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ObjectiveTo investigate the influence of the number of T-junctions between central venous catheter and pressure transducer on measurement of central venous pressure (CVP) in patients.Methods A prospective controlled study was conducted. The patients with CVP monitoring in Department of Critical Care Medicine of the Fifth Center Hospital in Tianjin from February to October in 2014 were enrolled. The patients were divided into three groups according to the number of T-junction between central venous catheter and pressure transducer: without T-junction control group and 1, 2, 3 T-junctions groups. In each patient, corresponding CVP values with different number of T-junctions placed between the central venous catheter and pressure sensors were determined within a certain period, and a square-wave graphic was obtained and preserved on the monitor. The own frequency (fn) and the attenuation coefficient (D) of the system of pressure measurement were calculated after measurement of the shock wave following a square-wave to obtain the distance between two vibrations and the amplitude of the shock wave. The difference in CVP, fn and D were compared among the groups.Results A total of 20 cases were enrolled, and 150 groups of data were collected.① With the increase in the number of T-junction, CVP showed a tendency of gradual reduction. The CVP of the groups of control and 1, 2, 3 T-junctions was (7.00±1.60), (7.00±3.00), (5.00±2.00), and (4.00±1.00) mmHg (1 mmHg = 0.133 kPa), respectively. The CVP of 3 T-junctions group was significantly lower than that of the control group (F = 9.333,P = 0.015).② With an increase in the number of T-junction, fn showed a tendency of gradual increase. The fn of groups control and 1, 2, 3 T-junctions was (12.30±0.79), (16.00±0.91),(18.10±1.75), (20.90±2.69) Hz, respectively. The fn of 1, 2, 3 T-junctions group was significantly higher than that of the control group (F1 = 45.962,F2 = 45.414,F3 = 46.830, allP = 0.000); the fn of groups 2 and 3 T-junctions was significantly higher than that of 1 T-junction group (F1 = 5.827,P1 = 0.042;F2 = 15.038,P2 = 0.004), but there was no significant difference between the groups of 2 T-junctions and 3 T-junctions (F = 3.800,P = 0.087).③ With an increase of the number of T-junction, D also showed a tendency of gradual increase. The D of 1, 2, 3 T-junction group was 1.62±0.27, 1.60±0.22, 1.82±0.25, and 2.15±0.58, respectively. There were no differences among four groups.ConclusionAfter the application of T-junctions between central venous catheter and pressure transducer, CVP values will be underestimated, the reason of which is considered to be the increase in length and thinner lumen of the T-junctions.
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Aortic valve preservation is indicated in cases of aortic regurgitation caused by sinotubular junction (STJ) dilatation with ascending aortic aneurysm. We performed aortic remodeling using a tailored Dacron graft for the rupture of a large ascending aortic aneurysm. The patient was a 68-year-old woman. She was admitted in shock with cardiac tamponade. Chest CT showed a large ascending aortic aneurysm, 11cm in maximum diameter. Echocardiography demonstrated moderate cardiac effusion and massive aortic regurgitation. The ascending aorta was dilated from the STJ to the innominate artery, but the aortic valve appeared normal. We decided to preserve the native aortic valve. We performed aortic root remodeling using a 26mm Dacron graft (Yacoub's procedure). An intraoperative endoscopic study revealed the disappearance of aortic regurgitation (AR). The coronary arteries were reconstructed by the Carrel patch technique. Postoperative aortography revealed trivial AR, and the patient was discharged two weeks after the operation. We conclude that this technique avoids the complications associated with mechanical valve implantation and necessary lifetime anticoagulation.