[Digital documentation of complications in visceral surgery: possibilities and evaluation of an instrument for quality management]. / Digitale Komplikationserfassung in der Viszeralchirurgie: Möglichkeiten und Evaluation eines Instrumentes für das Qualitätsmanagement.

Against the background of the growing economization of clinical medicine, in the last decades the topics of risk and complication management have also become more important in surgical disciplines. The standardization and reproducible documentation of outcome and complication data play a key role for valid quality control. In this article a digital system implemented at the surgical clinic of the Charité University Medicine in Berlin is analyzed with respect to its practicability for perioperative and postoperative monitoring of complications within the framework of quality assurance.

Challenging the in-vivo assessment of biomechanical properties of the uterine cervix: A critical analysis of ultrasound based quasi-static procedures.

Measuring the stiffness of the uterine cervix might be useful in the prediction of preterm delivery, a still unsolved health issue of global dimensions. Recently, a number of clinical studies have addressed this topic, proposing quantitative methods for the assessment of the mechanical properties of the cervix. Quasi-static elastography, maximum compressibility using ultrasound and aspiration tests have been applied for this purpose. The results obtained with the different methods seem to provide contradictory information about the physiologic development of cervical stiffness during pregnancy. Simulations and experiments were performed in order to rationalize the findings obtained with ultrasound based, quasi-static procedures. The experimental and computational results clearly illustrate that standardization of quasi-static elastography leads to repeatable strain values, but for different loading forces. Since force cannot be controlled, this current approach does not allow the distinction between a globally soft and stiff cervix. It is further shown that introducing a reference elastomer into the elastography measurement might overcome the problem of force standardization, but a careful mechanical analysis is required to obtain reliable stiffness values for cervical tissue. In contrast, the maximum compressibility procedure leads to a repeatable, semi-quantitative assessment of cervical consistency, due to the nonlinear nature of the mechanical behavior of cervical tissue. The evolution of cervical stiffness in pregnancy obtained with this procedure is in line with data from aspiration tests.

Mechanical biocompatibility of prosthetic meshes: a comprehensive protocol for mechanical characterization.

This study is aimed at a comprehensive and extensive characterization of the mechanical biocompatibility of mesh prostheses. A robust and simple experimental protocol and a set of parameters is proposed, addressing stiffness under uniaxial and biaxial loading conditions, anisotropy, influence of prior deformation history, local mismatch of deformation mechanisms, and changes in mechanical properties when embedded in a homogeneous matrix. These parameters can form the basis for comparison of different mesh types and for evaluation of their mechanical biocompatibility. Measurements were performed on nine mesh types used for hernia and/or pelvic repair, including heavier as well as lighter implants and covering a wide range of mechanical responses. A total of 93 experiments were performed and all parameters are represented for each mesh in a single diagram to facilitate the quantitative assessment of implant characteristics and their comparison. The mechanics of implants is a critical factor determining clinical performance which should be accounted for in mesh selection and for development of future implants.

Impact of transmural heterogeneities on arterial adaptation: application to aneurysm formation.

Recent experimental and computational studies have shown that transmurally heterogeneous material properties through the arterial wall are critical to understanding the heterogeneous expressions of constituent degrading molecules. Given that expression of such molecules is thought to be intimately linked to local magnitudes of stress, modelling the transmural stress distribution is critical to understanding arterial adaption during disease. The aim of this study was to develop an arterial growth and remodelling framework that can incorporate both transmurally heterogeneous constituent distributions and residual stresses, into a 3-D finite element model. As an illustrative example, we model the development of a fusiform aneurysm and investigate the effects of elastinous and collagenous heterogeneities on the stress distribution during evolution. It is observed that the adaptive processes of growth and remodelling exhibit transmural variations. For physiological heterogeneous constituent distributions, a stress peak appears in the media towards the intima, and a stress plateau occurs towards the adventitia. These features can be primarily attributed to the underlying heterogeneity of elastinous constituents. During arterial adaption, the collagen strain is regulated to remain in its homoeostatic level; consequently, the partial stress of collagen has less influence on the total stress than the elastin. However, following significant elastin degradation, collagen plays the dominant role for the transmural stress profile and a marked stress peak occurs towards the adventitia. We conclude that to improve our understanding of the arterial adaption and the aetiology of arterial disease, there is a need to: quantify transmural constituent distributions during histopathological examinations, understand and model the role of the evolving transmural stress distribution.

