Labor anesthesia 1st vid Flashcards by Carlos Valerio

What are the two types of amniotic membrane rupture mentioned in lecture? When does this rupture occur?

-Spontaneous Rupture of Membranes (SROM)
-Artificial Rupture of Membranes (AROM) Amniotomy
-Rupture may occur before onset of labor or during labor

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Is OA or OP preferred for delivery?

OA (Occiput Anterior)

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How long will the first stage of labor last for a woman having her first baby?

If Primiparous, 8 - 12 hours typically.

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How long will the first stage of labor last for a woman having already had a child before?

If Multiparous, 5 - 8 hours typically.

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What are the two phases of the first stage of labor?

Latent Phase
Active Phase

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What characterizes the Latent phase of labor?

Cervical Effacement (cervix thins out)
Minor cervical dilation (2-4cm)
Contractions q5-7 min w/ 30-40 sec duration

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What characterizes the active phase of the first stage of labor?

Cervical dilation up to 10cm (complete dilation)
Contractions q2-5min w/ 50-70 sec duration

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How long does the 2ⁿᵈ stage of labor last?

Typically 15 - 120 min

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What characterizes the 2ⁿᵈ stage of labor?

Full cervical dilation (10cm)
Contractions q 1.5-2min w/ 60-90s duration
Fetal Descent
Ends with Delivery

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What event characterizes the end of the 2ⁿᵈ stage of labor?

Fetal Delivery

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The 2ⁿᵈ stage of labor is considered prolonged if it lasts more than….

> 3 - 4 hours

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How long does the 3rd stage of labor last? When does the 3rd stage of labor begin?

-Duration: 15 - 30 min
-Onset: Begins after fetal delivery

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The 3rd stage of labor is prolonged if it lasts more than ….

30 minutes

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What marks the end of the 3rd stage of labor?

Delivery of the placenta

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In what stage of labor is the highest risk of uterine atony and post-partum hemorrhage (PPH) present? What can increase this risk of these consequences?

4th stage
prolonged 2nd Stage
-keep close eye on patient for uterine atony & PPH

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When does the 4th stage of labor occur?

1 hour post-partum

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What causes visceral pain in the 1st stage of labor?

-Stretching & distention of lower uterine segment and cervix.
↳this stimulates mechanoreceptors
-Mechanoreceptor stimulation:
↳leads to visceral pain

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How is the visceral pain associated with the 1st stage of labor transmitted?

Visceral pain transmitted by small, unmyelinated C-fibers
-These fibers enter spinal cord at T10 - L1

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What spinal levels are affected during the latent phase of the 1st stage of labor?

T10 - T12

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What spinal levels are primarily affected during the active phase of the 1st stage of labor?

T12 - L1

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What type of pain becomes more predominant in the 2ⁿᵈ stage of labor?
What are the characteristics of this pain?

Somatic Pain
- Sharp, easily localized
- Caused by stretching & compression of pelvic/perineal structures

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What nerve fibers are responsible for the somatic pain characteristic of the 2ⁿᵈ stage of labor?

Aδ fibers of the pudendal nerve

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What spinal levels are relevant to the somatic pain associated with the 2ⁿᵈ stage of labor?

T12 - S4
pain moves further into sacral dermatomes as labor progresses

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What inhaled anesthetic can a patient use to “self-anesthetize”? How is this delivered?

N₂O
-50:50 ratio of N₂O:O₂
-Demand valve connected to mask/mouthpiece
-delivery activated by negative pressure (spontaneous breathing)

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What receptors does N₂O work on?

- Inhibits: NMDA glutamate - Stimulates: dopaminergic, opioid, and αlpha 1 and alpha 2 adrenergic

What are some benefits of N₂O in labor pain?

-no decrease in uterine contractility -no neonatal depression

What nerve block is often used in conjunction with N₂O ?

Pudendal nerve block

What are adverse effects associated with N₂O?

N/V, Dizziness, Paresthesias, Xerostomia (dry mouth)

What can a combination of N₂O and Opioids result in?

hypoxia, LOC changes, and loss of airway reflexes.

Volatile anesthetic agents will cause what adverse effects?

-Dose dependent uterine smooth muscle relaxation -Maternal loss of airway reflexes and amnesia

What patients will have contraindications for ketamine use?

-Preeclampsia and hypertension ↳Due to ketamine increasing SNS

What is the obstetric dose of ketamine?

0.2 - 0.5 mg/kg

What is the IV onset & duration of ketamine?

Onset: 30 seconds Duration: 5-10 min

What is the IM onset & duration of ketamine?

Onset: 2-8 min Duration: 10 - 20 min

What are the ketamine infusion and loading doses?

Loading: 0.2 mg/kg (over 30 min) Infusion: 0.2 mg/kg/hr

What are the neonatal/maternal consequences of benzodiazepines?

- Neonatal/maternal respiratory depression - Neonatal hypotonicity - Neonatal impaired thermoregulation

What are the IM & IV doses of meperidine?

IM: 50 - 100mg IM q4hours IV: 25 mg IV q2-4 hours

What are the weight based doses of IV & IM morphine?

IV: 0.05 - 0.1 mg/kg IV IM: 0.1 - 0.2 mg/kg IM

What is the active metabolite of morphine? How does this metabolite affect the neonate?

-Morphine-6-glucuronide -longer half-life in neonate -↑ risk of neonatal respiratory depression

What is the PCA dosing of remifentanil?

