Case report
A 50 year old male weighing 75 kg was transferred to our center for
sudden chest pain lasting for 35 hours. He had an eight-year history of
hypertension, but did not receive regular medical treatment. He had no
known allergies, but had suffered from intermittent asthma for four
years, treated with an albuterol inhaler, and theophylline irregularly.
His last hospitalization was 13 months ago. He was febrile at 37.8
degree centigrade. His blood pressure was 65/45 mmHg, the heart rate was
97 beat per minute, and the central venous pressure was 20 mmHg. The
distal skin was pale and cold. He had a normal neurological exam. The
blood routine analysis showed that a white blood cell count of
18.2*109/L, and a neutrophil frequency of 86.4 percent. Computer
tomography angiography (CTA) found a large tear on the ascending aorta,
which extended to the common iliac artery, and presence of massive
pericardial fluid and patchy exudation in both lungs. Pneumonia was
diagnosed by fever, the blood routine and CT scans. Transthoracic
echocardiography reconfirmed diagnosis of TAAD, and revealed massive
pericardial fluid, and mild aortic valve regurgitation. The left
ventricular ejection fraction was 50%. Considering the unstable
dynamics, the patient was sent to the operating room immediately for
emergency surgery. Two million units of Penicillin was given
intravenously before he was sent to the operating room.
For premedication, 10 mg of morphine and 1 mg of penehyclidine
hydrochloride (anticholinergic drugs) was given intramuscularly, and 5
mg of dexamethasone and 0.25 g of aminophylline were given
intravenously. Anesthesia was achieved with fentanyl, midazolam,
atracurium besylate and isoflurane. After tracheal intubation, the lungs
were clear to auscultation, and peak inspiratory pressure was 18 mmHg.
Arterial blood gas analysis revealed no specific abnormalities. After
median sternotomy, institution of CPB proceeded uneventfully. Then the
aortic root repair and ascending aorta replacement was performed. When
the rectal temperature decreased to 23℃, deep hypothermia circulation
arrest (DHCA) and antegrade selective cerebral perfusion (SCP) was used
during the procedure of total arch remodeling by a triple-stent graft
implantation as we have previously described (14). After proximal and
distal anastomoses complete the crossclamp was removed, rewarming was
started. The aortic cross-clamp time was 54 minutes, and the total
circulatory arrest time was five minutes, while the SCP time was 20
minutes. When mechanical ventilation was resumed, expiratory wheezing
was heard, and the airway pressure was elevated to 50 mmHg. In addition,
the lungs remained inflated. After a few minutes, the lungs
over-expanded and bulged into the mediastinum.
The ventilator (Infinity C700 for IT, Drager medical GmbH, Germany) was
carefully checked and was found to be working satisfactorily. A suction
catheter was easily passed through the endotracheal tube, and no
secretions were removed. The lungs deflated when they were disconnected
from ventilator. However, they re-inflated after the ventilation was
resumed, even though the inspiratory pressure was lower down to 5 mmHg.
Fiber optic bronchoscopy was performed, and no tracheobronchial
abnormality or obstruction was found. The left atrial pressure was 7 cm
H2O. Hemodynamics were stable and transesophageal
echocardiogram confirmed normal biventricular function. No urticaria,
skin erythema or edema were present and an initial diagnosis of severe
bronchospasm was made.
To alleviate bronchospasm, ventilation with isoflurane was begun.
Intravenous amino-phylline 0.5 g and methylprednisolone 0.5 g was given,
followed by isoproterenol and metaproterenol inhalation by the
intratracheal route. 0.1ug*kg-1*min-1 of epinephrine was continuously
infused intravenously. However, the lungs showed sustained inflation for
60 minutes. Considering the long CPB time, VV- ECMO was performed. The
outflow cannula was set in the right femoral vein, and the inflow site
was the right jugular internal vein. A Quadrox oxygenator and a Rotaflow
Centrifugal pump (Maquet, Hirrlingen, Germany) were connected to the
extra-corporeal circuit. The flow rate was set at 3.5 L/min, and the
fraction of inspired oxygen was 40 percent. The ventilator was then
temporarily stopped, following which, the lungs were found to deflate
gradually. Next, ventilation was resumed under the pressure controlled
mode, and the peek inspiratory pressure was set as 10 mmHg. The positive
end expiratory pressure was set at 5 mmHg to prevent the collapse of the
alveoli. The patient was stabilized hemodynamically, and the patient was
weaned off CPB. Blood gas analysis revealed that the partial pressure of
oxygen was 175 mmHg, and the partial pressure of carbon dioxide was 40
mmHg. After careful hemostasis and sternal closure, the patient was the
sent to the adult intensive care unit (ICU). While at the ICU,
antibiotic therapy was continued. Methylprednisolone 80mg was given
every eight hours during the first 48 hours. Then the dose was reduced
gradually in 3 days. A bronchodilator was used for inhalation every four
hours. Eight hours later, the inspiratory pressure of the ventilator was
set to 18 mmHg with stable hemodynamics. ECMO was weaned 26 hours later
without hemorrhagic complications. The patient was weaned from the
mechanical ventilator and extubated four days post-operatively. The
remainder of the patient’s hospital stay was otherwise uneventful, and
he was discharged 12 days post-surgery.