Test 3: Labor Anesthesia & Analgesia Part 1 Flashcards
What is a Primip?
Someone pregnant for the first time
What is a Multip?
Someone who has delivered at least one child >20 weeks
What does SROM stand for?
Spontaneous Rupture of Membranes
What does AROM stand for?
Artificial Rupture of Membranes (AKA: Amniotomy)
What do OA and OP mean?
- OA and OP describe the direction the fetus is facing
- OA: Occiput Anterior (back of the baby’s head is towards the mom’s abdomen)
- OP: Occiput Posterior (back of the baby’s head is towards mom’s spine)
During delivery, what is the preferred baby’s position (OA or OP)?
Occiput Anterior (OA)
This position is also known as “Sunny Side Up”.
Occiput Posterior (More difficult delivery)
What does CLE stand for?
Continuous Labor Epidural
What does DPE stand for?
Dural Puncture Epidural
What does CSE stand for?
Combine Spinal Epidural
What will the four numbers following “P” (Para) in a provider’s note stand for?
- 1st Number: Term (37 weeks or >)
- 2nd Number: Preterm
- 3rd Number: Abortions (Miscarriage or Other Loss)
- 4th Number: Living Children
G2 P0101
G2: Pt is in their second pregnancy
P0101: 0 term birth, 1 pre-term birth, 0 abortions/miscarriage, 1 living child
G4 P2102
G4: Pt is in their 4th pregnancy
P2102: 2 term births, 1 pre-term birth, 0 abortions/miscarriage, 2 living children
The intact membrane of the amniotic sac protects the uterine content from __________.
Bacteria
The amniotic sac provides mechanical protection for the fetus and _____________.
Umbilical cord
How long does a woman have to give birth once their water breaks?
- 12 hours
- Anything longer will cause an increased risk of infection
How long will the first stage of labor last for a Primip?
How long will the first stage of labor last for a Multip?
Primip: 8-12 hours
Multip: 5-8 hours
What are the phases of the first stage of labor?
- Latent Phase
- Active Phase
What happens during the Latent Phase?
- Cervical Effacement (thins out)
- Minor cervical dilation (2-4 cm)
- Contractions: q5-7 mins lasting 30-40 secs
What happens during the Active Phase?
- Cervical dilation ramps up to 10 cm (complete)
- Contractions: q2-5 mins lasting 50-70 secs
What is the duration of the Second Stage of Labor?
15-120 minutes
What happens during the Second Stage?
- Full cervical dilation (10 cm)
- Contractions q1.5-2 mins lasting 60-90 secs
- Fetal descent
- Ends with delivery of fetus
The Second Stage is considered PROLONGED if it exceeds _________ (range) hours.
3-4 hours
What is a common cause of a prolonged Second Stage?
Cephalopelvic disproportion (Big Head)
What are the risks involved with a prolonged Second Stage?
- Risk for fetal trauma
- Severe umbilical cord compression
- Maternal trauma (physical, emotional)
- Postpartum hemorrhage
- Infection
- Admission to NICU
What is the duration of the Third Stage of Labor?
15-30 minutes
When does the Third Stage begin, and when does it end?
When is the Third stage considered “prolonged”?
- Begins after delivery
- Ends w/ delivery of placenta
- Prolonged after 30 mins
When is it considered the Fourth Stage of labor?
1st hour of postpartum
During the Fourth Stage, you have a great risk of what?
- Uterine Atony
- Postpartum hemorrhage (PPH)
What factors are involved in labor pain (long list)?
- Genetic influence
- Pelvic size/shape
- Fetal presentation
- Natural labor/ induction of labor/ augmented labor
- Most women c/o severe pain during contraction/ pushing
During the first stage of labor, what causes the mechanoreceptor stimulation?
Stretching and distention of lower uterine segment and cervix/ contractions → VISCERAL PAIN
What fibers transmit visceral pain?
Unmyelinated C-nerve fibers
Where do the C-nerve fibers enter the spinal cord?
T10 - L1
Where will pregnant women feel visceral pain?
- Hard to localize
- Lower abdomen, sacrum, back
- Can be difficult to treat d/t diffused nature
Visceral pain will affect these dermatome levels during the latent phase.
T10 - T12
Visceral pain will affect these dermatome levels during the active phase.
T12 - L1
What kind of pain will be more prominent in the Second Stage of Labor?
Somatic Pain
What fibers transmit Somatic Pain?
- Myelinated Aδ fibers via Pudendal nerve
Describe Somatic Pain.
- Sharp, easily localized
What causes Somatic Pain in pregnant women?
Caused by the stretching and compression of pelvis and perineal structures
What dermatomes are primarily affected during the second stage of labor?
- T12 - S4
- Moves further into sacral dermatomes as labor progresses.