The influence of the wider use of surfactant therapy on neonatal mortality among blacks and whites.

BACKGROUND: Surfactant therapy reduces morbidity and mortality among premature infants with the respiratory distress syndrome (RDS). Fetal pulmonary surfactant matures more slowly in white than in black fetuses, and therefore RDS is more prevalent among whites than among blacks. We reasoned that the increased use of surfactant after its approval by the Food and Drug Administration (FDA) in 1990 might have reduced neonatal mortality more among whites than among blacks. METHODS: We merged vital-statistics information for all 1563 infants with very low birth weights (500 to 1500 g) born from 1987 through 1989 or in 1991 and 1992 to residents of St. Louis with clinical data from the four neonatal intensive care units in the St. Louis area; we then compared neonatal mortality during two periods, one before and one after the FDA's approval of surfactant for clinical use (1987 through 1989 and 1991 through 1992). RESULTS: The use of surfactant increased by a factor of 10 between 1987 through 1989 and 1991 through 1992. The neonatal mortality rate among all very-low-birth-weight infants decreased 17 percent, from 220.3 deaths per 1000 very-low-birth-weight babies born alive (in 1987 through 1989) to 183.9 per 1000 (in 1991 through 1992; P = 0.07). This decrease was due to a 41 percent reduction in the mortality rate among white newborns with very low birth weights (from 261.5 per 1000 to 155.5 per 1000; P = 0.003). In contrast, among black infants, the mortality rate for very-low-birth-weight infants did not change significantly (195.6 per 1000 and 196.8 per 1000). The relative risk of death among black newborns with very low birth weights as compared with white newborns with similar weights was 0.7 from 1987 through 1989 and 1.3 from 1991 through 1992 (P = 0.02). The differences in mortality were not explained by differences in access to surfactant therapy, by differences in mortality between black and white infants who received surfactant, or by differences in the use of antenatal corticosteroid therapy. CONCLUSIONS: After surfactant therapy for RDS became generally available, neonatal mortality improved more for white than for black infants with very low birth weights.

Cesarean section versus vaginal delivery for the breech fetus weighing less than 1,500 grams.

Although previous studies have suggested that the breech infant weighing less than 1,500 gm benefits from cesarean section, the published results have not demonstrated statistically significant differences. We have evaluated pediatric outcome data for 240 breech infants and 525 vertex infants who weighed less than 1,500 gm, to determine whether route of delivery affects infant morbidity and mortality. Twenty-nine percent of these very small breech infants who were delivered by cesarean section died, as compared to 58% of breech infants of similar weight who were delivered vaginally (p less than 0.001). Comparable significant differences were found for the infants delivered at a university hospital as well as for those delivered at a group of nonuniversity hospitals. Apgar scores and the incidence and severity of intraventricular hemorrhage were not different for the cesarean section and vaginally delivered breech infants. Furthermore, the survival rate of the breech infants delivered by cesarean section equaled that of the vertex infants delivered either by cesarean section or vaginally.

Surgical mortality and morbidity in extremely low-birth-weight infants.

Twenty extremely premature infants (birth weight, less than 1,100 g) underwent 49 surgical procedures for acquired conditions, including necrotizing enterocolitis, other forms of gastrointestinal perforation, gastroesophageal reflux, patent ductus arteriosus, and hydrocephalus. Few congenital anomalies requiring operation were encountered in this group. The overall survival rate was 58%. Using a computerized data base to compare surgical patients with a weight-matched group of nonsurgical patients, it was shown that survival was similar and that adverse prenatal and perinatal influences were equally distributed between both groups. Surgery per se did not adversely influence survival in extreme low-birth-weight infants, and surgical patients are not a preselected group of stronger infants.