Magma Mixing in the 874 AD Hrafntinnuhraun Rhyolite Eruption

The exposed Icelandic crust contains ~10% rhyolite and ~90% basalt, and there is ample evidence in both recent and ancient rocks of interactions between rhyolitic and basaltic magmas. A spectacular and little-studied example is the c. 874 AD rhyolite eruption of Hrafntinnuhraun at the Torfajökull volcano, where after an initial explosive (Plinian) phase a large rhyolite lava field formed. In this lava field, one vent produced a hybrid lava which is a mechanically mixed blend of approximately 83% rhyolite and 17% basalt. Polarized light microscopy was conducted on a suite of Hrafntinnuhraun samples that include flow-banded rhyolites, vesicular basaltic enclaves, and hybrid lavas. The flow-banded rhyolites are nearly aphyric, containing plagioclase and augite phenocrysts, with minor hornblende and biotite. The enclaves contain abundant plagioclase, augite, and olivine. The hybrid lavas contain plagioclase, augite, and olivine, but also contain minor amounts of biotite and hornblende. To better evaluate the magma mixing process, one hybrid lava sample (83:17 rhyolite:basalt) was analyzed by EPMA. This sample contains mineral cargos belonging to both the rhyolite and basalt end-member magmas. Plagioclase compositions range from An22 to An87, with anorthite-rich grains displaying resorption textures. Of particular interest are olivine crystals derived from the basalt, which contain Fo-rich (~Fo80) interiors and narrow rims (~5- 10µm) with lower Fo content (~Fo70). Follow-up work on diffusion modelling will hopefully yield a timescale, thus providing valuable and new information on mixing processes in the conduit prior to the eruption and cooling of this hybrid lava

Human Factors Applied to Perioperative Process Improvement

Human factors/ergonomics (HF/E) is its own scientific discipline that can be applied to understanding performance in perioperative medicine. Humans are not perfect decision makers and are affected by a variety of factors that can greatly harm their ability to perform, including attention, bias, stress, and fatigue. HF/E has a unique perspective on human error, and HF/E can illustrate how moving away from blame can enhance safety. HF/E offers strategies for undertaking a systematic approach to assessment of work processes in perioperative medicine that can be used to increase safety and wellbeing of patients and providers

Mucormycosis in Australia: Contemporary epidemiology and outcomes

Mucormycosis is the second most common cause of invasive mould infection and causes disease in diverse hosts, including those who are immuno-competent. We conducted a multicentre retrospective study of proven and probable cases of mucormycosis diagnosed between 2004–2012 to determine the epidemiology and outcome determinants in Australia. Seventy-four cases were identified (63 proven, 11 probable). The majority (54.1%) were caused by Rhizopus spp. Patients who sustained trauma were more likely to have non-Rhizopus infections relative to patients without trauma (OR 9.0, p 0.001, 95% CI 2.1–42.8). Haematological malignancy (48.6%), chemotherapy (42.9%), corticosteroids (52.7%), diabetes mellitus (27%) and trauma (22.9%) were the most common co-morbidities or risk factors. Rheumatological/autoimmune disorders occurred in nine (12.1%) instances. Eight (10.8%) cases had no underlying co-morbidity and were more likely to have associated trauma (7/8; 87.5% versus 10/66; 15.2%; p <0.001). Disseminated infection was common (39.2%). Apophysomyces spp. and Saksenaea spp. caused infection in immuno-competent hosts, most frequently associated with trauma and affected sites other than lung and sinuses. The 180-day mortality was 56.7%. The strongest predictors of mortality were rheumatological/autoimmune disorder (OR = 24.0, p 0.038 95% CI 1.2–481.4), haematological malignancy (OR = 7.7, p 0.001, 95% CI 2.3–25.2) and admission to intensive care unit (OR = 4.2, p 0.02, 95% CI 1.3–13.8). Most deaths occurred within one month. Thereafter we observed divergence in survival between the haematological and non-haematological populations (p 0.006). The mortality of mucormycosis remains particularly high in the immuno-compromised host. Underlying rheumatological/autoimmune disorders are a previously under-appreciated risk for infection and poor outcome

Determinants of mortality in non-neutropenic ICU patients with candidaemia

Introduction: Candidaemia in critically-ill intensive care unit (ICU) patients is associated with high crude mortality. Determinants of mortality – particularly those amenable to potential modification – are incompletely defined. Methods: A nationwide prospective clinical and microbiological cohort study of all episodes of ICU-acquired candidaemia occurring in non-neutropenic adults was undertaken in Australian ICUs between 2001 and 2004. Multivariate Cox regression analyses were performed to determine independently significant variables associated with mortality. Results: 183 episodes of ICU-acquired candidaemia occurred in 183 patients during the study period. Of the 179 with microbiological data, Candida albicans accounted for 111 (62%) episodes and Candida glabrata, 32 (18%). Outcome data were available for 173: crude hospital mortality at 30 days was 56%. Host factors (older age, ICU admission diagnosis, mechanical ventilation and ICU admission diagnosis) and failure to receive systemic antifungal therapy were significantly associated with mortality on multivariate analysis. Among the subset who received initial fluconazole therapy (n = 93), the crude mortality was 52%. Host factors (increasing age and haemodialysis receipt), but not organism- (Candida species, fluconazole MIC), pharmacokinetic- (fluconazole dose, time to initiation), or pharmacodynamic-related parameters (fluconazole dose:MIC ratio) were associated with mortality. Process of care measures advocated in recent guidelines were implemented inconsistently: follow-up blood cultures were obtained in 68% of patients, central venous catheters removed within five days in 80% and ophthalmological examination performed in 36%. Conclusions: Crude mortality remains high in Australian ICU patients with candidaemia and is overwhelmingly related to host factors but not treatment variables (the time to initiation of antifungals or fluconazole pharmacokinetic and pharmacodynamic factors). The role and timing of early antifungal intervention in critically-ill ICU patients requires further investigation.Deborah J.E. Marriott, E. Geoffrey Playford, Sharon Chen, Monica Slavin, Quoc Nguyen, David Ellis and Tania C. Sorrell for the Australian Candidaemia Stud

Bites (Mammalian)

Mammalian bites are usually caused by dogs, cats, or humans, and are more prevalent in children (especially boys) than in adults. Animal bites are usually caused by the person's pet and, in children, frequently involve the face. Human bites tend to occur in children as a result of playing or fighting, while in adults they are usually the result of physical or sexual abuse. Mixed aerobe and anaerobe infection is the most common type of infection, and can occur in up to half of human bites.We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent complications of mammalian bites? What are the effects of treatments for infected mammalian bites? We searched: Medline, Embase, The Cochrane Library, and other important databases up to October 2009 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).We found five systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.In this systematic review we present information relating to the effectiveness and safety of the following interventions: antibiotic prophylaxis (human bites, non-human bites), antibiotics, debridement, decontamination, irrigation, primary wound closure, and tetanus vaccination (after mammalian bites)

Management of mammalian bites

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