Postperfusion lung syndrome following coronary artery bypass grafting: the timing of
extubation
Running title: Postperfusion lung syndrome
Shi-Min Yuan
Department of Cardiothoracic Surgery, Affiliated Hospital of Taishan Medical College, Taian
271000, Shandong Province, People’s Republic of China.
Correspondence to: Shi-Min Yuan, MD, PhD, Professor of Surgery & Head, Department of
Cardiothoracic Surgery, Affiliated Hospital of Taishan Medical College, 706 Taishan Street,
Taishan District, Taian 271000, Shandong Province, People’s Republic of China. Tel: +86
538 6237167; Fax: +86 538 8420042; E-mail: s.m.yuan@v.gg
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Abstract
The postperfusion lung syndrome is an uncommon event after open-heart surgery. However,
the timing of tracheal extubation after the operation remains controversy. A 58-year-old
female patient underwent coronary artery bypass grafting. She developed postperfusion lung
syndrome after the operation. In spite of stable cardiopulmonary condition, her SaO2 and
PaO2 were low. After 42 hours' intubation, she was successfully weaned and extubated. She
was doing well after the operation. Patients with postperfusion lung syndrome may benefit
from early extubation after the operation. Non-invasive ventilation support can be an adjunct
to the respiratory management if necessary.
Keywords: Coronary artery bypass; Heart-lung machine; Lung injury; Ventilation.
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Introduction
The postperfusion lung syndrome is an uncommon event after open-heart surgery with an
incidence of 1-2% [1]. In spite of the development of minimally invasive surgery and off-pump
coronary artery bypass techniques, pulmonary complications remain a leading cause of early
postoperative morbidity and mortality [2]. On the one hand, general anesthesia, thoracotomy
and sternotomy may inevitably cause respiratory function impairment; on the other hand,
aged patients may have innate lung diseases (asthma, emphysema, COPD or pulmonary artery
hypertension, etc.) may exacerbate the pulmonary complications [2]. Cardiopulmonary bypass
leads to systemic inflammatory response, which may involve pulmonary, renal, gut, central
nervous system, and myocardial dysfunction; coagulopathy; vasoconstriction; capillary
permeability; vasodilatation; accumulation of increased interstitial fluid; hemolysis; pyrexia;
and increased susceptibility to infections and leukocytosis [3]. When this pathological course
progresses prevailing with an acute lung inflammation, it is called postperfusion lung
syndrome [4]. Even though the treatment strategies for this syndrome have been described,
the timing of tracheal extubation remains controversy. This article aims to discuss this topic in
connection with a recent case.
Case Report
A 58-year-old female patient was admitted to the Department of Cardiology due to exertional
chest distress for 20 years. She had a history of hypertension and cerebral infarction. At the
initial admission, her blood pressure was 160/100 mmHg. Physical examination revealed no
rales over both lungs. Her heart rate was 68 beats/min, no heart murmur was audible.
Electrocardiogram revealed depressed S-T segment in leads I, aVL, and V4-6 and inverted T
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waves in leads V4-6 . Roentgenogram showed clear lung field (Fig. 1). She was diagnosed of old
myocardial infarction, acute coronary syndrome, primary hypertension, and cerebral
infarction. She received coronary angiography which showed a diffuse stenosis of LAD
60-80%, the first diagonal branch 70%, and mid-right coronary artery 90% (Fig. 2).
She underwent coronary artery bypass with the left internal mammary artery grafted to the
LAD, and a saphenous vein grafted sequentially to the first diagonal branch and the posterior
descending artery. The bypass time was 102 min and the crossclamp time was 72 min.
Prebypass blood-gas analysis revealed SaO2 was 91% and PaO2 was 64 mmHg.
At 8:30 AM of the first day after the operation, the module of the ventilator was changed into
CPAP, PEEP was decreased to 2 cmH2O, FiO2 to 40%, and the SaO2 was kept at 87%. At 9
o'clock, the mechanical ventilator was weaned from the patient, inspired with high
concentration of oxygen (5 L/min), and the SaO2 of the patient was kept at 82-83%. PaO2 was
51 mmHg. Meanwhile, the patient had a stable blood pressure 122/70 mmHg. She
complained no respiratory symptoms. The patient was conscious and demanded an
extubation by shaking her head. However, she was refused according to the guild line of
extubation of an SaO2 of 85% at the ICU. She was given sediment and the module of the
ventilator was changed back into PEEP 6, SIMV 10, and FiO2 60%. The patient's temperature
was normal, and no rales was audible. Blood examinations were normal for the electrolytes
and the proteins. Chest roentgenogram revealed small patchy shadows over both lungs (Fig. 3),
suggesting a diagnosis of postperfusion lung syndrome. Till then, she was intravenously
infused 310 ml, and her urinary output was 280 ml. She thus received intravenous furosemide
and high doses of methylprednisolone. She was stable and the SaO2 was 86-88% with
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intubation on the second day. She was with successfully weaned and further extubated, and
her SaO2 was 85-94% with low flow oxygen with nasal cannula. Non-invasive ventilation was
not needed. The ventilatory support time was 42 hours. Since then, she had an uneventful
course, and was discharged home 11th day after the operation.
Discussion
Postperfusion lung syndrome is a breathing complication developed within hours of cardiac
operation performed with the aid of cardiopulmonary bypass. The pathophysiological changes
may include ventilatory alcalosis, hypocapnia, hypoxemia and the rise in the alveolar arterial
oxygen gradient is increased during the second postoperative day [5]. Mitochondrial and
lamellar body damages and endothelial and alveolar swelling were major observations
following cardiopulmonary bypass under an electron microscope [6]. Postperfusion lung
syndrome seems to be related to the types of oxygenator used in the cardiac surgery, as the
clinical observations of the early years have revealed that Travenol bubble oxygenator may
bring about more severe pulmonary injury than with a membrane oxygenator [7]. Age of
patients, severity of disease, preoperative pulmonary function, prolonged duration of
extracorporeal circulation and myocardial ischemia have been found to be predisposing
factors responsible for the postoperative cardiopulmonary morbidities [8].
Patients with this syndrome may present with constitutional symptoms including weakness,
anorexia, fever, hypoventilation except for breathing problems like shortness of breath [9].
Apart from the usual management strategies, to treat the downstream, neutrophil-derived
effectors was proved to be an alternative way of therapy [10].
Invasive mechanical ventilation is associated with numerous complications and the return to
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spontaneous ventilation has many physiological benefits. Therefore, early weaning and
extubation have been proposed following trauma control surgery for these well-known reasons
in particular in those patients with stable cardiopulmonary conditions [11]. Protracted
ventilatory support may bring about mechanical damage to the patient's respiratory tract and
may alleviate the patient's immunity leading to infections and multiple organ dysfunction. If
the the patient remains hypo-oxygenation after extubation, non-invasive ventilation support
can be an adjunct to the respiratory management if necessary.
In conclusion, patients with postperfusion lung syndrome may benefit from early extubation
after the operation. Non-invasive ventilation support can be an adjunct to the respiratory
management if necessary.
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Legends of Figures
Fig. 1. Preoperative chest roentgenogram showed clear lung field.
Fig. 2. Coronary angiography which showed (A) a diffuse stenosis of the left anterior
descending coronary artery 60-80%, the first diagonal branch 70%, and (B) mid-right coronary
artery 90%.
Fig. 3. Postoperative chest roentgenogram revealed small patchy shadows over both lungs.
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Fig. 1.
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Fig. 2
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Fig. 3
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