Lidocaine nerve blocks

Lidocaine hydrochloride [73-78-9] (Xylocaine), is the most versatile local anesthetic agent because of its moderate potency and duration of action, rapid onset, topical activity, and low toxicity. Its main indications are for infiltration, peripheral nerve blocks, extradural anesthesia, and in spinal anesthesia where a duration of 30 to 60 min is desirable. Because of its vasodilator activity, addition of the vasoconstrictor, epinephrine, increases the duration of action of Hdocaine markedly. It is also available in ointment or aerosol preparations for a variety of topical appHcations. 

Amide-type agents include articaine, lidocaine, bupivacaine, prilocaine, mepivacain and ropiva-caine. These are metabolized in the liver by microsomal enzymes with amidase activity. The amide group is preferred for parenteral and local use. If by accident rapidly administered intravascularly these agents, especially bupivacaine but also lidocaine, can produce serious and potentially lethal adverse effects including convulsions and cardiac arrest. They can more easily accumulate after multiple administrations. Intravenous lidocaine is sometimes used for regional anesthesia, for infiltration procedures, for the induction of nerve blockade and for epidural anesthesia. However, it is also used as an antiarrhythmic. Bupivacaine is a long-acting local anesthetic used for peripheral nerve blocks and epidural anesthesia. 

Nerve block anaesthesia in general practice mostly concerns finger or toe blocks. Lidocaine or prilocaine, 10 mg/ml without adrenaline (norepinephrine), is used and is injected on each side of the finger or toe, in two portions by the four nerve branches. Injection of larger volumes than 1-2 ml/side carries a risk of ischaemia because of the firm tissue. The transport through the nerve sheath takes a few minutes, and for a satisfactory result one should wait 5-10 minutes before the planned intervention starts. 

Lidocaine hydrochloride Xylocaine) is the most commonly used local anesthetic. It is well tolerated, and in addition to its use in infiltration and regional nerve blocks, it is commonly used for spinal and topical anesthesia and as an antiarrhythmic agent (see Chapter 16). Lidocaine has a more rapidly occurring, more intense, and more prolonged duration of action than does procaine. 

Bupivacaine is an amide compound with a duration of nerve blocking effect of around 3 hours. It is about four times more potent than lidocaine (lignocaine) and has an intermediate-to-slow onset of action. Bupivacaine is prepared as the hydrochloride salt in aqueous solutions in concentrations of 0.25%, 0.50%, and 0.75%. The incidence of motor block increases with increasing concentration. High doses of bupivacaine are associated with cardiac toxicity. Particular care must be exercised to avoid inadvertent overdosage or when the drug is administered to patients taking concurrent cardioactive medication. 

Local anesthetics have weak direct neuromuscular blocking effects that are of little clinical importance. However, their effects on cardiac cell membranes are of major clinical significance, and some local anesthetics are widely used as antiarrhythmic agents (eg, lidocaine) (see Chapter 14) at concentrations lower than those required to produce nerve block. Others of the same amide class (eg, bupivacaine, ropivacaine) can cause lethal arrhythmias if high plasma concentrations are inadvertently achieved. 

The choice of local anesthetic for infiltration, peripheral nerve blocks, and central neuraxis (spinal/epidural) blockade is usually based on the duration of action required. Procaine and chloroprocaine are short-acting lidocaine, mepivacaine, and prilocaine have an intermediate duration of action and tetracaine, bupivacaine, levobupivacaine, and ropivacaine are long-... 

Sinnott CJ et al On the mechanism by which epinephrine potentiates lidocaine s peripheral nerve block. Anesthesiology 2003 98 181. [PMID 12502995]... 

Clinical use Mepivacaine has been employed for all types of infiltration and conduction nerve block anesthesia using solutions of 1.0 and 1.5 % lasting for 1.5 to 3 h. Epidural anesthesia with 2.0 % mepivacaine has a rapid onset with a dense motor block. Hyperbaric solutions of mepivacaine have also been used for spinal anesthesia (Tetzlaff, 2000). Mepivacaine has been used for topical applications, but other LA such as lidocaine are more effective. 

Clinical use Because of its poor penetration of intact mucous membranes, procaine is largely ineffective for topical applications and has been mainly used in injection in combination with adrenaline, although in general it has been replaced by other LAs such as lidocaine. For infiltration anesthesia, 0.25 to 0.5 % solutions of procaine have been used in doses up to 600 mg. For peripheral nerve block, a common dose of 500 mg of procaine has been given as a 0.5 to 2.0 % solution. 

