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5th Quarter > OB Anesthesia Exam #1 > Flashcards

OB Anesthesia Exam #1 Flashcards

1
Q

When do CV changes begin to occur during pregnancy?

A

they begin the 4th week of pregnancy

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2
Q

The HR increases ___ to ___% and peaks at ___ weeks gestation.

A
  • 20 to 30%

- 32 weeks

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3
Q

Cardiac output increases to ___%(begins ____ week of pregnancy) and the stroke volume increases to ____ to ___%

A
  • 40%
  • 5th
  • 20 to 50%
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4
Q

Cardiac output is at its greatest……

A

immediately after delivery as a result of increased central volume(may possibly get pulmonary edema or other CV issues)

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5
Q

Cardiac Output returns to baseline in ___ days

A

14

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6
Q

Thoracic changes during pregnancy:

A
  • diaphragm rises
  • heart shifts up and left
  • heart appears enlarged on CXR
  • ventricular walls thicken
  • End-Diastolic volume increases
  • Benign Grade I-II SEM(normal)
  • Diastolic Murmurs pathologic(consult cardiology)
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7
Q

Auto transfusion amount?
With adequate neuraxial analgesia, HR tends to drop wit each contraction. Why?
SVR?
LVE systolic volume/EF?

A
  • 300-500 ml/contraction
  • lower HR due to compensatory mechanism 2ndary to increased volume
  • SVR changes(decrease ~20% by end-term) due to decreased resistance in the uteroplacental, pulmonary, renal and cutaneous vascular beds.
  • decreasing SVR affects Diastolic pressure leading to a decrease in MAP
  • L ventricular end-systolic/EF=increased
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8
Q 
CV CHANGES:
cardiac output?
stroke volume?
heart rate?
diastolic BP?
systolic BP?
mean arterial pressure?
total peripheral resistance?
systemic vascular resistance
CVP/PCWP?
A 
CO +40%
SV +20 to 50%
HR +20 to 30%
DBP -10 TO 20 MMHG
SBP -0 TO 15 MMHG
MAP -15 MMHG
(BLOOD PRESSURES DECREASED DUE TO DILATED VASCULAR BEDS)
PVR -15%
SVR -20%
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9
Q

What is Supine Hypotensive Syndrome? and when does it become significant?

A
  • syndrome is caused by compression of Vena Cava by gravid uterus, which restricts venous return decreasing preload
  • becomes significant at 20 weeks
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10
Q

What are the signs and symptoms of Supine Hypotensive Syndrome?

A
  • max drop in BP may take 10 min to develop
  • normal physiologic response is tachycardia and vasoconstriction of lower extremities
  • results is decreased uterine BF and fetal oxygenation
  • mom may display diaphoresis, nausea, lightheaded, vomiting, pallor or “feeling faint”
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11
Q

What should be done if patient is experiencing supine hypotensive syndrome?

A

raise right hip and tilt onto left hip displacing the uterus off the vena cava

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12
Q

This position should be avoided in the OB patient:

  • semi fowler’s
  • prone
  • lateral
  • supine
A

supine

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13
Q

What is the primary hematology changes during pregnancy?

A

“Hypercoagulable”

  • Fibrinogen normally 200-400 goes to 400-650 mg/dl
  • parturient at risk of embolic event(one of the leading causes of maternal mortality)
  • platlets normal..slightly decreased in 3rd trimester
  • WBC rises during pregnancy. Mean-10500 and in labor may rise to 20000-30000
  • during pregnancy the P-50 of maternal hemoglobin increases to about 30 mmHg
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14
Q

During pregnancy, what clotting factors are increased, decreased and unchanged?

