
Lowell Harmison, National Institutes of 
Health : I'd just like to reflect on the comment 
about clinical testing. I think the philosophy of 
the Medical Devices Application Program and 
the National Heart and Lung Institute is given 
on page 97 of the official program and abstracts 
book for this conference. We are very much 
