maternal physiology 5/13

Question 0

1 issue in obstetric airway issues is…?

Answer 0

failed intubation d/t fact that parturiant airway can change drastically from pre labor to post labor (d/t fluid shifts etc).
—cause of most deaths regarding labor and delivery

Question 1

objectives:

Answer 1

1. describe the normal respiratory changes assoc. with pregnancy
2. describe the normal cardiovascular changes assoc. w/ pregnancy
3. describe the changes in the cardiac output assoc. w/ preg, labor and post partum

Question 2

pregnant woman at term has what changes in lung volumes:

-what happens to residual volumes?

Answer 2

• residual volumes decrease from 1000 to 800;

Question 3

pregnant woman at term has what changes in lung volumes:

-what happens to FRC?

Answer 3

-FRC decreases to 1350 from 1700 (d/t elevation of diaphragm)

Question 4

pregnant woman at term has what changes in lung volumes:

- what happens to total lung capacity?

Answer 4

-total lung capacity increases from 3200 to 4000.

Question 7

1. why does lung volume increase ( hormonally)?

2. how much is the change in ap diameter?

Answer 7

1. relaxin causes softening of ligaments causing rib cage to become more flexible increasing AP diameter.
2. 5-7 cm

Question 8

oxyhgb dissociation curve-

1. where is normal P50
2. what is normal P50 in a pregnant woman?
3. pre-ecclamptic woman P50

Answer 8

1. 26
2. 30
3. 24 (higher affinity for oxygen); causes lower oxygen to baby

Question 9

1. when rapid sequencing a pregnant woman, what do you put on first?
2. why?

Answer 9

1. put on oxygen first before pulse ox etc; strap the mask on
2. they have less oxygen tension and therefore desaturate quicker

Question 10

why will a woman with cardiac issues have problems post partum

Answer 10

blood volume that was going to uterus is now just circulating since uterus has shrunken. they will have overload issues if they have cardiac issues.

Question 11

what is the name for aspiration pneumonia during caeserean section

Answer 11

mendelson’s pneumonia

Question 12

what causes maternal changes in physiology?

Answer 12

• -hormones
• -mechanical effects of gravid uterus
• -increased metabolic and oxygen requirements
• -demands of feto-placental unit
• -placental circulation induced hemodynamic alterations

Question 13

Respiratory volume changes during pregnancy:

1. what happens to vT (in %)?
   - -what causes the changes?

Answer 13

Lung Volumes and Capacities

1. vT increases by 23% by first trimester (45% total)
   - -due to reduction of inspiratory reserve volume

Question 14

Respiratory volume changes during pregnancy:

2. what happens to TLC (total lung capacity)?

Answer 14

2. TLC unchanged

Question 15

Respiratory volume changes during pregnancy:

3. what happens to RV (residual volume)

Answer 15

3. RV decreases slightly

Question 16

Respiratory volume changes during pregnancy:

4. what happens to IC (by %)?
   - what trimester? why?

Answer 16

• 4. IC increases by 15% during third trimester

- due to increases in Vt and IRV

Question 17

Respiratory volume changes during pregnancy:

5. what happens to ERV (expiratory reserve volume)?

Answer 17

-5. Decrease in ERV

Question 18

Respiratory volume changes during pregnancy:

6. what happens to FRC ( functional residual capacity(by %))?
   - By what trimester?
   - why?

Answer 18

• 6. FRC decreased by 80%
• by term
• due to elevation of the diaphragm (decreased ERV, RV)

Question 19

inspiratory volume changes during pregnancy:

7. what does lying supine do to FRC (by %)?

Answer 19

-7. Supine position causes FRC to decrease to 70% of pp (pre pregnancy) volume

Question 20

ventilation and oxygenation changes:
what happens to minute ventilation?
-why?

Answer 20

MV increases due to increase in Vt
–related to hormonal changes and increased carbon dioxide production (increases 30% over pp)

• -

Question 21

ventilation and oxygenation changes:

What happens to alveolar ventilation (by %)?

