OB Flashcards

1
Q

Most physiologic changes occur in the ___ trimester, and most anatomic changes occur in ____

A

Physiologic = 1st trimester

Anatomic = 2nd and 3rd trimesters

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2
Q

Are the physiologic and anatomic changes in pregnancy good or bad?

A

Mostly good.

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3
Q

Respiratory changes in pregnancy

A

1) Increase in ventilation - D/t increased metabolic demand - Increase 40% TV and 15% RR - Increase 50% MV overall - High ventilation will decrease CO2 levels (goes into resp alkalosis pH = 7.44) 2) Decrease in airway resistance - d/t increased progesterone - Lung compliance unchanged 3) Increase in O2 Consumption - Increase by 20% - Curve shifts to the right (P50 increases from 26-28mmHg)

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4
Q

Anatomic respiratory changes in pregnancy

A

1) Cephalad diaphragm displacement 2) Weight gain and breast enlargement (pressure on the chest and boobs might get in the way of airway) 3) Vascular engorgement of the respiratory tract mucosa - Mucus membranes fragile 4) Edema of nasopharynx, oropharynx, and the cords

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5
Q

When is edema of the nasopharynx, oropharynx, and the cords most common?

A

During pre-eclampsia Remember there is HTN and loss of plasma proteins.

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6
Q

Effect of pregnancy on the FRC

A

Decrease by 20% Less safe apnea time!!

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7
Q

Why can pregnant ladies desat quickly?

A

Low FRC and high O2 consumption rate (20% higher than normal).

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8
Q

We can expect induction during pregnancy to be (faster/slower) than the non-pregnant patient. MAC should be (increased/decreased) by ____.

A

Faster induction Decreased MAC by 25-40%

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9
Q

Effects of maternal hyperventilation

A

Alkalosis - Shift to the left (will decreased O2 release to the fetus) - Constriction of the umbilical and uterine blood vessels This is only a problem with prolonged hyperventilation

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10
Q

Effects of elevating the diaphragm

A

Decreased FRC and displacement of the heart (look at EKG, listen for murmur, possible dysrhythmia)

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11
Q

Pregnancy and coagulation

A

Overall, it is a hypercoagulable state Increased clotting factors (fibrinogen and factors 5-8) Platelets remain unchanged or may decrease slightly

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12
Q

CO will be (increased/decreased) during pregnancy

A

Increased

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13
Q

What happens to BP and SVR in pregnancy

A

SVR will decreased by 20% - vessels lose their SNS tone BP will decrease slightly - ADH is cleared more rapidly - BP maintenance depends on RAAS b/c vessels have lost their SNS tone

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14
Q

Your pregnant patient is lying supine and starts to drop their BP. What is this and how is it treated?

A

Supine Hypotensive Syndrome - It’s possible compression of vena cava or aorta. Treatment: - Left or right uterine displacement (depending on which vessel is compressed) - Hydrate before induction - Treat hypotension with ephedrine or phenylephrine

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15
Q

Supine hypotension syndrome is a risk > ____ weeks and can decrease CO by up to ___%

A

20 weeks 30%

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16
Q

Plasma volume increases by ___% but RBC volume only increases by ___%.

A

Plasma 50% RBC 20% Causes a dilutional anemia

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17
Q

Normal blood loss during vaginal birth

A

500cc

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18
Q

Normal blood loss during a c-section

A

500-1,000cc

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19
Q

GI changes in pregnancy

A

As a result of physiologic and hormonal changes: - Delayed gastric emptying - Everything in the GI tract slowed overall - Secretions are more acidic - Stomach is displaced upward and at 45 degree angle to the right. This displaces the intra-abdominal portion of the esophagus into the thorax, decreasing tone to the lower esophageal sphincter, causing reflux

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20
Q

All parturients greater than ___ weeks are considered full stomachs

A

12 weeks Aspiration risk continues into the post-partum period, until the body has time to normalize hormonally, physiologically, and anatomically.

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21
Q

Aspiration prophylaxis in pregnancy

A

Give non-particulate antacids, H2 blockers, and/or reglan. Consider doing regional instead. If doing GA, do RSI.

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22
Q

Renal Changes in Pregnancy

A

High CO and large blood volume cause an increase in GFR by 60%. Creatinine clearance increases, decreaseing serum CR

Increased glucose excretion

increased bicarb excretion (compensation for respiratory alkalosis)

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23
Q

Hepatic Changes in Pregnancy

A

Slight increases in AST and ALT Bigger changes will be seen in HELLP syndrome (part of pre-eclampsia)

Biliary stasis and increased secretion of bile leads to increased gallbladder disease

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24
Q

Neuromuscular Changes in Pregnancy

A

1) Increase in endorphins! - Allows us to decrease MAC by 40% 2) Increased sensitivity to opioids, LAs, and catecholamines

25
Q

Why is MAC decreased in pregnancy?

A

1) Faster induction 2) Higher endorphins potentiates the effects of the VA

26
Q

Formula for uterine blood flow and normal values for UBF

A

(uterine arterial pressure - uterine venous pressure) / Uterine vascular resistance UBF during pregnancy: 500-700mL/min UBF when not pregnant: 50-100mL/min

27
Q

There is a direct correlation between uterine blood flow and

A

fetal umbilical venous O2

28
Q

When will uterine blood flow decrease?

