Local anesthesia epinephrine

Since blood levels are lowered up to 30% when vasoconstrictors are added to local anesthetics, localized neuronal uptake is enhanced because of higher local tissue concentrations in the region of drug administration, and the risks of systemic toxic effects are reduced. Furthermore, when used in spinal anesthesia, epinephrine acts directly on the cord to both enhance and prolong local anesthetic-induced spinal anesthesia by acting on a2 adrenoceptors, which inhibit release of... 

Topical local anesthesia is often used for eye, ear, nose, and throat procedures. Satisfactory topical local anesthesia requires an agent capable of rapid penetration across the skin or mucosa, and with limited tendency to diffuse away from the site of application. Cocaine, because of its excellent penetration and local vasoconstrictor effects, has been used extensively for ear, nose and throat (ENT) procedures. Cocaine is somewhat irritating and is therefore less popular for ophthalmic procedures. Recent concern about its potential cardiotoxicity when combined with epinephrine has led most otolaryngology surgeons to switch to a combination containing lidocaine and epinephrine. Other drugs used for topical anesthesia include lidocaine-bupivacaine combinations, tetracaine, pramoxine, dibucaine, benzocaine, and dyclonine. 

Iontophoresis has been used to deliver local anesthetics in the field of dentistry. Gangarosa [45] reported the iontophoresis of a 2% solution of lidocaine, with epinephrine (1 100,000) for the local anesthesia for extraction of retained deciduous teeth. Iontophoresis has also been used to desensitize teeth [46]. 

Precautions must be taken so that lidocaine hydriKhloridc solutions containing epinephrine salts are not used as cardiac depressants. Such solutions are intended only for local anesthesia and are not u.sed intravenously. The aqueous. solutions without epinephrine may be autoclaved several timc.s. if necessary. 

Prilocaine, a local anesthetic (4% with 1 200,000 epinephrine in 1 to 8 mL dental cartridge), is indicated for local anesthesia by nerve block or infiltration in dental procedures. 

Epinephrine as an adjunct in local anesthesia Vasocoirstriction respoitse to epinephrine causes local hemostasis, inhibiting distribution of local anesthetic away from the site of injection. 

Intramuscular tetrodotoxin Tectirt) was trialled, unsuccessfully, as a treatment for cancer patients in severe pain, but a tetrodotoxin-bupivacaine-epinephrine mixture is being investigated as a nerve block for prolonged local anesthesia. 

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. 

The answer is d. (Hardman, p T36J The addition of a vasoconstrictor, such as epinephrine or phenylephrine, to certain short-acting, local anesthetics is a common practice in order to prevent the rapid systemic absorption of the local anesthetics, to prolong the local action, and to decrease the potential systemic reactions. Some local anesthetics cause vasodilation, which allows more compound to escape the tissue and enter the blood. Procaine is an ester-type local anesthetic with a short duration of action due to rather rapid biotransformation in the plasma by cholinesterases. The duration of action of the drug during infiltration anesthesia is greatly increased by the addition of epinephrine, which reduces the vasodilation caused by procaine. 

Vasoconstriction. Local application of a-sympathomimetics can be employed in infiltration anesthesia (p. 204) or for nasal decongestion (naphazoline, tetra-hydrozoline, xylometazoline pp. 90, 324). Systemically administered epinephrine is important in the treatment of anaphylactic shock for combating hypotension. 

The vasoconstrictor actions of epinephrine and norepinephrine have been used to prolong the action of local anesthetics by reducing local blood flow in the region of the injection. Epinephrine has been used as a topical hemostatic agent for the control of local hemorrhage. Norepinephrine is infused intravenously to combat systemic hypotension during spinal anesthesia or other hypotensive conditions in which peripheral resistance is low, but it is not used to combat the hypotension due to most types of shock. In shock, marked sympathetic activity is already present, and perfusion of organs, such as the kidneys, may be jeopardized by norepinephrine administration. 

This consists in the injection of the local anesthetic into or around the nerve trunk or in the area of its distribution, so as to block off sensory impulses from the operative field. Because fatal effects may arise from the absorption of the anesthetic, the smallest amount of the least-toxic agent that is effective should be employed, under conditions that minimize absorption. Procaine with the addition of epinephrine (1 100,000) is generally preferred. A well-planned technique is important. It is not necessary to flood the entire field of operation, as in the earliest methods, nor even to infiltrate the whole line of incision, as in infiltration anesthesia. It is now aimed at confining the anesthetic mainly to the nerves, by placing it where the nerves chiefly run or injecting it into the nerves themselves. 

Infiltration anesthesia The injection of local anesthetic directly into tissue without taking into consideration the course of cutaneous nerves duration can be extended with the addition of epinephrine (vasoconstrictor)... 

The addition of epinephrine, a vasoconstrictor, to an injectable anesthetic prolongs the duration of anesthesia and decreases the rate of systemic absorption, thereby decreasing the risk of systemic toxicity. The duration of some anesthetics, such as bupivacaine, a long-acting anesthetic, cannot be significantly extended by adding epinephrine. Epinephrine also decreases local bleeding. Effective vasoconstriction is obtained with a concentration of 1 to 100,000 or even 1 to 200,000. The usual... 

In most minor surgical procedures of the eye, local infiltrative anesthesia is adequate. However, patients having multiple lesion removal or those exceptionally sensitive to pain may require a more complete regional anesthesia using an orbital nerve block. Nerve blocks provide excellent regional anesthesia without distortion of tissues but do not allow local epinephrine-induced hemostasis. 

In an abaxial sessamoid local anaesthetic model, the highest no-effect dose for the local anaesthetic effect of lidocaine was 4 mg (Harkins et al 1998). For caudal epidural anesthesia, dose rates of lidocaine alone of 0.25 (Csik-Salmon et al 1996) or 0.35mg/kg (Pikes et al 1989) have been proposed (i.e. 6-10 ml of a 2% solution). A maximum of 200 ml should be used for field blocks. The dose rates quoted for i.v. administration of either a 1% or 2% solution of lidocaine (without epinephrine (adrenaline)) are for loading doses of 0.65-5 mg/kg followed by a constant i.v. infusion of 25-100 gg/kg/min (Brianceau et al 2002, Doherty Frazier 1998). 

Hypersensitivity to amide-type local anesthetics, Adams-Stoke syndrome, supraventricular arrhythmias, Wolf-Parkinson-White syndrome. Spinal anesthesia contraindicated in septicemia. Caution Dosage should be reduced for elderly, debilitated, acutely ill safety in children has not been established. Severe renal/hepatic disease, hypovolemia, CHF, shock, heart block, marked hypoxia, severe respiratory depression, bradycardia, incomplete heart block. Anesthetic solutions containing epinephrine should be used with caution in peripheral or hypertensive vascular disease and during or following potent general anesthesia. Sulfite sensitivity or asthma for some local and topical anesthetic preparations. Tartrazine or aspirin sensitivity with some topical preparations. Anxiety, insomnia, apprehension, blurred vision, loss of hearing acuity, and nausea CNS depression, convulsion and respiratory depression... 

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. 

---