3. Physiology
        3.8. Maternal and foetal
            3.8.2. Maternal
3.8.2.2. Respiratory changes in pregnancy

Respiratory changes in pregnancy

[Ref: PK1:p349-350]

Changes to anatomy

Diaphragm

Thoracic cage

These changes are due to relaxin
* Secreted by corpus luteum
* Relaxes ligament attachments of the ribs

Other changes

 

Changes to lung volume

Significant changes in lung volume occurs from the 20th week

ERV and RV

Causes of ERV and RV change

  1. Elevation of the diaphragm (main cause)
  2. Increase in pulmonary blood volume

FRC

Tidal volume

NB:

Capacities

At term

NB:

According to [KB2:p248, AA5:p326]
* IRV is unchanged

 

Other changes

Compliance

--> Total lung compliance decreases by 20%

NB:

Minute ventilation

Component

NB:

Cause

 

Result

At term, (with full renal compensation)

Overall,

Other notes

Oxygen flux

According to [KB2:p249],

Overall,

Changes during and after labour

During labour

After delivery

 

Anaesthetic implication



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