Preanaesthetic medication

PRE-ANAESTHETIC MEDICATION

  • Use of drugs prior to anaesthesia - to have smooth and safe induction of anaesthesia and to establish balanced anaesthesia.
  • Merits of preanaesthetic medication:
    • Alleviate or minimize pain
    • Allay apprehension
    • Facilitate handling
    • Minimize undesirable reflex actions
    • Supplement general anaesthesia - decrease dose of anaesthetic and add extra analgesia and sedation
    • Minimize events in recovery

Major classes of drugs used as preanaesthetics

  • Tranquilizer – sedatives: Acepromazine,Chlorpromazine,Promethazine, Diazepam, Midazolam, Droperidol, Azaperone
  • Hypnotic sedatives : Pentobarbital, Chloral hydrate
  • Opioid analgesics : Morphine, Pethidine, Fentanyl, Pentazocine
  • α2 agonists : Xylazine, Detomidine
  • Dissociatives : Ketamine
  • Cholinolytics : Atropine, Glycopyrrolate (these agents inhibits the secretory activity of salivary glands that may help in prevention of regurgitation)

Complications of preanaesthetics

  • Opioids: respiratory depression, hypotension
  • Atropine: Mydriatic 
  • α2 agonists : cardiac depression

Preanaesthetic agents may potentiate  anaesthetic toxicity and prolong the recovery 

Neuroleptic  analgesia

  • A combination of neuroleptics (benzodiazepines, butyrophenones or phenothiazines) + opioids derivatives
  • At lower doses – produce preanaesthetic effect 
  • At higher doses - Neuroleptic analgesia which is enough depression to cause surgical anaesthesia
  • Popular combinations: Fentanyl + Droperidol ,Fentanyl + Fluanisone, Etorphine+ Acepromazine
Last modified: Monday, 17 October 2011, 11:54 AM