propofol

Question 1

what is the classification of propofol?

Answer 1

sedative-hypnotic

Question 2

what is the equilibration 1/2 time of propofol?

Answer 2

1-3 min

Question 3

what are uses of propofol?

Answer 3

• induction and maintenance of general anesthesia
• combine with sedation and regional anesthesia
• adjunct for MAC or TIVA

Question 4

what is the MOA of propofol?

Answer 4

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

Question 5

describe onset of propofol

Answer 5

-rapid onset of action d/t high lipid solubility

Question 6

describe metabolic clearance of propofol

Answer 6

• 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)

Question 7

when should propofol not be given in relation to clearance?

Answer 7

• hepatic failure
• absolutely no urine output
• can be given with renal failure

Question 8

what are CV effects of propofol?

Answer 8

• 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,

Question 9

what increases the risk of asystole or other hemodynamic instabilities occurring with propofol?

Answer 9

• 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

Question 10

what are respiratory effects of propofol?

Answer 10

• 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

Question 11

what are neurologic effects of propofol?

Answer 11

• 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

Question 12

what are some drug interactions with propofol?

Answer 12

• 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

Question 13

what are contraindications of propofol use?

Answer 13

• 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

Question 14

describe important sterile technique with propofol use

Answer 14

• 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

Question 15

what are complications of propofol?

Answer 15

• 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

Question 16

what should be done to help pain on injection with propofol?

Answer 16

• lidocaine

- sedation/versed as well as opioids help to reduce pain

Question 17

what are certain triggers associated with propofol induced seizures?

Answer 17

• 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

Question 18

what are primary benefits of propofol?

Answer 18

• antiemetic (inhibits CTZ)
• antioxidant
• amnestic
• smooth induction
• decreased airway reflexes especially upper airway
• may help with pruritis
• break status epilepticus
• analgesic properties

Question 19

what is the general induction dose of propofol?

Answer 19

1-2.5 mg/kg

Question 20

what is the induction dose of propofol for healthy adults?

Answer 20

2-2.5 mg/kg

Question 21

what is the induction dose of propofol for elderly or debilitated pts.?

Answer 21

0.5-1.5 mg/kg over 30+ sec

Question 22

what is the induction dose of propofol for cardiac and neuro cases?

Answer 22

cardiac: 0.5-1.5 mg/kg
neuro: 1-2 mg/kg

Question 23

what is the induction dose of propofol for pediatrics?

Answer 23

2-3 mg/kg over 20-30 sec

Question 24

what is the initial dose of propofol for a MAC case?

Answer 24

0. 5 mg/kg in a healthy adult

* reduce in 1/2 for elderly and debilitated

Question 25

what is the dose of propofol for ICU maintenance of a ventilated pt.?

Answer 25

• initial: 0.3-0.6 mg/kg/hr and titrate

- additional 10-20 mg boluses as needed

Question 26

what is the MAC propofol infusion rate for mild, moderate, and heavy sedation cases?

Answer 26

mild: 25 mcg/kg/min
moderate: 50 mcg/kg/min
heavy: 75-100 mcg/kg/min

Question 27

compare propofol to thiopental and ketamine

Answer 27

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

Question 28

describe fospropofol (Aquavan)

Answer 28

• 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

Question 29

what is fospropofol metabolized to?

Answer 29

• propofol, formaldehyde, phosphates
• formaldehyde: carcinogenic; however, the amount present is said to be scant and equivalent of that present after other drugs are metabolized

Question 30

how does effective dose of fospropofol compare to propofol?

Answer 30

2.5 mg/kg propofol compares to 12.5 mg/kg of fospropofol