Changes in pregnancy - cardiovascular and respiratory system Flashcards
how much does the heart volume increase during pregnancy
12%
When does the plasma volume increase (/40)
34/40
What week does the plasma volume reach its max
32-34/40
Percentage that plasma volume increase by
50% above non-pregnant values
Why is higher circulating volume of blood required in pregnancy
To provide extra blood for placental perfusion + to counterbalance the effects of increased arterial and venous capacity
How much does the heart rate increase by
10-20% - multiple pregnancy = up to 40%
What week does the heart rate increase by
32/40 -
How is the increased cardiac output balanced
by reduced peripheral resistance, due to progesterone acting on the smooth muscle of arterial walls
What are the changes to blood pressure
Decrease in systolic, greater decrease in diastolic
In labour, what changes occur to cardiac output
Increases t/f slight increase in BP
What factors can affect BP
Age and Parity
where does the majority of the increased blood flow go to
Uterus and 80% goes to placenta
How much is the blood flow to kidneys increased by
30-50%
Why is there increased blood flow to the skin
Thermoregulation
How much does plasma volume increase by
40-50%
How much does RBC increase by
20-30%
What does increased plasma volume lead to
a drop in Hb - up to 10%
What does WHO define anaemia as
<110g/L during pregnancy and <100g/L post pregnancy
How much does WCC increase by
8%
How does the heart move when pregnant
Shifts upwards and to the left
What changes occur to the arteries
Dramatic systemic and pulmonary vasodilation to increase blood flow
What changes happen to the veins
Vasodilatation and impeded venous return in lower extremities, facilitated by increased progesterone
What happens to stroke volume
Increased stroke volume bc of increased circulating volume
What is stroke volume
The volume of blood expelled from the ventricle during a contraction (heartbeat)
Why is there a higher circulating volume required in pregnancy
to provide extra blood for placental perfusion and to counterbalance the effects of increased arterial and venous capacity
What factors does blood pressure depend on
Cardiac output, peripheral vascular resistance, blood volume, blood viscosity
What hormone acts on the respiratory centre in the brain
Progesterone
How much is the total air taken in increased
40%
What effect does progesterone have on the muscles in the respiratory system
Relaxes intercostal muscles
How does the rib cage change
Increases in diameter by 2cm
How does respiratory rate change
It doesn’t
How does tidal volume change
Increases
How does oxygen consumption change
Increases
How does metabolic rate change
Increases
How does the functional residual capacity change
Decreases
How does an increase in blood volume benefit the woman and fetus
Protects against the potential harmful effects of impaired venous return
How does the increase in blood volume benefit the maternal organs
Provide extra perfusion of maternal organs
What does the increase in blood volume counterbalance
The effects of increased aterial and venous capacity
How does an increase in blood volume protect the woman during labour
Safeguards against adverse effects of excessive maternal blood loss at birth
What is haemodilution
An overall fall in iron levels which can present as iron deficency anaemia
