Predictors of early and late instability following conservative treatment of extra-articular distal radius fractures

Introduction The purpose of this study was to identify radiological predictors of early and late instability following conservative treatment of extra-articular distal radius fractures.Materials and methods An observational study design was employed using patient records and standardized radiological follow-up examinations as data sources. The database at a single institution was used to identify all patients with extra-articular distal radius fractures over the course of 1 year. A total of 71 patients with extra-articular distal radius fractures (50 dorsally displaced, 21 undisplaced) fulfilled the inclusion criteria. Patients were predominantly female (87%) with a pooled mean age of 64.9 years. All patients with displaced extra-articular distal radius fractures underwent closed reduction with subsequent cast immobilization. Undisplaced fractures were simply treated with cast immobilization. The primary outcomes were early (1 week) and late (6 weeks) instability of the fracture. Instability was defined as: (1) dorsal tilt >15°, (2) volar tilt >20°, (3) ulnar variance >4 mm, (4) radial inclination <10°.Results Degree of radial shortening and volar tilt were predictive of early instability (p<0.05), with dorsal comminution also approaching statistical significance (p=0.06). Radial inclination, age, radial shortening, and volar tilt were predictive of late failure (p<0.05). An unexpected result showed that one-third of undisplaced fractures went on to fail, most of which occurred in those patients over the age of 65 years.Conclusion An awareness of independent predictors of instability in extra-articular distal radius fractures is helpful in anticipating the final alignment outcome.     

Postoperative apnea, respiratory strategies, and pathogenesis mechanisms: a review

Recovery from anesthesia is ideally routine and uneventful. After extubation, the recovering postoperative patient ought to breathe without supportive care or additional oxygenation. It has been demonstrated in previous studies that postoperative pulmonary complications are clinically relevant in terms of mortality, morbidity, and length of hospital stay. Compromised postoperative ventilation can be described as the condition in which the postoperative patient does not have satisfactory spontaneous ventilation support and adequate oxygenation. Causes of impaired ventilation, oxygenation, and airway maintenance can be mechanical, hemodynamic, and pharmacologic. This review describes prevalence and differential diagnosis, including co-morbidities of postoperative apnea. The physiological mechanisms of breathing and prolonged postoperative apnea are also reviewed; these mechanisms include influences from the brainstem, the cerebral cortex, and chemoreceptors in the carotid and aortic body. Causes of prolonged postoperative apnea and management are also discussed.     

Self-calibrating parallel imaging with automatic coil sensitivity extraction.

Calibration of the spatial sensitivity functions of coil arrays is a crucial element in parallel magnetic resonance imaging (PMRI). The most common approach has been to measure coil sensitivities directly using one or more low-resolution images acquired before or after accelerated data acquisition. However, since it is difficult to ensure that the patient and coil array will be in exactly the same positions during both calibration scans and accelerated imaging, this approach can introduce sensitivity miscalibration errors into PMRI reconstructions. This work shows that it is possible to extract sensitivity calibration images directly from a fully sampled central region of a variable-density k-space acquisition. These images have all the features of traditional PMRI sensitivity calibrations and therefore may be used for any PMRI reconstruction technique without modification. Because these calibration data are acquired simultaneously with the data to be reconstructed, errors due to sensitivity miscalibration are eliminated. In vivo implementations of self-calibrating parallel imaging using a flexible coil array are demonstrated in abdominal imaging and in real-time cardiac imaging studies.     

Cystic fibrosis and the phenotypic expression of autosomal dominant polycystic kidney disease

Recent experiments in cultured cyst epithelial cells from kidneys of patients with autosomal dominant polycystic kidney disease (ADPKD) have shown that the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is present in the apical surface of these cells and mediates chloride (Cl-) and fluid secretion in vitro. To determine whether the presence of CF with the expression of mutated CFTR proteins modifies cyst formation in ADPKD, we studied a large family with both inherited diseases. ADPKD in this family is linked to PKD1. The family is composed of 26 members; 11 members with ADPKD, 4 members with CF, and 2 members with both diseases. Renal volumes measured by computerized tomography (CT), calculated creatinine clearances, and other clinical parameters in the family members with ADPKD and CF were compared with those in the family members with ADPKD alone, as well as to a large population of patients with ADPKD. The patients with CF and ADPKD, but not the CF heterozygote carriers with ADPKD, had less severe polycystic kidney and liver disease, as indicated by normal renal function; smaller renal volume, even when corrected for height and body surface area; and the absence of hypertension and liver cysts. These observations suggest that the coexistence of CF may reduce the severity of ADPKD.     

