IV Anesthetics Flashcards
What effect does propofol have on arterial blood pressure?
Decrease in arterial BP due to drop in SVR
Inhibition of sympathetic vasoconstrictor activity contributes to this effect.
What usually reverses hypotension following induction of propofol?
Stimulation accompanying laryngoscopy and intubation
What factors are associated with propofol-induced hypotension?
Large dose, rapid injection, old age
How does propofol affect heart rate and cardiac output?
Transient and insignificant but may be life threatening in extreme age, BB patients, and impaired LV function
What rare effect can occur due to marked drop in cardiac filling when using propofol?
Vagally mediated bradycardia
What is the effect of propofol on respiration?
Profound respiratory depressant that usually causes apnea following an induction dose
What ventilatory drive does propofol inhibit even at small doses?
Hypoxia ventilatory drive and normal response to hypercarbia
What reflex does propofol depress?
Upper airway reflex
How does the incidence of wheezing with propofol compare to barbiturates?
Lesser incidence of wheezing in both asthmatic and non-asthmatic patients
What cerebral effects does propofol have?
Decrease CBF, CBV, ICP, and IOP
What additional effects does propofol have?
Antiemetic, antipruritic, anticonvulsant effect
What excitatory phenomena can occur during propofol induction?
Muscle twitching, spontaneous movement, opisthotonus, hiccuping
What effect does midazolam have on the required propofol dose?
Reduces the required propofol dose by more than 10%
Which drugs can propofol be combined with for TIVA?
- Remifentanil
- Dexmedetomidine
- Ketamine
What is the mechanism of action of Propofol?
Potentiate GABA by activation of CL channel leading to neuron hyperpolarization.
Action is not reversed by flumazenil.
What is the composition of Propofol?
Oil in water emulsion composed of soybean oil, glycerol, and egg lecithin.
Should be used within 6 hours of opening ampule.
What is the recommended induction dose of Propofol?
1-2.5 mg/kg.
What is the maintenance infusion dose range for Propofol?
50-200 mcg/kg/min.
What is the sedation infusion dose range for Propofol?
25-100 mcg/kg/min.
What is the lipid solubility characteristic of Propofol?
Highly lipid soluble.
What is the fast first distribution half-life duration of Propofol?
2-8 minutes.
How does aging affect the dosing of Propofol?
Dose should be less due to low volume of distribution.
What does the clearance of Propofol exceed?
Hepatic blood flow.
What does the clearance of Propofol imply about its metabolism?
Existence of extra-hepatic metabolism.
What organs contribute to the extra-hepatic metabolism of Propofol?
Lungs, kidneys, and possibly the brain.
Does obesity affect the pharmacokinetics of Propofol?
No.
How does end-stage kidney disease affect the clearance of Propofol?
Does not affect the clearance.
Where are the metabolites of Propofol primarily excreted?
In the urine.
What class of drugs does Ketamine belong to?
Dissociative anesthetics
What is the mechanism of action of Ketamine?
- Antagonist of N-methyl D-aspartate in CNS
- Enhances sympathetic nervous system by inhibiting the reuptake of catecholamines
What are the routes of administration for Ketamine?
IV, IM, rectal, nasal, SC
What is the onset time for Ketamine when administered IV?
30 seconds
What is the onset time for Ketamine when administered IM?
2-4 minutes
How is Ketamine metabolized?
Hepatic metabolism via CYP450, producing norketamine
What is the potency of norketamine compared to Ketamine?
1/3 to 1/5 potency of Ketamine
How is Ketamine excreted from the body?
In urine and bile
What type of state does Ketamine produce in patients?
Dissociative state
What type of pain is Ketamine excellent at relieving?
Somatic pain
What type of amnesia does Ketamine cause?
Retrograde and anterograde amnesia
What is the emergence phenomenon associated with Ketamine?
Hallucinations, vivid dreams, or delirium upon awakening
What can reduce the emergence phenomenon when using Ketamine?
Premedication with benzodiazepines or co-administration with propofol
What effect does Ketamine have on cerebral blood flow (CBF) and intracranial pressure (ICP)?
Increase in CBF and ICP
What caution should be taken with Ketamine in neurosurgery patients?
