Assessment of three different mortality prediction models in four well-defined critical care patient groups at two points in time: a prospective cohort study.

BACKGROUND AND OBJECTIVE: Mortality prediction systems have been calculated and validated from large mixed ICU populations. However, in daily practice it is often more important to know how a model performs in a patient subgroup at a specific ICU. Thus, we assessed the performance of three mortality prediction models in four well-defined patient groups in one centre. METHODS: A total of 960 consecutive adult patients with either severe head injury (n = 299), multiple injuries (n = 208), abdominal aortic aneurysm (n = 267) or spontaneous subarachnoid haemorrhage (n = 186) were included. Calibration, discrimination and standardized mortality ratios were determined for Simplified Acute Physiology Score II, Mortality Probability Model II (at 0 and 24 h) and Injury Severity Score. Effective mortality was assessed at hospital discharge and after 1 yr. RESULTS: Eight hundred and fifty-five (89%) patients survived until hospital discharge. Over all four patient groups, Mortality Probability Model II (24 h) had the best predictive accuracy (standardized mortality ratio 0.62) and discrimination (area under the receiver operating characteristic curve 0.9), but Simplified Acute Physiology Score II performed well for patients with subarachnoid haemorrhage. Overall calibration was poor for all models (Hosmer-Lemeshow Type C-values between 20 and 26). Injury Severity Score had the worst discrimination in trauma patients. All models over-estimated hospital mortality in all four patient groups, and these estimates were more like the mortality after 1 yr. CONCLUSIONS: In our surgical ICU, Mortality Probability Model II (24 h) performed slightly better than Simplified Acute Physiology Score II in terms of overall mortality prediction and discrimination; Injury Severity Score was the worst model for mortality prediction in trauma patients.

Influence of a parenteral fish-oil preparation (Omegaven) on erythrocyte morphology and blood viscosity in vitro.

In most studies fish-oil had been administered by enteral route. Recently an parenteral marine fish-oil emulsion has been developed. With an intravenous infusion an immediate effect on the membrane lipid composition of circulating blood cells and endothelial cells may be expected. In this study we assessed the acute effects of a parenteral fish-oil emulsion on blood rheology and erythrocyte morphology in vitro. Blood from 15 healthy young volunteers was incubated in vitro with increasing concentrations of a parenteral fish-oil emulsion (Omegaven) at 37 degrees C for different time periods (2, 20, and 60 min). Plasma and whole blood viscosity were measured using a Couette viscometer. Red blood cell morphology was examined by light and scanning electron microscopy. High plasma concentrations of Omegaven increased whole blood viscosity at high and low shear rate (p<0.01 above 20%vol) and plasma viscosity to a lower extent (p<0.05 at 40%vol). Erythrocytes underwent cell swelling (increase of centrifuged hematocrit) and a dose-dependent echinocytic shape transformation, which indicates an intercalation of the compound in the outer hemileaflet of the cell membrane. These effects were already apparent after 2 min of incubation and were fully reversible upon wash-out of Omegaven. We conclude that the intravenous fish-oil preparation Omegaven interacts with the outer hemileaflet of the erythrocyte membrane and may affect membrane functions. At pharmacological concentrations these effects seem to be negligeable.

Prevalence of tracheostomy in ICU patients. A nation-wide survey in Switzerland.

OBJECTIVE: To assess the frequency, timing and technique of tracheostomy and its variation between different intensive care units (ICUs) in Switzerland. DESIGN: Retrospective, descriptive prevalence study. SETTING: A questionnaire was sent to all intensive care units formally recognized by the Swiss Society of Intensive Care Medicine. Excluded were paediatric ICUs. A total of 48 ICUs (70 %) responded. PATIENTS: In 1995 and 1996 the participating units had admitted 90,412 patients for a total of 243,921 ICU days. RESULTS: Seventy percent of the contacted ICUs answered the questionnaire. The prevalence of tracheostomy was 10% in the long-term ventilated patients (defined as > 24 h), or 1.3 % of all patients. Most tracheostomies were performed during the 2nd week of ventilation. The frequency of tracheostomy varied widely (0-60 %) and was only slightly associated with the different language regions of our country and with the policy of hospitals to accept or refuse intubated patients on their normal wards. Most units offered either conventional surgical tracheostomy (69 %) and/or percutaneous procedures (57 %). The decision to perform a tracheostomy was made mostly by the intensivist and the procedure was more often performed in the ICU (65 %) than in the operating theatre (35 %). Units where the intensivist had exclusive control used only percutaneous techniques. An overall complication rate of 13 % was reported, bleeding and infections being at the top of the scale. Only 27 % of the units performed late follow-up protocols. CONCLUSIONS: Despite its frequency, tracheostomy in Swiss ICUs is far from being standardized with regard to indication, timing and choice of technique.

[Preoperatively asymptomatic left adrenal incidentaloma]. / Präoperativ asymptomatisches Inzidentalom der linken Nebenniere.

Since the introduction of new, very sensitive imaging procedures (ultrasonography, CT, MRI) the incidence of incidentally discovered, asymptomatic adrenal masses has clearly increased. These tumours are a new challenge to develop therapy and preoperative evaluation strategies, as the following case report shows. In a 29-year-old asymptomatic female patient a large adrenal tumour on the left side was discovered on abdominal ultrasonography during pregnancy. The further endocrinological examinations were normal. The patient was operated on post partum. During intraoperative manipulation of the tumour we observed an excessive increase in blood-pressure and heart rate. Shortly after removal of the tumour and immediate sympatholytic treatment the situation was under control. The intraoperative clinical situation and histological work-up of the tumour led to the diagnosis of phaeochromocytoma. The problem of adrenal incidentalomas is discussed on the basis of the current literature and an algorithm for preoperative evaluation is presented.

[Comparison between ski and snowboarding accidents. Current overview from the ski area Arosa (Switzerland) (1988/89 to 1994/95)]. / Ski-und Snowboardunfälle im Vergleich. Ein aktueller Uberblick aus dem Skigebiet von Arosa (Schweiz) (1988/89 bis 1994/95).

The ski resort of Arosa (Switzerland) is geographically isolated and has recorded it winter sports accidents since 1969. Based on this reliable data, the ski (3877 in total) and snowboard (512 in total) accidents of the last seven years were statistically analyzed. The study showed that snowboarding isn't much more dangerous than skiing the number of accidents was about the same in both groups, whereas snowboarders were less likely to be admitted to a hospital or to get injured by collision. The average age of snowboarders was 21.6 years, almost 20 years lower than that of the skiers. Both sexes were about equally represented. Most snowboarders had injuries of the upper extremity (14% fractures of the radius, 9% distortions), particularly because of falling backward after losing balance. In both groups (skiers and snowboarders) 60% of all injuries were of low grade, which did not lead to long absence from work. The results are discussed and compared with already existing publications.