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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 6, November/December 2019
336
AFRICA
Effects of cardiopulmonary bypass on pulmonary
function in COPD patients undergoing beating heart
coronary artery bypass surgery
Erdem Çetin, Levent Altınay
Abstract
Background:
The aim of this study was to compare the effects
of cardiopulmonary bypass (CPB) on the postoperative
course of patients with chronic obstructive pulmonary disease
(COPD) following coronary artery bypass graft (CABG)
surgery.
Methods:
This retrospective study included 375 COPD
patients who underwent isolated CABG surgery with either
on-pump (group 1) or off-pump beating heart techniques
(group 2) between April 2014 and August 2018.
Results:
Group 1 included 42 (11.2%) and group 2 includ-
ed 333 (88.8%) patients. The mean mechanical ventilatory
support times of groups 1 and 2 were 10.6
±
36.2 and 5.1
±
2.61 hours, respectively (
p
=
0.561). The mortality rates of
groups 1 and 2 were 4.76% (two patients) and 1.50% (five
patients), respectively (
p
=
0.142).
Conclusion:
The on-pump beating heart CABG surgery did
not affect the postoperative mechanical ventilatory support
times in patients with COPD.
Keywords:
chronic respiratory disease, coronary artery bypass
surgery, beating heart coronary artery bypass, off-pump coro-
nary artery bypass, mechanical ventilation
Submitted 11/2/19, accepted 8/5/19
Published online 24/5/19
Cardiovasc J Afr
2019;
30
: 336–340
www.cvja.co.zaDOI: 10.5830/CVJA-2019-030
Off-pump (OPCAB) and on-pump beating heart (ONBHCAB)
coronary artery bypass graft (CABG) surgery have frequently
been utilised in the last decades in order to eliminate the untoward
effects of cardioplegia and ischaemia on the myocardium, such
as impaired contractility or myocardial stunning.
1
On the other
hand, cardiopulmonary bypass (CPB) has some detrimental
pulmonary and systemic effects because of the inflammatory
mediator activity triggered by the CPB itself.
2
Although the presence of chronic obstructive pulmonary
disease (COPD) is considered to be a high-risk factor for CABG
surgery and it is related to poorer early postoperative outcomes,
3,4
some studies do not support this observation.
5,6
Patients are
generally weaned from mechanical ventilatory support (MVS)
as soon as they are able to continue breathing on their own,
along with some other conditions such as stable haemodynamic
status, total consciousness and fully recovered motor functions.
The definition of prolonged mechanical ventilation (PMV)
varies according to the time threshold selected and it is related
to a postoperative mortality rate of up to 42%.
7
The incidence
of PMV has been reported to be between 2.9 and 8.6% and the
presence of a pre-operative respiratory disease has been found to
be a risk factor for PMV.
8,9
The aim of this study was to evaluate the effects of CPB
on postoperative pulmonary function in a subgroup of CABG
patients who all had COPD and were being operated on
with beating heart techniques for surgical coronary artery
revascularisation.
Methods
This study included 375 COPD patients who underwent isolated
beating heart CABG surgery between April 2014 and August
2018 in a single cardiac surgery centre. Group 1 included 42
(11.2%) ONBHCAB patients and group 2 included 333 (88.8%)
OPCAB patients. All operations were performed by the same
surgical team with either OPCAB or ONBHCAB techniques.
Patients who underwent emergency operations were excluded as
spirometry data could not be obtained.
A diagnosis of COPD was confirmed with both medical
history and spirometric analysis. Patients with dyspnoea, chronic
cough and sputum production, history of exposure to tobacco
smoke and with a post-bronchodilator ratio of forced expiratory
volume in the first second and forced vital capacity (FEV
1
/FVC)
less than 0.70 were classified as having COPD. The severity of
COPD airflow limitation was determined with regard to the
FEV
1
value, as suggested by the Global Initiative for Chronic
Obstructive Lung Disease (GOLD) study
10
(Table 1).
All spirometric evaluations were performed pre-operatively
and according to the criteria presented in the guidelines published
by the American Thoracic Society (ATS)/European Respiratory
Society (ERS).
11
Bronchodilator therapy was ceased before the
test, as suggested in the guidelines (short-acting
β
-agonists or
anticholinergic agents four hours, and long-acting
β
-agonists or
oral therapy with aminophylline 12 hours before analysis).
Each patient was asked to perform a minimum of three
blows. If eight manoeuvres had not produced a satisfactory set
of results, the test was terminated since the results would be
problematic.
12
In such cases, the test was repeated the following
day. Patients who could not participate in the spirometry tests
were excluded. Maximum FVC and FEV
1
values obtained from
Department of Cardiovascular Surgery, Karabük University,
Karabük, Turkey
Erdem Çetin, MD,
erdem1978@gmail.comDepartment of Cardiovascular Surgery, Bülent Ecevit
University, Zonguldak, Turkey
Levent Altınay, MD