Anaesthesia
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Subarachnoid haemorrhage is a common neurological emergency, which carries a high morbidity and mortality. It is usually caused by rupture of an intracerebral aneurysm or, less commonly, an arteriovenous malformation. Although most patients present to a non-neurosurgical hospital, they often require urgent neurosurgical or neuroradiological intervention. ⋯ Medical management is directed towards maintaining adequate cerebral perfusion pressure whilst avoiding large increases in arterial blood pressure. Nimodipine therapy must be started early in an attempt to prevent cerebral vasospasm. The treatment options available at the neurological centre include surgical treatment or endovascular obliteration of the aneurysm or arteriovenous malformation.
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Opioid induced respiratory depression is potentially fatal. The aim of this study was to validate a monitoring system that could be used to assess respiratory depression in postoperative patients. The hypercapnic ventilatory response was estimated non-invasively in 12 volunteers. ⋯ Bland-Altmann analysis showed the variation between these two methods was +/- 5 l x min(-1) x kPa(-1) (2 SD). Second, we confirmed that the venturi mask is suitable for delivering CO(2) challenges. Despite the variability in RIP measurements, a simple multimodal respiratory monitoring system could be developed that incorporates clinical observation and non-invasive measurement of the ventilatory response to CO(2).
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A 41-year-old woman presented with the clinical features of methaemoglobinaemia after drinking Chinese herbal medicine. A life threatening methaemoglobin level of 68% was measured. Both clinical and laboratory diagnostic difficulties were encountered. The pitfalls of pulse oximeter, blood gas analysis and co-oximeter interpretation during diagnosis and after methylene blue administration are discussed.
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Case Reports
Paradoxical embolism through a patent foramen ovale: an unexpected complication of tracheal extubation.
A 41-year-old male with insulin-dependent diabetes mellitus was admitted for an elective arthroscopic release of adhesive capsulitis of his left shoulder. At the end of the surgical procedure, he appeared to regain consciousness but then became unresponsive at the time of tracheal extubation after a violent bout of coughing, developing bilateral up-going plantar responses, decorticate posturing and abnormal pupillary reflexes. He was transferred to the intensive care unit. ⋯ Contrast echocardiography, performed using agitated saline delivered through a femoral venous line, revealed a large patent foramen ovale with evidence of right to left shunting. In the absence of risk factors for air embolism, the clinical diagnosis was one of paradoxical embolism of venous thrombus resulting in brain stem ischaemia. The patient was commenced on life-long aspirin to minimise future embolic risk.