Additional OB Flashcards
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
When do most physiologic changes occur?
When do most anatomical changes occur?
- physiology- 1st trimester
- anatomical- 2nd and 3rd timester
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
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)
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
What is the cutoff platelet count below which regional is not advised?
80,000
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%
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
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
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
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%
What change to pseudocholinesterase activity would you expect in a pregnant pt?
reduction of pseudocholinesterase activity
What endocrine changes would you expect in a pregnant woman?
- diabetes- insulin needs progressively increase through pregnancy
- leads to hyperglycemia, ketosis, fetal hypoxia
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
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
What factors affect uteroplacental blood flow?
(6)
- 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?
- Simple diffusion
- Active transport
- pinocytosis
Drugs that have high rates of placental transer are…
(5 qualities of the drugs)
- 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?
fetal acidosis
What should be monitors for mother and fetus?
- 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?
- <100/min
- fetal head compression
- maternal hypoxemia
- umbilical cord compression
- maternal hypotension
- uterine hyperstimulation
What are early decelerations?
- 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?
- Variable decelerations are variable in duration, intensity, and timing
- due to compression and decompression of cord
What are late decelerations?
- 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