A

INCREASED: factors I(fibrinogen), VII(proconvertin), VIII(antihemophiliac), IX(christmas factor), X(stuart-prower factor), XII(hageman factor)

DECREASED: factors XI(thromboplastin antecedent), XIII(fibrin-stabilizing)

UNCHANGED: factors II(prothrombin), V(proaccelerin)

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15
Q 
Coagulation Laboratory Test changes:
PT-
PTT-
TEG-
Fibrinopeptide A-
Antithrombin(AT)-
Platelet count-
Bleeding time-
Fibrin Degradation Products-
A
  • shortened 20%
  • shortened 20%
  • hypercoagulable
  • increased
  • decreased
  • no change or decreased
  • no change
  • increased
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16
Q 
TBV increases\_\_\_\_?
Plasma volume increases \_\_\_\_?
RBC volumen increases\_\_\_\_?
Why are plasma/blood volumes increased?
What is the result of these increases?
A
  • 25-40%
  • 40-50%
  • increases 20%
  • increased plasma volume due to increased levels of progesterone and estrogen
  • Result: relative or dilutional anemia exists
  • increased progesterone and estrogen yield enhanced renin-angiotensin-aldosterone activity*
  • RBC volume increased due to elevated erythropoietin seen after 8 weeks gestation*
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17
Q

What is the average blood loss for a vaginal deliver versus blood loss for an uncomplicated C/S?

A
  • vag(500 ml)

- C/S(800-1000 ml)

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18
Q

What are 5 anesthetic implications of CV and hematologic changes associated with the pregnant patient?

A
  1. beware of platelet countsprior to placing epidural know hospital policy
    - –>acute drops?s/S of low platelets? increased risk of an epidural hematoma?
  2. investigate elevated WBC
    - –>3rd trimester ~10500 mm, in labor ~20-30K mm
  3. Left uterine displacement(beware supine)
  4. be prepared for massive blood loss
  5. at term pseudocholinesterase activity is decreased 30%
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19
Q

Parturient request epidural placement. Upon inspection of CBC, WBC reflects a level of 12,500 mm^3. The next most appropriate action is to:

a. redraw the CBC
b. accept as normal for this population and proceed
c. reject as normal for this population and decline service
d. both a and c

A

accept as normal for this population and proceed

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20
Q

List 8 respiratory changes for the pregnant patient.

A
  1. capillary engorgement in upper airway
  2. O2 consumption increases 33% at rest and 100% during 2nd stage of labor
  3. MV increased 50%(breathing for two)
  4. VT increases 40%
  5. FRC decreases 20%
  6. arterial PaO2 decreases slightly due to fall in PaO2
  7. HCO3- levels decrease 4 meq/L to keep pH in normal range b/c of the respiratory alkalosis
  8. upward pressure of diaphragm
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21
Q

What are some issues related to capillary engorgement in the upper airway?

A
  • narrowed glottic opening
  • edema in nasal and oral pharynx, larynx and trachea
  • Mallampati score changes as labor progresses
  • friable tissue(bleeds really easy secondary to capillary engorgement)
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22
Q 
What are some issues related to the upward pressure of the diaphragm?
Expiratory Reserve Volume:
Residual Volume:
Vital Capacity:
Flow volume loops:
A

Mimics Restrictive Lung Disease

ERV=decreased ~20%
RV=decreased ~15-20%
VC=unchanged
Flow volume loops=unchanged

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23
Q

Intubating the Parturient:

A
  1. avoid nasal manipulation(capillary engorgement in upper airway)
  2. 6.5-7.0 ORAL ETT recommended
  3. may consider having a short-handled laryngoscope to navigate enlarged breast
  4. optimize ALL airway circumstances: “take her to the prom”
  5. get help
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24
Q

Anesthetic Implications in the Parturient:

  • maternal PaCO2 at term?
  • Increased MV during contraction leads to?
  • Preoxygenate?
A
  • ~32 mmHg
  • maternal hypocarbia(PaCO2 ~32/PH > 7.55)
  • –>this can lead to uteroplacental vasoconstriction, decreased respiratory drive-hypoxia and lethergy
  • MUST ADEQUATELY PREOXYGENATE secondary to decreased oxygen reserves, increased oxygen consumption and decreased FRC

Rapid desaturation during induction!!!

