SEE Obstetrics Anesthesia Review Flashcards
In pregnancy Cardiac output increases mostly because of an increase in _______.By how much does CO increase at term_____? SV by how mucH
an increase in stroke volume and, to a lesser extent, an increase in heart rate. SV 20-50%
CO increase by 40% at term
Blood volume during pregnancy (increase/decrease) , why ?By how much is it (increase/decrease)
Blood volume is markedly increased and prepares the parturient for the blood loss associated with delivery.
25-40%
Plasma volume during pregnancy? by what %?
What about blood cell volume? What %?
What does that cause? Total blood volume change?
Plasma volume is increased by 40-50%
Red Blood cell volume is increased by 20%
PV increase to a greater extent than red blood cell volume, resulting in a DILUTIONAL ANEMIA
Total blood volume increase by 25-40%
Minute ventilation during pregnancy and due to mostly
MV increases 45-50% (Nagelhout) and this is due mostly to an increase in tidal volume.
Oxygen consumption during pregnancy at rest? What about during labor?
Oxygen consumption is markedly increased by 33%; 100% during labor
Carbon dioxide production during pregnancy?
carbon dioxide production is similarly increased.
Pregnancy and Local anesthetics and MAC
Pregnant women have an increased sensitivity to local anesthetics and a decreased minimum alveolar concentration (MAC) for all general anesthetics.
What happens to Platelet count during pregnancy
remains stable or decreases slightly;
Coagulation factors and fibrinogen in pregnancy? What is the significance of the changes?
coagulation factors and fibrinogen are increased, resulting in a hypercoagulable state in pregnancy.
Major cause of Hypotension during pregnancy and how to relieve it?
Aortocaval compression results in profound hypotension and can be relieved by left uterine displacement.
All pregnant women are at increased risk of ______
aspiration
Because of the anatomic and physiologic changes to the gastrointestinal system with pregnancy, parturients should be considered to have a full stomach after what week?
weeks 12 of gestation vs 20 weeks
Pregnancy and labor and airway
associated with major airway changes that can result in a difficult intubation. This highlights the importance of a comprehensive airway evaluation prior to general anesthesia.
During pregnancy The heart rate (HR) is _____By ___% to _____% at term
increased by 20% to 30% at term.
Oxygen consumption increases by about how much in the full-term parturient?
33 percent in the full-term parturient, but minute ventilation increases by 50 percent at term. T
During pregnancy, the increased alveolar ventilation results in an
increase in the PaO2 to about 106 mmHg and a decrease in the PaCO2 to about 30-32 mmHg.
Pregnancy and plasma base
The plasma base (HCO3-) decreases from about 26 to 22 mEq/L, thus, the pH is essentially unchanged.
Provide analgesia by sparing motor blockade:
Ropivacaine
Bupivacaine
Endocrine hormones elevated with pregnancy
Total T3 and T4 (Not free )
Volume of the spinal CSF in pregnancy
Because the volume of epidural fat increases and epidural veins enlarge, the volume of spinal CSF is decreased in pregnancy.
Which anesthetic technique is most likely to reduce uterine blood flow in an obstetric patient?
Paracervical block
By the end of the first trimester, the cardiac output is How much greater than the non pregnant values?.
15-25 percent higher than nonpregnant values.
CO : 24 hours after delivery? When does it return to normal?
Cardiac output is still elevated for 24 hours after delivery and returns to normal slowly over a period of about 10 days
Despite the increased blood volume levels, plasma renin levels are
increased.
Can’t add bicarbonate to speed the onset of which LA ?
Although the addition of bicarbonate will speed the onset of a lidocaine epidural, the addition of bicarbonate to bupivacaine will cause it to precipitate.
Adding epinephrine or phenylephrine can enhance the ______of the anesthetic
Duration
Blood thinner that crosses the placenta in the greatest proportion?
Warfarin
Why is it recommended that an epidural anesthetic not be administered to a laboring parturient exhibiting cervical dilation less than 4 cm?
Dystocia
You have added an opioid to the local anesthetic used for a laboring parturient’s epidural. Where does the opioid exert its action?
The substantia gelatinosa
Airway resistance and pregnancy
NO CHANGE
Alveolar ventilation is increased by how much at term? what about FRC?
as much as 70% at term. The FRC decreases by 20-30%.
Follicular hyperplasia with pregnancy.
Follicular hyperplasia and increased vascularity result in a 50-70% increase in the size of the thyroid gland in pregnant patients.
Which of the following analgesics would be least appropriate to administer for postpartal pain control in a nursing mother?
Meperidine
What sensory level block would be appropriate for performing a cesarean section under epidural anesthesia?
T4
What are the 2 Coag. Factors decreased in pregnancy ?
Factors XI and XIII are decreased in pregnancy.
Factors that remains unchanged with pregnancy
II and V are unchanged.
Factors and pregnancy
Increased (factors I, VII, VIII, IX, X, and XII).
