Additional OB Flashcards by Maggie McDonell

What are the cardiac changes that occur during pregnancy?

When do they occur?

increased blood volume by 35%
- plasma increases more than RBC, causing dilutional anemia
CO increases 30-50%- from 5th week to 32 weeks
- CO increases more during labor
- returns to normal 14 days postpartum
HR increases 20-30%
SV increases 20-50%
Cardiac hypertrophy- stretched out, not bigger

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When do most physiologic changes occur?

When do most anatomical changes occur?

physiology- 1st trimester
anatomical- 2nd and 3rd timester

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CV changes you will see on ECG, ECHO, CXR, or auscultation

ECG
- tachycardia
- flat or inverted T wave or ST depresion of 1 mm in lead III, V2, V3
- RBBB, PACs, SVT
ECHO
- tricuspid, pulmonary regurg (94%), mitral regurg (27%)
- increased atrial and ventriculuar size
CXR
- increased vascular markings
- cardiomegaly with heart shifted to left
Auscultation
- wide, loud split S1
- soft systolic ejection murmor

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How is hypotension in pregnancy defined?

What causes it?

What does this mean for the baby?

treatment?

SBP< 100 mmHg
caused by supine position, induction agents, sympathetic block from regional blocks
uterine and fetoplacental blood flow decreases
treated by: LUD or side lying, hydration, ephedrine (5-10 mg IV)

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In addition to the increases in blood volumes, what are other hemotologic changes?

hypercoagulability- to help with clotting after giving birth
- clotting factors increase, no change to platelets
Plasma albumin decreases
plasma cholinesterase concentrations decrease
- lengthened succ, ester LA, and remifentanyl

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What is the cutoff platelet count below which regional is not advised?

80,000

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Respiratory changes

anatomical

breathing pattern

O2 consumption

Diaphragm pushed up, thoracic cage enlarges
decreased FRC by 20%
restrictive disease pattern
diaphragmatic breathing pattern
O2 consumption increases 30% at rest, CO2 increases 35%

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What is the significance of Progesterone for Respiratory changes?

When does it occur by?

stimulates respiratory center to increase ventilation
- MV increase by 50%
causes chest wall muscle relaxation which increases chest expansion
Sensitizes respiratory center to CO2
- allows for hyperventilation
- increased minute ventilation drives maternal PaCO2 to 30-32
- develop a compensated resp alkalosis with renal excretion of bicarb

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What happens to the Oxy-hgb curve?

What would an ABG look like?

Oxy-hgb curve shifts to right
- P50 values increase from 26 to 28
ABG:
- PaO2- low normal
- CO2- low
- Bicarb- low
- pH- normal

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What can you do to help manage the difficult airway of a pregnant patient?

have difficult airway cart available
avoid manipulation of upper airway (sxn or inserting airways)
HOB up
smaller ETT; 6.0 or 6.5
use “stubby” laryngoscope handle
regional when possible

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What are CNS changes seen in a pregnant woman?

increases in endorphins/altered pain thresholds
increased sensitivity to opioids, LA, and IA
MAC decreased by 40%

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What change to pseudocholinesterase activity would you expect in a pregnant pt?

reduction of pseudocholinesterase activity

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What endocrine changes would you expect in a pregnant woman?

diabetes- insulin needs progressively increase through pregnancy
- leads to hyperglycemia, ketosis, fetal hypoxia

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Which vein gets distended that we care about?

venous plexus
- caused by venal caval compression
- easier to hit vein when placing LA
decrease LA dose by 1/3 at >14 weeks
- because there is less space and they are more sensitive

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How does blood flow from the mother to the baby?

Mother has two maternal arteries that become max dilated at about 8 weeks
- cannot autoregulate for changes in BPs
Spiral arteries expel blood into intervillous spaces
- these arteries will constrict with alpha stimulation
Umbilical vein caries oxygenated blood from mother to baby
Blood immediately goes to fetus’ liver

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What factors affect uteroplacental blood flow?

(6)

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Aortocaval compression
maternal hypotension 9hemorrhage)
Sympathetic blockade
increases in uterine vascular resistance
- contractions, oxytocin, ketamine, abruptio placentae, severe HTN
maternal hypoxia, hypercarbia, and hypocarbia
catecholamines
- ephedrine, phenylephrine

What 3 processes can drugs use to cross the placenta?

