Premedication, analgesia, and anaesthetic Flashcards
what is the purpose of pre-medication?
- restraint
- reduce anxiety or stress
- achieve balanced anaesthesia
- reduction in dose of induction
what is balanced anaesthesia?
the use of multiple anaesthetic drugs in combination to provide general anaesthesia
what are some premedicants?
- phenothiazine
- alpha 2 adrenergic agonist
- alpha 2 adrenergic antagonist
what is a phenotiazines?
- acepromazine
what are some alpha 2 adrenergic agonist?
- medetomidine
- dexmedetomidine
- xylazine
what is an alpha 2 adrenergic antagonist?
atipamazole
what are some advantages of acepromazine?
- works well with opioids to product neuroleptanalgesia
- long lasting - 6 hours
- anti-arrhythmic action
- IM, SC or slow IV
- anti-emetic
what are some disadvantages of acepromazine?
- slow onset
- no analgesic effect
- poor muscle relaxation
- ceiling effect in large breeds
- hypotension
what are some advantages of alpha 2 adrenergic agonist?
- profound sedation
- good muscle relaxation
- profound drug sparing effect
- peripheral vasoconstriction reduces heat loss
- rapid recoveries
- given IM, IV, or SC
what are some disadvantages of alpha 2 adrenergic agonist?
- significant cardiovascular depression
- not suitable for severe liver disease
- can cause vomiting
- analgesic effect is reversed by atipamazole
- hypertension
what are some advantages of benzodiazepines?
- good sedation in sick/young animals
- minimal cardiovascular effects
- good sedation if used in an opioid
- anti-epileptic
- given IM, slow IV or SC
what are some disadvantages of benzodiazepines?
- minimal sedation in healthy animals
- can cause excitement
- muscle relaxation may impair breathing effort
- cannot be given in an infusion as they are absorbed in plastic
what are some classes of analgesics?
- opiates
- NSAIDS
- alpha 2
what are three types of pain?
- physiological (localised and appropriate)
- inflammatory (tissue damage associated with trauma or surgery)
- neuropathic (damage to the nervous system)
what is a noxious stimulus?
something that causes tissue damage
what is nociception?
the processing of noxious stimuli which activates nociceptors and their pathways
what is a pain pathway?
after repeated noxious stimulus has triggered the nociceptive pathway, the site of injury and surrounding tissues become highly sensitive to pain (wind up)
what is pre-emptive analgesia?
administering analgesics before the onset of noxious stimuli such as surgery
what are pure agonists?
occupy and strongly stimulate the sites and thus have a stronger effect
what are partial agonists?
occupy but don’t fully stimulate the sites
what enzymes do NSAIDS interfere with?
the cyclo-oxygenases (COX-1 + COX-2)
what are some side effects of NSAIDS?
- gastric ulceration
- renal damage
what are some ways to induce anaesthesia?
- intravenously
- intramuscularly
- via mask or induction chamber
what is propofol?
- induction agent
- quickly distributed - lasts 10-15 mins
- doesn’t cause arrhythmias
- can be given incrementally
- suitable for TIVA or PIVA