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25
Q

Beginning in 1st trimester women have _____ sensitivity of LA and general anesthetics. They also require ____ MAC of inhalational drugs…why?

A
  • increased
  • decreased
  • endogenous opiates and progesterone
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26
Q

Why are decreased LA dosages needed in the Parturient?

A
  • increase in sensitivity of nerves to LA
  • distended epidural venous plexus
  • increased epidural blood volume
  • increased pressure within epidural space
  • decreased volumes of both epidural and subarachnoid spaces

so VOLUME VOLUME VOLUME with epidurals!!!

All this lead to potential for increased block height

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27
Q

Due to elevations in the parturient’s sympathetic outflow, which of the following cardiac parameters occur at term?

a. increased CVP
b. decreased SVR
c. decreased LVESV
d. decreased EF

A

decreased SVR

28
Q

What are 4 spinal/epidural implications for the Parturient?

A
  1. enhanced cephalic spread of LA
  2. PDPH mor common(cause of dilated vertebral spaces)
  3. Intravenous epidural catheter threading more likely(descended veins)
  4. LA requirement decreased ~30%
29
Q

What are the GI changes of Parturient?

  • gastric reflex/heartburn/esophagitis(what % have):
  • gastric motility?
  • food absorption?
  • gastric pressure?
  • esophageal sphincter tone?
  • gastric volumes(>25ml)?
  • gastric pH(
A
  • ~30 to 70%
  • decreased gastric motility
  • decreased food absorption
  • increased gastric pressure
  • decreased esophageal sphincter tone
  • increased gastric volumes(>25mls)
  • decreased gastric pH(
30
Q

GI anesthesia implications:(3)

A
  1. > 12 weeks gestation=RSI with cricoid
  2. strict NPO for elective procedures
  3. 4-5xhigher risk of aspiration
31
Q

What precautions to take in cause of aspiration and treatment for?

A
  • Sodium citrate is most useful agent in raising gastric pH before induction of GA prior to C/S
  • If aspirates..initiate 100% ox and PEEP
  • prevent Mendelson’s syndrome
  • –>pHgastric vol > 25 ml(admin hypermotility agent=metoclopramide)
32
Q

What are the hepatic changes associated with pregnancy?

A
  • LFTs increase to upper limits of NORMAL
  • Decreased albumin(increased free-fraction of protein bound drugs)
  • subclinical pseudocholinesterase deficiency
  • –>serum cholinesterase activity decreases 30% so give less succ
33
Q

Renal changes:

  • kidney size?
  • ureters and renal pelves…..?
  • renal plasma flow?
  • GFR?
  • creatine clearance?
  • BUN?
  • serum creatinine?
  • Glucose resorptive capacity of the proximal tubules?
A
  • kidneys enlarge and return to pre-pregnant size by 6 months postpartum
  • ureters and renal pelves dilate by the end of first trimester due to hormonal changes
  • renal plasma flow increases 75-85%
  • GFR increases 50%
  • Creatinine clearance increases
  • BUN decreases
  • serum creatinine {} falls
  • glucose resorptive capacity of the proximal tubules decreases
34
Q

Uterine blood flow:

  • Supplied by?
  • What % of CO and how many ml/min?
  • O2 and CO2 are ___ limited?
  • Decreased UA blood flow or increased placental vascular resistance =?
  • How does volatiles affect UBF?
A
  • supplied by 2 uterine arteries
  • 10 of CO and 700-800 ml/min
  • –>150ml/min ~ myometrium
  • –>100ml/min ~ decidua
  • –>remainder ~ intervillous space
  • “perfusion limited”(by blood pressure)
  • decreased fetal O2
  • UBF: unchanged on 0.5-1.5 MAC w/ all VA
35
Q

What 4 factors decrease uterine arterial pressure?

A
  1. supine position
  2. hemorrhage/hypovolemia
  3. drug induced hypotension
  4. hypotension during sympathetic blockade
36
Q

What 4 factors increase uterine venous pressure?

