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In the parturient early decelerations signify
Vagal stimulation from head compression
What is the most common cause of postpartum hemorrhage?
Uterine atony
Which condition may present with painless vaginal bleeding during the second or third trimester of pregnancy?
Placenta previa
Magnesium sulfate produces tocolysis at
4-8 mEq/L
What is the most common cause of maternal mortality in patients with pregnancy-induced hypertension (PIH)?
Intracerebral hemorrhage
How much is CO increased during the first trimester of pregnancy?
30-40%
What is the average CO at term?
8.7 L/min
What happens to CO during labor?
Increased due to pain and catecholamine release; contracting uterus contributes 300-500 mL of additional intravascular volume
At what point during pregnancy is CO the greatest?
Immediately following delivery (it can increase by as much as 180%, an additional 50% of predelivery values from uterine autotransfusion)
What do late decelerations signify?
Uteroplacental insufficiency; they occur 20-30 seconds after the start of the contraction and are thought to be due to fetal myocardial ischemia.
What are variable decelerations secondary to?
Umbilical cord compression
What is the most effective intervention for preventing maternal hypotension?
Supine postioning with left uterine displacement
Detail normal baseline beat-to-beat variability in a healthy, mature fetus
< 5 bpm (minimimal)
6-25 bpm (moderate)
> 25 bpm (marked)

Represents a normally functioning autonomic nervous system
What happens during the latent phase of Stage I labor?
Cervical effacement but little dilation
What happens during the active phase of Stage I labor?
Rapid changes in cervical dilation; Stage I concludes when the cervix is fully dilated from regular contractions
What is responsible for more rapid induction, emergence and changes in depth of anesthesia among parturients?
Increased minute ventilation and decreased FRC
How is the Apgar score calculated?
Heart rate
Absent: 0, 100: 2

Respiratory effort
Absent: 0, Slow, irregular: 1, Good, crying: 2

Muscle tone
Flaccid: 0, Some flexion: 1, Active motion: 2

Reflex irritability
None: 0, Grimace: 1, Crying: 2

Color
Blue, pale: 0, Body pink, extremities blue: 1, All pink: 2
How may PDPH result in diplopia?
Traction on cranial nerve VI
Who is at greatest risk of developing PDPH?
Young, female, pregnant patients
What are normal urine changes in a parturient at term?
Mild glucosuria, proteinuria due to decreased renal threshold for glucose and amino acids
How does hemoglobin level change in a term parturient?
Decreased 20% (from dilutional anemia)
How do PaCO2 and PaO2 change in a term parturient?
PaCO2 is decreased 15%, PaO2 is increased 10% (from hyperventilation)
How does plasma cholinesterase activity change during pregnancy?
It is decreased
What is the most common surgical emergency encountered during pregnancy?
Appendicitis (1:350-1:10,000, 2/3 of all laparotomies)
Which spinal nerves transmit visceral pain during the first stage of labor?
T10-L1
In whom does PIH most frequently occur and to what is it attributed?
Primigravidas; Abnormal prostaglandin metabolism and endothelial dysfunction leading to vascular hyperactivity.  Increased thromboxane A2 and endothelin-1 (vasoconstrictors) and decreased levels of prostacyclin (a vasodilator).
What is the definitive treatment for PDPH?
Autologous blood patch
What are the factors associated with PDPH?
Bilateral, extends into the neck, associated with photophobia and nausea, occurs 12-72 hours after the dural puncture, aggravated by sitting up
When is carboprost (prostaglandin F2a) used?  What are the side effects?
Used if uterine contraction is not effective after administration of oxytocin or ergot alkaloids.  Smooth muscle contraction may produce bronchoconstriction, hypertension and pulmonary vasoconstriction.
How do epidural analgesics affect fetal monitoring?
They decrease fetal beat to beat variability
What interventions are suggested for parturients with MS?
Avoid hyperthermia (as little as 0.5 C increase may exacerbate symptoms), avoid spinal anesthesia, use low dose epidural anesthesia (0.1% bupivacaine), avoid sux (risk of hyperkalemia), use NDNMB's with caution
What steps should be taken after unintentional IV LA injection?
1.  Instruct the patient to hyperventilate (increases seizure threshold)
2.  Administer small dose of thiopental (50 mg)
3.  Avoid unconsciousness d/t full stomach
4.  Supplemental O2 should be in place
For convulsion:
1.  PROTECT THE AIRWAY, immediately administer succinylcholine, followed by RSI
2.  Give an anticonvulsant (diazepam 2.5-10 mg or thiopental 50-75 mg)
Is bupivacaine cardiotoxicity increased during pregnancy?
Yes
What concentration of bupivacaine is no longer recommended for anesthesia during labor?
0.75%
How is the risk of IV injection of toxic doses of LA minized during epidural placement?
An adequate test dose, fractionation of therapeutic dose in safe aliquots, administering the minimum total dose of LA possible
How does pregnancy affect MAC?
It progressively decreases (by as much as 40% at term).  This returns to normal by the third day after delivery.
How do parturients respond to local anesthetics?
With increased sensitivity.  Dose requirements may be reduced by as much as 30%.
The enlarging uterus causes what physiological change to consider when placing an epidural?
Obstruction of IVC distends epidural venous plexus, increasing the risk of IV injection.
What is the supine hypotension syndrome and what percentage of pregnant women develop this?
Hypotension associated with pallor, sweating, or nausea and vomiting (up to 20% of pregnant women experience this).
What are the GI changes during pregnancy?  Why is this important to the anesthetist?
Reduced gastric motility and tone of LES, hypersecretion of gastric acid.  This places the parturient at high risk for regurgitation and pulmonary aspiration.
What are the pros and cons to administration of ephedrine vs. phenylephrine to the parturient?
Ephedrine (predominantly beta adrenergic) was initially considered the vasopressor of choice.  Studies suggest that a-adrenergic agonists (such as phenylephrine and metaraminol) are as effective in treating hypotension and are associated with less fetal acidosis.
How do volatile anesthetics affect uterine blood flow?
Through a decrease in blood pressure, they reduce uterine blood flow in a dose dependent manner.  In concentrations less than 1 MAC, effects are minor.
When does the greatest strain on the parturient's heart occur?
Immediately after delivery (CO is increased by as much as 80% above prelabor values).  This is a result of uterine contraction, involution, and relief of IVC obstruction.
Does epidural or combined spinal-epidural anesthesia prolong labor?
If a dilute LA is used (bupivaine 0.125% or less) in combination with an opioid (fentanyl 5 mcg/mL or less) labor is not prolonged, and likelihood of C-Section is not increased.
When is extrauterine life possible?  What is this due to?
After 24-25 weeks, due to lung maturation (pulmonary capillaries are formed and come to lie in close approximation to an immature alveolar epithelium)
Which respiratory parameters increase in pregnancy?
O2 consumption (20-50%)
Minute ventilation (50%)
Tidal volume (40%)
Respiratory rate (15%)
PaO2 (10%)
Which respiratory parameters decrease during pregnancy?
Airway resistance (35%)
FRC (20%)
PaCO2 (15%)
HCO3 (15%)  
Which cardiovascular parameters increase during pregnancy?
Blood volume (35%)
Plasma volume (45%)
Cardiac output (40%)
Stroke volume (30%)
Heart rate (20%)
Which cardiovascular parameters decrease during pregnancy?
Systolic blood pressure (5%)
Diastolic blood pressure (15%)
Peripheral resistance (15%)
Pulmonary resistance (30%)
Which hematologic parameters decrease during pregnancy?
Hemoglobin (20%)
Platelets (10%)
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