OB Flashcards

1
Q

Describe the parturients blood gas levels:

A

pH - no change
PaO2 - increase - 104-108
PaCO2 - decrease - 28-32
Bicarb - decrease - 20

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2
Q

Describe O2 consumption in the parturient in the different stages of labor:

A

Term - increase 20%
First stage of labor - increase 40% over prelabor
Second stage of labor - increase 75% over prelabor

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3
Q

Describe CO of the parturient:

A

Increase 40% (10% goes to uterus)
HR increases 15%
SV increases 30%

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4
Q

Discuss CO during labor (as compared to pre-labor values)

A

1st stage: increases 20%
2nd stage: increases 50%
3rd stage: increases 80%

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5
Q

When does CO return to pre-labor values after birth?

A

24-48 hours

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6
Q

When does CO return to pre-pregnancy values?

A

About 2 weeks

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7
Q

How do twins affect CO?

A

Increase CO 20% above a single fetus pregnancy

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8
Q

Do MAP, SBP, or DBP change in the parturient?

A

MAP = no change (increased blood volume + decreased SVR = net even)
SBP = no change
DBP = decreased 15%

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9
Q

To which parturient should you apply left displacement of the uterus?

A

Anyone in the second or third trimester

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10
Q

How does intravascular fluid volume change in the parturient?

A

Increases 35% to prepare for hemorrhage in labor; creates dilution anemia

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11
Q

How do plasma volume and erythrocyte volume change in the parturient?

A

Plasma - increases 45%
Erythrocyte - increases 20%

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12
Q

What clotting factors increase in mom?

A

1, 7, 8, 9, 10, 12

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13
Q

What clotting factors decrease in mom?

A

11 and 13

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14
Q

What changes occur in antithrombin, protein s, and protein c?

A

antithrombin and protein s decrease. no change in protein c.

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15
Q

What changes occur in moms fibrinolytic system?

A

increased fibrin breakdown

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16
Q

Describe the parturients hematologic change overall?

A

Mom makes more clot, but she breaks it down faster.

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17
Q

How do PT and PTT change?

A

Decrease by 20%
Normal PT at term - 9.6-12.9s
Normal PTT at term - 24.7-35.0s

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18
Q

What occurs with platelet count?

A

Unchanged or decrease up to 10% due to hemodilution and consumption

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19
Q

How does MAC change in the parturient?

A

Decreases 30-40%

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21
Q

Does gastric volume increase or decrease in the parturient? Why?

A

Increases due to increased gastrin

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21
Q

How does gastric pH change in the parturient? Why?

A

Decreased due to increased gastrin

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22
Q

How does LES tone change in the parturient? Why?

A

Decreases due to increased progesterone and estrogen. Cephalad displacement also contributes.

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23
Q

Describe gastric emptying changes in the parturient:

A

No change before onset of labor; decreases after labor begins

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24
Q

What renal functions increase in the parturient and why?

A

GFR - increased blood volume and CO
Creatinine clearance - increase blood volume and CO
Glucose in urine - increased GFR and decreased renal absorption

