Maternal Physio - Pulmo Flashcards Preview

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Flashcards in Maternal Physio - Pulmo Deck (10)
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1
Q

Respiratory structure changes

A
  • Transverse diameter increases ≈ 2 cm → subcostal angle widens
  • Diaphragm rises about 4 cm
  • Thoracic circumference ↑ about 6 cm
  • Memory aid:*
  • TDC - 2, 4, 6
2
Q

Diaphragmatic excursion is ____ {lesser/greater) in pregnancy

A

Greater

3
Q

If the thoracic circumference increases by 6 cms, will the residual volume also increase?

A

No; that change is not enough to prevent reduction in the RV created by the elevated diaphragm

4
Q

Respiratory parameter that is unchanged

A
  • Respiratory rate
  • Lung compliance
  • Vital capacity
  • Inspiratory reserve volume
  • Summary:*
  • C Rate IRV VC
5
Q

Respiratory parameter that is increased

A
  • Tidal volume
  • Minute ventilatory volume
  • Minute oxygen uptake
  • Inspiratory capacity
  • Summary:*
  • IC TV Minute by Minute increasingly
6
Q

Respiratory parameter that is decreased

A
  • Functional residual capacity
  • Expiratory reserve volume
  • Residual volume
  • Total lung capacity
  • Memory aid:*
  • Functional T REx Decreased
7
Q

Normal acid-base status in pregnancy and mechanism

A

Compensated respiratory alkalosis due to more CO2 being blown off (increased tidal volume)

8
Q

Cause of physiologic dyspnea

A
  • Results from increased tidal volume that lowers the blood PCO2, which paradoxically causes dyspnea
  • Progesterone appears to act centrally:
    • lowers the threshold and increases the sensitivity of the chemoreflex response → ↑ respiratory effort
9
Q

Blood pH change and effect to dissociation curve

A

Increased only minimally

Shift to the left of the oxygen dissociation curve

↑ affinity of hemoglobin to maternal blood

Compensation: increase in 2, 3-diphosphoglycerate in maternal erythrocytes to shift the curve back to the right

10
Q

Physiologic advantage of maternal hyperventilation

A

Hyperventilation

Decreased CO2

Aids CO2 transfer from fetus to mother and facilitates O2 release to fetus