[09.27-28] Maternal Changes_Gastrointestinal, Cardiovascular, and Respiratory Systems V2

Stomach and intestines

Which organs are displaced cephalad (towards the head) due to the enlarging uterus?

Superolaterally

How is the appendix displaced due to the enlarging uterus?

Diaphragm

Which organ is pushed up due to the stomach and intestines going up, potentially causing hypoxia?

Right upper quadrant

Where might appendicitis present due to organ displacement during pregnancy?

Progesterone

What hormone is responsible for prolonged gastric emptying during pregnancy?

Labor, at term, after analgesia

During which situations is gastric emptying prolonged?

Heartburn, hemorrhoids, and nausea

Which symptoms are normal during pregnancy?

Lower esophageal sphincter tone is diminished, higher intragastric pressure, slower esophageal peristalsis

What causes heartburn during pregnancy?

Small meals

What intervention can help manage heartburn by allowing the gastrointestinal tract to keep up?

Constipation and elevated pressure in rectal veins

What causes hemorrhoids during pregnancy?

More fiber

What intervention can help prevent constipation caused by the enlarging uterus?

Elevated hepatic arterial and portal venous flow and increased liver stiffness

What changes occur in the liver during pregnancy?

Hypervolemia

What causes elevated hepatic arterial and portal venous flow?

Transient diabetes insipidus

What condition may arise due to increased plasma dilution and increased placental metabolism of vasopressin?

Total alkaline phosphatase, total albumin, leucine aminopeptidase

Which liver function test values increase during pregnancy?

AST (aspartate transaminase), ALT (alanine transaminase), bilirubin, serum albumin

Which liver function test values decrease due to increased plasma dilution?

Increased size

How does the gallbladder change in size during pregnancy?

Increased prevalence of gallstones

What is a common gallbladder-related issue during pregnancy?

Slower GI motility and decreased contractility

What contributes to the increased prevalence of gallstones during pregnancy?

Progesterone

What causes decreased contractility of the gallbladder?

Progressive elevation of the diaphragm

What displaces the heart to the left and rotates it on its long axis during pregnancy?

Larger cardiac silhouette and benign minimal pericardial perfusion (fluid build-up)

What can be seen in radiographic studies of the heart during pregnancy compared to a non-pregnant woman?

Exaggeratedly split

How is the first heart sound modified in pregnant women?

90%

In what percentage of pregnant women can a third heart sound be heard distinctly?

Systolic murmurs

What type of murmurs appear in most pregnant women, specifically 95%?

Along the sternal border (left)

Where are systolic murmurs typically heard in pregnant women?

Aortic or pulmonary origin

Systolic murmurs heard in pregnant women often coincide with what origin?

Grade 2/4

Systolic murmurs become abnormal if they are louder than what grade?

Continuous murmurs

What type of murmurs can be heard from breast vasculatures in pregnant women?

Mammary soufflé

What is another name for continuous murmurs heard from breast vasculatures?

Second intercostal space

Where are mammary soufflés located maximally?

Heart rate (HR) and stroke volume (SV)

What two factors is cardiac output a product of?

5th weeks AOG

When is an increase in cardiac output (CO) seen during pregnancy?

Stroke volume

What is primarily responsible for the early increase in cardiac output during pregnancy?

10-20 weeks AOG

When is the peak of increased pre-load seen during pregnancy?

40-50%

By how much does blood volume increase during pregnancy?

Plasma volume and RBC mass

Blood volume increases during pregnancy due to an increase in what?

Auto diuresis

What process, along with blood loss from delivery, helps blood volume return to normal pre-pregnant levels in postpartum?

5th weeks AOG

When does heart rate begin to increase during pregnancy?

32nd weeks AOG

When does heart rate increase to a maximal increment of 15-20 bpm during pregnancy?

30-50%

By how much does cardiac output increase during pregnancy?

300-500mL

How much additional blood is transferred from the uterus to the general circulation during labor contractions?

Vasodilatory effect of progesterone and prostaglandins

What causes the decrease in blood pressure during pregnancy?

35 and 25 mmHg

By how much does systolic and diastolic blood pressure transiently increase during labor, respectively?

Left lateral recumbent to the supine position

What change in maternal position can result in a decrease in cardiac output by 25-30% at term?

5-6 bpm

Turning a pregnant patient from the left lateral recumbent to the supine position can result in an increase in heart rate by how much?

Compression of the great vessels (aorta and IVC) by the gravid uterus

What causes supine hypotension syndrome?

10%

Supine Hypotension Syndrome happens in approximately what percent of women?

Decreases stroke volume and cardiac output

What effect does supine hypotension have on stroke volume and cardiac output?

Hypoxic

What will happen to the fetus when the placental blood flow is decreased?

Left lateral decubitus or recumbent position

What position relieves the compression of the great vessels in supine hypotension syndrome?