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Simple diffusion
Active transport
pinocytosis

Drugs that have high rates of placental transer are…

(5 qualities of the drugs)

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Low Molecular weight
Low PB
High degree of lipid solubility
small molecules
poorly ionized; non ionized
- maternal and fetal pH (ionization)
**maternal drug concentration also plays a role

What can cause ion trapping of drugs?

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fetal acidosis

What should be monitors for mother and fetus?

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maternal
- HR
- BP
- spO2
- intrauterine pressre (internal or external tocodynometer)
Fetus
- FHR (internal scalp electrode or external ultrasound)
- blood ph- scalp capillary sample

What is considered fetal bradycardia?

what can cause it?

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<100/min
fetal head compression
maternal hypoxemia
umbilical cord compression
maternal hypotension
uterine hyperstimulation

What are early decelerations?

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the onset and return of decelerations coincides with the start and the end of contractions
associated with fetal movement, stimulation, and uterine contractions

What are variable decelerations?

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Variable decelerations are variable in duration, intensity, and timing
due to compression and decompression of cord

What are late decelerations?

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Fetal HR returns to baseline AFTER the contraction has ended
caused by uteroplacental insufficiency or decreased uterine blood flow

How do you treat non-reassuring FHR patterns?

* LUD or knee to chest * supplemental O2 * rapid infusion of fluid * check BP and treat maternal hypotension (vasopressors) * stop oxytocin if labor was being augmented * use terbutaline instead or NTG * Assess sensory block of epidural/spinal- stop if causing hypotension * aminoinfusion- adds fluid to cavity to help reduce compression of cord * C-section

What are the different stages of labor?

* Stage 1: the cervix relaxes, causing it to dilate and thin out * Stage 2: Uterine contractions increase in strength and the infant is delivered * Stage 3: the placenta is expelled

Pre-op evaluation of OB history should include....

* Is this your first pregnancy? * Gravida = # times pregnant/ # conceptions * nulligravida- never pregnant * primigravida- pregnant for first itme * multigravida- pregnant at least 2 times * Parity = # pregnancies reaching viable gestational age (live births + still births) * Abertus = abortions or miscarriages before viability (\<20 weeks)

Pre-op evaluation of current pregnancy should include...

* Estimated date of deliver * LMP + 9 months + 7 days * Growth of fetus- WNL? * Placental location- placenta previa may alter delivery plans * Fetal movements- usually experienced at around 18-20 weeks gestation * Labor pains- more relevant in the third trimester * planned method of delivery- vaginal/c-section * Medical illness during pregnancy- any meds?

Pre-op evaluation details of each pregnancy should include...

* date of delivery * length of pregnancy * singleton/twins/or more? * spontaneous labor or induced * mode of delivery * type of pain reliev/anesthesia * complications? * wt of babies * current health of babies

Pre-op evaluation; history of complications of previous pregnancies should include...

* Antenatal * IUGR * Hyperemesis * pre-eclampsia * labor * failure to progress * perineal tears * shoulder dystocia * postnatal * postpartum hemorrhage * retained products of conception

What are some key symptoms to ask a pregnant patient about?

* Nauseia/vomiting- if severe may suggest hyperemesis gravidarum * abdominal pain- may need imaging * vaginal bleeding- fresh red blood, clots, or tissue * dysuria/ frequency- UTI * fatigue- anemia? * HA/ Visual changes/ swelling- pre-eclampsia * systemic symptoms- fever/malaise

How should you prepare for operation?

* Ask what kinds of analgesics have been given * large bore IV \>18 g * Aspiration prophylaxis on EVERY PT * non-particulate antacid, reglan, ranitidine * Hydration- (minimal 500 ml) * monitors for mother, contractions, and fetal HR monitor * emergency drugs and equipment available

What emergency drugs should you have on hand for a pregnant patient?

* For airway management: propofol, ketamine, midazolam, succ, opioids * for LA toxicity: midaz, propofol, intralipids * for maintenance of VS * ephedrine * epinephrine * phenylephrine * atropine * calcium chloride (for mg sulfate toxicity) * Na bicarb * naloxone * uterotonic meds * lidocaine * IVF

Additional OB Flashcards

(33 cards)