tailieunhanh - Anaesthesia, Pain, Intensive Care and Emergency - Part 8

Các tiêu chuẩn này đến từ đâu? Trong nhiều trường hợp, dự thảo đầu tiên của họ đã được tạo ra bởi các học viên sau đại học và kết quả từ "cập nhật" những lời khuyên của giáo viên tôn trọng của họ, các lệnh nhận được từ các chuyên gia tư vấn của họ và các thông tin thu được từ cuốn sách và Đại hội. | Regional anaesthesia in the patient with pre-existing neurological dysfunction 329 accurately predicts clinical outcome these studies illustrate the importance of minimising direct needle trauma during regional techniques especially in patients at increased risk of neurological complications. Neurological deficits after regional anaesthesia may be a direct result of local anaesthetic toxicity. Clinical and laboratory findings indicate that anaesthetic solutions are potentially neurotoxic 10-14 . It is generally agreed that local anaesthetics administered in clinically appropriate doses and concentrations do not cause nerve damage 15 . However prolonged exposure to high concentrations of local anaesthetic solutions may result in permanent neurological deficits. Patients with underlying nerve dysfunction may have a decreased requirement for local anaesthetic and a decreased threshold for neurotoxicity 12 . Indeed Yee et al. 16 have demonstrated that the dose requirement for local anaesthetics is decreased and potency increased in aged animals. This may have implications for the use of local anaesthetics in an ageing patient population. Neural ischaemia may occur as a result of systemic or local vascular insufficiency. Systemic hypotension with or without a spinal anaesthetic may produce spinal cord ischaemia in the watershed areas between radicular vessels resulting in flaccid paralysis of the lower extremities anterior spinal artery syndrome . The use of local anaesthetic solutions containing epinephrine or phenylephrine may theoretically result in local ischaemia especially in patients with microvascular disease but clinical data are lacking 11 17 . Furthermore large clinical studies have failed to identify the use of vasopressors as a risk factor for neurological injury. Most cases of presumed vasopressor-induced neurological deficits after spinal anaesthesia have been single case reports often with several other risk factors involved 18 . The neural double crush