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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 6, November/December 2019
AFRICA
339
since the ONBHCAB technique was particularly chosen in
patients with impaired left ventricular function. The OPCAB
technique is speculated to be safe and had similar clinical results
when compared with conventional CABG.
23-25
The in-hospital
mortality rate of group 2 was consistent with other results
reported in the literature.
26
Another type of haemodynamic mechanical support for
poor left ventricular function is the intra-aortic balloon pump
counter-pulsation. The rate of intra-aortic balloon pump
counter-pulsation in group 1 was significantly higher than in
group 2 (14.29 vs 3.30%, respectively,
p
<
0.001). As the mean
pre-operative LVEF was significantly lower in group 1, this result
was predicted.
PMV is another problem in these patients. Saleh
et al
.
reported the rate of PMV at 3.5 and 5.3% in moderate and
severe COPD patients, respectively, and they found a significant
difference when compared to normal patients.
9
Manganas
et
al
.
6
defined PMV as mechanical ventilation over 48 hours and
reported a non-significant difference between the rates of PMV,
which they documented at 2.6 and 3.0% in patient groups with
mild–moderate and severe COPD, respectively (
p
=
0.37). Two
patients needed PMV in the study population, one patient
(2.4%) in group 1 and one (0.3%) in group 2. This result was not
statistically significant (
p
=
0.081).
In this study, the difference in the mean MVS times of the
groups was not statistically significant but it was slightly longer
in group 1. There were three postoperative revisions in group
2 and none in group 1. It seems that it did not significantly
affect the mean MVS time of group 2 patients. The patients
were followed with a mechanical ventilator setting similar to
the traditional method, which was high tidal volume and low
positive end-expiratory pressure, until weaning from MVS.
27
Zupancich
et al
. suggested that mechanical ventilation itself
may be a co-factor that influences inflammatory reactions after
cardiac surgery.
28
They found higher inflammatory cytokine
levels in patients followed with high tidal volume/low positive
end-expiratory pressure than levels in patients followed with low
tidal volume/high positive end-expiratory pressure. They also
reported significantly higher partial pressure of carbon dioxide
levels in arterial blood, causing respiratory acidosis in patients
followed with low tidal volume/high positive end-expiratory
pressure, compared to levels in patients followed with high tidal
volume/low positive end-expiratory pressure. No respiratory
acidosis occurred in this group of patients, however, the
inflammatory cytokine levels could not be evaluated because of
lack of data.
A serious limitation of this study is the retrospective design.
Salivary cotinine levels or exhaled carbon monoxide levels could
not be measured so objective data on the smoking status of
the patients could not be acquired. Most of the patients could
not clearly list their medications for COPD. The patients were
followed up by lung disease specialists for COPD in other health
centres after being discharged from hospital so follow-up data on
their pulmonary function could not be retrieved.
Conclusion
OPCAB and ONBHCAB techniques can be safely utilised in
CABG surgery instead of conventional techniques in selected
patients. The ONBHCAB technique prevents the negative effects
of cardioplegia on the heart while it provides the haemodynamic
support of the CPB system. COPD has negative effects on
postoperative outcomes of CABG surgery. No difference was
found in MVS times of COPD patients operated with either the
OPCAB or ONBHCAB technique, so it can be stated without
hesitation that the ONBHCAB technique can be safely used in
COPD patients with impaired left ventricular function.
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