A noninvasive estimation of mixed venous oxygen saturation using near-infrared spectroscopy by cerebral oximetry in pediatric cardiac surgery patients

BACKGROUND: Near-infrared spectroscopy (NIRS) is a noninvasive optical monitor of regional cerebral oxygen saturation (rSO2). The aim of this study was to validate the use of NIRS by cerebral oximetry in estimating invasively measured mixed venous oxygen saturation (SvO2) in pediatric postoperative cardiac surgery patients. METHODS: Twenty patients were enrolled following cardiac surgery with intraoperative placement of a pulmonary artery (PA) or superior vena cava (SVC) catheter. Five patients underwent complete biventricular repair--complete atrioventricular canal (n=3) and other (n=2). Fifteen patients with functional single ventricle underwent palliative procedures--bidirectional Glenn (n=11) and Fontan (n=4). Cerebral rSO2 was monitored via NIRS (INVOS 5100) during cardiac surgery and 6 h postoperatively. SvO2 was measured from blood samples obtained via an indwelling PA or SVC catheter and simultaneously correlated with rSO2 by NIRS at five time periods: in the operating room after weaning from cardiopulmonary bypass, after sternal closure, and in the CICU at 2, 4, and 6 h after admission. RESULTS: Each patient had five measurements (total=100 comparisons). SvO2 obtained via an indwelling PA or SVC catheter for all patients correlated with rSO2 obtained via NIRS: Pearson's correlation coefficient of 0.67 (P<0.0001) and linear regression of r2=0.45 (P<0.0001). Separate linear regression of the complete biventricular repairs demonstrated an r=0.71, r2=0.50 (P<0.0001). Bland-Altman analysis showed a bias of +3.3% with a precision of 16.6% for rSO2 as a predictor of SvO2 for all patients. Cerebral rSO2 was a more accurate predictor of SvO2 in the biventricular repair patients (bias -0.3, precision 11.8%), compared with the bidirectional Glenn and Fontan patients. CONCLUSIONS: Regional cerebral oximetry via NIRS correlates with SvO2 obtained via invasive monitoring. However, the wide limits of agreement suggest that it may not be possible to predict absolute values of SvO2 for any given patient based solely on the noninvasive measurement of rSO2. Near-infrared spectroscopy, using the INVOS 5100 cerebral oximeter, could potentially be used to indicate trends in SVO2, but more studies needs to be performed under varying clinical conditions.     

Multiecho water‐fat separation and simultaneous R estimation with multifrequency fat spectrum modeling

Multiecho chemical shift–based water‐fat separation methods are seeing increasing clinical use due to their ability to estimate and correct for field inhomogeneities. Previous chemical shift‐based water‐fat separation methods used a relatively simple signal model that assumes both water and fat have a single resonant frequency. However, it is well known that fat has several spectral peaks. This inaccuracy in the signal model results in two undesired effects. First, water and fat are incompletely separated. Second, methods designed to estimate T in the presence of fat incorrectly estimate the T decay in tissues containing fat. In this work, a more accurate multifrequency model of fat is included in the iterative decomposition of water and fat with echo asymmetry and least‐squares estimation (IDEAL) water‐fat separation and simultaneous T estimation techniques. The fat spectrum can be assumed to be constant in all subjects and measured a priori using MR spectroscopy. Alternatively, the fat spectrum can be estimated directly from the data using novel spectrum self‐calibration algorithms. The improvement in water‐fat separation and T estimation is demonstrated in a variety of in vivo applications, including knee, ankle, spine, breast, and abdominal scans. Magn Reson Med 60:1122–1134, 2008. © 2008 Wiley‐Liss, Inc.     

受体介导的凝血酶对成骨细胞增殖及分化的作用

目的 通过凝血酶对成骨细胞的增殖及分化作用的研究来探讨受体介导的凝血酶的功能.方法 原代成骨细胞分别取自于蛋白酶激活受体(protease-activated receptor,PAR)-1敲除鼠和野生对照鼠的头颅骨.并利用凝血酶,人工合成的PAR-1或PAR-4特异性激活短肽对细胞进行处理,通过对5.溴-2-脱氧尿嘧啶的嵌入及细胞碱性磷酸酶活性的测定探讨PAR-1或PAR-4激活对细胞增殖和分化的影响.结果 在野生鼠成骨细胞,凝血酶及PAR-1激活肽均能促进的细胞增殖和降低碱性磷酸酶的活性,但PAR-4激活肽却无这些作用.然而在PAR-1 敲除鼠的成骨细胞无论是凝血酶还是PAR-4激活肽均不能改变细胞的增殖及碱性磷酸酶的活性.结论 本研究结果 表明凝血酶促进成骨细胞增殖及抑制其分化是通过PAR-1介导的.其他凝血酶受体并不具有此作用.