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27 Cards in this Set
- Front
- Back
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Blood/Gas (B/G) solubility coefficient
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A measure of the uptake of an agent by blood.
Low B/G = rapid induction and emergence. |
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Minimal Alveolar Concentration (MAC)
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The concentration of agent required to prevent movement in response to a skin incision in 50% of patients.
Low MAC = High potency |
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Least potent of inhalational agents.
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Nitrous oxide
MAC = 104% |
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Most common use of nitrous oxide.
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Due to its low solubility and high MAC, NO is often combined with a more potent agents to permit a lower dose of the potent agent, thus limiting side effects, reducing cost,and facilitating rapid induction and emergence.
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What is the most important clinical problem with NO?
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It is 30x more soluble than nitrogen, and thus will diffuse into and increase the pressure of closed gas spaces.
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In which situations is the use of NO contraindicated?
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Situations which involve closed spaces: pneumothorax, SBO, middle ear sx, retinal sx (intraocular gas bubble is created)
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Which inhalational agent is most potent?
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Halothane
MAC = 0.74% |
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What are the important side effects of halothane?
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1. powerful cardiac depressant
2. sensitizes the myocardium to catecholamine (problem when epinephrine is used in sx, e.g. as a local anesthetic in incisions) 3. associated with a rare form of fulminant hepatitis |
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What can be done to decrease the risk of fulminant hepatitis with halothane?
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The risk is increased 7x if repeated within 3 months. Therefore, avoid in adults who have received the agent within the preceding year.
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Is there a risk of fulminant hepatitis with halothane in children?
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No. No reports in children under age 8.
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What metabolic disease may be triggered by halothane?
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Malignant hyperthermia
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What are important side effects of enflurane?
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1. metabolized to fluoride and may be assoiciated with mild renal dysfunction (esp. in obese pts).
2. contraindicated in patients with seizure disorder. |
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What are the benefits of using isoflurane?
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1. low cost
2. less reduction in C.O. 3. less sensitization to cathecholamines 4. minimal metabolism |
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What is an important side effect of isoflurane?
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1. Tachycardia --> increased myocardial oxygen consumption
Caution in pts with CAD. 2. Pungent odor --> cannot be used for induction. |
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What are the benefits of using sevoflurane?
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1. rapid induction and emergence
2. lower incidence of post-op somnolence and nausea 3. pleasant odor --> good for induction. 4. better bronchodilation 5. CV side effects are minimal |
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What is a theoretical side effect of sevoflurane?
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Production of Compound A, a toxic metabolite, in the presence of soda lime or Baralyme. Seen in rats, not humans.
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Which inhalational agent produced the least amount of carbon monoxide in the presence of dry CO2 absorbent?
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Sevoflurane
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Which is the most volatile and least potent of the inhalational agents?
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Desflurane
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What is an important side effect of desflurane?
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tachycardia and hypertension
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Which IV induction agent is appropriate for asthmatic patients? Why?
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Ketamine or Propofol
They block vagus nerve-mediated cholinergic bronchoconstriction. |
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Which is the only IV induction agent that causes hypertension and tachycardia?
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Ketamine
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Which IV induction agent causes adrenal suppression?
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Etomidate
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Which IV induction agent causes dissociative analgesia?
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Ketamine
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Why can ketamine not be used for abdominal surgery?
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Ketamine does not cause muscle relaxation nor prevent visceral pain.
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Why should ketamine be used in combination with an agent such as glycopyrrolate?
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Ketamine induces copious oropharyngeal secretions. Glycopyrrolate is a drying agent.
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What is the primary role of midazolam?
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Powerful anxiolytic and amnestic effects.
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What are the major uses of opioids?
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1. reduce the MAC of inhalational agents
2. blunt the hypertension and tachycardia associated with manipulations, e.g. ET tube, surgical incisions 3. analgesic effects extend beyond the postemergence interval 4. provides powerful analgesia, hypnosis, and amnesia |
