Application of cerebral oximetry for a parturient with Takayasu's arteritis undergoing cesarean section -a case report-
A 53 kg, 157 cm, 35-year-old primigravida at the 38th week of pregnancy was admitted for a cesarean section due to breech presentation. She had been diagnosed with TA 7 years prior to this presentation. However she refused medications and further evaluation until delivery. Computed tomographic angiography performed 3 years prior had revealed that the left common carotid artery and left subclavian artery were totally occluded along with a thrombotic aneurysm 5.8 × 5.2 × 9.6 cm in size (). She also had a localized dissection in the low abdominal aorta and focal stenosis in the descending aorta as well as a large left coronary aneurysm and about 50% stenosis of the right coronary artery. Plain chest radiographs revealed a huge superior mediastinal mass which was suspected of an aneurysm with thrombus in the left subclavian artery (). Cardiac single photon emission computed tomography and echocardiography were performed preoperatively to follow up on her coronary artery statuses. These examinations showed an old myocardial infarct, a persistent perfusion defect in the basal inferior wall and a reduction in wall motion.\nThe patient had been diagnosed with Type III TA as determined by the involvement of the aortic arch and coronary artery as well as the descending thoracic and abdominal aortas. She developed dyspnea on exertion with New York Heart Association Functional Class III. On physical examination, peripheral pulsations were weak in all limbs except the right arm. Heart rate was 120 beats/min, and non-invasive blood pressure (NIBP) was 96/78 mmHg in the right upper limb and 95/69 mmHg in the left upper limb. NIBP in the lower limbs measured 148/99 mmHg on the right and 156/95 mmHg on the left. She was cooperative and neurological examinations indicated normal results. A slowly titrated epidural anesthesia was selected to maintain hemodynamic stability. Regional anesthesia functioned as a simple and reliable monitor of cerebral perfusion through the patient's level of consciousness. For these reasons, we planned and executed an elective caesarean section under epidural anesthesia.\nOn arrival at the operating room, we began intraoperative monitoring by electrocardiography, pulse oximetry and NIBP measurement. Electrocardiography was unremarkable with a heart rate of 126 beats/min and the pulse oximeter on her right index finger displayed a normal waveform with a saturation of 95-96% in room air. She was alert and oriented, and her initial NIBP was 113/77 mmHg in the right upper limb. Her left radial, brachial and axillary arteries pulsed feebly, whereas her brachial and axillary arterial pulsations were stronger on the right than on the left. An artery cannula was placed in the right radial artery under local anesthesia connected to a FloTrac™ sensor and Vigileo™ monitor system (Edward Lifesciences, Irvine, CA, USA) device for continuous cardiac output assessments to monitor continuous blood flow. The initial cardiac index was 1.5 L/min/m2. A cerebral oximeter probe (Invos™, Cerebral/Somatic Oximeter 5100C, Somanetics Corporation, Troy, MI, USA) was attached to the forehead. The initial regional cerebral oxygen saturation (rSO2) levels were 64% on the right and 51% on the left.\nAfter placing the patient in the left lateral recumbent position, the median approach was performed with loss of resistance technique using an 18 G Tuohy needle between the L4 and L5 lumbar spines. The catheter was inserted and fixed. Her position was then changed to the supine position with a wedge under her right hip. The height of the block was increased gradually to T5 by using 11 ml of 2% lidocaine injected through an epidural catheter. Oxygen was administered via a VentiR mask, and a capnometer was installed below her nose to monitor respiration. The value of rSO2 was stable. Ten minutes after skin incision, a 3,180 gram girl was delivered and her Apgar score was 8 at 1 minute and 9 at 5 minutes.\nThree minutes after delivery, the placenta was removed and 20 IU of oxytocin diluted in 1,000 ml of 0.9% saline continued to be intravenously infused. The rSO2 levels dropped from 64 to 61% on the right and from 51 to 39% in the left at 6 minutes after delivery. At that time, we were able to obtain NIBP measurements. Arterial blood pressure was 56/48 mmHg without changes in cardiac index. She complained of dysarthria, tinnitus, and stiffness of the posterior neck (). An intravenous infusion of phenylephrine (100 mcg) and rapid administration of colloid (300 ml over 10 minutes) improved dysarthria, tinnitus and stiffness of the posterior neck as rSO2 increased from 61 to 78% on the right and from 39 to 56% on the left. There was no corresponding change in arterial blood pressure and cardiac index with the increase of the NIBP to 81/71 mmHg. However, she still complained of numbness of the face and blurred vision. Her laboratorial test results were as follows: hemoglobin, 9.0 mg/dl; hematocrit, 26%; Na+, 135 mg/dl; K+, 3.03 mg/dl; and Ca2+, 0.85 mmol/L.\nThe patient's facial numbness and blurred vision were resolved 20 minutes after the neurologic symptoms developed. Over time, her arterial compliance was reduced and invasive arterial blood pressure waveform damped along with a progressive decline in pulse pressure (). She lost about 1,000 ml of blood and received, in total, 500 ml of colloid solution, 2,500 ml of crystalloid, and 1 unit of blood were infused.\nThe patient was transferred to the intensive care unit for special attention to neurologic symptoms with continuous arterial blood pressure monitoring. Even though no focal neurologic deficits, postoperative brain magnetic resonance imaging and a magnetic resonance angiographic study were performed to rule out acute cerebral infarction. Magnetic resonance imaging showed multiple old infarcts in the right frontal and left frontotemporoparietal areas and a suspicious acute left cerebellar small infarct. In addition, there were complete occlusions of the left subclavian, left common carotid, internal carotid and middle cerebral arteries. There were near-complete occlusions of the bilateral proximal vertebral arteries. The left distal vertebral artery was reconstituted by the left thyrocervical trunk (). She refused further treatments, including surgery. She was discharged on the sixth postoperative day.