This document summarizes rational use of opioids in anesthesiology. It discusses the mechanisms of action of opioids in inhibiting neurotransmitter release and altering ion conductance. It notes that opioids can block the stress response, allow for balanced anesthesia using reduced doses of other agents, and provide postoperative analgesia. However, opioids can also cause issues like histamine release, hypotension, urinary retention, decreased GI motility, and respiratory depression when combined with other sedatives. The effects of specific opioids like fentanyl, hydromorphone, methadone, remifentanil, and their properties, dosing, and comparisons are outlined. It emphasizes administering balanced anesthesia and avoiding morphine in some patients,

1. Rational Use of Opioids in Anesthesiology Yury Khelemsky, MD Assistant Professor Anesthesiology and Pain Medicine The Mount Sinai Medical Center

5. How opioids effect Ventilation

6. A and C, Reduction of the concentration of sevoflurane by increasing concentrations of fentanyl at which 50% or 95% of patients did not move at skin incision (MAC or MAC 95 , respectively). B and D, Reduction of the concentration of sevoflurane by increasing concentrations of fentanyl at which 50% or 95% of patients did not show sympathetic responses (an increase in heart rate or mean arterial pressure >15%) at skin incision (MAC-BAR or MAC-BAR 95 , respectively).

14. Opioid Comparison Opioid Onset (min) Peak (min) Duration (h) Elim T1/2 (h) Protein binding (%) IV equianalgesic dose to morphine 10mg IV (mg) Fentanyl <1 5 0.5-1 3.7 85 0.1 Methadone 15 15 4 8-59 90 5-10 Morphine 5 20 4 1.5 M6G-3 30 Hydromorphone 10 20 4 2.6 8-20 1.5 Sufentanyl <1 <5 0.5 18min 92 0.01 Remifentanyl <1 <1 5-10 4 70 0.05-0.1

15. Onset of Opioids

16. Context Sensitive Half-Life

17. Relative Potency Only about 50% cross-tolerance ( incomplete cross tolerance ) between opioids – if one is not effective or produces side-effects, try another.