Exam 3 (OB/GYN) Flashcards
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)
Ephedrine
5-10 mg IV mixed alpha and beta adrenergic agonist
traditional first line agent. readily crosses placenta
Phenlyephrine (Neosynephrine)
50 mcg IV bolus or continuous infusion 25-100 mcg/min.
selective alpha-1 adrenergic agonist. Preferred if you have to hang a drip. Watch patient’s heart rate.
Lidocaine (Spinal)
60-80 mg
Duration: 45-75 minutes
Fentanyl (Spinal)
10-25 mcg
duration: 180-240 minutes
improve intraop and post op discomfort; decreased intraop N/V
SE: itching, early resp. depression (seen with higher doses)
Sufentanil (Spinal)
- 5-5 mcg
duration: 180-240 minutes
Morphine PF Astramorph/Duramorph (Spinal)
100-200 mcg (0.1-0.2 mg)
duration: 720-1440 minutes
post-op pain control (12-24 hours)
SE: itching (opioid induced), late resp. depression.
be cautious with OSA and obesity.
NO Additional IV/PO narcotics can be ordered if you give this**
Precedex Dexmetomidine (spinal)
5-10 mcg.
Prolongs sensory and motor blockade and time to first request for post op pain by four hours. can minimize shivering.
watch out for bradycardia and hypotension.
Bupivacaine 0.5% (Epidural C/S anesthesia)
75-125 mg (1.5-2.5 mls). Intermediate onset, long duration.
Watch for cardiac toxicity.
Ropivacaine 0.5% (Epidural C/S anesthesia)
75-125 mg. Intermediate onset, long duration of action.
decreased of cardiac toxicity.
Fentanyl (Epidural anesthesia)
50-100 mcg. spinal and supraspinal sites of action. improved intraop anesthetic quality.
SE: itching, early resp. depression, somnolence.
caution with fetal absorption.
Morphine PF (Epidural anesthesia)
1.25-3.75 mg (~2mg)
Postop analgesia for 12-24 hours. Dose dependent itching and late respiratory depression.
Sodium Bicarbonate (HCO3) Epidural anesthesia
Add 0.1 ml to every 10 mls of Ropivacaine/Bupivacaine
Add 1 ml to every 10 mls of Lidocaine.
More LA in non-ionzied state = faster onset time.
improves quality of and prolongs block.
Oxytocin (Pitocin)
uterotonic. first line medication to prevent postpartum hemorrhage and treat. (naturally stored in posterior pituitary). can also be given to augment and induce labor.
lowers threshold for depolarization in uterine smooth muscle cells.
10 units IM/IV/intrauterine. after delivery of placenta or vaginal delivery 20 units in 1 Liter NS @ 900 ml/hr
SE: tachycardia, HoTN, myocardial ischemia, flushing, chest discomfort, hyponatremia (seizures –> coma)
Methergine (Methylergonovine)
uterotonic 2nd line agent for post partum hemorrhage.
0.2 mg IM ONLY Onset <10mins, lasts 2-4 hours. store in fridge.
treats uterine atony only. produces sustained uterine contractions/uterine tetany.
SE: intense vasoconstriction, HTN, ischemia/infarction, CVA/seizures, N/V, death.
Carboprost (Hemabate)
3rd line agent for postpartum hemorrhage. 250 mcg IM/IU every 15-30 mins (max 2 mg)
*15-Methyl Prostaglandin F2⍺** prostaglandins increase myometrial intracellular free Ca concentration leading to increase in myosin light chain kinase activity.
must store in refrigerator.
SE: diarrhea, N/V, increased SVR, bronchospasm, hypoxia. avoid if significant pulmonary HTN or CV disease
