Time-lapsed assessment of microcrack initiation and propagation in murine cortical bone at submicrometer resolution.

The strength of bone tissue is not only determined by its mass, but also by other properties usually referred to as bone quality, such as microarchitecture, distribution of bone cells, or microcracks and damage. It has been hypothesized that the bone ultrastructure affects microcrack initiation and propagation. Due to its high resolution, bone assessment by means of synchrotron radiation (SR)-based computed tomography (CT) allows unprecedented three-dimensional (3D) and non-invasive insights into ultrastructural bone phenotypes, such as the canal network and the osteocyte lacunar system. The aims of this study were to describe the initiation and propagation of microcracks and their relation with these ultrastructural phenotypes. To this end, femora from the two genetically distinct inbred mouse strains C3H/He (C3H) and C57BL/6 (B6) were loaded axially under compression, from 0% strain to failure, with 1% strain steps. Between each step, a high-resolution 3D image (700 nm nominal resolution) was acquired at the mid-diaphysis using SR CT for characterization and quantitative analysis of the intracortical porosity, namely the bone canal network, the osteocyte lacunar system and the emerging microcracks. For C3H mice, the canal, lacunar, and microcrack volume densities accounted typically for 1.91%, 2.11%, and 0.27% of the cortical total volume at 2% apparent strain, respectively. Due to its 3D nature, SR CT allowed to visualize and quantify also the volumetric extent of microcracks. At 2% apparent strain, the average microcrack thickness for both mouse strains was 2.0 microm for example. Microcracks initiated at canal and at bone surfaces, whereas osteocyte lacunae provided guidance to the microcracks. Moreover, we observed that microcracks could appear as linear cracks in one plane, but as diffuse cracks in a perpendicular plane. Finally, SR CT images permitted visualization of uncracked ligament bridging, which is thought to be of importance in bone toughening mechanisms. In conclusion, this study showed the power of SR CT for 3D visualization and quantification of the different ultrastructural phases of the intracortical bone porosity. We particularly postulate the necessity of 3D imaging techniques to unravel microcrack initiation and propagation and their effects on bone mechanics. We believe that this new investigation tool will be very useful to further enhance our understanding of bone failure mechanisms.

Interrelation of peri-operative morbidity and ASA class assignment in patients undergoing gynaecological surgery.

OBJECTIVE: The aim of this study was to estimate intra- and post-operative risk using the American Society of Anaesthesiologists (ASA) classification which is an important predictor of an intervention and of the entire operating programme. STUDY DESIGN: In this retrospective study, 4435 consecutive patients undergoing elective and emergency surgery at the Gynaecological Clinic of the University Hospital of Zurich were included. The ASA classification for pre-operative risk assessment was determined by an anaesthesiologist after a thorough physical examination. We observed several pre-, intra- and post-operative parameters, such as age, body-mass-index, duration of anaesthesia, duration of surgery, blood loss, duration of post-operative stay, complicated post-operative course, morbidity and mortality. The investigation of different risk factors was achieved by a multiple linear regression model for log-transformed duration of hospitalisation. RESULTS: Age and obesity were responsible for a higher ASA classification. ASA grade correlates with the duration of anaesthesia and the duration of the surgery itself. There was a significant difference in blood loss between ASA grades I (113+/-195 ml) and III (222+/-470 ml) and between classes II (176+/-432 ml) and III. The duration of post-operative hospitalisation could also be correlated with ASA class. ASA class I=1.7+/-3.0 days, ASA class II=3.6+/-4.3 days, ASA class III=6.8+/-8.2 days, and ASA class IV=6.2+/-3.9 days. The mean post-operative in-hospital stay was 2.5+/-4.0 days without complications, and 8.7+/-6.7 days with post-operative complications. Multiple linear regression model showed that not only the ASA classification contained an important information for the duration of hospitalisation. Parameters such as age, class of diagnosis, post-operative complications, etc. also have an influence on the duration of hospitalisation. CONCLUSION: This study shows that the ASA classification can be used as a good and early available predictor for the planning of an intervention in gynaecological surgery. The ASA classification helps the surgeon to assess the peri-operative risk profile of which important information can be derived for the planning of the operation programme.

Cost-effectiveness studies in ovarian cancer.

