Labor Anesthesia & Analgesia Pt. 1 (Exam III) Flashcards
What does SROM stand for?
Spontaneous Rupture of Membranes
What does AROM stand for?
Artificial Rupture of Membranes
Also known as Amniotomy.
Is OA or OP preferred for delivery?
OA (Occiput Anterior)
How long will the first stage of labor last for a woman having her first baby?
If Primiparous, 8 - 12 hours typically.
How long will the first stage of labor last for a woman having already had a child before?
If Multiparous, 5 - 8 hours typically.
What are the two phases of the first stage of labor?
- Latent Phase
- Active Phase
What characterizes the Latent phase of labor?
- Cervical Effacement
- Minor (2-4cm) cervical dilation
- Contractions q5-7 min w/ 30 sec duration
What characterizes the active phase of the first stage of labor?
- Cervical dilation up to 10cm
- Contractions q2-5min w/ 60sec duration
How long does the 2ⁿᵈ stage of labor last?
Typically 15 - 120 min
What characterizes the 2ⁿᵈ stage of labor?
- Full (10cm) cervical dilation
- Contractions q 2min w/ 60-90s duration
- Fetal Descent
- Ends with Delivery
What event characterizes the end of the 2ⁿᵈ stage of labor?
Fetal Delivery
The 2ⁿᵈ stage of labor is considered prolonged if it lasts more than….
3 - 4 hours
How long does the 3rd stage of labor last?
15 - 30 min
When does the 3rd stage of labor begin?
Begins after fetal delivery
The 3rd stage of labor is prolonged if it lasts more than ….
30 minutes
What marks the end of the 3rd stage of labor?
Delivery of the placenta
In what stage of labor is the highest risk of uterine atony and post-partum hemorrhage present?
4th stage
When does the 4th stage of labor occur?
1 hour post-partum
What causes pain via mechanoreceptor stimulation in the 1st stage of labor?
Stretching and distention of lower uterine segment and cervix
What causes the visceral pain associated with the 1st stage of labor?
C-fibers entering spinal cord at T10 - L1
What spinal levels are primarily affected during the latent phase of the 1st stage of labor?
T10 - T12
What spinal levels are primarily affected during the active phase of the 1st stage of labor?
T12 - L1
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
What nerve fibers are responsible for the somatic pain characteristic of the 2ⁿᵈ stage of labor?
Aδ fibers of the pudendal nerve
What spinal levels are relevant to the somatic pain associated with the 2ⁿᵈ stage of labor?
T12 - S4
What inhaled anesthetic can a patient use to “self-anesthetize”?
N₂O
What receptors does N₂O work on?
- Inhibits: NMDA glutamate
- Stimulates: dopaminergic, opioid, and αlpha
How much does N₂O depress uterine contractility?
Trick question. It does not.
Does N₂O causes neonatal depression?
No
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
Combination of N₂O and _______ can result in hypoxia, LOC changes, and loss of airway reflexes.
Opioids
Volatile anesthetic agents will cause uterine smooth muscle ________ in a dose-dependent modality.
relaxation
Preeclampsia and hypertension prevent this use of this drug.
Ketamine
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 is the ketamine infusion loading dose and rate?
Loading: 0.2 mg/kg (over 30 min)
Infusion: 0.2 mg/kg/hr
What are the neonatal consequences of benzodiazepines?
- Neonatal respiratory depression
- Neonatal hypotonicity
- Neonatal impaired thermoregulation
What is the IM dose of meperidine?
50 - 100mg IM q4hours
What is the IV dose of Meperidine?
25 mg IV q2-4 hours
What is the weight based dose of IV morphine?
0.05 - 0.1 mg/kg IV
What is the weight based dosing of IM morphine?
0.1 - 0.2 mg/kg IM
What is the active metabolite of morphine than can accumulate in the neonate?
Morphine-6-glucuronide
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?
Paracervical Block
What are the two fetal complications that can occur with paracervical block?
Fetal LAST (more severe)
Fetal Bradycardia (more common)
What nerve block is an alternative to pharmacologic pain management in the 2ⁿᵈ stage of labor?
Pudendal nerve block
What form of anesthesia covers both 1st and 2ⁿᵈ stage of labor?
Neuraxial
Epidural veins are decompressed in what position?
Lateral lying
Harder to place.
What is there an increase for cephalad spread of neuraxial LA in pregnant patients?
Due to apex of thoracic curvature shifting from T8 to T6.
Also from 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 epidural placement that is too early in labor?
- ↑ risk for instrumented delivery
- Prolonged 2ⁿᵈ stage of labor
- Risk of ineffective epidural and need for replacement
