Changes in Obstetric Physiology Flashcards

1
Q

Plasma Volume

A

Increases by 45% due to progesterone/oestrogen causing renin release and therefore activation of renin-angiotensin axis causing sodium retention and increase in total body water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Red cell mass

A

Increases by 20% due to increase in renal erythropoietin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Haemoglobin concentration

A

Falls to around 120 g/L - physiological anaemia of pregnancy (the increase in plasma volume is more than the increase in red cell mass)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

White cell count

A

Increases throughout pregnancy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Systemic vascular resistance

A

Reduces by 20% due to increased levels of oestrogen and progesterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Systolic and diastolic blood pressure

A

Reduced due to lower SVR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Heart rate

A

Increases by 25% as a response to reduced SVR (by 20%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Stroke volume

A

Increases by 25%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Cardiac output

A

Increases by 50% by third trimester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Aortocaval compression: compensation

A

Occurs typically after 20 weeks, may cause maternal hypotension - compensation is an increase in sympathetic tone causing vasoconstriction and tachycardia and utilisation of azygos veins and vertebral plexus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Aortocaval compression: complications

A

In 10% of mothers, causes inadequate blood pressure in the supine position (and may cause mother to lose consciousness)
However, may cause foetal hypoxia in the asymptomatic mother

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Coagulation: Factors and Fibrinogen

A

Gradually increase therefore pregnancy is a hypercoagulable state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Platelets

A

Function remains normal. Increased turnover.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Anatomical changes of the respiratory system

A

Capillary engorgement and increased oedema of the upper airway (therefore bleeding is more likely and intubation may be more difficult)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Minute ventilation

A

Increased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Functional Residual Capacity

A

Reduced by 20%

17
Q

Residual volume and expiratory reserve volume

18
Q

Inspiratory reserve volume

19
Q

FEV1, Vital Capacity, Total Lung Capacity

20
Q

Pre-oxygenation

A

Less effective due to reduced FRC

21
Q

Respiratory Rate

A

Increased by 10% (progesterone mediated hypersensitivity to CO2)

22
Q

Renal function

A

Increased (therefore reduced serum urea, creatinine and bicarbonate)

23
Q

Propensity to UTI

A

Increased due to progesterone mediated uterine smooth muscle relaxation causing urinary stasis

24
Q

Acid-base regulation

A

Increased RR causes reduced PCO2 causing leftward shift in oxyhaemoglobin dissociation curve

25
2,3-DPG concentration
Increased by 30%
26
Lower oesophageal sphincter tone
Reduced, increasing propensity to heartburn (worsened by displacement by gravid uterus) - progesterone induced smooth muscle relaxation
27
Upper oesophageal sphincter tone
Not affected
28
Gastric emptying
Pregnancy does not affect gastric emptying | However, labour increases gastric volume and decreases gastric emptying
29
Insulin production
Rises
30
Insulin resistance
Rises
31
Does insulin cross the placenta?
No
32
Superior boundary of the epidural space
Foramen magnum
33
Inferior boundary of the epidural space
Sacrococcygeal membrane
34
Anterior boundary of the epidural space
Posterior longitudinal ligaments, vertebral bodies
35
Posterior boundaries of the vertebral space
Vertebral laminae, ligamenta flava
36
Lateral boundaries of the vertebral space
Open, pedicles and intervertebral foraminae
37
Layers of ligament to the epidural space
``` Supraspinous ligament (crunchy, approx 2cm) Interspinous ligament (spongy, up to 6cm) Ligamentum flavum (variable thickness, tough, loss of resistance technique here) ```
38
Epidural test dose
Small enough that it will do no harm if in the wrong place e.g. subarachnoid