Inhalants

Question 1

how is anesthetic [ ] controlled?

Answer 1

the potency is directly linked to lipid solubility,

Question 2

explain the concentration vs. partial pressure vs. tension of inhalants

Answer 2

[] of drugs in the alverolar air and tissues are different, but the tension and Partial pressure (Pa) are the same. At equilibrium; alveolar, blood, and brain anesthetic partial pressures are the same. this influences the delivery of volatile anesthetics.

Question 3

the delivery of inhalants from alverolar gas to blood to brain depends on several factors. Name them

Answer 3

1. solubility of drug in tissues (Blood:Gas Partition Coefficient)
2. concentration of anesthetic in inspired air
3. ventilation rate
4. pulmonary blood flow

Question 4

the more insoluble a drug is the more likely you are to ______? why?

Answer 4

recover and onset quicker.

1. effect related to partial pressure, and low [] of poorly soluble drug with create ^ partial pressure
2. saturation rate of drug into tissues.

Question 5

recovery is (longer/short) from a highly soluble anesthetic?

Answer 5

longer, because it takes longer to lower the blood concentration.

Question 6

how are inhalants eliminated?

Answer 6

mainly by exhalation and also by respiratory rate and pulmonary blood flow.
poorly soluble drugs leave tissues faster-> fast recovery

Question 7

what is the metabolic pathway of inhalants?

Answer 7

extent of metabolism is related to toxicity
metabolites are harmful to liver, and usually only a problem with long, repeated exposures to halothane, or long procedures with sevoflurance

Question 8

What is MAC>

Answer 8

minimum alveolar concentration
used to compare potency of inhalent anesthetic. MAC50 is the concentration in inspired air that will prevent 50% of patients from feeling painful stimulus.

Question 9

the more potent a drug is; the (more/less) concentration is needed?

Answer 9

less

Question 10

describe the inhalant halothane

Answer 10

less used now, metabolites= cause liver damage

Question 11

what are physiological effects of halothane?

Answer 11

1. depresses tidal volume (depth)
2. depresses the myocaridum (decrease in CO)
3. increases sensitivity of myocardium to epinephrine -> can cause arrhythmia
   * *must be careful wtih this inhalant and the thermoregulation of a patient.

Question 12

what is malignant hyperthermia?

Answer 12

perople have mutated Ca2+ release RYR in skeletal muscle, halogen inhalant causes uncontrolled muscle contraction and increased body temp -> brain damage.
treated with muscle relaxant dantrolene

Question 13

what is the toxicity of halothane?

Answer 13

• metabolites are hepatotoxic. they are called trifluoroacetic acids, and bind to hepatic proteins——> hepatitis
• can also cause valves on machines to malfunciton

Question 14

what is isoflurane a more commonly used inhalant?

Answer 14

1. no hepatic or renal toxicity
2. low solubility
3. less depression of caridac output, but has dose-dependent drop in BP
4. less potent
5. highly stable
6. pungent odour :(
7. has much higher SSM (safety margin) than Halothane

Question 15

what is sevoflurance?

Answer 15

second most used- similar to isoflurance
even less soluble
lack of odour- great for kids
no dangerous metabolites
BUT is less table than isoflurance and breaks down when exposed to CO2 absorbants, and not great for long procedures.

Question 16

what is N2O

Answer 16

tru gar,
weak CNS depressant
used to reduce amount of other inhalants, and speeds uptake of volatile anesthetic. (used when masking down)
its a great analgesia, and is very safe.
it does form gas pockets in digestive tract, (may bloat)