Visceral pain is still significant as contraction continues.
What is a Doula?
- Support person
- Often non-medical
- Emotional & Physical Support
List complementary therapies for labor pain.
- Music
- Massage
- Reflexology
- Hypnosis
- Aromatherapy
- Acupuncture/ Acupressure
What is counterirritant?
- A counterirritant is a substance that creates irritation or mild inflammation in one location with the goal of lessening discomfort and/or inflammation in another location.
- IE: Intradermal sterile water injection
- Gate Control Theory
Who dis?
- Jon Snow
- Used chloroform to anesthetize Queen Victoria
- Bastard of Winterfell
- 998th Lord Commander of the Night’s Watch
What anesthetic gas is currently used to mitigate labor pain?
- Nitrous Oxide (Nitronox)
- Self dose
Describe the mechanism of action of how Nitrous Oxide alleviates labor pain.
- Inhibitory action at NMDA glutamate receptors
- Stimulate dopaminergic, opioid, α1, and α2-adrenergic receptors
Nitrous has no decrease in uterine contractility.
Nitrous does not cause neonatal depression.
Nitrous Oxide is blended in a 50:50 ratio with ___________ for patient self-administration.
Oxygen
Demand valve connected to face mask and activated by negative pressure.
What are the side effects of Nitrous Oxide?
- Nausea
- Dizziness
- Paresthesia
- Dry Mouth
What are the side effects of Nitrous Oxide + Opioid combination?
- Hypoxia
- LOC
- Loss of protective airway reflexes
What nerve block can augment the effects of Nitrous?
Pudendal Nerve Block
What are the effects of Volatile Anesthetics on uterine smooth muscle?
Dose-dependent uterine smooth muscle relaxation
What receptors does acetaminophen work on?
Weak inhibition of COX-1 and COX-2 receptors
When will acetaminophen have its maximum effect?
Max effect in 1 hour
What receptors does Ketamine work on?
Noncompetitive antagonism at NMDA receptors
Why should you not give Ketamine to someone with preeclampsia or HTN?
Ketamine increases HR and BP.
Other side effects include visual/auditory hallucinations
Ketamine is a _________ derivative.
phencyclidine
IV/IM Dose of Ketamine for Analgesia (Sub-anesthetic)
0.2 - 0.5 mg/kg
IV onset and duration of Ketamine
Onset: 30 seconds
Duration: 5-10 minutes
IM onset and duration of Ketamine
Onset: 2-8 minutes
Duration: 10-20 minutes
Infusion Loading Dose of Ketamine.
Infusion Rate of Ketamine.
Loading Dose: 0.2 mg/kg over 30 minutes
Infusion: 0.2 mg/kg/hr
Why would you want to avoid BZD for parturients?
- BZD can cross the placenta
- May cause maternal and neonatal respiratory depression
- Neonatal hypotonicity, impaired thermoregulation
- Amnesia
Pros and Cons of using opioids for labor pains
PRO: Ease of administration, low cost, no specialized equipment or personnel
CON: N/V, Sedation, Itchiness, Placental transfer to fetus
IM dose of meperidine for labor pain
50-100 mg q4 hours
IV dose of meperidine for labor pain
25 mg q2-4 hours
Is meperidine lipid soluble?
- Yes. Lipid Soluble.
- Can cross the placenta readily
What is the active metabolite of meperidine?
Normeperidine → can cause seizures.
IV dose of morphine for labor pain
0.05 - 0.1 mg/kg
Active metabolite for morphine.
What is the consideration for neonates?
- Morphine-6-glucuronide
- Longer half-life in neonates, can accumulate → Respiratory depression
IM dose of morphine for labor pain
0.1 - 0.2 mg/kg
Because morphine is hydrophilic, what does that do to the onset?
Slower onset
Because fentanyl is lipophilic, what does that do to the onset?
- Faster onset
- Readily crosses the placenta, works quickly
Active metabolite for fentanyl.
- No active metabolites
- But repeated doses may lead to accumulation → Respiratory Depression
IV dose of fentanyl for labor pain
50-100 mcg/hr
How is Remifentanil metabolized?
Plasma esterases
PCA administration dose of Remifentanil?
- Ultra short-acting
- Bolus 20-40 mcg w/ 2-3 minute lockout
What agonist-antagonist opioid has an improved analgesic score over Fentanyl?
Butorphenol (Stadol)
Dose of Butorphenol.
Half-life
- IV/IM: 1-2 mg q3-4 hours
- Half-life: 4.6 hours
Dose of Nalbuphine (Nubain)
Half-life.
- IV/IM/SQ: 5-20 mg q4-6 hours
- Half-life: 5 hours
What are the negative side effects of Nalbuphine for the fetus?
Fetal bradycardia
Why is Toradol avoided during labor?