20 - 40mcg (lockout of 2-3 min)

What is the IV/IM dose of butorphanol?

1-2mg IV/IM q3-4 hours

What is the dose of nalbuphine?

5 - 20 mg IV/IM/SQ

What opioid can result in significant fetal bradycardia?

Nalbuphine

Why is toradol typically not used in labor?

- Suppresses uterine contractions - Premature constriction of DA - Inhibits PLT aggregation

What nerve block is typically provided by the OBGYN during the 1st stage of labor? How effective is it?

Paracervical (ganglion) Block -provides short-term pain relief in the 1st stage of labor

What are the fetal complications that can occur with paracervical block?

Fetal LAST (most severe) Fetal Bradycardia (most common) Risk of injection into fetal scalp

What nerve block is an alternative to pharmacologic pain management in the 2ⁿᵈ stage of labor?

Pudendal nerve block

What is the only form of analgesia that provides complete analgesia for both stages of labor?

Neuraxial

Epidural veins are decompressed in what position?

Lateral lying -↓risk of intravascular cath placement *Harder to place*.

Why is there an increased risk for cephalad spread of neuraxial LA in pregnant patients?

Due to apex of thoracic curvature shifting from T8 to T6. *Also from↓ epidural space secondary to epidural vein engorgement*.

What are absolute contraindications to neuraxial anesthesia?

- Refusal - Uncooperative patient - Uncontrolled hemorrhage w/ ↓volume - Epidural site infection - Bleeding issues/disorder - Anticoagulated

What are the risks associated with placing epidural too early in labor?

- ↑ risk for instrumented delivery - Prolonged 2ⁿᵈ stage of labor - Risk of ineffective epidural and need for replacement

What is meant by OA in regards to OB? What about OP?

OA (Occiput Anterior) -back of baby's head is facing mother's anterior abdomen OP (Occiput Posterior) -back of baby's head is facing mother's spine

What is the expanded gravida para acronym? What does it stand for?

GTPAL: -Gravida **After P "para"** -Term -Preterm -Abortion/miscarriage -Living Children

What are the functions of the amniotic sac?

-Protect uterine contents from bacteria -Mechanical protection for fetus and umbilical cord

After rupture of membrane when should delivery take place in order to minimize infection risk?

Within 12 hours

What is one cause of prolonged second stage of labor? What are some complications associated with prolonged second stage?

What are the factors that affect labor pain?

What is one downside that can be seen with labor augmented with Pitocin?

Labor augmented with Pitocin may be **more painful earlier in labor**

What characteristic of visceral pain makes it difficult to treat with opioids? What method of analgesia is effective for visceral pain?

Visceral pain is hard to localize d/t diffuse nature Peripheral afferent blockade (Neuraxial anesthesia) is more effective for visceral pain

Is visceral pain present in the 2nd stage of labor?

Yes! Visceral pain is still significant as contractions continue.

What is a doula? How are they utilized in labor?

Doula- a support person for the patient -often non-medical -emotional/physical support **doula can still be present if patient receives epidural**

What are the complementary therapies discussed in lecture?

What is counterirritation and what is its role in labor pain?

Causing irritation/pain intentionally Role: to distract body from labor pain -releases endorphins to help combat labor pain ex: squeezing comb -Idea is to take advantage of gate theory and use physiologic distraction

What are some considerations when using inhaled anesthetics for labor pain (not including general anesthesia)?

-Must use sub-anesthetic concentrations -Parturient must remain conscious -Partner/coach in verbal contact at all times

How high is the risk of N₂O overdose with self-administration?

Very hard to OD -d/t fast on/off nature of N₂O -if patient loses consciousness they drop mask (ending N₂O delivery)

How does N₂O administration change with epidural placement?

N₂O is not allowed after epidural placement -N₂O and epidural both indicated for labor pain

Though rare, in what scenarios will volatile anesthetics be used for vaginal deliveries?

Exceptions include **twin births and instrumented vaginal deliveries**

What is the max effect of acetaminophen?

1 hour

What are the advantages and disadvantages of opioid use in the pregnant patient?

What are some characteristics of meperidine? (include side effects)

-Lipid soluble (crosses placenta easily) -Side effects: respiratory depression & itching -Active metabolite: normeperidine ↳CNS stimulant l/t seizures

What is the solubility of morphine? How does this affect the onset?

Hydrophilic; slower onset.

What is the drug profile of Fentanyl? What are the active metabolites and solubility?

No active metabolites ↳repeated doses may l/t accumulation Lipophilic ↳readily crosses placenta (but works quickly)

What makes remifentanil an ideal opioid for delivery?

Ultra short acting ↳metabolized by plasma esterases

How does butorphanol (Stadol) compare to fentanyl?

Stadol has improved analgesic scores when compared to fentanyl

What are the cons of pudendal block?

-minimizes urge to push -rapid maternal absorption of local (LAST risk) -risk for inadvertent injection into pudendal artery -fetal trauma or fetal LA injection

What are the meds and supplies that should be available when administering neuraxial anesthesia?

What are the anesthesia assessments prior to neuraxial anesthesia?

What are some Neuroanatomy changes seen with pregnancy?

Decreased intervertebral gap associated with lumbar lordosis -"tight spaces" Forward rotation of pelvis -Touffier's line elevated Thoracic apex shifts from T8 to T6

From lecture, what may Café au lait (brown spots on skin) indicate?

Neurofibromatosis