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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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Huntington's disease (HD) is an autosomal dominant neurodegenerative disease. A cardinal histopathologic feature of HD is the progressive loss of striatal medium spiny neurons. As there is no effective treatment for this fatal disease so far, we explore the therapeutic potential of nortriptyline to identify drugs that might be effective treatments for HD. N548mu [ 1955-128] huntingtin stable ST14A cell line was cultured and incubated in the presence or absence of serial concentrations of nortriptyline. Then R6/2 transgenic HD mice were treated with nortriptyline from five to twenty-one weeks of age. Nortriptyline protected striatal cells expressing mutant huntingtin when shifted to a nonpermissive temperature. Nortriptyline delay the disease onset to 127 d in R6/2 mice as compared with 102 d in saline-treated controls, but nortriptyline did not significantly delay mortality. As a gross marker of lack of systemic toxicity, there was no significant difference in the weight of the treated and control R6/2 mice. The results demonstrate that clinically reasonable doses of one of the identified drugs, nortriptyline, delays disease onset in a mouse model of the disease more than any previously identified compound. The most desirable features of a drug for HD are minimal toxicity and the ability to extend symptom-free living. Nortriptyline appears to be one such good candidate.