General anaesthesia - general considerations Flashcards
Define anaesthesia
The use of a drug to provide temporary (reversible) loss of sensation to a region or the whole body
Define analgesia
Loss of pain
Define general anaesthesia
Loss of sensation of the whole body. The state of reversible unconsciousness, muscle relaxation and analgesia
Define surgical anaesthesia
The loss of consciousness, analgesia and muscle relaxation sufficient enough to undergo painless surgery
Define balanced anaesthesia
Use of a combination of drugs to produce surgical anaesthesia
Define dissociative anaesthesia
The state of anaesthesia produced by drugs (ketamine) that dissociate the thalamocortic and limbic system, resulting in a cataleptic state, usually with muscle rigidity
Define neurolepanalgesia
Combination of neuroleptic agent and analgesic agent to produce a state of heavy sedation and analgesia (e.g. acepromazine + morphine)
Stages of anaesthesia?
- Preanaesthetic
- Induction
- Maintenance
- Recovery
- Postoperative pain management
Routes of administration of GA
IV
IM
SC
inhalational
Stages of general anaesthesia
- Stage of induction
- Stage of involuntary excitement
- Stage of surgical anaesthesia
- Paralytic stage
Patient evaluation
- ID
- History
- Clinical exam
- Lab tests
Classification of patient for surgery
I. healthy, e.g. for castration
II. mild-moderate systemic disease, e.g. tendon rupture
III. severe systemic disease, e.g. dehydration
IV. severe systemic disease, with constant threat to life, e.g. colic
V. moribund (not expected to survive in 24 hours)
E. emergency
Patient preparation before surgery
Food withdrawal - 12 hours in cats and dogs - 18-24 hours in horses - 24 hours in ruminants Water withdrawal - 6 hours in ruminants
