Originally posted by sbic56
How does somnolence occur with a bivucaine/Fentenyl epidural? I was under the impression that the narcotic never left its' intended space.
First, if the narcotic never left the "intended space," the epidural space, it would never be metabolized and would forever more affect the patient. We try to use narcotics with a somewhat shorter half life than "forever." The epidural space does have a blood supply, and all medications injected into it are eventually taken out and undergo metabolism and elimination.
But, that doesn't really have anything to do with your initial question, which is why somnolence occurs with a narcotic containing epidural. Like nearly all other drugs, narcotics achieve their intended effect through a drug-receptor interaction. Suffice it to say that the receptors involved in pain control and sedation can be affected by medication injected into the epidural space, and therefore, in sufficient doses, fentanyl administered epidurally can cause sedation, somnolence, depressed respiration, and all the other effects narcotics are known for.
Kevin McHugh, CRNA