Ovarian cancer is the fifth leading cause of cancer-related deaths. The costs associated with this cancer impact both on the affected individual and on the health system. Screening is currently unproven as a strategy for improving outcomes for women with ovarian cancer. Randomized controlled trials, however, are underway, estimating any impact of screening with ultrasound and CA125 on ovarian cancer mortality. Paclitaxel and carboplatin combination, the standard first-line chemotherapy regimen for ovarian cancer, has not been compared with cisplatin and cyclophosphamide regarding the cost-effectiveness and cost-utility, but for paclitaxel and cisplatin, numerous studies have addressed these issues. The estimated incremental costs resulting from these studies fall well within the generally accepted range for new therapies. Although acquisition costs of new chemotherapy drugs exceed those of older drugs, the impact of costly drugs on total costs may be cost saving due to less costs related to supportive and palliative care. The most important costs for the patient, the pain and suffering associated with ovarian cancer and its treatment, are hard to quantify. Nevertheless, patients' quality of life must be considered when making a clinical decision to treat this disease. A review of available cost-effectiveness studies is presented and discussed.

Impact of the reduction of anaesthesia turnover time on operating room efficiency.

BACKGROUND AND OBJECTIVE: We investigated whether an increase in anaesthesia staffing to permit induction of anaesthesia before the previous case had ended ('overlapping') would increase overall efficiency in the operating room. Hitherto, the average duration of operating sessions was too long, thus impeding the timely commencement of physicians' ward duties. METHODS: The investigation was designed as a prospective, non-randomized, interrupted time-series analysis divided into three phases: (a) a baseline of 3.5 months, (b) a 2.5 month intervention phase, in which anaesthesia staffing was increased by one attending physician and one nurse, and (c) a further 2 months under baseline conditions. Data focussed on process management were collected from operating room staff, anaesthesia personnel and surgeons using a structured questionnaire collected daily during the entire study. RESULTS: Turnover time between consecutive operations decreased from 65 to 52 min per operation (95% CI: 9; 17; P = 0.0001). Operating room occupancy increased from 4:28 to 5:27 h day-1 (95% CI: 50; 68; P = 0.005). The surgeons began their work on the ward 35 min (95% CI: 30; 40) later than before the intervention and their overtime increased from 22:36 to 139:50 h. CONCLUSIONS: The time between surgical operations decreased significantly. Increased operating room efficiency owing to overlapping induction of anaesthesia allows more intense scheduling of operations. Thus, physicians and nurses can be released to spend more time with their patients in the ward. Improving the efficiency of the operating room alone is insufficient to improve human resource management at all levels of a surgical clinic.

Appropriateness and necessity research on the Internet: using a "second opinion system".

Appropriateness and necessity research of various procedures in medicine may be the most complex field of innovation in healthcare and technology assessment. Nevertheless, the appropriateness of the indication of any medical intervention is probably more important than the outcome since even ideal quality components of structures, processes and outcomes become irrelevant without a proper indication. The first part of our appropriateness initiative in interventional cardiology and gynecology was to formulate guidelines. To define the appropriateness for coronary angiography, coronary revascularization and hysterectomy, literature-based consensus methods were used. The second part was to disseminate the guidelines in a user-friendly manner via the Internet. Therefore, we relied on a system-driven query facility for propositional (experts) rules. The next part of the appropriateness initiative may be a user-friendly Internet-based data collection system to validate the national accepted guidelines. Most important may be that only data that is needed can be collected using a refined database technology. The described Second Opinion System can be found under: http:sos.inf.ethz.ch. Research on indications with data on clinical outcome may open new opportunities to validate indication guidelines using Internet/database technology for data analysis and browsing of decision graphs concerning clinical decision-making. This new technology facilitates the evaluation of appropriateness and necessity criteria in combination with clinical outcomes.

Quality assessment in gynecology and obstetrics. Projects and experience in Switzerland.

The first steps in quality assessment of results of performance in gynecology and obstetrics were taken by the Swiss Association of the OB/GYN Clinics of the Swiss Society of Obstetrics and Gynecology in the 1980's. Currently, medical data of more than 800,000 patients are available, allowing a good comparison of the quality of results. Concerned that purchasing coverage for health services was made exclusively on the basis of cost, resulting in lower public health quality, the Swiss Society of OB/GYN set up a Board of Quality Assessment in 1995. Not only the quality of results, but also the quality of indications, structures and processes are considered by using a modified Donabedian model. Moreover, standardized patient information forms have been worked out for 15 gynecological and five obstetrical operations. Since hysterectomy is the most common major gynecological operation in Switzerland, the evaluation of the quality of the indications is of substantial interest. Guided by the RAND Appropriateness Method, criteria for quality assessment with respect to appropriateness and necessity of hysterectomy have been drawn up. Swiss guidelines and 125 different clinical scenarios are defined by a panel of 22 OB/GYN experts. The aim of this project is to offer an interactive second opinion system, called "Swiss Guidelines for Hysterectomy", and anonymous self-assessment of quality. Appropriateness and necessity of medical procedures have to be defined by medical professionals providing a proper balance between the patient's desires and financial demands.