Acute and Evolving MRI of High-Altitude Cerebral Edema: Microbleeds, Edema, and Pathophysiology.

MR imaging of high-altitude cerebral edema shows reversible WM edema, especially in the corpus callosum and subcortical WM. Recent studies have revealed hemosiderin deposition in WM long after high-altitude cerebral edema has resolved, providing a high-altitude cerebral edema "footprint." We wished to determine whether these microbleeds are present acutely and also describe the evolution of all MR imaging findings. In 8 patients with severe high-altitude cerebral edema, we obtained 26 studies: 18 with 3T and 8 with 1.5T scanners, during the acute stage, recovery, and follow-up in 7 patients and acutely in 1 patient. Imaging confirmed reversible cytotoxic and vasogenic WM edema that unexpectedly worsened the first week during clinical improvement before resolving. The 3T SWI, but not 1.5T imaging, showed extensive microbleeds extending beyond areas of edema seen acutely, which persisted and with time coalesced. These findings support cytotoxic and vasogenic edema leading to capillary failure/leakage in the pathophysiology of high-altitude cerebral edema and provide imaging correlation to the clinical course.

Community IntraVenous Antibiotic Study (CIVAS): protocol for an evaluation of patient preferences for and cost-effectiveness of community intravenous antibiotic services.

INTRODUCTION: Outpatient parenteral antimicrobial therapy (OPAT) is used to treat a wide range of infections, and is common practice in countries such as the USA and Australia. In the UK, national guidelines (standards of care) for OPAT services have been developed to act as a benchmark for clinical monitoring and quality. However, the availability of OPAT services in the UK is still patchy and until quite recently was available only in specialist centres. Over time, National Health Service (NHS) Trusts have developed OPAT services in response to local needs, which has resulted in different service configurations and models of care. However, there has been no robust examination comparing the cost-effectiveness of each service type, or any systematic examination of patient preferences for services on which to base any business case decision. METHODS AND ANALYSIS: The study will use a mixed methods approach, to evaluate patient preferences for and the cost-effectiveness of OPAT service models. The study includes seven NHS Trusts located in four counties. There are five inter-related work packages: a systematic review of the published research on the safety, efficacy and cost-effectiveness of intravenous antibiotic delivery services; a qualitative study to explore existing OPAT services and perceived barriers to future development; an economic model to estimate the comparative value of four different community intravenous antibiotic services; a discrete choice experiment to assess patient preferences for services, and an expert panel to agree which service models may constitute the optimal service model(s) of community intravenous antibiotics delivery. ETHICS AND DISSEMINATION: The study has been approved by the NRES Committee, South West-Frenchay using the Proportionate Review Service (ref 13/SW/0060). The results of the study will be disseminated at national and international conferences, and in international journals.

Core-peripheral temperature gradient as a diagnostic test in dyspnoea.

OBJECTIVES: To evaluate whether the core-peripheral temperature gradient could be used to distinguish between cardiac and respiratory causes of dyspnoea. METHODS: In total, 50 patients were enrolled in the study, based on the following inclusion criteria: (a) a primary presenting complaint of dyspnoea; (b) age > 40 years; (c) respiratory rate > 20 breaths/min; (d) hypoxia. The tympanic temperature and the temperature of the nasal tip were recorded, and the patient's discharge data and chest x ray results checked. Where there was discordance, arbitration was carried out by another researcher. RESULTS: Four patients were excluded, hence the final study sample was 46 patients. There was a statistically significant difference between the mean temperature gradients of the two study populations (p < 0.001). A gradient of > 8 degrees C was able to rule in a cardiovascular cause (92% specificity) whereas one of < 5 degrees C could rule it out (100% sensitivity). CONCLUSION: The test is safe, non-invasive and inexpensive. Although there were some limitations to the study, the test can still be commended as a useful adjunct to the emergency assessment of the acutely breathless patient.

High-altitude cerebral edema evaluated with magnetic resonance imaging: clinical correlation and pathophysiology.

CONTEXT: Because of its onset in generally remote environments, high-altitude cerebral edema (HACE) has received little scientific attention. Understanding the pathophysiology might have implications for prevention and treatment of both this disorder and the much more common acute mountain sickness. OBJECTIVES: To identify a clinical imaging correlate for HACE and determine whether the edema is primarily vasogenic or cytotoxic. DESIGN: Case-comparison study. SETTING: Community hospitals accessed by helicopter from mountains in Colorado and Alaska. PATIENTS: A consecutive sample of 9 men with HACE, between 18 and 35 years old, 8 of whom also had pulmonary edema, were studied after evacuation from high-altitude locations; 5 were mountain climbers and 4 were skiers. The control group, matched for age, sex, and altitude exposure, consisted of 3 subjects with high-altitude pulmonary edema only and 3 who had been entirely well at altitude. Four patients with HACE were available for follow-up imaging after complete recovery. MAIN OUTCOME MEASURES: Magnetic resonance imaging (MRI) of the brain during acute, convalescent, and recovered phases of HACE, and once in controls, immediately after altitude exposure. RESULTS: Seven of the 9 patients with HACE showed intense T2 signal in white matter areas, especially the splenium of the corpus callosum, and no gray matter abnormalities. Control subjects demonstrated no such abnormalities. All patients completely recovered; in the 4 available for follow-up MRI, the changes had resolved entirely. CONCLUSIONS: We conclude that HACE is characterized on MRI by reversible white matter edema, with a predilection for the splenium of the corpus callosum. This finding provides a clinical imaging correlate useful for diagnosis. It also suggests that the predominant mechanism is vasogenic (movement of fluid and protein out of the vascular compartment) and, thus, that the blood-brain barrier may be important in HACE.

Assessment of an objective structured clinical examination (OSCE) for undergraduate students in accident and emergency medicine.

Conventional techniques for assessing the knowledge and clinical competence of undergraduate medical students are widely acknowledged as being unsatisfactory. We introduced an objective structured clinical examination (OSCE) for our fourth year medical students at the end of their accident and emergency (A&E) medicine attachment. This paper outlines the organisation of the examination and the results of a comparison of marks obtained from the OSCE, from a multiple choice type examination and from a subjective rating of the students performance by their teachers. We found the OSCE to be an acceptable form of examination to both medical students and examiners. Our results show significant correlation between marks obtained on the OSCE exam and subjective rating of the students ability. There was no statistically significant relationship to marks obtained on a multiple choice questionnaire exam. The OSCE format is particularly appropriate to A&E medicine where the participation of patients in traditional clinical examinations is impractical.