SGU SVM Term 4 Anesthesiology MT - F2019

SGU SVM Term 4 Anesthesiology MT - F2019 What is the Meyer-Overton correlation for anesthetics? Correct Answer: It is based on the lipid cell membrane as the site of action, and the chart compares the oil:gas partiti ...

SGU SVM Term 4 Anesthesiology MT - F2019 What is the Meyer-Overton correlation for anesthetics? Correct Answer: It is based on the lipid cell membrane as the site of action, and the chart compares the oil:gas partition coefficient and the potency of an anesthetic drug How do inhalant anesthetics act on excitatory and inhibitory neurotransmission? Correct Answer: Depresses excitatory neurotransmission; enhances inhibitory neurotransmission What affect does inhalant anesthetics have on the spinal cord? Correct Answer: Generates muscle relaxation What affect does inhalant anesthetics have on the CNS? Correct Answer: Hypnosis Which gets knocked out first when using inhalant anesthetics: mobility or consciousness? Correct Answer: Consciousness What two factors make determine the kinetics of inhalant anesthetics? Correct Answer: Blood-gas partition coefficient and oil-gas partition coefficient. What is Dalton's Law of Partial Pressures? Correct Answer: Total pressure of a mixture of gases is the sum of the partial pressures of all component gases. Ptot= P1+P2+P3+... What is the Saturated Vapor Pressure? Correct Answer: The pressure (in mmHg) the vapor molecules exert when liquid and vapor phases are in equilibrium (ability to evaporate) What is the boiling point, and which inhalant anesthetic has the highest BP and which has the lowest BP? Correct Answer: Temperature at which vapor pressure of the liquid = atmospheric pressure. N2O has the lowest boiling point (-89C) whereas Desflurane has the highest (23.5C) Why is a special vaporizer needed when using Desflurane as an inhalant anesthetic Correct Answer: The boiling point is very close to room temperature Blood:gas partition coefficient Correct Answer: Solubility of anesthetic agent in the blood, which dictates the speed of induction, recovery and change of anesthetic depth What does a low blood:gas coefficient mean? Correct Answer: Gases will exert a high partial pressure so changes will be fast (anesthetic leaves blood quickly) What does a high blood:gas coefficient mean? Correct Answer: Anesthetic stays in blood longer so changes will be slower Oil:gas partition coefficient Correct Answer: Correlates with the potency of an anesthetic drug - The higher the solubility (in oil) the more potent the anesthetic (Meyer-Overton rule) What is the relationship between oil:gas partition coefficient and minimum alveolar concentration (MAC)? Correct Answer: They are inversely related to each other, meaning that an anesthetic with a high oil:gas is very potent, meaning the MAC will be low since less of the drug is needed to maintain anesthesia What is the Minimum Alveolar Concentration (MAC)? Correct Answer: The concentration of an anesthetic at 1 atm that produces immobility in 50% of subjects exposed to a supramaximal noxious stimuli (the lower the MAC, the more potent the drug is) What is Fick's Law of Diffusion? Correct Answer: The net diffusion rate of a gas across a fluid membrane is proportional to the difference in partial pressure, proportional to the area of the membrane, and inversely proportional to the thickness of the membrane What are 6 factors that affect the diffusion rate of a gas? Correct Answer: 1. Pressure difference 2. Solubility 3. Surface available for exchanges 4. Thickness of the barrier 5. Molecular weight of the gas 6. Temperature of the fluid How does Cardiac Output (CO) effect the uptake of anesthesia? Correct Answer: The greater the CO, the more blood is passing through the lungs carrying away anesthetic What effect does a low CO (caused by myocardial failure, bradycardia, shock) have on Pa? Correct Answer: Increase in the rate of rise of the Pa What effect does a high CO (excitement, etc.) have on Pa? Correct Answer: Delays the alveolar rise in Pa How does a patient recover from an inhalant anesthetic? Correct Answer: By reducing the partial pressure of inhalant anesthetic in the CNS which will allow the return to consciousness How can you speed up the recovery of a patient from anesthesia who is attached to a rebreathing (circle) system? Correct Answer: Increase the FGF Increase the minute volume Empty reservoir bag in scavenging How can you speed up the recovery of a patient from anesthesia who is attached to a non-rebreathing system? Correct Answer: Turn the vaporizer off Which inhalant anesthetic has the highest reduction in cardiac output and direct myocardial depression? Correct Answer: Halothane Which inhalant anesthetic has the least reduction in cardiac output and direct myocardial depression? Correct Answer: Desflurane Which inhalant anesthetic generates the least amount of peripheral vasodilation? Correct Answer: Halothane Which inhalant anesthetic causes the most respiratory depression? Correct Answer: Isoflurane What effect can the halogenated inhalant anesthetics have on the uterus? Correct Answer: Cause relaxation Which inhalant anesthetic can cause hepatitis? Correct Answer: Halothane Which inhalant anesthetic can cause malignant hyperthermia in pigs? Correct Answer: Halothane Which inhalant anesthetic contributes most to global warming? Correct Answer: Desflurane How do local anesthetic agents work? Correct Answer: Produces a reversible blockade of the propagation of the action potential, to anesthetize a region of the body, with or without muscle paralysis, and are applied at target site.