Knowledge
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A growing collection of landmark papers relevant to intensive care and critical care medicine.
These papers are practice changing and hold current, ongoing significance beyond their historical importance.
This is a dynamic and changing document that will be updated, pruned and added to as appropriate. Many of these papers have free full-text provided by the publisher because of their significance.
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The potential for dexamethasone and other glucocorticoids to prolong peripheral nerve blocks was first noted almost 20 years ago.
While the effect has been observed with several different blocks (upper & lower extremity, and even TAP blocks), the clinical significance varies and several questions still remain:
Is the effect exclusive to perineural dexamethasone? Several studies have observed similar effects for both IV and perineural dexamethasone (though less profound than other papers).
Is the effect safe? This is perhaps the most concerning, as there are suggestions that the effect may represent an enhancement of the well-known neurotoxicity of local anaesthetic agents.
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The association of anesthesia in the sitting beach-chair position with intra-operative stroke, continues to be controversial. Although some studies have identified this as a risk, it is still a rare complication, albeit devastating.
Expert opinion suggests intra-arterial blood pressure monitoring is best practice, but most importantly with consideration for actual cerebral perfusion pressure given the sitting position.
Some research suggests regional anaesthesia, possibly combined with spontaneous ventilation GA (rather than relaxation GA with IPPV) offers unique benefits that better maintain cerebral oxygenation, although the exact difference is unclear.
Similarly, the benefit and role of non-invasive cerebral perfusion monitoring has not been conclusively shown, although it appears logical that it may offer benefit in these patients.
Case studies of patients suffering cerebral ischaemia under beach-chair, do point to combinations of poor intra-operative blood pressure management and possibly pre-existing mild cardiovascular disease (eg. hypertension) as contributing to some degree.
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