Analgesia For L&D Flashcards
Benefits of Analgesia L&D
- Decreased catecholamines
- Decreased maternal oxygen consumption
- Decreased hyperventilation
- Indwelling epidural can avoid emergency GA (especially difficult airway, obese, pre-eclamptic, anyone with increased risk of C/S)
Increased pain reported by
Nulliparous
Fetal malposition/dystocia
Dysfunctional labor
Induced labor
What decreases pain sensitivity
Upregulation of descending pain modulating pathways (NE & serotonin)
Increased endogenous endorphins
Progesterone mediated tolerance
What stage of labor involves uterine contraction & dilation
- involves the cervix, uterus, upper vagina
- visceral afferent fibers enter spinal cord at T10-L1 (paracervical ganglion)
- sympathetic chain at L2 and L3
First stage of labor
What stage of labor involves the expulsion of the fetus
- involves mid and lower vagina, vulva, perinum
- somatic afferent fibers enter spinal cord at S2-S4 pudendal nerve
Second stage of labor
What stage of labor involves the delivery of the infant to expulsion of the placenta?
Third stage
Estrogen competes for which receptor
Mu
Opioids do what to FHR variability
Reduced FHR variability
Efficacy and side effects are drug dependent or dose dependent
Dose dependent
Which systemic opioid does not accumulate in the fetus?
Remifentanil 25-50 mcg IV q5-10min
But maternal monitoring required
Why is meperidine no longer popular in OB
Active metabolite - respiratory neonatal depression and neurobehavioral changes
25-50 mcg IV q2hr
Which systemic opioid accumulates in fetal blood
Sufentanil
Systemic opioid doses for Morphine and Fentanyl
Morphine 2-5 mg IV q2-3 hr
Fentanyl 25-50 mcg IV q 30-45 min
Which two systemic opioids have a ceiling effect on respiratory depression?
Nalbuphine 10-20 mg IV q3-6hr
Butorphanol 1-2 mg IV q4-6 hr
Why should nitrous gas be used alone for pain relief?
When used alone, no risk of maternal hypoxia and no adverse effects on the neonate
What effect does nitrous have on early stages of labor
Preserves contractility and no neonatal depression
Which regional anesthesia method is not continuous for vaginal delivery
Single shot spinal
Which regional anesthesia method has a slow onset compared to the others
Continuous epidural
Which three regional anesthesia methods have the ability to extend to anesthesia for C/S
Continuous epidural
Continuous spinal
CSE
Epidural requires smaller or larger doses compared to spinal
Larger
Which regional anesthesia method avoids the need to access neuraxial canal through lumbar interspace? Also requires large volumes/doses May be more technically difficult Higher r/o infxn Risk of inadvertent fetal injection
Continuous Caudal
Which regional anesthesia methods require low dose LA and opioids?
CSE, continuous spinal, single shot spinal
Which regional anesthesia method has a higher risk of maternal toxicity and fetal drug exposure; and which has a higher risk of fetal bradycardia?
Continuous epidural and CSE
Which regional anesthesia method has a complete analgesia with opioid alone thus an increased risk of puritis
CSE
Which regional method has no dural puncture requirement and which has a large dural picture increased risk of PDPH
Epidural and Spinal
Which regional method has a possibility of OD and total spinal if mistaken for epi cath
Continuous spinal
Neuraxial contraindications
Refusal or inability to cooperate Elevated ICP Coagulopathy and recent pharmacologic anticoag Skin infection at site Uncorrected Maternal hypovolemia
Which skin prep is preferred for neuraxial anesthesia?
