The most suitable agent for IV induction and maintenance in a day care surgery?
Correct Answer: Propofol
Description: Ans. c (Propofol) (Ref: Morgan's 3rd edition, p. 173,804; Lee Anaesthesia 12th edition, p. 417).Currently, propofol has superceded thiopentone as an i.v. anaesthetic, both for induction as well as maintenance. It lacks airway irritancy and is particularly suited for outpatient surgery, because residual impairment is less marked and shorter-lasting. Incidence of postoperative nausea and vomiting patient acceptability is very good.DAY CARE ANESTHESIAMSIAPMMivacurium(Muscle relaxant of choice)Succinylcholine(for intubation)Isoflurane & Desflurane(Inhalation agent of choice)Alfentarnil(for Amnesia)Propofol(as inducing) agent of choice)Midazolam(For relief of anxietyand sedation)PROPOFOLChemistry and Formulations# The active ingredient in propofol, 2,6-diisopropylphenol, is essentially insoluble in aqueous solutions and is formulated only for IV administration as a 1% (10 mg/mL) emulsion in 10% soybean oil, 2.25% glycerol, and 1.2% purified egg phosphatide.Dosage and Clinical Use# The induction dose of propofol in a healthy adult is 1.5 to 2.5 mg/kg and it has an onset and duration of anesthesia similar to thiopental. For short procedures, small boluses (10% to 50% of the induction dose) every 5 minutes or as needed are effective. An infusion of propofol produces a more stable drug level (100 to 300 mg/kg per minute) and is better suited for longer-term anesthetic maintenance. Propofol elicits pain on injection.Pharmacokinetics and Metabolism# Propofol's shorter duration after infusion can be explained by its very high clearance, coupled with the slow diffusion of drug from the peripheral to the central compartment. The rapid clearance of propofol explains its less severe hangover compared with barbiturates, and may allow for a more rapid discharge from the recovery room. Propofol is metabolized in the liver to less active metabolites that are renally excreted; however, its clearance exceeds hepatic blood flow, and an hepatic metabolism has been demonstrated. Propofol is highly protein bound, and its pharmacokinetics, like those of the barbiturates, may be affected by conditions that alter serum protein levels.Side Effects# Nervous System. The CNS effects of propofol are similar to those of barbiturates. Propofol decreases CMRO:, cerebral blood flow, and intracranial and intraocular pressures by about the same amount as thiopental. Unlike thiopental, propofol is not a proven acute intervention for seizures.# Cardiovascular. Causes fall in blood pressure that can be explained by both vasodilation and mild depression of myocardial contractility. As with thiopental, propofol should be used with caution in patients at risk for or intolerant of decreases in blood pressure.# Respiratory and Other Side Effects. At equipotent doses, propofol produces a slightly greater degree of respiratory depression than thiopental. Patients given propofol should be monitored to ensure adequate oxygenation and ventilation. Although propofol does cross placental membranes, it is considered safe for use in pregnant women, and like thiopental, only transiently depresses activity in the newborn.
Category:
Anaesthesia
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