FENTANYL

Enlarged pupils

Intravenous fentanyl is often used for anesthesia and as an analgesic.^] To induce anesthesia, it is given with a sedative-hypnotic, like propofol or thiopental, and a muscle relaxant.To maintain anesthesia, inhaled anesthetics and additional fentanyl may be used.^[29] These are often given in 15–30 minute intervals throughout procedures such as endoscopy and surgeries and in emergency rooms.^[

For pain relief after surgery, use can decrease the amount of inhalational anesthetic needed for emergence from anesthesia. Balancing this medication and titrating the drug based on expected stimuli and the person’s responses can result in stable blood pressure and heart rate throughout a procedure and a faster emergence from anesthesia with minimal pain.

Fentanyl is the most commonly used intrathecal opioid because its lipophilic profile allows a quick onset of action (5–10 min) and intermediate duration of action (60–120 min).^[32] Spinal administration of hyperbaric bupivacaine with fentanyl may be the optimal combination. The almost immediate onset of fentanyl reduces visceral discomfort and even nausea during the procedure.

Fentanyl is sometimes given intrathecally as part of spinal anesthesia or epidurally for epidural anaesthesia and analgesia. Because of fentanyl’s high lipid solubility, its effects are more localized than morphine, and some clinicians prefer to use morphine to get a wider spread of analgesia.^[34] It is widely used in obstetrical anesthesia because of its short time to action peak (about 5 minutes), the rapid termination of its effect after a single dose, and the occurrence of relative cardiovascular stability.^[35] In obstetrics, the dose must be closely regulated in order to prevent large amounts of transfer from mother to fetus. At high doses, the drug may act on the fetus to cause postnatal respiratory distress.^[35] For this reason, shorter acting agents such as alfentanyl or remifentanil may be more suitable in the context of inducing general anaesthesia.^[36]