- NSAIDs suppresses uterine contractions
- Promote premature closure of fetal ductus arteriosus
- Inhibit platelet aggregation
- OK to give to mother after baby is delivered
What is the goal of a paracervical block?
- Block transmission through paracervical ganglion
- Short-term pain relief in the first stage of labor
- Performed by OB provider
What are the risks involved with a paracervical block?
- Maternal complications: LAST and syncope
- Risk of injection into fetal scalp
- Fetal bradycardia
What is the most severe fetal complication with a paracervical block?
Fetal Local Anesthetic Systemic Toxicity
What is the most common fetal complication with a paracervical block?
Fetal bradycardia
When will a paracervical block be contraindicated?
- Patients with uteroplacental insufficiency
- Non-reassuring FHR
What is the nerve block that is an alternative to pharmacologic pain management in the 2nd stage of labor?
Pudendal Nerve Block
What are the drawbacks of a pudendal nerve block?
- Minimizes the urge to push
- Rapid maternal absorption of LA
- Risk injection into the pudendal artery
- Risk for LAST
- Fetal trauma or injection of LA into the fetus
What is the only form of analgesia that provides complete analgesia for both stages of labor?
Neuraxial Techniques
What actions are required before performing neuraxial interventions?
- Anesthesia consent
- Preprocedural assessment (Airway, etc)
- Routine lab testing is not required for healthy parturients (Plts)
What pressors are used for hypotension secondary to neuraxial anesthesia?
- Ephedrine (crosses placenta)
- Phenylephrine (best for repeated doses)
List drugs and items to have within reach when preparing for neuraxial anesthesia.
- Vasopressors
- Emergency Drugs
- Induction agents
- Muscle relaxants
- Intralipids
- O2 source/ mask/ Ambu bag
- Suction
- Airway equipment
When is the best time to get anesthesia informed consent on a parturient?
- Right at admission
- Optimal timing before the onset of labor or early labor
Is IV access optional for neuraxial anesthesia?
No. You must have IV access before a spinal or epidural.
Better to Preload or Co-Load fluids when performing neuraxial anesthesia.
Better to co-load fluids with neuraxial anesthesia.
How often does the blood pressure cycle during the initial stage of neuraxial anesthesia dosing be dosed?
- Cycle 1-5 minutes during initial stage
- Change cycle to 15 minutes after initial 20-30 mins
Besides BP, what other monitors will the patient be on?
- Pulse OX
- FHR (document pre and post FHR)
EKG is not required
What are the two positioning options when performing neuraxial anesthesia?
- Sitting
- Lateral
What is the benefit of performing neuraxial anesthesia in a lateral position?
- Less risk of intravascular catheter d/t epidural veins decompressed.
- Position may be more comfortable for the patient
What happens to the apex of the thoracic curvature when a patient is pregnant?
Why is this important to know for neuraxial anesthesia?
- Apex of thoracic curvature shifted from T8 → T6
- Increase risk of cephalad spread
What does epidural vein engorgement indicate for neuraxial anesthesia?
- Smaller epidural spaces
- ↑ Risk of venous cannulation
What causes “tight spaces” in the lumbar spine?
Decrease intervertebral gap associated with lumbar lordosis.
What causes the Touffier’s line to be elevated?
Forward rotation of the pelvis
Where is the Tuffier’s line located?
- Level of the posterior superior iliac crest.
- Located between L4 and L5
What are the absolute contraindications for neuraxial anesthesia?
- Patient refusal
- Uncooperative patient
- Uncontrolled hemorrhage w/ hypovolemia
- Epidural site infection
- Severe bleeding/ clotting disorder
- Anticoagulation
What are the relative contraindications for neuraxial anesthesia?
- Elevated ICP d/t mass lesion
- Local anesthetic allergy
- Language barrier w/o interpreter
- Severe fetal depression
- Severe maternal cardiac dz
- Active coagulopathy
- Untreated systemic infection
- Pre-existing neurologic deficit
- Skeletal anomalies
- Hardware in spine
What are these spots called?
What could these spots indicate?
- Café-au-lait spots
- More than six café-au-lait spots can be a sign of an underlying genetic condition like neurofibromatosis type 1 (NF1).
What are the risks involved when an epidural is placed too early?
- Risk for instrumental delivery (Vacuum or forceps)
- Prolonged second stage of labor
- Risk for epidural becoming ineffective and needing to be replaced
What are the risks involved when an epidural is placed too late?
- Patient can no longer get into a good position
- Patient can no longer stay still
- Provider preference
What are the five options of neuraxial anesthesia?
- Epidural (CLE)
- Dural puncture epidural (DPE)
- Combined spinal-epidural (CSE)
- Single shot spinal / intrathecal
- Continuous spinal / intrathecal
