McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 2 7 General and local anaesthetic agents

be taken to prevent skin breakdown. Other problematic effects are associated with the route of administration and the amount of drug that is absorbed systemically. These effects are related to the blockade of nerve depolarisation throughout the system. Effects that may occur include CNS effects such as headache (especially with epidural and spinal anaesthesia), restlessness, anxiety, dizziness, tremors, blurred vision and backache; GI effects such as nausea and vomiting; cardiovascular effects such as peripheral vasodilation, myocardial depression, arrhyth- mias and blood pressure changes, all of which may lead to fatal cardiac arrest; and respiratory arrest. Clinically important drug–drug interactions When local anaesthetics and succinylcholine are given together, increased and prolonged neuromuscular blockade occurs. There is also less risk of systemic absorption and increased local effects if these drugs are combined with adrenaline. Prototype summary: Lignocaine Indications: Infiltration anaesthesia, peripheral and sympathetic nerve blocks, central nerve blocks, spinal and caudal anaesthesia, topical anaesthetic for skin or mucous membrane disorders. Actions: Blocks the generation and conduction of action potentials in sensory nerves by reducing sodium permeability, reducing the height and rate of rise of the action potential, increasing the excitation threshold and slowing the conduction velocity. Topical Not generally absorbed systemically T 1/2 : 10 minutes, then 1.5 to 3 hours; metabolised in the liver, excreted in the urine. Adverse effects: Headache, backache, hypotension, urinary retention, urinary incontinence, pruritus, seizures; when locally applied: burning, stinging, swelling, tenderness. Pharmacokinetics: Route Onset Peak Duration IM 5–10 mins 5–15 mins 2 hours

avoid hypersensitivity reactions ; impaired liver function, which could alter metabolism and clearance of the drug ; low plasma esterases, which could lead to toxicity of esters ; heart block, which could be exacerbated by the drug effects ; shock to prevent altered local delivery and absorption ; and current status of pregnancy or breastfeeding, which are cautions to the use of the drug. ■ ■ Perform a physical assessment to establish a baseline status before beginning therapy and for any potential adverse effects. ■ ■ Inspect site for local anaesthetic application to ensure integrity of the skin and to prevent inadvertent systemic absorption of the drug. ■ ■ Assess the person’s neurological status, including level of orientation, reflexes, pupil size and reaction, muscle tone and response and sensation, to evaluate the effectiveness of the drug and monitor for potential toxic neurological effects. ■ ■ Monitor vital signs, including temperature, pulse and blood pressure, and assess respiratory rate and auscultate lungs for adventitious sounds to identify changes and possible systemic absorption. ■ ■ Monitor laboratory test results, such as liver function tests and plasma esterases (if appropriate), to determine possible need for dose adjustment. ■ ■ Refer to the Critical thinking scenario for a full discussion of care for a person who is receiving local anaesthesia. ■ ■ Have emergency equipment readily available to maintain airway and provide mechanical ventilation if needed. ■ ■ Ensure that drugs for managing hypotension, cardiac arrest and CNS alterations are readily available in case of severe reaction and toxicity. ■ ■ Ensure that the person receiving spinal anaesthesia or epidural anaesthesia are well hydrated and remain lying down for up to 12 hours after the anaesthesia to minimise headache. ■ ■ Establish safety precautions to prevent injury during the time that the person has a loss of sensation and/or mobility. ■ ■ Provide meticulous skin care to the site of administration to reduce the risk of breakdown . ■ ■ Provide comfort measures to help the person tolerate drug effects. Provide pain relief, as well as skin care and turning to prevent skin breakdown , and supportive care for hypotension to prevent shock or serious hypoxia. ■ ■ Offer support and encouragement to help the person cope with the procedure and drugs being used. Implementation with rationale

Care considerations for people receiving local anaesthetic agents

Assessment: History and examination

■ ■ Assess for contraindications and cautions: any known allergies to these drugs or to parabens to