A
  1. vena caval contraction
  2. uterine contractions
  3. drug induced uterine hypertonus(oxytocin, LA)
  4. skeletal muscle hypertonus(seizures, valsalva)
37
Q

Factors causing decreased UBF secondary to increased uterine vascular resistance?

A
  1. endogenous vasoconstrictors
    - –>catecholamines(stress)
    - –>vasopressin(in response to hypovolemia)
  2. exogenous vasoconstrictors
    - –>epinephrine
    - –>vasopressors(phenylephrine>ephedrine)
    - –>LA(high concentrations)
38
Q

Placental transfer and fetal effects of drugs is dependent upon(diffusion)? 5 things?

A
  1. magnitude of {} gradient
  2. molecular weight(smaller substances pass through easier)
  3. lipid solubility
  4. state of ionization
  5. maternal protein binding
39
Q

What are the fetal:maternal ratios of these drugs?

  1. morphine
  2. vecuronium
  3. glycopyrrolate
  4. labetalol
  5. ephedrine
  6. diazepam
  7. metoprolol
A
  1. morphine 0.61
  2. vecuronium 0.07
  3. glycopyrrolate 0.22
  4. labetalol 0.38
  5. ephedrine 0.7
  6. diazepam 1.0
  7. metoprolol 1.0

(baby gets the same amount as mother 1mg/1mg)

40
Q

Describe what characterizes the three stages of labor

A
  • 1st Stage of Labor: onset of cervical dilation to complete cervical dilation(10 cm)
  • 2nd Stage of Labor: delivery of the fetus
  • 3rd Stage of Labor: expulsion of placenta

The time is takes to progress through these stages is dependent upon: parity, effective uterine contractions, size of pelvis, type of pelvis and fetal presentation

41
Q

What is meant by the terms gravida and para?

A 
gravida = # of pregnancies
para = # of fetus carried to a viability(20 weeks or longer)
42
Q

1st Stage of Labor pain is a result of, mediated by and described as what?

A
  • primary result of cervical distention, stretching of lower uterine segment and myometrial ischemia
  • mediated by T10-L1 visceral C fibers(so this is the level that should be blocked by a regional block.)
  • described as non-localized aching, dull and cramping
43
Q

2nd Stage of Labor pain begins when, is mediated by and is described how?

A
  • begins when cervical dilation is complete and presenting part descends into pelvis
  • pain impulses carried by somatic nerves via Pudendal nerves…mediated by S2, S3, S4 in addition to T10-L1
  • –>LA induced lumbar epidural block provides complete anesthesia for BOTH 1st and 2nd stage of labor pain
  • sharp pain, fast pain…..a delta fibers

pain medication affects mothers ability to deliver fetus…25g spinal with sufenta or 25 mcg fentanyl can help…for a vaginal birth the spinal/epidural must be blocked at T10 down(so the umbilicus down)

44
Q

The first stage of labor has two phases. What are these two phases and the characteristics of them both?

A
  • The first stage of labor consists of cervical effacement and dilation*
  • Latent Phase: defined as onset of labor- point at which cervix begins to rapidly change
  • Active Phase: begins at 2-3 cm dilation. Cervix undergoes max rate of dilation ~ 1-1.2 cm/hr.

When labor ceases to follow this pattern, it is said to be “dysfunctional”

45
Q

What is the most readily available method for assessing fetal condition?

A
  • Fetal heart rate monitoring
  • it is not a specific predictor of feta well-being
  • FHR reveals info pertaining to anesthetic intervention

Overall FHR predicts baseline status

46
Q

How does the Fetal heart rate monitor work?

A
  • FHR recorded on a graph running 3cm/min
  • uterine tone or pressure recorded concurrently on second channel below FHR tracing
  • non invasive tracing(abd U/S) or invasive(scalp electrode)
  • invasive embedded 2 mm and requires ROM with partially dilated cervix
47
Q

Fetal oxygenation is limited mostly by what? Decreases in maternal BP or uterine artery blood flow also decreases what?

