Ex1 OB 1 Flashcards
CVS system changes in pregnancy
increased HR, SV
therefore increased CO
Respiratory system changes in pregnancy
- displacement of diaphragm superiorly
- decreased FRC
- increased risk of apnea/dyspnea
- hyperventilation
GI changes during pregnancy
- N/V
- heart burn + acidity
Major cardiovascular changes during pregnancy
- increased intravascular volume
- increased cardiac output
- decreased vascular resistance
- supine HOTN
Changes to the heart during pregnancy
heart enlarges, displaces upward + to Left
Why does CO change during pregnancy?
Increase in both HR, SV
Decrease in SVR
Decreased SVR is due to
initiating factor: estrogens, progesterone, prostacyclin
CO is greatest when?
Right after delivery
When does moms CO return to baseline?
~ 2 weeks after delivery
What compensates for the blood loss during delivery?
contractions of engorged uterus provide 300-500mL autotransfusion into maternal circulation –> increased CO
Common cause of moms HOTN
While laying flat on back: weight of placenta + amniotic sac can compress IVC
Increased risk of ____ in mom d/t decreased vascular resistance/venodilation?
epidural vein puncture
While placing epidural, what should be ensured?
Remaining midline (avoid epidural veins)
90% of pregnant women have a ____
late systolic or ejection murmur
Common murmurs in pregnant women are attributable to
increased stroke volume
decrease in blood viscosity
At term, what may be seen on the CXR?
Larger cardiac silhouette d/t diaphragm shifting heart up + Left
What changes may be seen in 3rd trimester on EKG?
Increased incidence of dysrhythmias (PAC, PVC, SVT) d/t Left Axis shift on ECG
Second trimester
20-28 weeks gestation
important but preventable cause of fetal distress
aortocaval compression
-after 20-28w gestation
aortocaval compression
gravid uterus obstructs aorta + inferior vena cava (while supine) –> no blood supply to placenta (uteroplacental circulation) –> no blood supply to baby –> asphyxia
What will be seen on the fetal heart monitor if aortocaval syndrome occurs?
Late decelerations
How to avoid aortocaval syndrome?
Tilt parturient to left side
3rd trimester
29-40 weeks
Cause of LE edema, venous stasis
Chronic partial caval obstruction in 3rd trimester
Beginning location of aortic compression
L3-L4
upper body BP may remain normal
Changes in blood volume during pregnancy are due to
increased mineralocorticoid activity –> sodium retention + increased body water content
Blood volume changes during pregnancy
increased:
plasma volume ( +50%
total blood volume (+45%)
red cell volume (+25%)
Which increases more during pregnancy: plasma volume or red cell volume?
Plasma volume
Changes in blood volume lead to ____ during pregnancy
relative dilutional anemia
TBV at term
85-100 mL/kg
Healthy parturients can tolerate up to _____ mL blood loss without a transfusion
1500mL
High Hgb levels may indicate
Normal Hgb > 11
High Hgb = > 14
*may indicate low volume state caused by preeclamsia, HTN, or inappropriate diuresis
Approximate intravascular volume change
1000-1500 mL
*helps compensate for EBL
EBL vaginal
300-500 mL
EBL section
800-1000mL
Coagulation changes during pregnancy
- coagulation factors + fibrinogen increase
- platelets remain same or decrease 10% during 3rd trimester
Factors that increase during pregnancy
I, VII, VIII, IX, X, and XII
Factors that decrease during pregnancy
XI and XIII
Coagulation lab changes in pregnancy
PT -20%
PTT -20%
No change: platelets or bleeding time
Coagulation lab changes in pregnancy: thromboeleastography
hypercoagulable
Coagulation lab changes in pregnancy: antithrombin III
decreased
Coagulation lab changes in pregnancy: fibrin degradation products
increased
Coagulation lab changes in pregnancy: plasminogen
increased
What may worsen airway edema in pregnancy?
- preeclampisa
- trendelenberg position
- Tx w/ tocolytics
Average size ETT in pregnancy
6-6.5
changes in airway during pregnancy
- capillary engorgement of mucosal lining
- mucous membranes = friable
- swelling of false vocal cords (narrowed glottis)
- weight gain/breasts = hinder laryngoscopy
key for successful airway placement
- proper axis alignment (via positioning)
- short laryngoscopy handles
- know where glidescope is at all times (video laryngoscope)
What does diaphragmatic elevation cause?
- less negative intrathoracic pressure
- decreased FRC, ERC, RV (20%)
significant PFT changes
compensatory increase in thoracic anterior-posterior diameter
What change in moms body causes the majority of respiratory changes?
Hormones (increased progesterone)
+
Enlarged Uterus
What physical changes in moms body causes respiratory changes?
Enlarged uterus –> ribcage becomes wider, back broader (+ diaphragm pushed up)
Why is mom at a higher risk of rapid oxygen desaturation during periods of apnea?
Combo:
decreased FRC + increased O2 consumption
What is mandatory prior to GA in pregnant patients?
Preoxygenation
Risk of pain/anxiety during labor in relation to respiratory system
increased RR –> hypocapna, faintness, perioral numbness
–> fetal hypoxia/distress
What occurs to 2,3-DPG during pregnancy?
Why does this change?
- 2,3-dpg concentration increases
- lowers affinity of maternal Hgb for O2
Reason for change of 2,3-dpg
Lowers moms affinity of Hgb for O2 –> facilitates dissociation of oxygen from Hgb thru intervillous space in placenta, enhances delivery of O2 to growing fetus
Dissociation curve is affected during pregnancy how?
increased 2,3-DPG shifts O2 Hgb dissoc. curve to the Right (P50 increases from 27-30 mmHg)
Most significant Respiratory changes
Decreased FRC
No change in VC
Increased TV
Decreased ERV
When does mom’s minimal alveolar concentration return to normal?
3 days post-partum
Effect of pregnancy on MAC
decreases by up to 40%