Adequate perfusion to the uterus and placenta

Assuming the left lateral decubitus or recumbent position results in what perfusion?

Relaxant effect of progesterone and Endothelium-derived relaxing factors (e.g., nitric oxide, prostacyclin) on venous walls

What causes venous compliance to increase progressively during pregnancy?

Blood stagnation in the lower extremities

What does an increase in venous compliance result in, regarding blood flow?

Occlusion of the pelvic veins and IVC by the gravid uterus

What contributes to dependent edema, varicosities, and hemorrhoids in pregnant women in the supine position?

Deep vein thrombosis

What is the most lethal of all complications during pregnancy related to circulation?

Renin-Angiotensin-Aldosterone Axis

What system is intimately involved in blood pressure control via sodium, potassium, and water balance?

Maternal kidneys and placenta

Where is renin produced?

Maternal and fetal liver & Augmented estrogen production

Where is angiotensinogen produced and what augments it's production?

First trimester

When is angiotensinogen important for blood pressure maintenance?

Water retention and vasoconstriction

What effects do elevated levels of angiotensinogen have?

Sodium retention, potassium excretion, and blood volume expansion

What are the effects of aldosterone in pregnancy?

Refractoriness to the vasoconstrictive-pressor effects

A normal pregnancy develops and maintains what to increased levels of RAAS?

Preeclamptic

In pregnancies that are destined to be what, this refractoriness is completely not present?

Progesterone related

Diminished vascular responsiveness to angiotensin II may be what related?

Atrial Natriuretic Peptide (ANP) and Brain Natriuretic Peptide (BNP)

What are the two cardiac natriuretic peptides?

Non-pregnant range

During normal pregnancy, are cardiac natriuretic peptides maintained in the non-pregnant range or elevated?

Extracellular fluid volume expansion and elevation in plasma aldosterone

What is ANP involved in?

Screening for depressed left ventricular systolic function and prognosis of chronic heart failure

What may ANP and BNP be useful in?

Preeclampsia

In particular, what was BNP found to be increased in patients with?

Chamber wall stretching

What stimulates cardiomyocytes to secrete cardiac natriuretic peptides?

Natriuresis, diuresis, and vascular smooth-muscle relaxation

What processes do cardiac natriuretic peptides provoke to control blood volume?

Vascular tone, blood pressure, and sodium balance

What processes does increased production of prostaglandins play a central role in during pregnancy?

Prostacyclin (PGI2)

What is the principal prostaglandin of endothelium?

Vasodilation

What does prostacyclin maintain during pregnancy?

Preeclampsia

Deficiency of PGI2 is associated with pathological vasoconstriction, particularly in the pathogenesis of what?

Natriuretic

Renal medullary prostaglandin E2 synthesis is elevated during late pregnancy and presumed to be what?

Preeclampsia

The ratio of PGI2 to thromboxane in maternal urine and blood may be important indicators of what?

Vasoconstrictor

Is endothelin-1 a vasodilator or vasoconstrictor?

Angiotensin II, arginine, vasopressin, and thrombin

What stimulates the production of endothelin-1?

ANP, aldosterone, and catecholamines

Endothelin-1 stimulates the release of what?

Preeclampsia

Is endothelin-1 elevated in preeclampsia?

Vasodilator

Is nitric oxide a vasodilator or vasoconstrictor?

Preeclampsia

Lack or abnormal synthesis of nitric oxide has been linked to what?

4 cm

Approximately how much does the diaphragm rise due to the enlargement of the uterus during pregnancy?

2 cm

Approximately how much does the transverse diameter of the thoracic cage lengthen during pregnancy?

6 cm

Approximately how much does the thoracic circumference increase during pregnancy?

Functional residual capacity (FRC)

Which lung capacity decreases by 20-30% or 400-700 mL during pregnancy?

Expiratory reserve volume (ERV) and Residual volume (RV)

What are the subcomponents of FRC that decrease during pregnancy?

Maternal hyperventilation and hypocapnia

What does the increase in maternal tidal volume result in?

Progesterone

What is the enhanced respiratory drive primarily due to?

5-10%

By how much does inspiratory capacity rise during pregnancy?

No change or decreases by less than 5% at term

What happens to total lung capacity during pregnancy?

Reduction in FRC and its subcomponents ERV and RV

What are the most significant changes in lung volume during pregnancy?

Upward displacement of maternal diaphragm

The reduction in FRC and its subcomponents ERV and RV are primarily the result of what?

Rise progressively as gestation advances

What happens to peak expiratory flow rates as gestation advances?

Unaffected

How is lung compliance affected by pregnancy?

Increased

How is airway conductance affected by pregnancy?

Reduced

How is total pulmonary resistance affected by pregnancy?

Progesterone

Airway conductance is increased possibly because of what?