CHG
Immediate action, residual activity, effectiveness against wide range of microorganisms
Which skin prep is contraindicated
Providine iodine and iodine base
What are the disadvantages of Epidurals
Side effects
Prolongs labor (15-20 min)
Inhibits ability to push
Fetal bradycardia after CSE
Which neuraxial anesthesia has the most effective mode in pain relief, best benefit to risk ratio, safest for CS, provides anesthesia for 1st and 2nd stages of labor, provides a differential blockade
Epidural
Preload patient with how many cc’s of fluid before an epidural
250-500
True or False: Temperature increase is likely in epidural
True
What physiological changes do you consider with epidural placement
Hormonal : Progesterone in CSF, Alkalinity of CSF (give acid prophylaxis)
Epidural veins engorged
Physical: exaggerated flexion causes aortocaval compression, iliac crest level
What happens with intravascular injection of epidural test dose
HR changes 20 BPM within 45 seconds
Circum-oral numbness/ringing in ears
What happens with subarachnoid injection with epidural test dose
Rapid onset of sensory and motor blockade
With/without hypotension
What should you do after injection of epidural test dose?
Aspirate
Check BP q5 min after bolus up to 15-30 min
What is the most commonly used amide LA in OB (concentration too)…
0.25% bupi
What about bupi limits placental transfer?
Its highly protein bound
What is the onset and peak of bupi
Onset 8-10 min
Peak 20
How long does 8-10 mls of 0.25% bupi lasts?
2 hours
Why would you want diluted bupi (0.125%)?
You would want diluted bupi to provide a differential blockade (sensory)
And you are able to give more volume to provide adequate analgesic spread
What are the continuous infusions of bupi?
0.0625 or 0.125% with fentanyl 2mcg/ml
What bupi concentration is contraindicated with epidurals?
0.75%
Which is the ester LA with the fastest onset of action for epidurals?
2-Chloro
Metabolized by pseudocholinesterase
5-10mls of 2% 2chloro provides relief for how long
40 min
Which LA adversely effects the efficacy of subsequent epidural bupi and opioids by antagonizing mu and kappa receptors
2 chloro
What makes 2 chloro the best choice for stat CS for fetal distress?
Fetal acidosis doesn’t increase placental transfer
Intermediate duration of action (between 2chloro and bupi)
Lidocaine
Concentrations of Lidocaine used for epidurals
1% and 0.75%
Lidocaine crosses placenta much or less easier than bupi?
Much Easier
What effect does IV lidocaine have on UBF
Decreases UBF with vasoconstriction
Which LA provides a strong motor block
Lidocaine
Which LA provides an increased risk of neurotoxicity if injected into the subarachnoid space?
Lidocaine
What are the epidural bolus and continuous infusions doses for bupi?
Bolus 0.065-0.25% initially 5-10ml slowly titrate more to expand segmental block
Continuous 0.065-0.125% (fentanyl 1-2mcg/ml)
Lidocaine is not used for epidurals due to placental transfer, strong motor block, and _______
Tachyphylaxis
What is a top off dose of bupi?
0.25% 4-10 ml
Someone calls you saying that the catheter is in the epidural space but the extent of the block is inadequate
What steps do you take?
- Is infusion rate high enough? Have they used bolus option?
- fetal malpresentation? (Not getting enough relief depending on their position)
- Inject dilute solution of LA with or without opioid
- Alter maintenance technique
- If unsuccessful replace catheter
Someone calls you for an asymetric block
What do you do?
- Inspect and withdraw 1cm and resecure
- Inject dilute LA with or without opioids
- Alter maintenance technique
- Place less blocked side in dependent position
- If unsuccessful replace catheter
Someone calls you that the catheter is in the epidural space but there is breakthrough pain
What do you do?
- Is the infusion rate high enough? Have they used the bolus option?
- Inspect catheter site and withdraw 1cm
- Inject more concentrated solution of LA with/without opioid
- Alter maintenance technique
- If unsuccessful replace catheter
What effect does epidural analgesia have on uterine activity
Decreases it for 10-15 min but resumes to normal within 30
Affects more intensity of uterine contractions instead of frequency
What does epidural analgesia do to pitocin?
Inhibits secretion of it
Uterine vasoconstriction happens when with epidural analgesia?
If it’s placed intravascularly
CSE doses
10 mcg of sufentanil and 2.5 mg of bupi
25 mcg of fentanyl and 2.5 mg of bupi
Which needle is inserted first with CSE
Epidural with positive LOR
Then spinal inserted to reach intrathecal space
What causes CSE to have a rostral spread?