What hormone is responsible for the increased in Total T3 and T4 seen with pregnancy?
Estrogen
Which hormone is responsible for the increase in plasma volume during pregnancy?
Progesterone
Which hormone is responsible for the enhanced Renin-angiotensin- Aldosterone during pregnancy?
Progesterone
What happens gastric motility during pregnancy and which hormone is responsible?
Decrease gastric motility; Progesterone
What happens lower esophageal sphincter tone during pregnancy and which hormone is responsible?
Reduction of LES tone; Progesterone
PaCO2 levels increase or decrease during pregnancy? to what range? by what weeks does this change occur?
Decrease
30-32 mmHg
By 12 weeks of gestation
Electrolyte abnormality rarely seen and why?
Metabolic alkalosis because there is a compensatory decrease in serum bicarbonate form 26 to 22 mEq/L
Normal PaO2 during pregnancy : level is
Greater than 100 mmHg
Nonparticulate oral antacid no more than (timing) _____prior to surgery
1 hour before surgery
During C-section confirm block level at ______prior to surgical start
T4
Average blood loss C-section
500 -1000 ml
Normal Amniotic fluid volume is
700ml
Action of reglan
Increase gastric ph
enhance emptying
Creatinine levels during pregnancy
Decrease because of an increase in GFR
Pain pathways during labor: Area Uterus and cervix innervation
T10 to L1-L2
Pain pathways during labor: Area Perineum
S2 - S4
In the perineum: Pain impulses carried by
Somatic nerve fibers
Pudental nerve
Uterus and cervix pain impulses carried by
Visceral AFFERENT TYPE C fibers
Uterine blood flow at term increases to a max of _____
800 ml/min
Uterine blood flow at term accounts for how much of the maternal cardiac output
10%
Fetus send O2 poor blood to the placental via
2 umbilical arteries
Does UBF autoregulate?
No
Drugs characteristics that favor diffusion accross placenta : weight, solubility, ionization, protein binding
Low molecular weight (Less than 500 Da)
High lipid solubility
Low degree of ionization
Low protein binding
Drugs that do not cross: PHING
Protamine Heparin Insuline Neuromuscular Blocking agents Glycopyrollate
2nd stage of labor begins at _______ends
Full dilation 10cm
ends with delivery of the fetus
Meperidine cross placenta?
yes; although less likely than morphine in causing resp depression
Hallmark of PDPH
Lying Supine relieves pain
sitting and standing pain returns
Success rate of epidural blood patch
75%
Explains Epidural blood patch procedures
- Epidural needle is placed in the epidural space (same space better, or space below)
- Once needle is in place, assistant perform a peripheral venipuncture and draws aseptically 20 ml
- the blood slowly injected in epidural space 15-20 ml ideal
During epidrual blood pathc, back pain
Stop temporarily .
After epidural patch, pt should remain at rest for at least
1 hr
LAST early signs of toxicity
Circumoral numbness
lightheadedness
visual and auditory disturbances
Rapid response to LAST seizure
Give benzodiazepines
Preeclampsia definition
SBP > 140 or higher
DBP>90 or higher AFTER 20 weeks of gestation
ACCOMPANIED WITH PROTEINURIA.
Only definitive way of ending disease process of preeclampsia is
Delivery of the fetus.
3 risk factors for placenta previa
Uterine scars from prior uterine surgery
Prior placenta previa
Advance maternal age
Which one is more common accreta, increta or percreta
Accreta 70%
Maternal catastophes involving these 3 put the greatest risk to the fetus
Severe Hypoxia
Hypotension
Acidosis
Uterine blood flow formula
Uterine blood flow = Uterine arterial pressure - Uterine venous pressure / Uterine Vascular resistance
Any factor that causes maternal hypotension will _____uterine arterial pressure and thereby ______UBF
decrease; decrease
3 things cause by neuraxial anesthesia that can cause maternal hypotension
Aortocaval compression
Hypovolemia
Sympathetic blockade.
Other than a decrease uterine arterial pressure, what else can decrease UBF?
Increase uterine venous pressure (such as vena cava compression, seizure, valsava)
What are the elgot alkaloids?
Methylergonovine
Ergometrine
Dose of methylergonovine is ___ route?
0.2 mg IM
When can a second dose methylergonovine be given
2-4 hours.
3 oxytocic drugs used in OB
Oxytocin
Ergot Alklaoids (methylergonovine -methergine, ergometrine)
Prostaglandins (Carboprost)
Oxytocin should not be diluted with what solution
Hypotonic solution such as D5
First line of treatment for uterine atony
Oxytocin
Most common cause of hemorrhage
uterine atony
Oxytocin may precipitate (side effect):
Diastolic Hypotension
Flushing
Tachycardia (Nagelhout)
Most common used prostaglandin for treating pospartum hemorrhage?
carboprost (15-methyl prostaglandin)