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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 4, July/August 2016
AFRICA
245
Similarly, Sohn
et al
. stated that there was a decrease in the
postoperative platelet counts of patients who were operated on
using a phosphorylcholine-coated oxygenator.
10
Our results have shown that IgG and IgM levels were
increased in group 1 at the end of CPB. This finding suggests
that phosphorylcholine-coated oxygenators may induce humoral
immunity. Lante
et al
. however found that both IgG and IgM
concentrations were decreased after cardiac surgery.
11
The complement system may be activated due to factors
such as ischaemia, hypoxia, haemodilution or contact with
foreign bodies.
12
In our series, C3c levels were found to be
significantly increased in group 1 at the end of CPB. Adsorption
of complements to the uncoated surfaces of fibres may be an
explanation for this difference. It must be remembered that even
the simple circulation of blood in extracorporeal systems may
lead to activation of complements.
6
Similar to our results, de Somer
et al
. found no difference
between uncoated and phosphorylcholine-coated systems with
regard to C3 and C4 levels. The increase in C3 levels up to
the first postoperative day in the phosphorylcholine-coated
group was assumed to be associated with prevention of protein
adsorption by the coating.
9
Baksaas
et al
. found no difference
with regard to levels of C3 and C4 between patients operated on
using uncoated and bio-passive coated surfaces.
13
Watanabe
et al
.
reported that there was an increase in C3 levels in both groups
in the postoperative period.
14
In another study, comparison
of phosphorylcholine- and heparin-coated oxygenators
demonstrated a rise in C3 levels in both groups.
15
Suhara
et al
. found thromboses on the surface of uncoated
oxygenator fibres.
16
Niimi
et al.
reported decreased adherence of
platelets to the fibres in heparin-coated systems.
17
However, no
difference was detected with regard to protein adsorption in the
same study.
17
Gunaydin reported that less protein adsorption was
observed on phosphorylcholine-coated oxygenators.
18
The results of our study have shown that levels of albumin
and total protein appeared significantly higher at the end of
the operation. This increase was more in the uncoated group in
our series, which is to be expected since proteins and albumin
have a greater tendency to adhere to uncoated surfaces. Electron
microscopy also exhibited a thicker protein layer on the surface
of uncoated oxygenator fibres and this finding is in conjunction
with the increased likelihood of adherence of immune system
elements to uncoated surfaces.
Some limitations of this study must be noted. First, our
sample size was small and strict criteria for inclusion of patients
were not adhered to. Moreover, the impact of metabolic,
environmental, genetic, racial and geographic factors, which
could have influenced the results, could not be completely
controlled. Therefore, interpretations and extrapolations must
be made with caution. However, we hope that the results of this
study will pioneer further trials on this topic.
Conclusion
Despite the fact that phosphorylcholine-coated oxygenators were
developed to decrease the immune response during coronary
artery bypass surgery, our results have shown that a notable
humoral immune response still exists with the use of these
materials.
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