Nm 602 Module 4 Study Guide/unit B

Front 1

What are the major hemodynamic changes that occur during the antepartumperiod?

Back 1

pg 267 pregnancy associated w/ physiology significant but reversible changes in maternal hemodynamics and cardiac function. Described in table 9-1 (pg 268)
●oxygen consumption- increase
●O2 delivery-no change to increase
●blood volume-increase
●Total body water-increase
●resistance changes (systemic and pulmonary circulation)- decrease
●blood pressure (systolic slight or no decrease) diastolic -decrease
●myocardial contractility> all increase

Front 2

What are the causes of these hemodynamic changes?

Back 2

pg 267 result of hormonal influences, changes in other organ systems, & mechanical forces

Front 3

Describe the anatomic changes to the heart during pregnancy

Back 3

pg 267 upward displacement of the diaphragm by uterus, SHIFT heart upward & laterally; sl heart enlargement and left heart border straightened

Front 4

What is cardiac output?

Back 4

Pg 269 product of heart rate x stroke volume & is one of most significant hemodynamic changes encountered during pregnancy.

Front 5

How much does maternal cardiac output increase by 8 weeks gestation?=

Back 5

50%

Front 6

What is the primary cause of increased cardiac output during these early weeks of pregnancy?

Back 6

Caused by changes in heart rate and stroke volume; rise in CO in early preg due to increase stroke volume

Front 7

How does maternal position affect cardiac output?

Back 7

Pg 269 resting CO, fluctuates markedly with changes in body position.

Front 8

Why is supine positioning more likely to lower cardiac output?

Back 8

Greater decline in CO than that in sitting or lateral recumbent. Compression of inferior vena cava by uterus in 3rd tri = decreased venous return, stroke volume and CO.

Front 9

Explain how increased metabolism, increased oxygen consumption, the placenta as an arteriovenous shunt, and the decrease in peripheral vascular resistance affect cardiac output.

Back 9

pg 269 Increase o2 requirements are most likely result of contractility-promoting influences of placental circulation. The concomitant increase in blood volume prob explains the increase in CO. Changes in uterine blood flow might also contribute to increase CO..
●How does multiple gestation affect cardiac output? – increase in CO due to increase in INOTROPHY. Peak is greater; decline in late pregnancy is smaller.
●How do the increased estrogen levels in pregnancy affect cardiac output? Pg 270 Progesterone, estrogens and prolactin also cause changes in HEMO by directly affecting the myocardium. Estrogen alters STPase relationship in myocardium thereby increasing the contractility of heart & altering stroke volume.

Front 10

How much does maternal heart rate increase during pregnancy?

Back 10

10-20 BMP (10-20%) by 32 weeks

Front 11

Describe the blood pressure during each trimester of a normal pregnancy. What are the physiologic reasons for these changes?

Back 11

BP (esp diastolic) decreased. Initial decrease due to lag in compensation for changes in peripheral vascular resistance. Decrease nadir at 24-32 weeks > gradually increase to nonpreg baseline by term. (fig 9-2)

Front 12

What are the physiologic changes that explain the decrease in systemic vascular resistance of pregnancy?

Back 12

Pg 271 SVR decreases by 5 weeks and reach lowest by 16-34 weeks. SVR due to collagen fibers and hypertrophy of smooth muscles, remodeling of maternal spiral arteries and low-resistance uteroplacental circulation which receives large proportion of CO. ALSO prob due to PROGESTERONE

Front 13

How many milliliters of blood per minute flows through the uterus at term?

Back 13

500-600 mL/min @ term pg 271

Front 14

Describe the changes in
●heart sounds

Back 14

exaggerated split & loudness of both components of 1st heart sounds – first heard 12-20 weeks cont to 2-4 weeks pp

Front 15

Describe the changes in benign murmur

Back 15

MOST 92-95% have systolic murmur >last 2 tri 2nd to increased cardiovascular load. Heard best left sternal border 3rd intercostal space.

Front 16

Describe the changes in
●changes in electrocardiograph

Back 16

pg 274 ECG changes occur as position of heart shifts with enlarging uterus. Small Q wave, inversion of p not uncommon, T and ST changes also seen

Front 17

Describe the changes in echocardiograph seen in pregnancy

Back 17

increase in left end diastolic dimensions during 2nd & 3rd tri. Prob due to expanded blood volume & increased filing during diastole.

Front 18

During labor, each contraction will cause about ______ milliliters of additional volume to the maternal circulation. How does this affect cardiac output?

Back 18

300-500
Pg 274= INCREASE CO with cumulative effect over the course of labor. 12-31% increase 1st stage labor, up to 50% 2nd stage

Front 19

Describe the changes in cardiac output during the immediate postpartum period.
What are the physiologic causes for these changes?

Back 19

Despite blood loss with delivery , CO significantly elevated 1-2 hours PP -60-80% higher than pre-labor levels. Within 10-15 minutes there is sharp decline that stabilizes at pre-labor values by 1 hour.
Reduction of gravid uterus pressure and improved venacaval blood flow, The increase in CO is most likely protective.

Front 20

Describe the supine hypotensive syndrome (SHS).

Back 20

Late in pregnancy before fetus engaged, uterus is mobile enough to fall back against inferior vena cava in supine position (figure 9-6 pg 276) causes VENA CAVAL TAMONADE

Front 21

What is the physiologic basis for SHS?.

Back 21

Usually the fall in CO due to posture change is compensated for by an increase in peripheral resistance. This allows systemic BP and HR to not change. 8-10% women decrease HR & BP = dizzy weakness etc- REVERSED with position change- Wedge