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25
What renal functions decrease in the parturient and why?
Creatinine and BUN - increased creatinine clearance
26
How many mL/min of blood flow does the uterus receive?
700-900 mL/min, which accounts for 10% of CO
27
How does serum albumin change in the parturient? How does this affect the free fraction of highly protein bound drugs?
Albumin is decreased, so the free fraction is increased.
28
Is pseudocholinesterase increased or decreased in the parturient?
Decreased (no meaningful effect on sux metabolism)
29
What is uterine blood flow dependent on?
Does NOT auto regulate, so dependent on MAP, CO, and uterine vascular resistance (low resistance system)
30
What reduces uterine blood flow?
Decreased perfusion. Ex: maternal hypotension (sympathectomy, hemorrhage, aortocaval compression) Increased resistance. Ex: uterine contraction, hypertensive conditions that increase uterine vascular resistance
31
What drug characteristics favor placental transfer?
Low molecular weight <500 Daltons High lipid solubility Non-ionized Non-polar
32
What drugs do not cross the placenta?
Heparin Insulin NMBs Glycopyrrolate
33
Describe Stage 1 of labor:
Beginning of regular contractions to full cervical dilation (10cm)
34
Describe Stage 2 of labor:
Full cervical dilation to delivery of the fetus
35
Describe Stage 3 of labor:
Delivery of the placenta
36
When do the latent and active phases of labor occur?
Stage 1: Latent ends when the cervix dilates to 2-3 cm Active begins 3-10 cm
37
Why is lidocaine not popular for labor analgesia?
Produces strong motor block (good for C-section)
38
What local anesthetic reduces the efficacy of epidural morphine and why?
2-chloroprocaine. It antagonizes opioid receptors (mu and kappa)
39
What is the dosing of epidural opioids?
Fentanyl bolus - 50-100 mcg Fentanyl infusion - 1.5-3 mcg/mL Sufentanil bolus - 5-10 mcg Sufentanil infusion - 0.2-0.4 mcg/mL
40
Discuss opioid spinal dosing:
Fentanyl: 15-25 mcg Sufentanil: 1.5-5 mcg Morphine: 125-250 mcg Meperidine: 10-20 mg
41
Discuss spinal adjunct medications and doses:
Epinephrine: 2.25-200 mcg Clonidine: 15-30 mcg
42
Discuss epidural bolus dosing of adjuncts:
Epinephrine: 25-75 mcg Clonidine: 75-100 mcg Neostigmine: 500-750 mcg
43
Discuss epidural continuous infusion dosing of adjuncts:
Epinephrine: 25-50 mcg/hr Clonidine: 10-30 mcg/hr Neostigmine: 25-75 mcg/hr
44
What are 3 ways a patient can develop a total spinal?
1. An epidural dose injected in the subarachnoid space 2. An epidural dose injected in the subdural space 3. A single shot spinal after a failed epidural
45
How does a total spinal present?
Rapid progression of sensory and motor block Dyspnea, difficulty phonating, and hypotension Loss of consciousness
46
What does a fetal heart rate of 110-160 indicate?
Normal acid-base balance and intact CNS and ANS of the fetus
47
What does a fetal heart rate of <110 indicate?
Bradycardia. Fetal causes: asphyxia or acidosis Maternal causes: hypoxemia or drugs that decrease uteroplacental perfusion
48
What does a fetal heart rate >160 indicate?
Tachycardia. Fetal causes: hypoxemia, arrhythmias Maternal causes: fever, choriamnionitis, atropine, ephedrine, terbutaline
49
At what magnesium level does loss of deep tendon reflexes occur?
7-12 mg/dL
50
At what level of magnesium do seizures occur?
<1.2 mg/dL
51
Respiratory depression occurs at what magnesium level?
>12 mg/dL
52
What medications can be used for tocolysis to suppress labor?
Beta 2 agonists, magnesium, calcium channel blockers, nitric oxide donors (not common d/t hypotension)
53
Discuss oxytocin
First line utertonic SE: water retention (similar structure to vasopressin), hyponatremia, hypotension, reflex tachycardia, coronary vasoconstriction Give IV or directly into uterus (rapid IV admin can cause CV collapse) hepatic metabolism half-life: 4-17 min
54
Discuss methergine
second line uterotonic Ergot Alkaloid Dose 0.2 mg IM (IV admin can cause significant vasoconstriction, hypertension, and cerebral hemorrhage) hepatic metabolism half-life = 2 hours
55
Discuss prostaglandin F2
third-line uterotonic Hemabate or Carboprost dose: 250 mcg IM or injected into uterus SE: N/V, diarrhea, hypotension, hypertension, **bronchospasm**
56
What medications should you give for aspiration prophylaxis to a pregnant mother?
Sodium citrate - neutralize gastric acid H2 receptor antagonist (ranitidine) - reduce gastric acid secretion Gastrokinetic agent (metoclopramide) - hasten gastric emptying and increase LES tone
57
Ideally, how long should surgery be delayed postpartum?
2-6 weeks
58
If surgery cannot be delayed in a pregnant patient, what is the best trimester to undergo anesthesia?
2nd trimester avoids higher risk of teratogenicity in the 1st trimester (13-60 days is organogenesis) avoids increased risk of preterm delivery that's highest in the 3rd trimester