Lidocaine Xylocaine Rapid Intermediate Infiltration Peripheral Nerve Block Epidural Spinal Transdermal Topical Sympathetic block Intravenous regional block... 

Sakai T, Tomiyasu S, Yamada H, et al. Quantitative and selective evaluation of differential sensory nerve block after transdermal lidocaine. Anesth Analg. 2004 98 248-251. 

A frequently cited example of an important natural-product-derived drag is the neuromuscular blocker d-tubocurarine, derived from the South American plant curare, which was used by South American Indians as an arrow poison (see Chapter 26). Tubocurarine led to the development of decamethonium, which, although structurally dissimilar to tubocurarine, was nevertheless synthesized based on the then prevalent presumption that tubocurarine contained two quaternary nitrogens. Similarly, synthetic local anesthetics, such as lidocaine, benzocaine, and dibucaine, were synthesized to mimic the nerve-blocking effect of cocaine, a natural alkaloid obtained from the leaves of Coca eroxylum, but without the adverse side effects that have led to its abuse. 

Etidocaine is a long-acting derivative of lidocaine but is far more potent. It is effective for infiltration anesthesia, peripheral nerve block, and epidural and caudal blockade. 

Bupivacaine is long-acting 3 h) (see Table 18.1) and is used for peripheral nerve blocks, and epidural and spinal anaesthesia. Whilst onset of effect is comparable to lidocaine, peak effect occurs later (30 min). 

A 22-year-old man had a generalized tonic-clonic convulsion and loss of consciousness after an attempted superior laryngeal nerve block using 2% lidocaine 2 ml (282). The seizure was not terminated by intravenous diazepam 10 mg and he was intubated after intravenous thiopental and suxamethonium. He required two boluses of ephedrine 10 mg to maintain... 

Lidocaine Sodium channel bl(xkade Hepatic Local irritation, infusion effects Topical or single IV doses for local nerve block... 

Gentle abrasion with sandpaper or intraepidermal erbium laser treatment help accelerate penetration of the ETCA solution considerably. When sandpaper abrasion is used, a topical anesthetic should be applied (a swab with 2% lidocaine with adrenaline (epinephrine)) after the abrasion, before applying the acid. With an erbium laser, a nerve block or ring block is necessary. 

Lidocaine as a preventive ( ) this point is highly debatable, since arrhythmia can be avoided simply by taking more than 1 hour to apply the phenol. Simple lidocaine used to do nerve blocks before the phenol peel should be considered a cautious technique. 

Facial nerve blocks (FNB see p. 265) are quick and easy to administer, are not painful and cause few complications in the hands of an experienced doctor. A drop of 2% lidocaine can be injected very superficially with a fine-gauge needle 32G in precisely the same place that the nerve itself is injected with a 25G5/8 gauge needle. It is not possible to see the backflow of blood before injection with a 32G needle. 

The small, outer eyelid nerve block (0.5 cm of lidocaine without adrenaline) anesthetizes the zygomatic and lachrymal branches of the facial nerve (Figures 33.6 and 33.7). 

Nerve blocks can be given in cases of very painful outbreaks. A mixture of lidocaine with adrenaline (epinephrine) and ropivacaine or bupivacaine" can be used. In some cases, the doctor will have to prescribe opioids to relieve severe pain. However, treatment with opioids might well get rid of the pain but will not affect the itching. It could even aggravate the pruritus. The itching sometimes resists hydroxyzine and diphenhydramine. Asken reported that he once had to inject propanolol intravenously to relieve unbearable pruritus. 

A localized Litton or Baker-Gordon peel can be carried out with short-acting nerve blocks with 2% lidocaine without adrenaline (epinephrine). The pain is also short-lived. Phenol provides anesthesia that extends about 1 cm beyond the frosting, and the phenol can be applied slowly, step by step. 

Khodorova A, Konrad Meissner K, Leeson S, Strichartz GR 2001 Lidocaine selectively blocks abnormal impulses arising from noninactivating Na channels. Muscle Nerve 24 634-647... 

Lidocaine hydrochloride is a local anesthetic/vasopressor preparation. Lidocaine stabilizes neuronal membranes by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action. Epinephrine stimulates both alpha and beta receptors within sympathetic nervous system relaxes smooth muscle of bronchi and iris and is an antagonist of histamine. They are indicated for production of local or regional anesthesia by infiltration techniques such as percutaneous injection, by peripheral nerve block techniques such as brachial plexus and intercostals, and by central neural techniques such as lumbar and caudal epidural blocks. 

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