British journal of anaesthesia
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Anaesthesia-related neurotoxicity in the developing brain has been observed in animal models and suggested by observational human trials. Conclusive, quality evidence directing significant practice change is however lacking. Anaesthetists should be aware of the current evidence and future directions of research into this important area.
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Variation in arterial pressure and plethysmographic waveforms has been shown to be predictors of cardiac output response to fluid challenge. The objective of this study was to evaluate the ability of arterial and plethysmographic waveform variables to predict hypotension during blood loss. ⋯ Arterial and plethysmographic waveform variables were augmented with increasing blood loss in all patients. Older patients, patients who received anti-hypertensive drugs, or both developed hypotension earlier than others. Baseline values were weak predictors of hypotension during stepwise blood withdrawal. No clinically significant increase in HR was observed, regardless of tolerance of arterial pressure to blood withdrawal.
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Randomized Controlled Trial
Haemodynamic effects from aortocaval compression at different angles of lateral tilt in non-labouring term pregnant women.
Aortocaval compression (ACC) can result in haemodynamic disturbances and uteroplacental hypoperfusion in parturients. Its detection is difficult because in most patients, sympathetic compensation results in no signs or symptoms. However, profound hypotension may develop after sympathectomy during regional anaesthesia. In this prospective observational study, we aimed to detect ACC by analysing haemodynamic changes in term parturients who were positioned sequentially at different angles of lateral tilt. ⋯ Patients with ACC can be identified by the CO changes from serial measurements between supine, 15°, or full lateral tilt. Our findings suggest that in non-labouring parturients, ACC is asymptomatic and can be effectively minimized by the use of a left lateral tilt of 15° or greater.
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Post-ischaemic benzodiazepine administration is neuroprotective, but chronic administration of benzodiazepines can induce tolerance, such that the neuroprotective effect may be reduced. This study investigated whether benzodiazepine tolerance can worsen ischaemic injury and whether neuroprotection by post-ischaemic benzodiazepine administration is affected by benzodiazepine tolerance. We also investigated whether antagonism of benzodiazepine receptors by flumazenil was able to restore neuroprotection during benzodiazepine tolerance. ⋯ Benzodiazepine tolerance can worsen ischaemic neuronal injury and abolish the neuroprotection provided by post-ischaemic diazepam. Pre-treatment with flumazenil treatment reversed benzodiazepine tolerance and restored neuroprotection by post-ischaemic diazepam. These findings may suggest that management of patient's risk of developing cerebral ischaemia may need to take into account current use.