59
What non-OB procedures lead to the highest incidence of preterm labor?
intra-abdominal and pelvic surgery
60
What inhalation agent should be avoided in the pregnant patient and why?
Nitrous oxide showed congenital disabilities in animals who received it for 1-2 days due to inhibition of DNA synthesis (lack data in humans); many avoid nitrous in the first 2 trimesters
61
When is a pregnant patient considered a full stomach?
18-20 weeks gestation Treat like full term (RSI, aspiration prophylaxis, etc.) Treat like full term also applies to immediate postpartum period
62
Why should you avoid hyperventilation in the pregnant mother?
Normal PaCO2 ~30 mmHg -> hyperventilation reduces placental blood flow -> risk of fetal asphyxia
63
What medication class should a pregnant mother avoid after the first trimester and why?
NSAIDs due to potential to close the ductus arteriosus.
64
When is chronic htn in the parturient diagnosed? When does it return to normal?
Before 20 weeks gestation. It does not return to normal after delivery.
65
When does gestational htn occur in the parturient and how is it diagnosed?
After 20 weeks gestation. It's only diagnosed post-delivery when BP returns to normal (rules out chronic htn).
66
When is preeclampsia diagnosed in the parturient and what are the diagnostic criteria?
htn >140/90 (mild) or >160/110 (severe) develops after 20 weeks gestation. Proteinuria is typically present.
67
Can preeclampsia exist without proteinuria? If so, what would be present instead?
Yes. Instead could have: persistent RUQ or epigastric pain persistent CNS or visual symptoms fetal growth restriciton thrombocytopenia elevated serum liver enzymes
68
At what BP is severe eclampsia diagnosed? When does it progress to eclampsia?
BP > 160/110. Progresses to eclampsia when mom develops seizures.
69
Maternal physiologic effects of preeclampsia
70
What is thought to be the cause of preeclampsia?
Abnormal placental implantation leads to elevated vascular resistance and decreased placental blood flow. The placenta and fetus don't receive an adequate amount of O2 or metabolic substrate to normally develop.
71
What placental production changes occur with preeclampsia?
Produces 7xs more thromboxane than prostaglandin, which favors vasoconstriction, platelet aggregation, and reduced placental blood flow. Also releases cytokines that lead to endothelial dysfunction through the body.
72
Mild Preeclampsia vs Severe Preeclampsia: BP
<160/<110 vs >160/>110 due to increased thromboxane vasoconstriction
73
Mild Preeclampsia vs Severe Preeclampsia: proteinuria
< 5 g/24H, < 3+ dipstick >= 5 g/24H, >= 3+ dipstick Due to destruction of glomerular capillary endothelium
74
Mild Preeclampsia vs Severe Preeclampsia: 24H urine total
> 500 mL <= 500 mL Due to destruction of glomerular capillary endothelium and renal edema
75
Mild Preeclampsia vs Severe Preeclampsia: edema
generalized edema in both pulmonary edema only in severe (due to HF) due to decreased oncotic pressure & increased vascular permeability
76
Mild Preeclampsia vs Severe Preeclampsia: cyanosis
no - mild yes - severe
77
Mild Preeclampsia vs Severe Preeclampsia: headache
no - mild yes - severe due to cerebral edema
78
Mild Preeclampsia vs Severe Preeclampsia: visual impairment
no - mild yes - severe due to vasoconstriction of ocular arterioles
79
Mild Preeclampsia vs Severe Preeclampsia: epigastric pain
no - mild yes - severe due to liver subcapsular hemorrhage and hypoxic liver
80
Mild Preeclampsia vs Severe Preeclampsia: HELLP syndrome
no - mild yes - severe
81
Mild Preeclampsia vs Severe Preeclampsia: platelet count
> 100,000/mm3 < 100,000/mm3 due to consumption by endothelial damage
82
Mild Preeclampsia vs Severe Preeclampsia: fetal growth
normal impaired due to uteroplacental hypo perfusion
83
What is the definitive treatment for preeclampsia/eclampsia?
delivery of the fetus and placenta
84
When can mother with preeclampsia be medically managed?
Mild symptoms + young fetus -> bed rest and observation
85
When is immediate delivery required in the preeclamptic patient?
Symptoms become severe or fetal distress ensues
86
When and why should you employ antihypertensive medications in mom?
Treat BP >160/110 to prevent cerebrovascular accident, myocardial ischemia, or placental abruption.
87
What antihypertensives can be given for maternal acute htn?
labetalol 20 mg IV followed by 40-80 mg q 10 min, max 220 mg hydralazine 5 mg IV q 20 min, max 20 mg nifedipine 10 mg PO q 20 min, max 50 mg nicardipine infusion at 5 mg/hr, titrated 2.5 mg/hr q 5 min, max 15 mg/hr
88
How long do risks of complications related to severe preeclampsia continue?
Up to 4 weeks postpartum. Stroke and pulmonary HTN risk highest postpartum period.
89
Discuss seizure prophylaxis in eclampsia:
Mag sulfate loading dose of 4 g over 10 min infusion 1-2 g/hr Mag tox treatment: 10 mL 10% CaGluconate IV
90
