轮廓匹配的有限差分法

本文提出一种匹配相似轮廓线的有限差分法,这个方法是在Duncan方法的基础上开发的。Duncan的方法是通过优化一个二次指标函数来匹配两条轮廓线的。这个指标函数由一个与弯曲能量有关的曲率差项和一个弹性约束项组成。Cohen指出Duncan的方法可能造成两条轮廓线上点不是按顺序一一对应。他提出用有限元法来解这个问题。本文采用新的弹性约束项,得到的优化方程不但容易计算而且有明确的物理意义,本文讨论了用有限差分法解这个方程的方法,对于复杂形状的轮廓匹配可以用多尺度法来解决。     

Surviving intensive care: a report from the 2002 Brussels Roundtable

The traditional goal of intensive care has been to decrease short-term mortality. While worthy, this goal fails to address the issue of what it means to survive intensive care. Key questions include whether intensive care survivors have optimal long-term outcomes and whether ICU care decisions would change if we knew more about these outcomes. The 2002 Brussels Roundtable, "Surviving Intensive care", highlighted these issues, summarizing the available evidence on natural history and risk factors for critical illness and outlining future directions for care and research. Critical illness is associated with a wide array of serious and concerning long-term sequelae that interfere with optimal patient-centered outcomes. Although traditional short-term outcomes, such as hospital mortality, remain extremely important, they are not likely to be adequate surrogates for subsequent patient-centered outcomes. As such, it is important to focus specifically on how critical illness and intensive care affects a patient's and relatives' long-term health and well-being. There are a large number of potential pre-, intra-, and post-ICU factors that may improve or worsen these outcomes, and these factors are subjects for future research. In addition, future clinical trials of ICU therapies should include long-term follow-up of survival, quality of life, morbidity, functional status, and costs of care. Follow-up ought to be for at least six months. The SF-36 and EuroQOL EQ-5D are the best-suited instruments for measuring quality of life in multicenter critical care trials though further methodologic research and instrument design is encouraged. There are also opportunities today to improve care. Key to taking advantage of such opportunities is the need for a global awareness of critical illness as an entity that begins and ends outside the ICU 'box'. Specific interventions that show promise for improving care include ICU discharge screening tools and ICU follow-up clinics.     

Results of systematic screening for minor degrees of fetal renal pelvis dilatation in an unselected population

OBJECTIVE: The purpose of this study was to determine the incidence of minor degrees of renal pelvis dilatation that is detected by antenatal ultrasound scanning in an unselected population and its value in the prediction of significant uropathies. STUDY DESIGN: This prospective study was conducted over a 24-month period. Infants with an anteroposterior pelvic diameter of >or=4 mm in the second trimester and/or >or=7 mm but <15 mm in the third trimester were enrolled. RESULTS: Pyelectasis was found in 4.5% of 5643 fetuses (1.5% with significant uropathy). Among the 213 infants whose cases were followed, 132 infants (62%) had renal anomalies, but only 83 infants (39%) had significant uropathies. The ability of the third-trimester renal pelvis dilatation to predict renal abnormalities showed a positive predictive value of 69%. Pyelectasis that was detected only in the second trimester revealed a significant uropathy in 12% of the infants. CONCLUSION: Pyelectasis was found in 4.5% of fetuses. The third-trimester anteroposterior renal pelvis diameter of >or=7 mm was the best ultrasound criterion to predict postnatal uropathies.     

Results of systematic voiding cystourethrography in infants with antenatally diagnosed renal pelvis dilation

OBJECTIVES: To assess the yield of neonatal renal ultrasonography as a predictor of abnormalities on voiding cystourethrography (VCUG). STUDY DESIGN: We prospectively followed 264 infants with antenatal renal pelvis dilation. Two successive neonatal renal ultrasound examinations were performed at day 5 and 1 month after birth. VCUG was performed in all infants. RESULTS: Neonatal ultrasound findings were abnormal in 190 infants (72% of total). Among them, 63 (33%) had an abnormal VCUG. The most common abnormalities were primary vesico-ureteral reflux (VUR) in 30 infants, VUR into the lower pole of a duplex kidney in 14, refluxing megaureter in 9, posterior urethral valves in 5, and ureterocele in 5. When both neonatal ultrasound findings were normal (74 infants), the VCUG showed abnormalities in only 5 (6.7%) patients (4 low-grade primary VUR and 1 posterior urethral valve). The sensitivity, specificity, positive predictive value, and negative predictive value of 2 successive ultrasound scans in the neonatal period to predict an abnormality on VCUG were 93%, 35%, 33%, and 93%, respectively. CONCLUSIONS: A normal-appearing urinary tract on 2 successive neonatal ultrasound scans rarely coexists with abnormal findings at VCUG. Therefore, in such patients, VCUG does not seem justified.     

