Local Anaesthesia Flashcards
What is a local anaesthetic ?
a drug or agent which reversibly blocks neuronal transmission in the applied region causing a temporary loss of sensation/pain, without affecting consciousness
What is a general anaesthetic?
a drug or agent which produces a loss of response to painful stimulation (analgesia) and a loss of reflexes (motor and autonomic) with a reversible loss of consciousness
What is an analgesic?
a drug or agent which relieves and prevents pain without a loss of consciousness
What is a sedative?
a drug or agent which reduces irritability, excitement or nervousness
Where is LA injected?
Near nerve branches innervating the small, specific area of the body near the surgical site
Briefly state some reasons why LA is clinically useful
temporary and rapid in action, completely reversible
sufficient potency to provide complete anaesthesia
sufficient in duration to complete procedure comfortably
not irritating to tissues
does not produce allergic reaction (hypoallergenic)
not addictive
low degree of systemic toxicity
high therapeutic ratio
What was the first naturally occurring local anaesthetic
cocaine
Found in coca leaves
Who was the first clinician to inject cocaine to perform a peripheral nerve block? When did this take place?
William Halsted (1884)
What does a low therapeutic index refer to ?
This is when there is a small difference between the therapeutic and toxic doses of a drug
Give an example of a toxic effect of cocaine
respiratory depression
There is a potential for abuse an addiction when using cocaine. Briefly state why this is the case
CNS stimulant, psychological dependence
crave drugs euphoric and stimulatory effects
What are the short term CNS effects of cocaine?
Mydriasis (dilated pupils)
headache
nausea
vomiting
muscle tremors
twitching
pseudohallucinations (cocaine bugs)
What are the long term CNS effects of cocaine?
Generalised seizures
hallucinations
gross muscle tremors and twitching
decreased responsiveness to stimuli
increased deep tendon reflexes
incontinence
What are effects of a cocaine overdose on the CNS?
Generalised convulsions
cerebral infarction and haemorrhage
pupils fixed and dilated
flaccid paralysis
loss of vital support functions
CNS depression
coma
What are the short term cardiovascular system effect of cocaine?
vasoconstriction
hypertension
tachycardia
pallor
What are the long term cardiovascular effects of cocaine?
cardiac dysrhythmias
hypertension
tachycardia
peripheral cyanosis
What is cyanosis?
blue/grey lips or skin; happens when there is not enough blood supply to these areas
What are effects of a cocaine overdose on the cardiovascular system?
aortic dissection
MI
cardial arrest
What are short term respiratory effects of cocaine?
increase in breathing rate and depth
What are long term respiratory effects of cocaine?
abnormally rapid breathing (tachypnoea)
shortness of breath/gasping (dypnoea)
irregular breathing pattern
What are the effects on a cocaine overdose of the respiratory system?
respiratory depression
respiratory failure
cyanosis (lack of oxygen)
gross pulmonary oedema
paralysis of respiration
What are the short term effect of cocaine on the body temperature?
elevation
What are the long term effects of cocaine on the body temperature?
sever hyperthermia
What is the effect of a cocaine overdose on the body temperature?
Severe hyperthermia