[Effect of ambient light variations on luminance ratio of CRT monitor and image contrast in ultrasonography].

Variation in the luminance ratio of a cathode ray tube(CRT)monitor and the ultrasonographic images at different levels of ambient light(0-150 lux)was investigated to obtain optimum ambient light in the ultrasonography suite. The maximum and minimum luminances of test patterns and ultrasonographic images were measured after three technicians independently optimized the brightness and contrast of the CRT monitor and ultrasonographic images at different levels of ambient light. Furthermore, the luminance ratio was calculated from the maximum luminance divided by the minimum luminance. When ambient light increased, it was difficult for the technicians to optimize the brightness and contrast settings of the CRT monitor to maintain a high luminance ratio at 0 lux. The luminance ratio decreased rapidly as ambient light increased up to 20 lux. However, the luminance ratio decreased gradually when ambient light was higher than 20 lux. It is necessary to take into consideration the ambient light to maintain a high luminance ratio of ultrasonographic images.

[Perioperative management for transurethral resection of bladder tumor (TUR-Bt) associated with congenital antithrombin III deficiency].

Congenital antithrombin III (ATIII) deficiency is a hereditary disease that predisposes to thromboembolic complications. We report perioperative management for twice in a patient with congenital ATIII deficiency. A 69-year-old man with congenital ATIII deficiency, with history of deep vein thrombosis (DVT) in his left popliteal vein, was scheduled for transurethral resection of bladder tumor (TUR-Bt). The plasma ATIII activity was 57% of normal vale. As ATIII concentrates 3,000U per day had been administered intravenously since the second day before the operation, the plasma ATIII activity was 147% on the operation day. TUR-Bt was performed in the lithotomy position under general anesthesia. ATIII concentrates 3,000 U per day were administered intravenously for two days after the operation and low molecular weight heparin (LMWH) 2,500 U per day was administered subcutaneously for five days after the operation. One year later he had a recurrence of bladder tumor. The plasma ATIII activity was 54%. ATIII concentrates 3,000 U per day had been administered intravenously since the three days before the operation. The second TUR-Bt was also performed in the lithotomy position under general anesthesia. ATIII concentrates 1,500 U per day were administered intravenously for three days after the operation. LMWH was not administered due to postoperative bleeding from the bladder. He had no thromboembolism during each perioperative period. The lithotomy position with fixation of both hips and both knees may decrease venous blood flow, increase muscle compartment pressure of the lower extremities, predispose to DVT in the lower extremity, and lead to pulmonary thromboembolism (PE). Control of blood coagulation and maintenance of sufficient venous blood flow in the lower extremities with ATIII adjuvant therapy and LMWH administration during the perioperative period are important for TUR-Bt in a patient with congenital ATIII deficiency to prevent DVT and PE.