In vitro degradation behaviour of a friction stir processed magnesium alloy.

In this study, the in vitro degradation behaviour of a friction stir processed AZ31 magnesium alloy was investigated. Electrochemical experiments in simulated body fluid suggest that friction stir processing marginally enhances the degradation resistance of the alloy, which could be attributed to the dissolution of secondary phase particles. Homogenisation of the microstructure reduces galvanic corrosion. It is envisaged that the beneficial effect would be more pronounced for magnesium alloys which contain high volume fraction of galvanic corrosion inducing secondary phase particles.

Influence of circumferential notch and fatigue crack on the mechanical integrity of biodegradable magnesium-based alloy in simulated body fluid.

Applications of magnesium alloys as biodegradable orthopaedic implants are critically dependent on the mechanical integrity of the implant during service. In this study, the mechanical integrity of an AZ91 magnesium alloy was studied using a constant extension rate tensile (CERT) method. The samples in two different geometries that is, circumferentially notched (CN), and circumferentially notched and fatigue cracked (CNFC), were tested in air and in simulated body fluid (SBF). The test results show that the mechanical integrity of the AZ91 magnesium alloy decreased substantially (∼50%) in both the CN and CNFC samples exposed to SBF. Fracture surface analysis revealed secondary cracks suggesting stress corrosion cracking susceptibility of the alloy in SBF.

[Relation between long-term artificial respiration and respiratory tract infection in 104 patients in a surgical intensive care unit]. / Beobachtungen zum Zusammenhang zwischen Dauerbeatmung und Atemwegsinfektion bei 104 Patienten einer operativen Intensivstation.

The authors studied over a period of two years prospective connections between long-term artificial respiration and infections of the lower respiratory tract. A distinction was made between colonisation (RTC) and infection (RTI). Besides the incidence rate of RTC and RTI the severity of the infection was recorded. The connections between the underlying disease, the duration of artificial respiration, the age of the patient and the antibiotic treatment with the pathogenesis of RTC and RTI were studied. In more than half of the patients RTC could be demonstrated already within the first 24 hours; differences were related to underlying disease, start of ventilation and antibiotic treatment. The RTI incidence rate in all 104 ventilated patients was 67.3%. 19.2% of these already had RTI when respiration was initiated. Thus 48.1% of the patients developed RTI during artificial respiration. The diagnosis RTI was most frequent on the fourth day of respiration, and 80% of all RTI cases had appeared by the fifth day. The highest incidence was seen in patients with a thoracic trauma (85.7%). This group of patients also included the majority of life threatening cases of RTI. In one-quarter of the patients who developed RTI during artificial respiration there was no significant deterioration of pulmonary gas exchange; in 56% however, respiration was impaired to a life-threatening extent. The age of the patients did not have any bearing on the incidence rate and severity of RTI; however, all patients under artificial respiration who were over 70 years of age, died if the severity of the RTI had to be classified as life-threatening.(ABSTRACT TRUNCATED AT 250 WORDS)

[Epidural fentanyl analgesia for the relief of postoperative pain (author's transl)]. / Peridurale Analgesie mit Fentanyl in der operativen Intensivtherapie.

The results are reviewed which were obtained with epidural administration of fentanyl for the relief of pain in 134 patients who had undergone abdominal surgery or had sustained multiple fractures of the ribs. Single doses of 0.1 mg of fentanyl were given epidurally via an indwelling catheter inserted between L1/L2 or L2/L3 or, in the case of 7 patients with multiple rib fractures, between Th8/Th9. The results were satisfactory to excellent. An increase in the volume of the fentanyl solution from 10 ml to 20 ml increased the number of patients who were free from pain from 61 per cent to 81 per cent. The analgesic effects of individual doses lasted 2-8 hours (average 5.5 h). Persons with multiple rib fractures needed further injections on average every 3.5 hours. In these cases epidural fentanyl administration also proved valuable in combination with artificial ventilation. There were no serious side-effects. A comparison of the clinical efficacy of fentanyl proved that the same doses of the drug were more effective if given epidurally than if injected intramuscularly. The serum concentrations of fentanyl showed considerable individual variations after both intramuscular and epidural administration with peak values varying correspondingly. Epidural injections caused a steeper rise in concentration than did intramuscular administration. Although none of the patients developed respiratory depression the possibility of respiratory failure should be taken into account when employing epidural fentanyl analgesia. The method is very effective in intensive therapy for relieving postoperative or post-traumatic pain, but is unsuitable for the relief of chronic pain because the analgesic effect is comparatively short-lived.

Hygienic problems in anaesthesia and intensive care therapy. / Hygienische Probleme im Bereich der Anästhesie und Intensivtherapie

Cross infection has become a serious risk to hospitalized patients. Potential sources of infection by anaesthetic apparatus and equipment and the danger arising from disregard of proper asepsis are discussed. Prophylactic and hygienic measures to minimize these hazards are reviewed. Since patients receiving intensive therapy are particularly are risk very high hygienic standards are a "must" in these units. The need for thoroughly and regularly checking all equipment for contamination is emphasized.