PCA
morphine PCA dosing
Basal 0-2 mg/hr
Bolus dose 1-2 mg
Bolus interval 6-10 min
epidural uptake
diffusion across the dura -> systemic absorption
epidural fat
Lipid solubility
* fentanyl 800X> morphine
*sufenatil 1600x> morphine
pruitis
most common especially in OB
*face, neck, upper thorax
cephalad migration to trigeminal nucleus
Tx= naloxone, antihistamines, gabapentin
time course of withdrawal for Morphine/Heroin
onset - 6 to 18 hrs
peak 36-72 hrs
duration 7-10 days
methadone
used in opioid withdrawal and chronic pain
hydromorphone
bolus dose 0.2-0.4 mg
bolus interval 6-10 min
epidural dosing
5-10x more
depression of ventilation
delayed - 6 -12 hrs
most reliable sign - depressed LOC secondary to hypercarbia
Tx = naloxone @ 0.25 mcg/kg/hr IV
peak 6-12 hours
duration 4-5 days
hydromorphone
morphine derivative
5x more potent than morphine
less hydrophillic
0.5 mg IV -> 1-4 mg total
redose Q4Hr
*no histamine
*active metabolite
fentanyl PCA
0-60 mcg/h
bolus 20-50 mcg
bolus interval 5-10
spinal absorption
cephalad movement in CSF depends on lipid solubility
morphine> fentanyl and sufentanil (move slower bc lipid soluble)
herpes simplex labialis
viral reactivation occurring 2-5 days after epidural opioid
early withdrawal symptoms
diaphoresis, lacrimation, yawning, coryza, restlessness, insomnia
codeine dosing/pharmacokinetics
PO/IM only
IV leads to histamine release and hypotension.
E1/2 = 3-3.5 hrs
Liver metabolism
Cough suppresant dose = 15 mg
Analgesia = 60 mg
epidural admin/CSF peak
fentanyl - 20 min
sufentanil 6 min
morphine 1-4 hr
spinal dosing
large doses in the spinal cord lead to more remains in CSF and migrate cephalad
neonatal morbidity
negligible in breast milk
peak withdrawal symptoms
abdominal cramps, N/V, diarrhea
tramadol
mu agonist with weak kappa and delta
PO 3 mg/kg
interacts with Coumadin
epidural plasma peak
fentanyl 5-10 min
sufentanil <5 min
morphine 10-15 min
opioid receptors neuraxial
Lamina II (substantia gelatinosa)
*no sympathectomy, sensory block or weakness
other side effects of neuraxial opioids
N/V
urinary retention
sedation
CNS excitation - tonic skeletal muscle rigidity like seizure
time course of methadone withdrawal
onset 24-48 hour
peak 3-21 days
duration 6-7 weeks
all the opioid agonists (15)
morphine, M6g, codeine, fentanyl, remifentanil, alfentanil, sufentanil, meperidine, oxycodone, oxymorphone, propoxyphene, methadone, hydromorphone, hydrocodone, heroin, tramadol