Cardiovascular Changes in Pregnancy

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How is CVP effected?

No change to CVP - Dilated sytemmic & pulmonary circulation

When does increases in intravascular fluid volume begin?

THe 1st trimester

↑ CO primarily due to ↑ SV (preload) and HR: 10th week? 3rd trimester? During labor? During contraction?

10th week ~ 10% aove norm 3rd trimester - 40% above norm Labor 30% above norm During contraction 45% above norm

Average expansion of vol. at term?

1500 ml

What must SBP be kept at to maintain maternal perfusion pressure to the vasculature and meet fetal demands?

>100mmHg

Hemoglobin parameter at term gestation? Blood vol. Plasma vol. RBC vol.

Blood vol. +45% Plasma vol +55% RBC vol. +30%

Cardiovascular changes during pregnancy: ICREAASES

Inteavacual vol. ↑ 35% Plasma vol. ↑ 45% RBC vol. ↑ 20% CO. ↑ 40-50% SV. ↑ 30% HR. ↑15-25% Femoral ven press. ↑ 15%

What happens to the mothers oxyhemoglobin dissociation curve at term?

Shift to the Rt. P50 shifts Rt (26.7 - 30.2) at term. Remember Rt shift = O2 is more easily released to the tissue.

↑ intravascular fluid vol. off sets blood loss with delivery. Vaginal delivery EBL? C-sec delivery EBL?

Vaginal 500-600 ml avg. C-section 800-1000 ml avg.

During pregnancy SVE does what?

↓ ~20%

During pregnancy Peripheral vascular resistance does what?

↓ ~34% Offsets the ↑ in CO & intravasc. fluid vol.

What cardiovascular parameter does not change during pregnancy?

CVP = no change

How much does uterine BF increase by term?

Uterine BF increases from 50ml/min to 700-900ml/min by term.

Autotransfusion and 24 ven. return is associated with?

Uterine involution→ ven return of blood. (returning to its pore-pregnant size & state)

How much does erythrocyte (RBC) volume increase?

~20-30%

How much does plasma volume increase?

~45%

4 other cardiovascular changes inpregnancy?

↑ HR ↑ CO ↑ heart size ↑ peripheral ciurculation

Increased CO is do to what?

↑ SV (preload) ↑ HR

# 1 cardiovascular change in pregnancy?

↑ intravascular volume

How does the hear ↑ in size?

↑ volume, ↑ stretch and force of contraction & ↑ ize of myocytes.

Why does SVR and PVR ↓ during pregnancy?

↓ in vessel tone d/t Alpha and Beta receptor down regulation & proticyclin changes → ↑ renal, uterine, & extremity BF.

What causes vessel tone to ↓ during pregnancy?

Alpha & Beta receptor down regulation and prostocyclin changes that result in ↑ renal, uterine, and extremity BF. = CVP no change

Net effects of ↑ CO, ↓SVR & ↓ PVR?

Art. BP remains normal or slt. ↓ during uncomplicated preg (DBP ~10-20 mmHg)

Why does the parturient have hemodilution?

Blood vol. increases more then RBCs increase.

When is CO greatest?

Emmidiately after delivery. As mus as 80% above prelabour val. -d/t autotransfusion & ↑ ven. return returns to normal slowly over 14 days

How does anemia result with an increased RBCs?

Hemodilution Anemia results from: ↑ in plasma vol : ↑ RBC vol.

What does an ECHO reveal about the ↑ heart during pregnancy?

LVH by 12 weeks with 50% ↑ mass by term. 94% at term exhibit tricuspid and pulmonic regurge 27% MR

Is O2 transport ↑ or ↓ during pregnancy?

Lower HCT ↓ O2 carrying capacity (19.5 to 16 vol/100ml) but.. COmpensated by ↓ ventililation (avg. O2 tension is 103torr) ↑ CO Vasodilation of uterus and kidneys Vasodilation = ↑ BF to target organs

Cardiovascular changes during pregnancy: DECREASES

MAP. ↓15 mmHg SBP. ↓ 0-15 mmHg DBP. ↓ 10-20 mmHg SVR. ↓ 20% PVR. ↓ 35%


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