Injectables Flashcards
What are a few basic pharmacokinetic principles?
Generally anesthetics are:
- Very liposoluble
- Highly protein bound- reach brain quickly
- Redistributed to other tissue
- Accumulate in fat
What is the volume of distribution?
How much the central compartment of a patient will dilute the drug administered; liposoluble drugs have large Vd d/t first pass uptake from central circulation, decreasing plasmatic concentration
‘Central compartment’ - great vessels, heart, lungs, aorta
Why is it important to give a loading dose prior to setting a CRI of a drug?
B/c all tissues besides the target tissue (typically CNS) hinder the rise of drug plasmatic concentration and effect due to their liposolubility, thus they must be saturated with a loading dose
What tissues fit in the rich vessel group?
Heart, lungs, splanchnic viscera, kidneys, CNS
What is the principle of a CRI? How is it performed?
To maintain a constant plasmatic concentration to continue to provide the desired effect following the loading bolus; matching drug CRI to the elimination rate of the drug
What is the most common cause of postoperative hypoxia in healthy patients?
Respiratory depression due to pre-meds or anesthetic agents, such as opioids
Why is it critical to have postoperative pulse oximetry and capnography monitoring on a patient following the surgery?
Patients can present hypoventilation or hypoxia when they’re removed from the 100% FiO2 of the surgery suite
What is the mechanism behind why opioids cause hyperthermia in cats?
They are known to cause excitation as well as increase mm activity in cats, which could cause hyperthermia
Describe propofol
- most widely used induction agent in veterinary patients
- fast acting
- no problem if given perivascular
- short CV depression
- apnea, resp depression
- CNS friendly
- Contamination after 6 hours opened - benzyl alcohol prolongs shelf-life and decreases contamination
What is the difference between normal Propofol and Propofol 28?
Contains 2% benzoyl-alcohol, so shelf-life is 28 days after opened Only FDA approved for dogs
Why should you not mix diazepam in the same syringe with other drugs?
because precipitation of the added drug can occur due to the propylene glycol in diazepam (except for ketamine)
Why is propofol a good choice for head trauma and liver failure patients?
it protects against increases in ICP and decreases cerebral metabolic rate and cerebral perfusion pressure and has fast hepatic/extra-hepatic metabolism
What are the effects of propofol?
- induction in 30 sec
- excitation (bolus)
- apnea
- duration 10-15 min
- cumulative
- splenic engorgement
What is the MOA of propofol?
MOA: action at GABA receptors > incr influx of Cl- > causing hyperpolarization
What is the half life of propofol?
1 hour
