LIDOCAINE

Adults and children above 12 years of age The dosage is adjusted according to the response of the patient and the site of administration. 4). The maximum single dose of lidocaine when given with adrenaline is 500 mg. The following table is a guide for the more commonly used techniques in the average adult.

The figures reflect the expected average dose range needed. Standard textbooks should be consulted for factors affecting specific block techniques and for individual patient requirements. The clinician’s experience and knowledge of the patient’s physical status are of importance in calculating the required dose.

Elderly or debilitated patients require smaller doses, commensurate with age and physical status. Each dose Type of block % Conc. g. minor nerve blocks and infiltration) Infiltration 1 up to 15 up to 150 Surgical operations Intercostals (per nerve) 1 2-5 Max.

15 ml 20-50 Max. 150 mg Surgical operations Postoperative pain and fractured ribs Pudendal 1 10 100 Instrumental delivery Major Nerve Block Paracervical (each side) 1 10 100 Surgical operations and dilatation of cervix Obstetric pain relief Sciatic 2 15 300 Surgical operations For local anaesthesia only.

In general, surgical anaesthesia requires the use of higher concentrations and doses. When a less intense block is required, the use of a lower concentration is indicated. The volume of drug used will affect the extent and spread of anaesthesia.

Care should be taken to prevent acute toxic reactions by avoiding intravascular injection. Careful aspiration before and during the injection is recommended. An accidental intravascular injection may be recognised by a temporary increase in heart rate.

The main dose, should be injected slowly, at a rate of 100-200 mg/min, or in incremental doses, while keeping in constant verbal contact with the patient. If toxic symptoms occur, the injection should be stopped immediately.

In common with other local anaesthetics, adverse reactions to lidocaine with adrenaline are rare and are usually the result of excessively high blood concentrations due to inadvertent intravascular injection, excessive dosage, rapid absorption or occasionally to hypersensitivity, idiosyncrasy or diminished tolerance on the part of the patient.

In such circumstances systemic effects occur involving the central nervous system and/or the cardiovascular system. The adverse reaction profile for lidocaine with adrenaline is similar to those of other amide local anaesthetics. g. g.

nerve trauma) or indirectly by the needle puncture. Tabulated list of adverse reactions Frequencies are defined as very common (≥1/10), common (≥1/100 to <1/10), uncommon (≥1/1,000 to <1/100), rare (≥1/10,000 to <1/1,000), very rare (<1/10,000) or not known (cannot be estimated from the available data).

1 Acute systemic toxicity Systemic toxic reactions primarily involve the central nervous system (CNS) and the cardiovascular system (CVS). 9). CNS reactions are similar for all amide local anaesthetics, while cardiac reactions are more dependent on the drug, both quantitatively and qualitatively.

Signs of toxicity in the central nervous system generally precede cardiovascular toxic effects, unless the patient is receiving a general anaesthetic or is heavily sedated with drugs such as benzodiazepine or barbiturate. Central nervous system toxicity is a graded response with symptoms and signs of escalating severity.

The first symptoms are usually, circumoral paraesthesia, numbness of the tongue, light-headedness, hyperacusis, tinnitus and visual disturbances. Dysarthria, muscular twitching or tremors are more serious and precede the onset of generalised convulsions.

These signs must not be mistaken for a neurotic behaviour. Unconsciousness and grand mal convulsions may follow which may last from a few seconds to several minutes. Hypoxia and hypercarbia occur rapidly following convulsions due to the increased muscular activity, together with the interference with respiration and possible loss of functional airways.

Regional anaesthetic procedures should always be performed in a properly equipped and staffed area. Equipment and drugs necessary for monitoring and emergency resuscitation should be immediately available. When performing major blocks, or using large doses, an IV cannula should be inserted before the local anaesthetic is injected.

9). Lidocaine with adrenaline should not be given intravenously. The effect of local anaesthetics may be reduced if an injection is made into an inflamed or infected area. Attempts should be made to optimise the patient’s condition before major blocks.

Although regional anaesthesia is frequently the optimal anaesthetic technique, some patients require special attention in order to reduce the risk of dangerous side effects: - Patients with epilepsy. - Patients with impaired respiratory function.

- Older people and patients in poor general condition. - Patients with partial or complete heart conduction block - due to the fact that local anaesthetics may depress myocardial conduction. - Patients with advanced liver disease or severe renal dysfunction.

g. 5). - Patients with acute porphyria. Lidocaine solution for injection is probably porphyrinogenic and should only be prescribed to patients with acute porphyria on strong or urgent indications. Appropriate precautions should be taken for all porphyric patients.

: - Injections in the head and neck regions may be made inadvertently into an artery, causing cerebral symptoms even at low doses. - Paracervical block can sometimes cause foetal bradycardia/tachycardia, and careful monitoring of the foetal heart rate is necessary.

- There have been post-marketing reports of chondrolysis in patients receiving post-operative intra-articular continuous infusion of local anaesthetics. The majority of reported cases of chondrolysis have involved the shoulder joint.

1 or to local anaesthetics of the amide type. The use of a vasoconstrictor is contraindicated for anaesthesia of fingers, toes, tip of nose, ears and penis.