HELLP Syndrome
Hemolysis Elevated Liver enzymes Low Platelet count Develops in 5-10% of those with preeclampsia SS: epigastric pain and upper abdominal tenderness higher risk for DIC and abnormal bleeding from the liver
91
What is the definitive treatment for HELLP syndrome?
Delivery However, could present for first time in postpartum period
92
MAC values for maternal acute vs chronic cocaine use:
acute intox: MAC increased chronic use: MAC decreased
93
OB risks of maternal cocaine use:
spontaneous abortion premature labor placental abruption low APGAR
94
CV risks in maternal cocaine use:
tachycardia dysrhythmias coronary vasoconstriction myocardial ischemia
95
CNS risks in maternal cocaine use:
cerebral vasoconstriction ischemia seizures stroke
96
What antihypertensive do you caution use of in maternal cocaine use?
Caution beta block -> HF if SVR elevated significantly due to myocardial depression from B1 block or further increased SVR from B2 block
97
What antihypertensives can be used in maternal cocaine use?
Labetalol - reasonable due to blockage of alpha-mediated peripheral vasoconstriction Vasodilators - but could cause hypotension
98
How do you treat hypotension in maternal cocaine use?
Phenylephrine Ephedrine may not elicit response in chronic use due to catecholamine depletion
99
What lab should you check before neuraxial placement in maternal cocaine use?
Platelet count. Chronic cocaine abuse can cause thrombocytopenia.
100
What is the preferred anesthetic for abnormal placental implantation?
General. Big risk for tremendous blood loss due to impairment of uterine contractility. However, neuraxial is safe.
101
What two conditions is abnormal placental implantation closely associated with?
Placenta previa Previous c-sections
102
Discuss placenta previa and risk factors:
placenta partially covers cervical os when attaches to lower uterine segment PAINLESS VAGINAL BLEEDING often requires c-section risk factors: previous c-sections, history of multiple births
103
Placental abruption risk factors include:
All increase driving pressure to placenta.. PIH preeclampsia chronic HTN cocaine use smoking excessive alcohol use
104
Discuss placental abruption:
maternal pain + vaginal hemorrhage and fetal hypoxia risk of amniotic fluid embolism that leads to DIC obtain large-bore IV and have blood products ready prep for c-section; vaginal delivery possible if fetus is stable
105
What is the most common cause of postpartum hemorrhage? What risk factors lead to this?
Uterine atony multiparty multiple gestations polyhydramnios prolonged oxytocin infusion before surgery
106
What are treatments for obstetric bleeding?
uterine massage oxytocin ergot alkoloids manual massage intrauterine balloon if these don't work
107
What conditions often lead to DIC in the parturient?
DIC placental abruption intrauterine fetal demise often accompanied by circulatory shock
108
Discuss APGAR scores:
Normal: 8-10 Moderate distress: 4-7 Impending demise: 0-3
109
What categories are included in the APGAR system?
Heart rate Respiratory effort Muscle tone Reflex irritability Color
110
APGAR Score: heart rate
0: absent 1: < 100 bpm 2: > 105 bpm
111
APGAR Score: respiratory effort
0: absent 1: slow, irregular 2: normal, crying
112
APGAR Score: muscle tone
0: limp 1: some flexion of extremities 2: active motion
113
APGAR Score: reflex irritability
0: absent 1: grimace 2: cough, sneeze, or cry
114
APGAR Score: color
0: pale, blue 1: body pink, extremities blue 2: completely pink
115
How soon after delivery should neonatal SpO2 increase?
Should increase from 60% to 90% within 10 minutes.
116
Should O2 be used to assist ventilation in the newborn? Why or why not?
No, it increases the risk of an inflammatory response. Room air should be used instead.
117
What is the best indication of adequate ventilation in resuscitation of a neonate?
The resolution of bradycardia. If ventilation doesn't improve cardiovascular performance, emergency drugs should be given.
118
What three routes can emergency medications be given to a neonate?
Umbilical vein, ETT, or IO
119
Discuss emergency meds for neonatal resuscitation:
Epi: 1:10,000, dose 10-30 mcg/kg IV or 0.05-0.1 mcg/kg intratracheal Volume expansion: PRBCs 10 ml/kg over 5-10 minutes NS LR
120
Discuss emergency meds for neonatal resuscitation:
Epi: 1:10,000, dose 10-30 mcg/kg IV or 0.05-0.1 mcg/kg intratracheal Volume expansion: PRBCs 10 ml/kg over 5-10 minutes NS LR
121
Neonatal resuscitation algorithm
122
What physiologic increases does progesterone cause?
Minute ventilation (decreased PaCO2 and increased HCO3 excretion) RAAS activity (increased blood volume -> increased CO) Vascular muscle relaxation (decreased SVR and decreased PVR) Sensitivity to local anesthetics
123
What physiologic decreased does progesterone cause?
Airway resistance (increased bronchodilation) MAC Lower esophageal sphincter tone