CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 6, July 2013
224
AFRICA
Ventilation during cardiopulmonary bypass did not
attenuate inflammatory response or affect postoperative
outcomes
AHMET BARIS DURUKAN, HASAN ALPER GURBUZ, NEVRIYE SALMAN, ERTEKIN UTKU UNAL,
HALIL IBRAHIM UCAR, CEM YORGANCIOGLU
Abstract
Introduction:
Cardiopulmonary bypass causes a series
of inflammatory events that have adverse effects on the
outcome. The release of cytokines, including interleukins,
plays a key role in the pathophysiology of the process.
Simultaneously, cessation of ventilation and pulmonary
blood flow contribute to ischaemia–reperfusion injury in
the lungs when reperfusion is maintained. Collapse of the
lungs during cardiopulmonary bypass leads to postoperative
atelectasis, which correlates with the amount of intrapul-
monary shunt. Atelectasis also causes post-perfusion lung
injury. In this study, we aimed to document the effects
of continued low-frequency ventilation on the inflamma-
tory response following cardiopulmonary bypass and on
outcomes, particularly pulmonary function.
Methods:
Fifty-nine patients subjected to elective coro-
nary bypass surgery were prospectively randomised to two
groups, continuous ventilation (5 ml/kg tidal volume, 5/min
frequency, zero end-expiratory pressure) and no ventilation,
during cardiopulmonary bypass. Serum interleukins 6, 8 and
10 (as inflammatory markers), and serum lactate (as a mark-
er for pulmonary injury) levels were studied, and alveolar–
arterial oxygen gradient measurements were made after the
induction of anaesthesia, and immediately, one and six hours
after the discontinuation of cardiopulmonary bypass.
Results:
There were 29 patients in the non-ventilated and
30 in the continuously ventilated groups. The pre-operative
demographics and intra-operative characteristics of the
patients were comparable. The serum levels of interleukin 6
(IL-6) increased with time, and levels were higher in the non-
ventilated group only immediately after discontinuation of
cardiopulmonary bypass. IL-8 levels significantly increased
only in the non-ventilated group, but the levels did not differ
between the groups. Serum levels of IL-10 and lactate also
increased with time, and levels of both were higher in the
non-ventilated group only immediately after the discontinu-
ation of cardiopulmonary bypass. Alveolar–arterial oxygen
gradient measurements were higher in the non-ventilated
group, except for six hours after the discontinuation of
cardiopulmonary bypass. The intubation time, length of stay
in intensive care unit and hospital, postoperative adverse
events and mortality rates were not different between the
groups.
Conclusion:
Despite higher cytokine and lactate levels and
alveolar–arterial oxygen gradients in specific time periods,
an attenuation in the inflammatory response following
cardiopulmonary bypass due to low-frequency, low-tidal
volume ventilation could not be documented. Clinical param-
eters concerning pulmonary and other major system func-
tions and occurrence of postoperative adverse events were
not affected by continuous ventilation.
Keywords:
cardiopulmonary bypass, respiration, artificial,
lactic acid, interleukins
Submitted 28/3/13, accepted 24/5/13
Cardiovasc J Afr
2013;
24
: 224–230
DOI: 10.5830/CVJA-2013-041
Since the development of the first heart–lung machine in the
1950s, cardiopulmonary bypass (CPB) has been the only way
to provide a motionless and bloodless field. During CPB,
circulation is maintained by mechanical pumps and venous blood
is artificially oxygenated.
1
Cardiopulmonary bypass is a non-physiological state
where blood is exposed to artificial surfaces; laminar flow is
employed instead of pulsatile flow, the heart is exposed to
cold cardioplegic arrest and the body temperature is lowered.
These key derangements lead to a series of inflammatory events
involving the endothelium, leukocytes, platelets, complement
system and the coagulation cascade, with the release of various
cytokines.
2
Surgical trauma, blood product transfusion and
haemodilution also participate in this inflammatory process.
3
During CPB, pulmonary arterial circulation and alveolar
ventilation are ceased and only bronchial arterial circulation
supply oxygen to the lungs.
3
After weaning from CPB, pulmonary
reperfusion leads to ischaemia–reperfusion injury (I/R), with
the release of oxygen free radicals and the resultant lipid
peroxidation and endothelial damage.
4
Maintaining ventilation
and pulmonary flow during CPB attenuates the inflammatory
response.
3,5
In this study, we aimed to compare ventilation and
non-ventilation regimes during CPB in patients undergoing
on-pump coronary artery bypass grafting (CABG). Its influence
on pulmonary injury was evaluated using lactate levels and
Department of Cardiovascular Surgery, Medicana
International Ankara Hospital, Ankara, Turkey
AHMET BARIS DURUKAN, MD,
HASAN ALPER GURBUZ, MD
HALIL IBRAHIM UCAR, MD
CEM YORGANCIOGLU, MD
Department of Anesthesia, Medicana International Ankara
Hospital, Ankara, Turkey
NEVRIYE SALMAN, MD
Department of Cardiovascular Surgery, Ankara Yuksek
Ihtisas Hospital, Ankara, Turkey
ERTEKIN UTKU UNAL, MD
