Fentanyl produces respiratory depression by direct action on brain stem respiratory centers. The respiratory depression involves a reduction in the responsiveness of the brain stem respiratory centers to both increases in carbon dioxide tension and electrical stimulation. Fentanyl causes miosis, even in total darkness. Pinpoint pupils are a sign of opioid overdose but are not pathognomic (., pontine lesions of hemmorhagic or ischemic origins may produce similar findings). Marked mydriasis rather than miosis may be seen due to hypoxia in overdose situations.
What should I do after the procedure?
20-30 minutes after the procedure, you move your area of usual discomfort to try to provoke your usual pain. You report your remaining pain (if any) and record the relief you experience during the next week in a "pain diary" we provide*. You may or may not feel improvement during the first few hours after the injection. This depends on if the joints injected are your main pain source. The pain diary is an important component of your care. It helps your treating physician to be informed of your results so future tests and/or needed treatment can be planned.