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Anes. Pharm I Test 2
neuraxial opioids
Question | Answer |
---|---|
Describe anatomically how a CRNA would give an epidural neuraxial opioid dose? | Needle would go through the ligamentum flavum but not through the drug mater; it is a theoretical space |
Describe anatomically how a CRNA would give a spinal neuraxial opioid dose? | Needle would go though the dura mater and into the subarachnoid space; you would know you have reach subarachnoid space r/t aspiration of CSF |
Which receptors are present in high concentrations in the dorsal horn of the spinal cord? | mu, kappa, and delta |
Which are the main receptors present in the substantial gelatinosa? | mu |
The epidural dose should be _____ the subarachnoid dose | 5x - 10x |
What is the epidural dose of morphine? The spinal dose? | epidural: up to 5 mg; spinal: 0.25 - 1 mg |
Neuraxial analgesia is specific for ______ pain rather than _______ pain | visceral; somatic |
True or false: neuraxial opioid analgesia does NOT include a sympathetic denervation, skeletal muscle weakness, or loss of perception of pressure | True! |
If you are going to give morphine in the epidural space or subarachnoid space, you must ensure that it is what? | preservative free |
What is the mechanism of action of opioids placed in the epidural space? | they diffuse across the dura to affect mu receptors on the spinal cord and are absorbed systemically to produce effects like IV opioids |
The higher the lipid solubility of an opioid given epidurally, the _____ absorption systemically | more |
Why is morphine typically the drug of choice for epidural administration? | lower lipid solubility means slower onset, but longer duration |
The more lipid soluble, the _______ the diffusion into the CSF | faster |
When does epidural fentanyl reach peak CSF concentration? | 20 minutes after epidural administration |
When does epidural Sufentanil reach peak CSF concentration? | 6 minutes after epidural administration |
When does epidural morphine reach peak CSF concentration? | 1 - 4 hours after epidural administration |
What percentage of epidural dose of morphine enters the CSF? | only 3% |
When does fentanyl reach peak blood concentration after epidural administration? | 5 - 10 minutes |
When does sufentanil reach peak blood concentration after epidural ministration? | < 5 minutes |
When does morphine reach peak blood concentration after epidural administration? | 10 - 15 minutes |
How can you decrease vascular absorption of epidural opioid? | by injecting epinephrine into the epidural space along with the opioid; vasoconstriction = less absorbed into vasculature |
If epinephrine is added to the morphine solution injected into the subarachnoid space, what happens to the analgesic effect? | it is enhanced compared with the injection of morphine alone because it stays there longer and is not taken up into the vasculature as readily r/t vasoconstriction |
What is the dose and duration of epidural fentanyl? | 50 - 100 mcg; duration: 1 - 3 hours |
What is the dose and duration of epidural morphine? | 2 - 5 mg; duration: 4 - 24 hours |
___________ affects the degree of cephalad movement of opioids in the CSF | lipid solubility (higher lipid solubility limits movement) |
True of false: body position accelerates cephalad movement of opioids in CSF | False! coughing or straining can accelerate movement |
Are side effects of neuraxial opioids due to the presence of them in the CSF or in systemic circulation? | either in CSF or systemic circulation |
What are the four classic side effects of neuraxial opioids? | pruritis, N/V, urinary retention, depression of ventilation |
What can occur 2 - 5 days post epidural administration of morphine? | reactivation of herpes virus; r/t cephalad movement of opioid and interaction of trigeminal nucleus |