A

1) Decrease in perfusion pressure (maternal hypotension SBP

29
Q

Is the uterine vascular bed able to autoregulate?

A

NO! This is why BP management in parturients is critical

30
Q

We are most worried about fetal ion trapping with these drugs

A

LAs

31
Q

Generally all of our anesthetics will cross the placenta except

A

NMBs

32
Q

What is a protective mechanism that the fetus has against drug OD?

A

Blood from the umbilical vein first goes to the liver

33
Q

What is the baseline fetal HR?

A

120-160 May vary by 5-10bpm and variations are a good and normal thing.

34
Q

Causes of fetal tachycardia

A

Maternal fever or infection Atropine administration Late sign of fetal hypoxia

35
Q

LATE decelerations may be from

A

Compromised blood flow to the fetus (maternal hypotension, cord compression, etc)

36
Q

SEVERE decelerations will go below __bpm and last longer than ___

A

70 1 minute Fetus is in distress! We need to deliver!

37
Q

Treatment for shitty fetal heart rate patterns

A

1) LUD (left uterine displacement) - Compression could be decreasing CO by 30% 2) O2 3) Correct any contributing factors (treat hypotension, stop oxytocin, check for prolapsed cord in her vajay, assess for vaginal bleeding that could be from the placenta)

38
Q

Stages of Labor

A

1st Stage - From beginning of regular painful contractions to full cervical dilation - Longest stage of labor and divided into two phases - This is mostly visceral pain (Block T10-L1) –> Latent Phase: 1st and longest part. Contractions start and are getting stronger and cervix is thinning –> Ative Phase: Second and shorter phase. The cervix is actively dilating to 10cm 2nd Stage - From full cervical dilation to delivery - This is the most painful stage*** - This is somatic, stretching pain (Block S2-4) 3rd Stage - From delivery of neonate to delivery of the placenta

39
Q

Staging and neuraxial block requirements

A

1st Stage (T10-L1) 2nd Stage (T10-S4) 3rd Stage (T10 b/c it involves the vag and uterus)

40
Q

Risks for intense pain during pregnancy

A

Young maternal age (ya so tight) Increased maternal weight (excess tissue in the way) Occiput posterior presentation Increased fetal weight (fat baby) Use of tocolytics

41
Q

Opioids popular in pregnancy

A

Fentanyl and meperidine (Demerol) Sufentanil not as popular because it can cause fetal bradycardia

42
Q

Common analgesic interventions in parturients

A

Opioids Ketamine Agonist/Antagonists (Nubain & Stadol) Intrathecal Opioids Epidurals CSE

43
Q

Can epidurals prolong labor?

A

Yes, it can prolong Stage 1

44
Q

Relative contraindications for regional anesthesia

A

Primary herpes Obstructive cardiac lesions R or L intracardiac shunts Active CNS disease PIH (pregnancy induced HTN) MG (possible respiratory compromise)

45
Q

Epidurals should be placed below this level

A

Below L2

46
Q

Does the level of epidural block depend on baracity of the LA?

A

NO. It would matter in spinals. NOT epidurals!

47
Q

Most common LAs in pregnancy

A

Amides: Lidocaine, bupivacaine, and ropivacaine Esters: Chlorprocaine, tetracaine, and mepivacaine

48
Q

Epidural concentrations used for bupivacaine

A

.125% - .25% Used with or without an opioid

49
Q

Epidural concentrations used for ropivacaine

A

.125% - .2%

50
Q

Benefits of having a continuous laboring epidural (CLE)

A

More constant level of analgesia More even block More stable VS Greater safety Able to use if need to give surgical block for emergent c-section

51
Q

Procedure for continuous epidural infusion

A

1) Give test dose with epi. Wait 3-5 min before initiation of bolus (may be difficult to detect b/c mother is probs already tachy from pain) 2) Give bolus injection 3) Start continuous infusion once adequate block obtained (at LEAST T10 level)

52
Q

Block above this level will start to affect cardiac accelerators

A

T4

53
Q

Sometimes the first sign of a sympathectomy may be

A

N/V If your patient starts having N/V after epidural placement - check BP for hypotension. We don’t want SBP

54
Q

Effects of epidural on labor

A

Slows Stage 1 Can halt labor if cervix dilated

55
Q

Caudal Block

A

Type of epidural not common in OB. Needs high volumes. May be ok in Stage II

56
Q

Paracervical block

A

Usually done by OBGYN - LA injected submucosally in the vagina on either side of the cervix. May be used for Stage I (while cervix is dilating), but there is high risk of fetal bradycardia from LA injection.

57
Q

Pudendal block

A

Good block for Stage II (delivery) Inject LA on both sides of vagina into the sacrospinous ligament. Good perineal anesthesia.

58
Q

Parturients are most likely easy or difficult airway?

A

Difficult Edema of oropharynx and cords

59
Q

If doing a spinal block for c-section, you should block at this level

A

T4-6