General Anesthetics Flashcards
What are the characteristics of a general anesthesia?
1) amnesia
2) analgesia
3) unconsciousness
4) inhibition of sensory and autonomic reflexes
5) skeletal muscle relaxation
How does GABA cause IPSP?
GABA receptors that are activated will open a Cl- channel. Cl- will enter the cell making it more negative which makes it more difficult to reach threshold and trigger an AP.
What is the Minimum Alveolar Concentration?
Minimum Alveolar Concentration @ 1ATM that prevents movement during a skin incision in 50% of patients.
What is the ED95 for the MAC?
1.3 times the MAC
What is the MAC influenced by?
Temperature
Age
Other drugs
What is the MAC NOT influenced by?
Sex
O2
pH
BP
What happens to the rate of induction when CO increases?
It will cause slower induction
What is the mechanism of inhaled anesthetics?
Act at the GABAa receptor-chloride channel and facilitate the GABA mediated neuronal inhibition at these receptor sites. Nevertheless, the exact mechanism of inhaled anesthetics remains unclear.
What is a measure of potency of an anesthetic?
MAC
What is cascade?
The faster the agent gets from one compartment to the next, the slower it reaches equilibrium.
What are factors that determine anesthetic delivery to the brain?
(1) inspired concentration
(2) transfer of the gas to the arterial blood
(3) transfer of the agent to the brain
What are the factors that determine uptake of anesthetic into the blood?
- Solubility
- Partial Pressure Difference
- Cardiac Output
What is the effect of solubility on equilibrium?
More soluble agents reach equilibrium slower than less soluble agents. Th blood compartment is “larger” for more soluble agents.
What drives the movement of the inhaled drugs?
Partial pressure difference.
What is the order of the organs receiving the drug?
Vessel rich organs first, then skin and muscle and fat is last.
What happens with increased blood flow?
Increased blood flow near alveolus slows equilibrium because it increases uptake
•Therefore, it also slows FA/FI
What will a venous blood sample of a patient under anesthetic look like?
Venous blood sample will be red in the patient because
the metabolic rate decreases and O2 consumption decreases
How does ventilation affect the speed of induction?
The rate of rise of anesthetic gas tension in arterial blood is directly dependent on the minute ventilation.
What is the blood/gas partition coefficient, λ?
It represents the ratio of anesthetic concentration in blood to anesthetic concentration in a gas phase when the two are in partial pressure equilibrium
What are the IV drugs?
Propofol
Thiopental
Ketamine
Etomidate
What are the effects of propofol?
Vasodilator leading to decreased BP
Respiratory depression causing apnea
What is the emergence time from propofol like?
Rapid
What are the effects of thiopental on the various organ systems?
Vasoconstrictor so it can cause limb ischemia
Puts the brain to sleep as it is lipid-soluble and diffusesrapidly through biological membranes, including the blood-brain barrier
Can take a long time for emergence though
What is unique about ketamine and respiration?
Bronchodilator so it keeps patients breathing
What is etomidate used for?
It is used only for induction. A primary advantage of etomidate is its ability to preserve cardiovascular and respiratory stability better than does thiopental.
How does ketamine affect the HR and BP?
Increases HR and BP
What are the anesthetic properties of NO?
AC for nitrous oxide is 110 percent of one atmosphere and thus it is incapable of independently producing surgical anesthesia outside of a hyperbaric chamber. It is used clinically as a supplement to other agents.
Induction and emergence are rapid
