Opioids |
Epidural |
Morphine 40 mcg/kg for postoperative analgesia—risk of respiratory depression |
Fentanyl 1–2 mcg/kg bolus (infusions act via systemic uptake) |
Sufentanil probably acts via systemic uptake—no advantage over IV administration |
Spinal |
Morphine 100–200 mcg for postoperative analgesia up to 24 h—risk of delayed respiratory depression |
Fentanyl 10–25 mcg |
Improves quality and duration of spinal anesthetics without delaying recovery |
Useful for ambulatory spinal anesthesia |
Increased pruritus with procaine and 2-chloroprocaine |
Sufentanil probably acts via systemic uptake |
Vasoconstrictors |
Epidural |
Epinephrine 5 mcg/ml (1:200,000). Total dose not to exceed 0.25 mg |
Effective prolongation of block and recovery with lidocaine and 2-chloroprocaine, and reduced plasma levels of lidocaine |
Will intensify block and reduce plasma levels of bupivacaine, but less effect on duration |
Minimal effect with ropivacaine |
Phenylephrine may result in systemic uptake and reduced cardiac output |
Spinal |
Epinephrine 0.2 mg will intensify block, prolong duration of blockade |
Less effect on duration of high dose bupivacaine |
Not advantageous in ambulatory settings due to prolongation of recovery and delay of discharge times |
Do not use with 2-chloroprocaine |
Phenylephrine can have profound effect on duration of blockade, but may increase risk of TNS |
Clonidine |
Epidural |
Typical dose of 150 mcg or 2 mcg/kg for 6–8 h of analgesia |
Additive analgesia when combined with opiates |
More profound hypotension when used in upper thoracic epidural space |
Cardiovascular effects are not significantly greater than local anesthetic alone |
Less oxygen desaturation and urinary retention compared to opioids, but can produce sedation |
Spinal |
15 mcg for low-dose/ambulatory spinal anesthetics |
Higher doses will prolong motor block and recovery time |
Doses up to 150 mcg have been used, but with increasing sedation and cardiovascular depression |
Sodium Bicarbonate |
See Table 8–1 for recommended doses |
More effective on speed of onset with lidocaine and mepivacaine than with bupivacaine or ropivacaine epidural anesthesia |
Effect on speed of onset may not be clinically relevant |
Can intensify epidural blockade, especially in sacral dermatomes |
May be associated with hypotension |
Monitor solution for precipitation |
Neostigmine |
Epidural doses of 1–2 mcg/kg seems to be beneficial |
Main concern is protracted nausea |
Clinical utility in spinal anesthesia is yet to be determined due to high incidence of nausea |
Depot Formulations, Ketamine, Ketorolac, Adenosine,Midazolam |
Some evidence of potential benefit |
Clinical safety and utility is yet to be determined |