Because of their high lipophilicity, they enter the brain very quickly and are removed from the brain by redistribution.
Ketamine
• It can be administered intravenously, intramuscularly, orally and rectally.
• It induces significant enzyme induction in the liver, therefore, tolerance may develop if it is administered at short intervals and in large numbers.
• It is an NMDA receptor blocker (noncompetitive blocking).
• Increases cerebral blood flow, metabolic rate, oxygen consumption and CSF pressure.
• Does not cause nausea-vomiting.
• Creates dissociative anesthesia (analysis and amnesia, similar to catatonia, without significant loss of consciousness, the patient appears awake).
• Waking up from anesthesia can be quite noisy (hallucination, nightmare)
• It increases intraocular pressure and causes nystagmus.
• Increases blood pressure and cardiac output, it is a good option for the patient in shock.
• Since it also increases the oxygen consumption of the myocardium, it should not be used in myocardial infarction.
• It causes bronchodilation and does not cause significant depression on respiration.
• It should be used together with anticholinergics as it increases the external secretion glands.
• Mood and memory impairment may occur.
• It has analgesic effect.
• It can be used alone in minor operations.
• It is used in situations where it is difficult to maintain blood pressure such as shock, general condition disorder and old age.
• It is used in open heart surgery.
• It is used to provide anesthesia induction in young children.
• Although it causes myoclonus and an increase in EEG activity, it is an anticonvulsant and can be used as a last step agent in status epilepticus.
Propofol
• It acts by binding to GABAA.
• It is not recommended to be used in people with egg allergy.
• Attention should be paid to the sterility of propofol (6 hours), as the emulsion may allow bacterial growth.
• It causes pain at the injection site. It can be reduced by injecting larger veins and mixing propofol with lidocaine prior to injection.
• The anesthetic effect ends with the redistribution of the drug from the central lipophilic tissues of the brain to the peripheral compartments.
• Metabolism is primarily hepatic. Inactive water-soluble metabolites are excreted renally.
• Its analgesic effect is weak.
• It depresses the cardiovascular system and causes dose-dependent hypotension.
• Suppresses laryngeal reflexes.
• It has an antiemetic effect.
• It is a good choice for outpatient surgery, as it does not cause postoperative nausea and vomiting and maintains the clarity of the mental state well.
• It does not cross the placenta, it can be used safely in pregnant women.
• Decreases cerebral blood flow, metabolism and intracranial pressure.
• It reduces intraocular pressure.
• Prolonged and high-dose infusions of propofol may cause propofol infusion syndrome characterized by cardiac failure, rhabdomyolysis, metabolic acidosis, renal failure, hyperkalemia, hypertriglyceridemia, and hepatomegaly in critically ill children and adults.
Increases intracranial pressure | Those that reduce head and intraocular pressure |
Ketamine, Nitrous oxide, Halothane, | Propofol, Etomidate, Thiopental |
Enflurane, Methoxyflurane | |
etomidate
• It is structurally unlike other anesthetic agents, it has an imidazole ring.
• It may cause pain during injection (due to propylene glycol), which can be reduced with intravenous lidocaine before administration.
• Although it directly binds to GABAA receptors and increases the affinity of the receptors for GABA, it acts preferentially over the beta subunit of GABAA receptors.
• Protects coronary hemodynamics well.
• It decreases cerebral metabolic oxygen consumption and cerebral blood flow, decreases intracranial pressure.
• Decreases adrenal steroid synthesis (inhibits 11-B hydroxylase enzyme).
• It should not be used in adrenocortical insufficiency.
• It is inconvenient to use in Porphyria.
• Causes subcortical disinhibition, which may cause Myoclonic involuntary movements during drug induction.
midazolam
It is a short-acting benzodiazepine.
It has anterograde amnesia-producing effect.
May cause paradoxical / disinhibitory reaction in the form of excitation and aggregation.
It is frequently used in adult and pediatric premedication.
It has no analgesic activity.
Flumazenil is a specific benzodiazepine competitive antagonist with high affinity for the benzodiazepine receptor site.
Thiopental
They inhibit the reticular activating system in the brain stem.
By increasing the activity of GABAA receptors, they prolong the open time of the relevant chloride ion channels.
It reduces cerebral metabolic oxygen consumption, cerebral blood flow and intracranial pressure.
should be used with caution in people.Those with respiratory problems due to severe laryngospasm and respiratory depression
It is highly alkaline (pH 9-10) and precipitates as crystals when added to other acidic drug preparations. This can irreversibly occlude intravenous catheters.
It causes severe tissue necrosis, pain when given outside the vein.
No analgesic effect; It can even cause hyperalgesia.
It causes endothelial damage, vasoconstriction and thrombosis when applied intraarterially.
The anesthetic effect results in redistribution of the drug from the central lipophilic brain tissues to the peripheral lean muscle compartments.
undergo slow terminal elimination by hepatic metabolism, biliary conjugation, and renal excretion.
Contraindicated in patients with porphyria, status asthmaticus and barbiturate allergy.
Dexmedetomidine
It has a sedative effect by activating alpha 2 adrenergic resetters in CNS.
It produces sedation and analgesia without significant respiratory depression.
should not be infused continuously for more than 24 hours; because rebound hypertension, rebound excitability and arrhythmia may develop.
Strong analgesia | Those who do not do analgesia |
nitrous oxide | Propofol |
Ketamine | etomidate |