Volume in epidural compresses intrathecal space
Achieving a higher level with a smaller dose
Neuraxial anesthesia method for an unintended intrathecal placement of a planned epidural catheter?
Continuous spinal
Continuous spinal has what doses?
Fentanyl 10-25mcg with bupi 1-2.5mg
Bupi 0.125% with fentanyl 2mcg/ml run at 1-1.5 ml/hr
When is a single shot spinal or “saddle block” done?
Immediately prior to delivery with patient in sitting position for 3-5 min
For what stage of labor is a saddle block done for?
STAGE 2 - S2-S4
What LAs are used for single shot spinal?
25-50mg of lido
4-6mg of tetra
6-8mg of bupi
How do you make a single shot spinal adequate for stage 1 of labor
Give larger amounts of LA to get to T10 level
What neuraxial anesthesia method is useful for forceps delivery and breech babies
Single shot spinal
Fluid bolus for single shot spinal
500-1000ML
When is saddle block performed with contractions?
Between them to minimize cephalad spread
Level of block following a spinal is affected by what three things
Baricity of LA
Position of patient
Drug dosage
Which neuraxial anesthesia method is available for patient with lumbar fusion history
Caudal block
Co-administration of opioid with LA decreases or increases pruritis
Co-admin of opioid and epi decreases or increases pruritis
Decreases
Increases
What other side effects are there for neuraxial anesthesia besides hypotension and pruritis
Fever, shivering, urinary retention
Tx of pruritis for neuraxial anesthesia
Centrally acting opioid agonist/antagonist or partial agonist-antagonist
- narcan 40-80mcg IV, 1-2 mcg/kg/hr infusion
- Nalbuphine 2.5-5mg IV
- naltrexone 6mg PO
Benadryl
What hormone enhances the cardiac toxic potential of bupi?
Progesterone
How can you prevent PDPHA
- Spinal needle 25-27g
- U/S
- caffeine and hydration
Tx for PDPHA
Intrathecal catheter placement Analgesics Horizontal position Caffeine Sumatripan (imitrex) Epidural blood patch epidural access 12-20 ml of pt’s blood
Which nerve injury is associated with the compression between the descending fetal head and sacrum
Also associated with mid to high forceps use
Lumbosacral trunk L4 L5
Nerve injury associated with injury in the lithotomy position bc of hyperacute hip flexion and use of retractors during CS
Femoral L2-L4 and lateral femoral cutaneous nerve L2-L3
Nerve injury associated with incorrect lithotomy positioning with knee extension and external hip rotation
Sciatic L4, L5 S1-3
Nerve injury with lithotomy positioning from acute flexion in thigh to groin
Esp with obese women
Obturator L2-L4
Nerve injury from lithotomy that shows foot drop
Common peroneal L4-5 S1-2
Saphenous nerve injury is affected from what
Lithotomy
What complications can you see with paracervical block
Maternal rare
Fetal transient bradycardia
Direct injection into presenting part
DOA of paracervical block
30-60 min
Which block Does not affect duration of labor
Paracervical
How do you perform paracervical block
Inject 2ml of LA under epithelium, not deeper than 3mm NO EPI At 3, 5, 7, 9 o’clock Optional 2 and 10 oclock Aspirate prior to injection
What are the two approaches for pudendal block
Transvaginal and transperineal
What are the complications from pudendal block besides provider needle stick?
Maternal hematoma, systemic toxic reaction, trauma to sciatic, puncture of rectum, fetal injection
Steps for a pudendal block
Needle embedded in sacrospinous ligament Need LOR Aspirate through 180 degree rotation 3-5ml of LA injected Needle advanced 1cm further and another 3-5ml solution injected
Which drug is safer for uterine relaxation and episiotomy repair ?
Uterine relaxation - NTG
Episiotomy repair - local and ketamine < 0.5 mg/kg
If you must do GA, which induction drugs are preferred with GA
Thiopental, prop, ketamine, or etomidate