Best practice & research. Clinical anaesthesiology
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Although retrobulbar and peribulbar regional anaesthetic techniques are used (by both anaesthesiologists and ophthalmologists) in various types of eye surgery, topical anaesthesia of the conjunctiva and cornea, followed--as needed--by sub-Tenon's block, is now common in routine cataract surgery. Intracameral administration of local anaesthetic by the ophthalmologist is also performed. Sedation during ophthalmic surgery is distinctly lighter than for other surgery because it is essential that the patient remains alert and can cooperate with the surgeon. ⋯ With a catheter placed into the nostril, the patient (whose head is draped and 'hidden') can have the end-tidal CO2 monitored. Finger index (FI), a palpation method that assesses the ease of performing retrobulbar block, is introduced. Because of the risk of life-threatening complications in ophthalmic regional anaesthesia, the services of an anaesthesiologist must be available and training of anaesthesia residents in ophthalmic regional anaesthesia is highly recommended.
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Best Pract Res Clin Anaesthesiol · Jun 2005
ReviewThe pharmacokinetics of ropivacaine in hepatic and renal insufficiency.
In patients with chronic end-stage liver disease, the peak plasma concentrations of ropivacaine after a single intravenous ropivacaine dose are similar to those in healthy subjects. However, patients with end-stage liver disease have about a 60% lower mean ropivacaine clearance than healthy subjects and are thus expected to have over two-fold higher steady-state ropivacaine plasma concentrations during a continuous ropivacaine infusion. ⋯ However, uraemic patients have significantly higher alpha-1-acid glycoprotein plasma concentrations than non-uraemic patients, and the peak plasma concentrations of free ropivacaine (related to toxicity) are similar in both groups. The pharmacokinetics of intravenously administered ropivacaine in patients with renal insufficiency and the possibility of clinically significant (S)-2',6'-pipecoloxylidide metabolite accumulation during continuous or repeated ropivacaine administration in these patients remain to be clarified.
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In recent years, regional anaesthesia in children has generated increasing interest. Continuous peripheral nerve blocks have an important role in the anaesthetic arsenal, allowing effective, safe and prolonged postoperative pain management. Indications for continuous peripheral nerve blocks depend on benefits/risks analysis of each technique for each patient. ⋯ New techniques, such as transcutaneous stimulation or ultrasound guidance, appear to facilitate nerve and plexus identification in paediatric patients. Nevertheless, continuous peripheral nerve block may mask compartment syndrome in certain surgical procedure or trauma. Finally, ropivacaine appears to be the best local anaesthetic for continuous peripheral nerve blocks in children, requiring low flow rate with low concentration of the local anaesthetic.
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Best Pract Res Clin Anaesthesiol · Jun 2005
ReviewBupivacaine, levobupivacaine and ropivacaine: are they clinically different?
Two new, long-acting local anaesthetics have been developed after the evidence of bupivacaine-related severe toxicity: levobupivacaine and ropivacaine. Both these agents are pure left-isomers and, based on their three-dimensional structure, they have less toxic potential both on the central nervous system and on the heart. ⋯ Evaluating randomised, controlled trials that have compared these three local anaesthetics, this chapter supports the evidence that both levobupivacaine and ropivacaine have a clinical profile similar to that of racemic bupivacaine, and that the minimal differences observed between the three agents are mainly related to the slightly different anaesthetic potency, with racemic bupivacaine>levobupivacaine>ropivacaine. However, the reduced toxic potential of the two pure left-isomers supports their use in those clinical situations in which the risk of systemic toxicity related to either overdosing or unwanted intravascular injection is high, such as during epidural or peripheral nerve blocks.
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Best Pract Res Clin Anaesthesiol · Jun 2005
ReviewClinical pharmacology and the use of articaine for local and regional anaesthesia.
Quicker onset and shorter elimination time favours (+/-) articaine as a short-acting local anaesthetic for regional anaesthesia in day-case settings, e.g. arthroscopy (shoulder, knee), hand and foot surgery, and dentistry, because patients treated with articaine will be 'drug free' more quickly than those who receive other local anaesthetics. Articaine diffuses better through soft tissue and bone than other local anaesthetics. The concentration of articaine in the alveolus of a tooth in the upper jaw after extraction was about 100 times higher than that in systemic circulation. ⋯ Intrinsic half-lives of articainic acid are: t1/2alpha 12 minutes, and t1/2beta 64 minutes (1 hour). In dentistry, articaine is the drug of choice in the vast majority of literature. In other regional anaesthesia techniques (intravenous regional anaesthesia, epidural, spinal and plexus blocks) there are not enough data to prove that (+/-) articaine is safer and more effective than the short-acting local anaesthetics lidocaine, (+/-) prilocaine or (+/-) mepivacaine.