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Emergency Vascular Surgery A Practical Guide - part 6

Cũng như với việc kiểm tra vật lý, xét nghiệm máu lặp đi lặp lại theo học lâm sàng của bệnh nhân có thể có giá trị chẩn đoán tuyệt vời trong giai đoạn cấp tính của bệnh. Nhẹ tình trạng thiếu máu là phổ biến, | 8.5 Management 97 As with the physical examination repeated blood tests according to the patient s clinical course might be of great diagnostic value during the acute stage of the disease. Mild anemia is common while severe anemia indicates rupture and bleeding. Hemolysis with elevated bilirubin or lactic acid concentrations can also be found. A leukocytosis with a count of 10 000-15 000 is common. Blood gases might reveal a metabolic acidosis due to anaerobic metabolism in ischemic tissue. Urinary tests showing hematuria indicates renal involvement. A plain chest x-ray in standard anteroposterior and lateral projections is rarely diagnostic but the following findings indicates the presence of aortic dissection Abnormal shadow adjacent to the descending thoracic aorta Deformity of the aortic knob Density adjacent to the brachiocephalic trunk Enlarged cardiac shadow Displaced esophagus trachea or bronchus Abnormal mediastinum Irregular aortic contour Loss of sharpness of the aortic shadow Pleural effusion Expanded aortic diameter Helical CT is accurate for determining the presence of an aortic dissection and provides information for classification. The identification of an intimal tear is however difficult and motion artifacts of the ascending aorta are sometimes misinterpreted as dissection. MRI is highly accurate and gives valuable information about the pathoanatomy. Unfortunately it cannot be performed in hemodynamically unstable patients who are on ventilator support. TEE Transesophageal echocardiography is often considered as one of the most valuable diagnostic tools making it possible to determine the type and extent of the aortic dissection especially distally. It has limitations in visualization of the distal ascending aorta and the arch. TTE Transthoracic echocardiography is on the other hand superior for evaluating involvement of the proximal part of the descending aorta in the dissection. Together TEE and TTE yield a sensitivity and specificity .