Exam 3 (OB/GYN) Flashcards
(39 cards)
N2O Nitronox (Nitrous Oxide)
inhibits NMDA glutamate receptors
stimulates dopaminergic, opioid, alpha-1 and alpha-2 adrenergic receptors.
*Patient cannot have opioids, epidural, or neuraxial analgesia because they have to remain conscious**
Volatile Agents
More effective than Nitrous, must have anesthesia present. **causes uterine smooth muscle relaxation*
caution with losing airway and amnesia.
Systemic medications (non-opioids and sedatives) Acetaminophen
Multimodal analgesia weakly inhibits COX-1 and COX-2
peaks in one hour.
Ketamine Systemic medications (non-opioids and sedatives)
noncompetitive antagonism at NMDA receptors. IV/IM
*DO NOT GIVE w/Preeclampsia or HTN parturients**
Loading 0.2 mg/kg over 30 mins; infuse: 0.2 mg/kg/hr
onset 3-5 minutes (IV) duration 5-10 mins.
Benzodiazepines Systemic medications (non-opioids and sedatives)
bind to specific site on GABA receptor.
crosses placenta easily = maternal & neonatal resp. depression.
(not normally used during labor)
Opioids
can be used for PCA, low cost, easy admin.
Not strong enough for labor pains. N/V, sedation, placental transfer to fetus. maternal/fetal resp. depression
Meperidine
opioid. 50-100mg q4hours or 25mg IV q2-4 hours
SE: N/V, sedation, resps depression, delayed gastric emptying (same for fetus)
repeated doses cause toxic metabolite build up in fetus (lowers their APGAR score)
Morphine
0.05-0.1 mg/kg IV (0.1-0.2 mg/kg IM)
rarely used during labor.
metabolite: morphine-6-glucuronide = longer half life in the neonate.
This results in increased side effects observed in the neonate.
Fentanyl
50-100mcg/hr. readily crosses placenta
risk of ion trapping with acidotic fetus (basic drug pH)
short duration of action = inadequate pain coverage resulting in request for neuraxial analgesia.
Remifentanyl
ULTRA short acting and rapid elimination = no fetal/paternal accumulation.
common to use in PCA 20-40mcg bolus with 2-3 minute lockout.
good alternative when neuraxial anesthesia is not an option. still watch for resp. depression.
Butorphenol (Stadol)
agonsit/antagonist 1-2mg IV/IM q3-4 hrs
2mg Stadol = 10mg Morphine but still causes resp. depression. Lasts longer than fentanyl (half life = 4.5 hrs)
SE: itching, respiratory depression. “dirty drug”
Nalbuphine (Nubain)
agonist/antagonist 5-20mg IV/IM/SQ q4-6hrs. duration is 3-6hrs.
agonizes: kappa, delta, mu (partial) receptors
crosses placenta (same maternal/neonate SE caution as w/opioids)
*Can cause sinusoidal fetal heart pattern**
Toradol
NSAID.
NOT recommended at all (so why include it???)
suppresses uterine contractions
Promotes premature closure of fetal ductus arteriosis
Neuraxial Analgesia (Epidural Meds)
want: rapid onset of action, long duration, excellent sensory/motor differential blockade without effects to mom or baby.
Most common: bupivacaine, ropivacaine, opioids
Not common: lidocaine, 2-Chloroprocaine
Bupivacaine
amide. Epidural: 0.0625%-0.125% (12-20ml) initial dose
Spinal: 7.5-15 mg (dependent on Ht/Wt and stage of labor).
GOOD: long duration of action (90-120 mins), separation between motor and sensory effects, no diminishing response with repeated doses, high safety profile
BAD: slow onset (10-20 mins), CV and neuro toxicity (lipids are the antidote).
slow onset countered with co-administration of fentanyl/sufenta
Ropivacaine
amide. Epidural: 0.1%-0.2% (4-20 ml)
Spinal: 15-25 mg duration: 60-120 minutes
GOOD: separation between motor and sensory effects, high safety profile > bupivacaine (less potent than bupivacaine)
BAD: slow onset time (10-20 mins), CV and neuro toxicity
give with opioid to speed onset.
Lidocaine
amide. Epidural: 0.75%-1.0%
not routinely used because of strong motor blockade, decreased effectiveness with subsequent doses, and fetal ion trapping.
used for: (rapid breakthrough pain)
perineal tear/repair: 1.5-2% (5-10ml)
Rapid sacral analgesia: 0.5-1% (5-10ml)
identify nonfunctional catheter: 2% (5-10ml)
epidural anesthesia: 300-500 mg
2-Chloroprocaine 3%
ester. not typically used because of short duration and poor differential blockade.
USES: quick/emergent C/S (rapid onset), perineal repair. 450-750 mg
can interfere with other LA by decreasing effectiveness of them, tachyplylaxis.
Opioids (epidural administration)
Fentanyl 50-100 mcg / 15-25 mcg (spinal)
Sufentanil 5-10 mcg / 1.5-5 mcg (spinal)
and Morphine (not preferred) / 125-250 mcg spinal.
direct action at spinal and supraspinal opioid receptors (decreases dose requirements of LAs by 20-30%)
lipophilic = quick onset, decreased side effects, denser block, higher patient satisfaction. increased itching though.
morphine = delayed onset of action/resp. depression
Dexmedetomidine (Precedex) epidural
alpha-2 agonist. 0.4-0.5 mcg/ml
decreases LA requirements, non-opioid spinals, denser block with decreased motor blockade.
Epinephrine (epidural additive)
nonselective adrenergic agonist. 1:400K to 1:800K.
100-200 mcg/0.1-0.2 mg (spinal dose)
2.5-5 mcg/ml (epidural anesthesia)
vasoconstricts epidural vasculature (prolongs LA effect). usually only used to prolong block when converting to a C/S delivery.
BAD: increased motor blockade = slowing of labor progression via Beta-2 agonism after systemic absorption.
Labor Epidural Infusion
continuous infusion at 8-15 ml/hr with:
Bupivacaine 0.05%-0.125%
Ropivacaine 0.1%-0.2%
+/- Fentanyl 1-2mcg/ml or Sufenta 0.2-0.4 mcg/ml
dosing is based on: dilation, labor progress, patient height.
Labor PCEA
patient self administers similar to PCA (can include background infusion). helps decrease provider repeat dosing (easier for us).
BAD: program/setup error, non-patient initiated boluses, inappropriate for specific patients.
background infusions could over administer drug and cause motor blockade.
Fluid Management
Coload is preferred when using crystalloids** administration of fluid bolus when CSF accessed to prevent hypotension
10-20 ml/kg crystalloid before spinal
500 ml of colloid (can be give preload or coload)
