Anaesthesia, local adrenaline with

Infiltration anaesthesia is applied fan-shaped, with as few needle punctures as possible, in close proximity of the wound or the skin area to be treated. An aspiration should always take place to avoid intravascular injection. Suitable alternatives are lidocaine (lignocaine) or prilocaine for injection 5-10 mg/ml, with or without adrenaline. When making an incision of an abscess it is sometimes difficult to use a local anaesthetic if there is a pronounced inflammatory reaction, since the effect of the anaesthetic is reduced due to an increased acidity level. While adrenaline reduces bleeding and delays dispersion of the anaesthetic, local anaesthetic/adrenaline combinations are contraindicated for local anaesthesia of digits, on the face or where the skin survival is at risk. 

Dental anaesthesia—The total amount of local anaesthetics injected is much smaller (20-80 mg of lignocaine) than that used for othr purpose. Lignocaine (2%) with adrenaline (1 80,000) is the standard local anaesthetic preparation used in dentistry which produces good soft tissue and pulpal anaesthasia and also reduce postextraction bleeding. 

Adrenaline along with local anaesthetics may be used for infiltration, nerve block and spinal anaesthesia for prolonging the action and to reduce the systemic toxicity of local anaesthetics. 

Dose. For local anaesthesia, the total dose of lignocaine hydrochloride by injection should not exceed 300 mg (4.5 mg/kg), unless administered with adrenaline. For ventricular arrhythmias, initally 50 to 100 mg intravenously, followed by an infusion. 

Intravenous. A double cuff is applied to the arm, inflated above arterial pressure after elevating the limb to drain the venous system, and the veins filled with local anaesthetic, e.g. 0.5-1% lidocaine without adrenaline (epinephrine). The arm is anaesthetised in 6-8 min, and the effect lasts for up to 40 min if the cuff remains inflated. The cuff must not be deflated for at least 20 minutes. The technique is useful in providing anaesthesia for the treatment of injuries speedily and conveniently, and many patients can leave hospital soon after the procedure. The technique must be meticulously conducted, for if the full dose of local anaesthetic is accidentally suddenly released into the general circulation severe toxicity and even cardiac arrest may result. Bupivacaine is no longer used for intravenous regional anaesthesia as cardiac arrest caused by it is particularly resistant to treatment. Patients should be fasted and someone skilled in resuscitation must be present. 

Cocaine has sympathomimetic actions (tachycardia, peripheral vasoconstriction, and hypertension). Combined use with sympathomimetics such as adrenaline increases these effeets, and the risk of life-threatening arrhythmias. This risk may be further inereased if halothane anaesthesia is used (two of the above patients reeeived halothane ). See also Anaesthetics, general + Anaesthetics, local , p.92 and Anaesthetics, general + Ino-tropes and Vasopressors , p.99. 

Perason G, Siwera B. The ride of potentiatii effect of local anaesthesia with adrenalin in patients treated with tricyclic antidepressants. Swed Dent J (1975) 68,9-18. 

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