Test 3: 39 TIVA Flashcards
what 5 things need to happen for anesthetics to be successful
immbolity
unconsciousness
analgesia
muscle relaxation
inhibition of autonomic reflexes
pharmacokinetic vs pharmacodynamic
kinetic: what body does to drug (breaksdown in liver)
dynamic: what drug does to body (cause bradycardia)
3 independent pharmacokinetic variables
volume of distribution
clearance
target plasma concentrations
how to measure volume of distribution
measure tissue distribution of a drug
Vd= (amount of drug administered)/ (amount of drug found in plasma)
how to predict loading dose needed
desired plasma concentration x volume of distribution
how to determine maintenance dose
clearance= dose/AUC
CRI dose = desired plasma concentration (Cpt) x Cl
what characteristics do you want for TIVA drugs
- Fast onset
- Short duration
- High therapeutic index
- Minimal or no side effects
- Insensitive context half life (no accumulation)
- Low cost
- Long shelf life
what drugs are used for small animal TIVA
- Propofol
- Alfaxalone
- Opioid (morphine, fentanyl, remifenntanil)
- Lidocaine
- Dexmedetomidine
- Ketamine
what drugs are used for large animal TIVA
- Ketamine
- GG, Benzodiazepines
- Alpha 2 agonists (xylazine, detomidine, dexmedetomidine, romifidine)
- Lidocaine
what can happen with intermittent multiple boluses for TIVA
example of small animal intermittent multiple boluses TIVA
Example for short procedure (skin biopsy)
1. Premedication Methadone 0.2 mg/kg IV
2. Propofol bolus until loss of righting reflex IV
3. Evaluate anesthetic depth ( eye position, strength of palpebral reflex, jaw tone) top up if needed 0.5 mg/kg of propofol
4. Provide oxygen (face mask)
5. Have ability to intubate & ventilate if patient stops breathing (too deep)
how to do CRI for TIVA
do loading dose to get to theraptutic level quickly, then maintain with CRI
what is a triple drip
CRI for large animal
GKX (GG 10%, Xylazine 1mg/ml, ketamine 2 mg/ml) add 1g of ketamine, 500 mg of xylazine to 500 ml of Guaifenesin 5 or 10%
problems with TIVA
- dosage based on models of healthy animals
- context sensitive 1/2 life- takes longer to recover
- IV access problematic in very small patients (birds, rodents, etc)
- Not possible to measure real time plasma drug levels (only predict)
- Cost of drugs
advantages of tiva
- No pollution
- No need for anesthesia machine
- Cardiovascular stability
- Propofol reduces ICP
- Suitable for prolonged sedation