PROPOFOL
Introduction:
- Most frequently used intravenous anesthetic today.
- Structure: Consists of phenol ring with isopropyl group attached (2, 6 di-isopropylphenol).
- Metabolized in liver.
- Significant extrahepatic metabolism also occurs in lungs and excreted via kidney.
Preparations:
- Oil-based preparation (soybean oil, egg lecithin & glycerol).
- Solution color: Milky white.
Precaution:
- To be used within 6 hrs after opening vial
- Due to death from egg lecithin contamination.
- Egg lecithin – Good medium for bacterial growth.
Recent propofol preparations:
- Contains disodium edetate or sodium metabisulfite as antimicrobial agent.
- Prevents contamination issues.
Actions:
- Decreases intraocular pressure.
- Reduces BP.
Uses:
- Intermittent injection or continuous infusion for total i.v. anesthesia (TIVA) when supplemented by fentanyl.
- Anesthetic of choice for induction, intubation in ICU & malignant hyperthermia patients.
- Induction dose = 1-2.5 mg/kg iv.
- Particularly suitable for outpatient surgery (day-care surgery) –
- Due to less marked residual impairment & short-acting.
- Used for both induction & maintenance.
- Used for LA-induced seizure.
Advantages:
- Cerebroprotective.
- Reduce ICT, cerebral metabolism, oxygen consumption & cerebral perfusion.
- No anticonvulsive action (unlike thiopentone).
- No muscle relaxant action (like thiopentone).
- Antiemetic action –
- Reduces post-operative nausea & vomiting.
- Antipruritic action –
- Relieves pruritic in cholestasis & spinal opiates.
- Rapid recovery after anesthesia or sedation even after prolonged infusion.
- Safe in porphyria (unlike phenobarbitone).
- Does not trigger malignant hyperpyrexia.
- No respiratory irritation.
- Easy airway instrumentation done –
- Suppressing airway reflex & cause greater degree of laryngeal muscle relaxation.
- Does not effect corticosteroid synthesis or alter normal response to ACTH stimulation.
- Accidental intra-arterial injection or extravasation of propofol does not produce adverse reactions.
Adverse effects:
- Increased life-threatening infections:
- By decreasing polymorphonuclear leukocyte chemotaxis but not adherence, phagocytosis & killing.
- (Note: Thiopentone blocks all these)
- Causes dose-dependent myocardial depression.
- Causes bradycardia & apnea.
- Produces muscle twitching & myoclonus.
- Pain on injection & rarely thrombophlebitis.
Propofol infusion syndrome:
- Lethal syndrome, associated with propofol infusion for 48hrs or longer.
- Occurs in children & critically ill.
- Due to failure of free fatty acid metabolism & mitochondrial respiratory chain.
- Features: Cardiomyopathy with acute cardiac failure, metabolic acidosis, skeletal myopathy, hyperkalemia, hepatomegaly & lipemia.
Exam Important
- Propofol infusion syndrome occurs due to failure of free fatty acid metabolism & mitochondrial respiratory chain due to propofol infusion for 48hrs or longer.
- Features of propofol infusion syndrome include cardiomyopathy with acute cardiac failure, metabolic acidosis, skeletal myopathy, hyperkalemia, hepatomegaly & lipemia.
- Propofol infusion syndrome occurs in children & critically ill patients.
- Propofol decreases polymorphonuclear leukocyte chemotaxis but not adherence, phagocytosis & killing.
- Propofol increases life-threatening infections.
- Propofol causes dose-dependent myocardial depression.
- Easy airway instrumentation is done with propofol because it suppressing airway reflex & cause greater degree of laryngeal muscle relaxation.
- Unlike phenobarbitone, propofol is safe in porphyria.
- Even after prolonged infusion or sedation rapid recovery possible with propofol.
- Antipruritic action of propofol relieves pruritic in cholestasis & spinal opiates.
- Antiemetic action of propofol reduces post-operative nausea & vomiting.
- Propofol is cerebroprotective by reducing ICT, cerebral metabolism, oxygen consumption & cerebral perfusion.
-
When supplemented by fentanyl, intermittent injection or continuous infusion for total i.v. anesthesia (TIVA).
-
Propofol
is
particularly suitable for outpatient surgery (day-care surgery).
- Anesthetic of choice for intubation in ICU & malignant hyperthermia patients is propofol.
- Propofol is used for both induction & maintenance.
- Propofol to be used within 6 hrs after opening vial due to egg lecithin contamination causing death.
- Egg lecithin is a good medium for bacterial growth.
- Recent propofol preparations contains disodium edetate or sodium metabisulfite as antimicrobial agent preventing contamination issues.
- Propofol is the most frequently used intravenous anesthetic today.
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