Caution due to increased CBF and ICP
What effect does Ketamine have on intraocular pressure (IOP)?
Mild increase in IOP
What cardiovascular effects does Ketamine have?
Increase in HR, BP, and CO
What condition may attenuate the cardiovascular effects of Ketamine?
Catecholamine depleted patients (e.g., trauma or sepsis)
What is the respiratory effect of Ketamine?
Minimal respiratory depression, preserves airway reflexes and spontaneous breathing
What benefit does Ketamine provide to patients with asthma?
Bronchodilation
What can be used to counteract increased salivation from Ketamine?
Pretreatment with glycopyrrolate
What is the induction dose of ketamine for IV administration?
1-2 mg/kg
This dosage is specific for induction purposes.
What is the induction dosage for IM administration of ketamine?
3-5 mg/kg
This dosage is specific for induction purposes.
What is the sedation dosage of ketamine range for IV administration?
0.1-0.5 mg/kg
This dosage is used for sedation.
What is the analgesia dosage of ketamine for IV administration?
0.2-0.5 mg/kg
This dosage is used for analgesia.
What is ketamine infusion dosage for analgesia?
0.1-0.5 mg/kg/h
This dosage is used for continuous analgesia infusion.
What are CNS side effects of ketamine ?
- Emergence reactions
- Increased CBF/CP
- Hallucination
These side effects are related to the central nervous system.
What cardiovascular side effects can occur while using ketamine ?
- Hypertension
- Tachycardia
These side effects are related to cardiovascular function.
What are respiratory side effects of ketamine?
- Minimal depression
- Hyper salivation
These side effects pertain to respiratory function.
What are other potential side effects of ketamine ?
- Vomiting
- Increased IOP
These side effects can occur but are not classified under CNS, CVS, or respiratory.
What is a contraindication of ketamine related to CNS?
Increased ICP
This condition poses a risk for patients receiving the medication.
What is a contraindication related to ocular pressure?
Increased IOP
This condition poses a risk for patients receiving the medication.
What cardiovascular conditions are contraindicated?
- Severe coronary artery disease
- Uncontrolled hypertension
These conditions can complicate the use of the medication.
What psychological history is a contraindication when using ketamine ?
History of psychosis
This history can lead to adverse reactions.
What is the mechanism of action of Etomidate ?
Enhances gamma-aminobutyric acid (GABA) neurotransmission by acting on GABA-A receptors
Produces hypnosis without significant analgesia.
What is the onset time of Etomidate ?
30-60 seconds
Rapid onset due to quick redistribution from the brain.
What is the duration of action of Etomidate ?
3-5 minutes
Short duration due to rapid redistribution.
How is Etomidate metabolized?
Undergoes hepatic metabolism via ester hydrolysis and is excreted renally
This indicates the drug’s elimination pathway.
What is the recommended induction dose of Etomidate for general anesthesia?
0.2-0.5 mg/kg IV
This dose is typically used for induction.
Why Etomidate is preferred for induction in hemodynamically unstable patients?
Due to minimal cardiovascular effects
This makes it safer for patients with unstable hemodynamics.
What clinical situation Etomidate is commonly used in?
Rapid sequence intubation in critically ill patients
It is favored for its rapid action and safety profile.
What is one advantage of Etomidate related to hemodynamic stability?
Minimal effects on heart rate, blood pressure, and cardiac output
This is crucial for maintaining stability during anesthesia.
How does Etomidate affect cerebral metabolism?
Decreases cerebral metabolic rate (CMRO2), cerebral blood flow, and intracranial pressure
Useful in neurosurgical cases for these reasons.
What is a significant disadvantage of Etomidate related to adrenal function?
Inhibits 11ß-hydroxylase, reducing cortisol and aldosterone synthesis
This can be problematic in critically ill or septic patients.
What percentage of patients may experience myoclonus as a side effect?(Etomidate)
30-60%
Involuntary muscle movements are a common side effect.
What is a common postoperative side effect of Etomidate ?
Nausea and vomiting
It has a higher incidence compared to other induction agents.
What causes pain on injection of Etomidate ?
Its propylene glycol formulation
This is a known issue with some injectable anesthetics.
True or False: Etomidate has analgesic properties.
False
It requires adjuncts for pain management.