A
  • by uteroplacental blood flow, NOT maternal oxygenation
  • uteroplacental blood flow

responsible for decels

48
Q

What is the normal FHR, what characterizes brady/tachy and the causes of both?

A
  • normal FHR is 110 - 160

- Brady(FHR

49
Q

The number 1 reason for a brady FHR is?

A

a paracervical block

50
Q

What is the single best indicator of fetal well-being and indicates adequate fetal oxygen reserve?

A

FHR variability

51
Q

What does variability represent and what are the descriptive terms used to describe variablity?

A
  • variability represent an intact central nervous system and normal cardiac function
  • variability descriptors: absent, minimal(25bpm)
52
Q

What is the ideal FHR variability?

A

moderate(6-25bpm)

53
Q

What are some causes of FHR variability?

A

Causes of CNS depression, hence decreased variability: hypoxia, fetal sleep, acidosis, anencephaly, drugs(CNS depressants, autonomic agents, magnesium, and opioids), and defects in fetal cardiac conduction system

54
Q

FHR variability increases with…….?

A

advancing gestational age

55
Q

What are some causes of decreased variability?

A

hypoxia, fetal sleep, acidosis, anencephaly, drugs(CNS depressants), fetal heart defects

56
Q

On the FHR monitor, absent variability is characterized by……?

A

a “smooth line”

57
Q

On the FHR monitor, minimal variability is characterized by……?

A
58
Q

On the FHR monitor, moderate variability is characterized by……?

A

6 - 25 bpm around baseline

59
Q

On the FHR monitor, marked variability is characterized by……?

A

> 25 bpm variation around baseline

each line is 10 bpm

60
Q

What are accelerations, when do they occur and what is meant when the FHR pattern is said to be reactive?

A
  • abrupt increases in FHR above baseline
  • occur in response to fetal movement and indicate adequate oxygenation
  • FHR is said to be REACTIVE when there are 2 or more accelerations in a 20 min period
61
Q

Decelerations are NOT normal and are classified as early, variable and late. Describe each classification of decels:

A

EARLY DECELERATIONS:

  • occur in concert with uterine contractions
  • begins when contractions begins and returns to baseline when contraction ends

VARIABLE DECELERATIONS:

  • sudden decrease in FHR that occurs irrespective of uterine contraction
  • may occur in response to Umbilical Cord Compression
  • abrupt onset to nadir = 15 secs/ 30 seconds after peak contraction
  • onset, nadir and recovery of decal follow beginning, peak and end of contraction
  • flip the patient, place them on oxygen, possible fluid bolus, call the OB
62
Q

If FHR recording during pre anesthesia assessment suggest hypoxia……

A
  • exercise caution in deciding to proceed with neuraxial analgesia
  • –>check severity of fetal hypoxia(variability and decals)
  • –>sympathectomy secondary to epidural or spinal may worsen fetal condition
63
Q

What are some anesthetic considerations for Intrauterine resuscitation in the presence of a non reassuring FHT?

A
  • changing maternal position
  • rapid infusion of IV fluids
  • discontinuing oxytocin
  • maternal O2 delivery
  • if hypotensive, delivery of vasopressors
  • use of tocolytic agents
64
Q

Factors to ponder when considering anesthetic technique:

A
  • cervical dilation and effacement
  • parity
  • labor pattern
  • fetal well being and tolerance to labor
  • OB assessment with accompanying RED FLAGS
  • patient’s desire or willingness to receive anesthetic
65
Q

What to do when confronted with a non-reassuring FHR tracing:

A
  • call for help
  • turn LUD, RUD or on all fours
  • administer O2
  • consider adjusting or stopping epidural infusion
  • assess vital signs
  • fluid bolus??
  • OB/RN may stimulate fetal scalp, adjust or stop Piton, assess MgSO4, call an emergency C/S

5th Quarter (11 decks)

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