reasons for anaesthesia
Restraint (including capture of wild animals) Surgery Diagnostic procedures Therapy Legal requirements
Anaesthesia - define
loss of sensation caused by pharmacological
depression of nerve function
General anaesthesia - define
state of unconsciousness produced by controlled ,reversible, drug-induced intoxication of the CNS in which the patient neither PERCEIVES nor RECALLS noxious stimuli
Local anaesthesia - define
temporary blockade of sensory nerves (usually with simultaneous block of motor nerves)
components of general anaesthesia
Unconsciousness analgesia (anti-nociception) Muscle relaxation Homeostasis Normal oxygen delivery
side effects of anaesthesia
Cardiovascular and respiratory depression
Depressed homeostatic mechanisms – baroreceptor reflex, pulmonary hypoxic response
Specific drug effects – e.g NSAIDs and renal function
balanced anaesthesia - define
use of smaller doses of several drugs, each having a specific action
pre-anaesthetic assessment
History Physical examination Conduct any tests indicated Results of any tests Formulate perioperative plan
TIVA - define
total intravenous anaesthesia
pre-op preperatation
Pre‐anaesthetic assessment
Fasting - Species specific
Miscellaneous
Premedication
depth of anaesthesia
Deep’ enough to prevent movement and awareness
‘Light’ enough so prevent lasting damage - Kidneys, CNS, Muscle
waste gas - nitrous oxide
Inhibits DNA synthesis
Can cause changes in bone marrow
Chronic exposure can cause spinal cord degeneration
minimise exposure to waste gas
Use scavenging systems (AGSS) properly
Service all anaesthetic machines and vaporizers regularly
Avoid mask or chamber induction of anaesthesia
Inflate endotracheal tube cuff properly
Fill vaporizers at end of day if possible with key-fillers or ‘Quick Fill’ system
Cap empty bottles of anaesthetic before discarding
Leave patients attached to circuit as long as possible, with ETT cuff inflated
