propofol Flashcards
what is the classification of propofol?
sedative-hypnotic
what is the equilibration 1/2 time of propofol?
1-3 min
what are uses of propofol?
- induction and maintenance of general anesthesia
- combine with sedation and regional anesthesia
- adjunct for MAC or TIVA
what is the MOA of propofol?
inhibits neuronal activity at the post synaptic GABA receptors by increasing chloride conductance into cell
- GABA’s natural function is to reduce activity of neurons
- acts via ion mediated receptors (chloride): chloride influx increased, preventing depolarization
- hyperpolarization of post synaptic membrane inhibits neuronal activity
- gives desired hypnosis and sedation effects
describe onset of propofol
-rapid onset of action d/t high lipid solubility
describe metabolic clearance of propofol
- rapid clearance
- short half life: 2-8 min of initial dose
- hepatic clearance
- 30-60 ml/kg/min cleared (changes if hepatic blood flow altered)
- metabolites excreted renally (but renal failure does not affect clearance of parent drug)
when should propofol not be given in relation to clearance?
- hepatic failure
- absolutely no urine output
- can be given with renal failure
what are CV effects of propofol?
- decrease in arterial BP r/t drop in SVR (elderly, speed of injection, large doses)
- vagal like effects (drop in HR & BP) can lead to asystole,
what increases the risk of asystole or other hemodynamic instabilities occurring with propofol?
- prone to oculocardiac reflex (aka vagal ocular reflex)
- eyes surgery, visceral/peritoneal tugging
- pre-existing impair ventricular function (significant drop in CO)
- decreases ventricular filling pressures
- decreases contractility
- SVR= (MAP-CVP)/CO x 79.9
what are respiratory effects of propofol?
- profound ventilator depressant (apnea after induction doses and sometimes after sedation doses)
- inhibits hypoxic drive (normal response to hypercarbia is altered)
- upper airway reflexes are depressed more than with thiopental
- great for use with LMA and intubation (no spasm)
- some histamine release but less than barbiturates and ketamine (don’t use in asthmatics with ACTIVE bronchospasm or wheezing)
- can give to asthmatics with no s/s of constriction
- large doses used with status asthmaticus, rationale being large dose will overcome bronchospasm
what are neurologic effects of propofol?
- decreases ICP and CBF
- significant drop in CPP (MAP-ICP) with elevated ICP
- normal 80-100 mmHg
- critical reduction of CPP (< 50 mmHg
- sustained CPP <25 results in irreversible brain damage
- suppresses memory by inhibition of post-synaptic neurons
- decrease intraocular pressure
- antiemetic
- antipruritic
- excitatory phenomena (muscle twitiching, spontaneous movement, hiccups) YET breaks status epilepticus
- avoid use in pts with known seizure hx (not contraindicated)
- predominant anticonvulsant effects
what are some drug interactions with propofol?
- old formulations potentiated actions of NDMBs (newer do not)
- slight synergistic effect with midazolam
- opioids have faster onset and total dose required may be lower
- asystole episodes increased with opioids
what are contraindications of propofol use?
- egg and soybean allergies (not true contraindication, but caution and avoid if can)
- not approved for OB use
- markedly increased ICP
- avoid in severe CAD pts. (hypotension)
- not approved for pediatric ICU sedation
- some newer formulas may contain sulfites (sulfa allergy)
- prior sensitivity or unexplained reaction to propofol
- inexperienced airway management personnel
- rapid bolus in the elderly and debilitated
describe important sterile technique with propofol use
- composition supports bacterial growth
- administration should be completed within 6 hrs
- death and severe sepsis has been associated with contamination
- ampules should be used within 6 hrs even if containing sulfites
what are complications of propofol?
- pain on injection: changes in pH from preservatives
- allergic reactions (allergy to NMB increases)
- seizure activity (should consider it an allergy)
- infection from contamination (supports growth of E.Coli and Pseudomonas A. and Candida A)
- crosses placenta
- abuse potential
- mood changes
- introvert to extrovert behavior
- hallucinations
- amorous behavior
what should be done to help pain on injection with propofol?
- lidocaine
- sedation/versed as well as opioids help to reduce pain
what are certain triggers associated with propofol induced seizures?
- epileptic history or family history
- movement disorders
- history of prior propofol admin
- allergy to NDMB
- history of chemical dependency
- heightened emotional state prior to surgery
- presence of hyperventilation or fever
- fast rate of propofol admin
what are primary benefits of propofol?
- antiemetic (inhibits CTZ)
- antioxidant
- amnestic
- smooth induction
- decreased airway reflexes especially upper airway
- may help with pruritis
- break status epilepticus
- analgesic properties
what is the general induction dose of propofol?
1-2.5 mg/kg
what is the induction dose of propofol for healthy adults?
2-2.5 mg/kg
what is the induction dose of propofol for elderly or debilitated pts.?
0.5-1.5 mg/kg over 30+ sec
what is the induction dose of propofol for cardiac and neuro cases?
cardiac: 0.5-1.5 mg/kg
neuro: 1-2 mg/kg
what is the induction dose of propofol for pediatrics?
2-3 mg/kg over 20-30 sec
what is the initial dose of propofol for a MAC case?
- 5 mg/kg in a healthy adult
* reduce in 1/2 for elderly and debilitated
what is the dose of propofol for ICU maintenance of a ventilated pt.?
- initial: 0.3-0.6 mg/kg/hr and titrate
- additional 10-20 mg boluses as needed
what is the MAC propofol infusion rate for mild, moderate, and heavy sedation cases?
mild: 25 mcg/kg/min
moderate: 50 mcg/kg/min
heavy: 75-100 mcg/kg/min
compare propofol to thiopental and ketamine
propofol -rapid onset and quick clearance -smoother induction -can be used for maintenance -antiemetic -europhorogenic -potential to induce seizures -pain on injection thiopental -more seizure protective -more organ protective (brain) -slower awakening time and longer sedative effects -less pain on injection -some histamine release ketamine -increased sleep time (than propofol) -contraindicated in seizures, spinal cord, and brain injury, significant cardiac disease, and hypermetabolic states -increased NV -reduced respiratory depression -less pain on injection -increased salivation
describe fospropofol (Aquavan)
- prodrug of propofol
- not approved for general, but approved for sedation/MAC cases
- takes more drug than propofol to produce same effect to loss of consciousness
- delayed time to peak concentrations, wake up may be delayed
what is fospropofol metabolized to?
- propofol, formaldehyde, phosphates
- formaldehyde: carcinogenic; however, the amount present is said to be scant and equivalent of that present after other drugs are metabolized
how does effective dose of fospropofol compare to propofol?
2.5 mg/kg propofol compares to 12.5 mg/kg of fospropofol
