The plasma concentration of the induction agent falls rapidly with time (Fig 1).

Question: What is happening to the drug in the body?

Answer

The plasma concentration of the induction agent falls rapidly with time (Fig 1).

Question: What is happening to the drug in the body?

Answer: There are at least two processes going on:

• The drug is moving out of the blood stream and is being distributed to other tissues
• The drug is being metabolized and/or excreted from the body

Question: What determines to which tissues the drug is initially distributed?

Answer

The plasma concentration of the induction agent falls rapidly with time (Fig 1).

Question: What is happening to the drug in the body?

Answer: There are at least two processes going on:

• The drug is moving out of the blood stream and is being distributed to other tissues
• The drug is being metabolized and/or excreted from the body

Question: What determines to which tissues the drug is initially distributed?

Answer: The blood flow. Tissues that have a high blood flow, i.e. vessel-rich tissues, take up the drug more quickly. Eventually the vessel-poor tissues take up the drug as it recirculates in blood. The vessel-poor tissues include fat; the very lipid-soluble induction agents are readily taken up by fatty tissue.

Question: How does this uptake by vessel-rich tissues affect the duration of hypnosis?

Answer

The plasma concentration of the induction agent falls rapidly with time (Fig 1).

Question: What is happening to the drug in the body?

Answer: There are at least two processes going on:

• The drug is moving out of the blood stream and is being distributed to other tissues
• The drug is being metabolized and/or excreted from the body

Question: What determines to which tissues the drug is initially distributed?

Answer: The blood flow. Tissues that have a high blood flow, i.e. vessel-rich tissues, take up the drug more quickly. Eventually the vessel-poor tissues take up the drug as it recirculates in blood. The vessel-poor tissues include fat; the very lipid-soluble induction agents are readily taken up by fatty tissue.

Question: How does this uptake by vessel-rich tissues affect the duration of hypnosis?

Answer: The clinical effect depends on the plasma concentration.