Anesthetics

LOCAL ANESTHETICS (sodium channel blockers) 

MOA: 

• Block Na entry in the axonal membrane 

• Sensory and motor impulses affected since this is a nonselective process 

• Blocks perception of pain first, then cold, warmth, touch, and deep pressure 

Epinephrine added: 

• Constricts blood vessels to keep anesthetic localized 

• Extends duration of action 

• Reduces risk of toxicity 

LIDOCAINE 

• Anesthetic, antidysrhythmic sodium channel blocker, amide 

• Frequently used local anesthetic 

• IV, IM, or SQ, topical 

• May contain EPI (never give this kind IV) 

AE: 

• CNS toxicity 

• Excitement to AMS

• Cardiovascular 

• Bradycardia? 

Black box warning: 2% oral products accidental ingestion by children, seizure, brain injury, cardiac abnormalities, DEATH 

Lipid rescue: lipid infusion therapy for toxicity 

• Lipids bind to lidocaine toxin and pull it out of the body 

• Binding agent 

LOCAL ANESTHESIA ROUTES 

Spinal anesthesia – spinal headache and urinary retention 

• To avoid spinal headache encourage fluids, lay flat, LI and  below, avoid spinal cord 

NURSING CARE LOCAL ANESTHESIA 

• Use smallest amount 

• Apply to small area 

• Avoid open skin 

• Wear gloves 

• Advise client to avoid strenuous exercise 

• Don’t wrap the area 

• If injecting, aspirate 

• Rescue equipment available

• Check gag reflex prior to eating 

• Teach patient that area may be numb for several hours

• If blocks are given - increased risks for falls safety  

• Assess for bradycardia, hypotension, altered LOC, or decreased RR 

• Assess area where local was given  

GENERAL ANESTHESIA 

• Rapid and complete loss of sensation & consciousness 

• Balanced with IV and inhaled 

BALANCED ANESTHESIA 

• Propofol & short acting barbituates - induction 

• Neuromuscular blocking agents - muscle relaxation 

• opioids/nitrous oxidew - analgesia 

NURSING: GENERAL ANESTHETIC 

• Screen for history of anesthetic rx (malignant hyperthermia) 

• Patent IV access/adjunct medications (anxiety/pain) 

• Assess LOC/airway/circulation 

• Shivering common after anesthesia

• BP, HR, and TEMP 

• TCDB/early ROM/ambulation if not contraindicate 

• Pain 

• Reorient frequently 

• Educate when alert and w client and caregiver 

PROPOFOL (Diprivan) 

– intravenous anesthetic – 

• Rapid onset 

• Most used agent for anesthesia due to safety profile 

• Used for induction or maintenance in general anesthesia 

• Use with caution in patients receiving other benzos or opioids 

• Resp depression/apnea 

• hypotension/circulatory depression 

• Injection site pain 

• Infection 

• Anaphylaxis 

• Laryngospasm 

Propofol infusion syndrome: 

• Severe metabolic acidosis 

• hyperkalemia/renal failure 

• Rhabdomyolysis 

• Cardiac failure 

• Treated with mechanical ventilation, IV fluids, vasopressors 

INHALED ANESTHETICS 

MOA: enhance at inhibitory synapse and depress at excitatory 

• Therapeutic gases 

• Volatile liquids 

  • Liquid at room temp/vapor when inhaled 

NITROUS OXIDE 

– therapeutic gas – 

• General inhaled aesthetic 

• Low anesthetic potency but high analgesic 

• Ideal for short surgical or dental procedures 

• Administered in semi-closed method through a tube or by mask 

AE: post op n/v 

ISOFLURANE (Forane) 

• Inhaled general anesthetic high potency GABA and glutamate receptor agonist 

• Volatile liquid 

• Rapid onset

• Smooth induction 

• Muscle relaxation 

• Weak analgesic 

ADRs: 

• Dose-dependent resp depression, hypotension 

• Malignant hyperthermia 

• Mild n/v or tremor 

CI: 

• Hx of malignant hyperthermia 

• Head trauma or brain neoplasms due to possible increases in intracranial pressure 

• Older patients are more susceptible to hypotension caused by the drug 

MALIGNANT HYPERTHERMIA 

• Rare rx associate with anesthesia 

• Life threatening 

• Rapid hypermetabolic rx 

  • Sustained muscle contraction 

  • Increased HR

  • Increased temp 

  • Muscle breakdown 

  • Acidosis 

Tx: 

• DC  medication 

• Dantrolene 

• Supportive care 

ADJUNCTS TO ANESTHESIA 

• Anticholinergics: dry secretions and suppress bradycardia caused by anesthesia 

• Benzodiazepines (sedatives): given to reduce anxiety, fear, or pain, promote amnesia 

• Opioids: morphine given to counteract pain from surgery 

• Antiemetics 

• Neuromuscular-blocking agents 

ACETYLCHOLINE PATHO REVIEW 

• Depolarization 

• Repolarization 

• Cholinesterase 

• Pseudocholinesterase 

• competing/nondepolarizing

• Depolarizing 

SUCCINYLCHOLINE 

• Binds to acetylcholine receptors at neuromuscular junctions 

• Depolarizing 

AE: 

• Apnea

• Hypotension

• Malignant hyperthermia 

• Hyperkalemia w cardiac arrest 

• Muscle pain

• Neuromuscular blockade may be prolonged in pt with low plasma pseudocholinesterase levels 

NEUROMUSCULAR BLOCKING AGENTS/PARALYTICS 

• Cause paralysis only 

• No LOC 

• No sedation 

• No analgesia

• No amnesia 

• Baseline neuro assessment 

• Dosage of the neuromuscular blocking drugs should be maintained by using peripheral nerve stimulation during the surgical procedure 

• Close monitoring: sedation 

• d/c ASAP 

• Monitor for malignant hyperthermia 

• Post-neuro evaluation and continued pt monitoring are necessary steps after surgery is completed 

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MUSCLE SPASMS & SPASTICITY 

Spasms 

• Involuntary contraction of skeletal muscle 

• Overuse, injury, medications, epilepsy, electrolyte imbalances, dehydration, poor circulation, neurological d/o 

Spasticity 

• Continuous state of contraction 

• Damage to CNS: head injury, SCI, lesions, stroke 

Nursing: 

• Loss of coordination/mobility = increase r/o

• Pain 

• Loss of independence w/ ADLs 

NON-PHARMACOLOGICAL TX 

• Immobilization 

• hot/cold therapies 

• Acupuncture 

• Physical therapy 

• Surgery (for severe spasticity) 

• Herbal therapy (proceed w caution) 

DANTROLENE SODIUM (Dantrium, Revonto) 

• Skeletal muscle relaxant 

• Direct acting antispasmodic/calcium release blocker 

Goal: decrease pain and increase mobility, tx for malignant hyperthermia 

AE: 

• Weakness

• Drowsiness

• Diarrhea

• Dysphagia

• Hoarseness

• n/v

• ED

IV: vesicant (increase pH) 

Black box: liver failure