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 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