Long-term clinical outcome of infants with mild and moderate fetal pyelectasis: validation of neonatal ultrasound as a screening tool to detect significant nephrouropathies

OBJECTIVE: To assess the long-term outcome of infants with mild and moderate fetal pyelectasis and to determine the predictive value of neonatal ultrasound imaging in identifying significant nephrouropathies. STUDY DESIGN: This prospective study included 213 infants with antenatal mild to moderate pyelectasis who were followed for up to 2 years. Postnatal renal ultrasound examinations were performed at day 5 and months 1, 3, 6, 12 and 24 after birth. Voiding cystourethrography was performed in all infants. RESULTS: Normal or nonsignificant findings were diagnosed in 130 of 213 (61%) infants. Significant nephrouropathies were diagnosed in 83 of 213 (39%) infants. The sensitivity, specificity, positive predictive value, and negative predictive value of two successive neonatal renal ultrasound examinations performed at day 5 and 1 month to predict significant nephrouropathies were 96%, 76%, 72%, and 97%, respectively. In 102 of 213 (48%) infants with normal neonatal renal ultrasound scans, we later found only three of 102 (3%) cases with significant nephrouropathies. CONCLUSIONS: We found in a population of infants with mild to moderate fetal pyelectasis a 39% incidence of significant nephrouropathies. Ultrasound is an excellent screening tool with high sensitivity and negative predictive value that allows avoidance of unjustified medical follow-up in patients with two normal neonatal ultrasound scans.     

Medical follow-up study of 5-year-old ICSI children

Children born after intracytoplasmic sperm injection (ICSI) are still a matter of concern. The purposes of the present study were to investigate the physical outcome in 5-year-old children born after ICSI and compare them with children born after spontaneous conception. Three hundred singleton children from Belgium, Sweden and the USA, born after ICSI, were matched by maternal age, child age and gender. In one centre, matching was also performed for maternal education. The main end-point was growth. Secondary end-points were general health, e.g. common diseases, chronic illnesses, surgical interventions and physical/neurological examinations. Standard deviation scores assessed growth. Growth assessed as stature at follow-up was similar in the two groups, despite a higher rate of preterm birth and low birth weight in the ICSI children. Common diseases and chronic illnesses occurred at similar rates in both groups. More ICSI children underwent surgical interventions and required other therapy e. g. physiotherapy and dietary therapy. Physical/neurological examinations revealed few abnormalities in either group. In conclusion, infertility treatment by ICSI does not adversely affect growth during childhood. The children's general health seems satisfactory.     

Human herpesvirus-6 infection after lung and heart-lung transplantation: a prospective longitudinal study

BACKGROUND: Although human herpesvirus (HHV)-6 is now recognized as a frequent pathogen after transplantation, the real impact of this infection in patients undergoing transplantation remains unclear. METHODS: During 27 months, 30 consecutive heart-lung- and lung-transplant recipients were included on the day of transplantation and prospectively followed during 100 days for HHV-6 infection. RESULTS: HHV-6 infection occurred in 20 (66%) patients after a median delay of 18 days after transplantation. The virus was detected by polymerase chain reaction or culture, or both, in 15.7 % of blood specimens, in 14.5% of bronchoalveolar lavage fluids, and in many organs at postmortem examination; it was found by culture in eight patients. No clinical manifestations could clearly be associated with HHV-6 alone. However, patients with HHV-6 infection had a higher mortality rate than patients without HHV-6 infection (7 of 20 vs. 0 of 10; P=0.04), and all the deceased patients died during periods of HHV-6 infection. We did not observe higher incidence of infectious or graft-rejection episodes in HHV-6-positive patients. However, eight of nine viral or fungal infections occurred during HHV-6 infection and three were directly responsible for death. CONCLUSION: Although frequently detected after transplantation, HHV-6 was not associated with any specific clinical manifestation. The higher mortality rate observed in patients with HHV-6 infection was not related to a higher incidence of bacterial infections or graft rejection but might be associated with more viral and fungal infections.