Answer 21

– Increased alveolar ventilation, 30% over pregnancy

Question 22

ventilation and oxygenation changes:

-how is ventilation in 1st trimester different from later months?

Answer 22

– hyperventilation first trimester, dyspnea during later months.

Question 23

ventilation and oxygenation changes:

• Progesterone’s effects on respiratory:(a,b,c)
• what do progesterone & estrogen do for respiration?

Answer 23

• • Progesterone:
    a) is a respiratory stimulant
    b) Increases chemoreceptor sensitivity
    c) Increases leftward shift of CO2 response curve
• • increased estrogen and progesterone levels increased Hypoxic ventilatory response.

Question 24

ventilation and oxygenation changes:

-what is the pH change caused by pregnancy changes (alkalosis or acidosis)?

Answer 24

– Alkalosis

Question 25

ventilation and oxygenation changes:
what are alveolar PaO2 changes?
–why?

Answer 25

Alveolar PaO2 increased to 100-105mmHg (from 94)

–due to alveolar ventilation

Question 26

ventilation and oxygenation changes:

1. what is the change in oxygen uptake at rest?
   - -with contractions?
2. what else changes the oxygen uptake?
3. what do CRNAs do that improves this? how?

Answer 26

1. Oxygen uptake (consumption)increases markedly; 20% at rest, ­
   - -63% with ​​increased contractions
2. metabolism, ­increased work required in breathing
3. regional anesthesia during first stage of labor helps to eliminate increase in oxygen consumption–(decreases catecholamines).

Question 27

ventilation and oxygenation changes:

1. what are pregnant persons more vulnerable to?
2. short periods of apnea cause what?
3. what should ALWAYS be done patient before delivery (think o2 tension)?

Answer 27

1. more vulnerable to hypoxia.
2. Can see precipitous drop in PaO2 after short periods of apnea.
3. ALWAYS PREOXYGENATE !!!

Question 28

ventilation and oxygenation changes:

1. what “shift”occurs in oxy/hgb dissociation curve? to what amount?
   - what does this cause?
2. what happens to oxygen carrying capacity?

Answer 28

1. OXY/HGB curve shifted to right (30.2mmHG)
   - -have enhanced O2 unloading to the tissues.
2. O2 carrying capacity decreases from 19.5 to16.0 vol/100ml (hyperventilation ­ PaO2 102mmHg)

Question 29

1. what changes occur in capillaries?
2. what symptoms will be seen?
3. what might symptoms mimic?
4. what should you be careful with?
5. what may happen to airway?
6. what size airways should you have available?

Answer 29

1. Capillary Engorgement
2. congestion leading to swelling to nasal mucosa, respiratory tract, oropharynx, larynx, ​​​​​​trachea, and vocal cords
3. ​can have symptoms of URI and laryngitis
4. ​care with manipulation (suctioning, airways,laryngoscopy)
5. ​upper airway obstruction may occur early due to edema and ​​​​​engorgement
6. ​6.0 -7.0 cuffed tube (glottis often swollen); always have a smaller tube avail

Question 30

1. what should be done as far as evaluation of the airway (when)?
2. why?

Answer 30

1. initially (then make your plan)
   - - again before labor (then re-evaluate your plan)
2. because the airway can change alot d/t engorgement within minutes to hours

Question 31

1. female weight gain=___% of pre pregnancy weight or approximately __kg:
2. what is the breakdown of body weight:
   - uterus
   - amniotic fluid
   - fetus and placenta
   - blood volume and interstitial fluid
   - new fat and protein

Answer 31

1. 17% of pp weight or 12 kg
2. uterus=1 kg
   - –amniotic fluid=1 kg
   - –fetus and placenta=4 kg
   - –blood volume and interstitial fluid=4 kg
   - –new fat and protein=4 kg

Question 32

what (preventable) condition causes increases in adverse affects and ceserean deliveries?

Answer 32

obesity