Principles and Pharmacology Flashcards
Give four examples of IV anaesthetic drugs (general anaesthesia)
Thiopentone (aka thiopental sodium)
Propofol
Etomidate
(Ketamine)
What is minimum alveolar concentration (MAC)?
MAC is the concept of the concentration of the drug required in the alveoli which is required to produce anaesthesia with any particular agent. Therefore, a low MAC value means an agent is potent.
Give five examples of inhaled analgesic drugs
Isoflurane
Desflurane
Sevoflurane
Nitrous oxide
What is the most common sequence of general anaesthesia?
Intravenous induction followed by inhalational maintenance.
Describe the indications for muscle relaxants
ventilation & Intubation
when immobility is essential e.g. microscopic surgery, neurosurgery
body cavity surgery (access)
Describe the potential problems associated with muscle relaxants
awareness
incomplete reversal
- airway obstruction, ventilatory insufficiency in immediate post op period
apnoea = dependence on airway & ventilatory support
Give two classifications of muscle-relaxing drugs
Non-depolarising neuromuscular blocks
Depolarising neuromuscular blocks
What is the “triad” of anaesthesia?
Analgesia
Hypnosis (unconsciousness)
Relaxation
What effects do general anaesthetics have on the cardiovascular system?
Depress CV centre
- reduce sympathetic outflow
- negative inotropic/chronotropic effect on the heart
- vasodilation
What effects do general anaesthetics have on the respiratory system?
Respiratory depression
- reduced hypoxic/hypercapnoeaic drive
- greatly decreased tidal volume; can persist for several days post-op
- increase respiratory rate
Paralyse cilia
What are the two main possible airway complications of general anaesthesia?
Obstruction
- including laryngospasm
Aspiration
- gastric contents, blood, surgical debris
Describe the indications for intubation
Protect airway from gastric contents
Need for muscle relaxation and therefore artificial ventilation
Shared airway with risk of blood contamination
Need for tight control of blood gases (e.g. neurosurgery)
Restricted access to airway
Describe the indications for regional anaesthesia
avoidance of general anaesthesia severe resp disease • less resp physiological impact avoid airway problems • difficult intubation • obstruction (OSA) allergies / reactions to GA agents
Describe the contra-indications for regional anaesthesia
Patient refusal Fixed cardiac output • aortic / mitral stenosis Infection Bleeding diathesis / anticoagulation Technical difficulties Spinal problems / neurology
Give five examples of local anaesthetics
Lignocaine (aka lidocaine) Bupivacaine Prilocaine Ropivacaine Levobupivacaine
How do local anaesthetic agents work?
They are sodium channel blockers: prevent propagation of the action potential
List the possible signs and symptoms of local anaesthetic toxicity
Circumoral and lingual numbness and tingling Light-headedness Tinnitus, visual disturbances Muscular twitching Drowsiness Cardiovascular depression Convulsions Coma Cardiorespiratory arrest
