Anaesthesia
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The objective of this study was to compare linear and non-linear analysis of heart rate variability (HRV) in terms of correlation with haemodynamic fluctuation during induction of general anaesthesia. Pre-operatively, HRV was estimated by the MemCalc method in 114 patients scheduled for general anaesthesia. ⋯ As an index of non-linear analysis of HRV, ultra short-term entropy (UsEn) correlated better with blood pressure fluctuation than did the ratio of the power of low frequency component of HRV to that of high frequency component (LF/HF). In contrast, although LF/HF significantly correlated with heart rate increase caused by tracheal intubation, the correlation between UsEn and heart rate fluctuation was not significant.
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An 82-year-old ASA 2 patient underwent routine sub-Tenon's block for cataract surgery. One minute after injection of the local anaesthetic, the patient had a generalised tonic-clonic seizure and developed refractory ventricular fibrillation; subsequent resuscitation was unsuccessful. With no evidence for intravascular injection, the lack of structural brain abnormalities, and the most striking feature on post mortem examination being severe triple vessel coronary artery disease, it was concluded that this was primarily cardiac in origin; however, the possibility of brainstem anaesthesia should also be considered.