Regional anaesthesia: awake or asleep?

摘要

We read with interest Feely et al.'s survey and were surprised by their finding, that the vast majority of anaesthetists performed both upper, and particularly lower limb blocks after induction of general anaesthesia . Furthermore, for certain blocks over half of those who believed it was safer to perform the block prior to general anaesthesia admitted that this was not their actual practice.It would have been intriguing to explore why this was the case. Presumably, one reason was to avoid patient discomfort. Whilst -we consider it important to minimise patient discomfort during peripheral nerve blockade (PNB), this can be achieved without resorting to general anaesthesia. We perform over 2500 regional anaesthetics annually at the Toronto Western Hospital, none of them under general anaesthesia. Instead we sedate the patients as required with titrated doses of intravenous midazolam. Occasionally we will supplement this with fentanyl or propofol if the block is particularly painful or the patient is particularly anxious. We avoid over-sedation so as to be able to detect significant pain, paraesthesia or early signs of local anaesthetic toxicity during block performance. Unlike the majority of the respondents, we routinely use ultrasound to localise nerves. Compared to neurostimulation, ultrasound can reduce performance time, needle passes and procedure related pain [2, 3].