Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Nov 2004
ReviewMaximum recommended doses of local anesthetics: a multifactorial concept.
The current recommendations regarding maximum doses of local anesthetics presented in textbooks, or by the responsible pharmaceutical companies, are not evidence based (ie, determined by randomized and controlled studies). Rather, decisions on recommending certain maximum local anesthetic doses have been made in part by extrapolations from animal experiments, clinical experiences from the use of various doses and measurement of blood concentrations, case reports of local anesthetic toxicity, and pharmacokinetic results. The common occurrence of central nervous system toxicity symptoms when large lidocaine doses were used in infiltration anesthesia led to the recommendation of just 200 mg as the maximum dose, which has remained unchanged for more than 50 years. ⋯ As a rule, conditions (eg, end-stage pregnancy, high age in epidural, or spinal block) or diseases (uremia) that may increase the rate of the initial uptake of the local anesthetic are indications to reduce the dose in comparison to one normally used for young, healthy, and nonpregnant adults. On the other hand, the reduced clearance of local anesthetics associated with renal, hepatic, and cardiac diseases is the most important reason to reduce the dose for repeated or continuous administration. The magnitude of the reduction should be related to the expected influence of the pharmacodynamic or pharmacokinetic change.
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Reg Anesth Pain Med · Nov 2004
Editorial CommentAnesthesia and surgical outcomes: an orphean ambition.
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Headache is a common symptom caused by a wide variety of diseases. Primary headaches include migraine, cluster headache, tension-type headache, and other less common diseases. It is important to differentiate these headaches from secondary headaches caused by vascular, neoplastic, infectious, metabolic, or toxic disorders. ⋯ Detoxification from the offending drug is essential for headache improvement. Cervicogenic headache is common and needs to be diagnosed correctly since it may require specific therapy. Nerve blocks are useful for some patients with primary, as well as secondary, headaches.