Anaesthesia Flashcards
(69 cards)
what problems can occur in general anaesthesia?
> polypharmacy so higher chance of reaction
muscle relaxation
- requires artificial ventilation
- airway management
separation of relaxation and hypnosis can lead to awarness
what do genera anaesthetics act on?
the neuronal ion channels opening up cl channels hyper polarising them
what tissues do IV anaesthetic agents pass though?
first the blood the into the viscera then into the muscle then into the fat
what is the MAC?
the maximum alveolar concentration, a measure of potency (low number high potency)
what is the affect of general anaesthesia on the central cardiovascular system?
depresses it
> decreased sympathetic outflow
> negative inotropic effect on the heart
> vasodialtion
what is the direct effect of general anaesthesia on the cardiovascular system?
> negatively inotropic
vasodilation decreasing the peripheral vascular resistance
vasodilation decreasing the venous return and cardiac output
what is the effect of general anaesthesia on the respiratory system?
> paralyses cilia
decreases the FRc (lower lung volumes, VQ mismatch)
resp. depressants (decreased hypoxic and hypercarbic drive, decreased tidal volume, increased uptake)
when are muscle relaxants indicated?
> ventilation and intubation
immobility is essential (microscopic and neurosurgery)
body cavity surgery
what problems occur with muscle relaxants?
> awareness
incomplete reversal causing airway obstruction
apnoea- dependence on ventilation and support
why is intra-operative analgesia often needed?
> prevents arousal
opiate contribute to hypnotic effects of GA
suppression of the reflex response to painful stimuli (tachycardia, hypertension)
what does toxicity of local or regional anaesthesia depend on?
> dose
rate of absorption
patient weight
drug
how might local anaesthetic toxicity present?
> coma > drowsiness > numbness and tingling > light headedness > tinnitus > visual disturbance > muscle twitching > CVS depression > cardiopulmonary arrest
what is differential blockade?
there is different penetration to different nerve types (myelinated thick fibres are spared and pain fibres are blocked easily)
what is the physiological affect of a neuroaxial block?
> inspiratory function spared
expiratory function relatively impaired
decreased FRC
increased V/Q match
what agents can be used in induction of general anaesthesia?
> Propofol
> thiopentone
how are conscious levels monitored?
> movement
resp. pattern
processed EEG
is the airway is open and unobstructed it is……….?
maintained
what airway complications can occur in general anaesthesia?
> obstruction
- ineffective triple airway manoeuvre
- airway device malposition
- laryngospasm (forced reflex adduction of the vocal cords)
> aspiration
- gastric contents
- blood
- surgical debriment
what triple airway manoeuvre is used to maintain the airway?
> head-tilt
chin lift
jaw thrust
why might you intubate?
> protect airway from gastric contents
need for muscle relaxation
need for tight control of blood gases
restricted access to airway (maxfax)
what risks are there for the unconscious patient?
> airway > temperature > loss of protective reflexes > consent and identification > pressure areas > venous thromboembolism risk
how is the unconscious patient monitored?
> FiO2 > ECG > ETO2 > SPO2 > resp. parameters > agent monitoring > temperature > venous and arterial monitoring > processed ECG > urine output
what is the process of emergence?
> muscle relaxant is reversed
resumption of spontaneous respiration
return of airway reflexes/control
extubation
what is the role of anaesthetists preop assessment?
> identify risk > optimise > minimise risk > inform and support he patient > consent (reducing complications, delays, anxiety, mortality and length of stay)
