Respiratory Disease

Question 1

Why is there an increased oxygen demand in pregnancy?

Answer 1

Increased metabolic rate

20% increased consumption of O2

Question 2

What is the change in the minute ventilation in pregnancy?

Answer 2

40-50% increased

Mostly due to an increase in tidal volume (rather than RR)

Question 3

What is normal on a ABG in pregnancy?

Answer 3

Mild fully compensated respiratory alkalosis
Arterial pH 7.44
Maternal hyperventilation causes arterial pO2 to increase and pCO2 to fall
Compensatory fall in serum bicarbonate to 18-22

Question 4

What is the effect of pregnancy on functional residual capacity?

Answer 4

Diaphragmatic elevation in late pregnancy
Decreased FRC

Vital capacity remains unaltered

Question 5

How is PEFR and FEV1 affected by pregnancy?

Answer 5

Unaffected

Question 6

How many women have dyspnoea of pregnancy?

Answer 6

Up to 75%

Increased awareness fo the physiological hyperventilation of pregnancy
Leading to a subjective feeling of breathlessness

Commonest in third trimester
Classically, it is present at rest or while talking and may paradoxically improve during mild activity

Question 7

What is the commonest chronic medical illness to complicate pregnancy?

Answer 7

Asthma, affecting up to 7% women

Question 8

What is the pathogenesis of asthma?

Answer 8

Smooth muscle spasm in the airway walls
Inflammation with swelling and excessive production of mucous

Causes
Reversible bronchoconstriction

Question 9

How is asthma diagnosed?

Answer 9

Personal or family hx atop

Low PEFR or FEV1 / FVC ratio (<0.7)
Reversibility of bronchoconstriction

Question 10

What is the effect of pregnancy and labour on asthma?

Answer 10

May improve, deteriorate or remain unchanged

Those with severe asthma are at greater risk of deterioration

Acute asthma in labour is unlikely because of the increased endogenous steroids at this time

Question 11

What is the effect of asthma on pregnancy?

Answer 11

Severe poorly controlled asthma with chronic hypoxaemia can lead to
PIH / PET
PTL / B
FGR and LBW
Neonatal morbidity
- TTN, neonatal hypoglycaemia, neonatal seizures, NICU admission

Question 12

What disease can exacerbate asthma?

Answer 12

GORD

Question 13

Women with asthma and what other factors are at risk of death?

Answer 13

Psychosocial factors

• Psychiatric illness
• Drug or alcohol use
• Unemployment
• Denial

Question 14

The estimated radiation to the fetus from a CXR is

Answer 14

Less than 0.01mGy

Maximum recommended exposure in pregnancy is 5rad

CNP

Question 15

What are adverse clinical features of pneumonia?

Answer 15

RR > 30
O2 sat <92
Hypotension SBP < 90
Acidosis, raised lactate
Bilateral / multilobar involvement on CXR

Question 16

How should PCP be treated in pregnancy?

Answer 16

High dose cotrimoxazole

Question 17

Among women with TB in pregnancy, what is the % with extra-pulmonary TB?

Answer 17

50%

Question 18

How is TB diagnosed?

Answer 18

Acid fast bacilli
Mantoux test
For non-pulmonary TB: PCR from biopsy / tissue
QuantiFERON- TB

Question 19

What is the management of TB in pregnancy?

Answer 19

Rifampicin (co-prescribe Vit K)
Isoniazid (co-prescribe pyridozine 50mg / day)
Pyrazinamide and/or ethambutol

Monthly LFTs due to risk of isoniazid / Rifampicin hepatotoxicity

Monitor fetal growth (pulmonary TB may be associated with LBW)

Neonatal BCG vaccination

Question 20

What are the clinical features of Cystic Fibrosis?

Answer 20

1. Early, repeated and persistent lung infection, bronciectasis and respiratory failure
2. Pancreatic insufficiency - malnutrition and DM

Question 21

What is the pathogenesis of CF?

Answer 21

Dysfunction of all exocrine glands
Abnormal mucous production and high sweat sodium
Abnormalities in the CF transmembrane conductance regulator protein, a trans membranous chloride channel, causing impaired movement of water and electrolytes across epithelial surfaces, leading to impaired hydration of secretions in glandular organs

AR

Question 22

What is the effect of pregnancy on CF?

Answer 22

Well tolerated
Mortality increased in women with moderate-severe lung disease

Deterioration in lung function
Pulmonary infective exacerbations
Congestive cardiac failure

Women may deteriorate and die while the child is still young

Question 23

What is the effect of CF on pregnancy?

Answer 23

Poor maternal weight gain
PTL
FGR - increased with chronic hypoxia and/or cyanosis

Question 24

In CF, what are the contraindications to pregnancy?

Answer 24

Pulmonary hypertension
Cor pulmonary
FEV1 < 30-40% predicted

Question 25

How should women with CF be counselled pre-pregnancy?

Answer 25

Screened for contra-indications

Screening for DM
Determination of carrier status of the partner

Women may deteriorate while the child is still young and die

Question 26

What is the management of CF in pregnancy?

Answer 26

Nutrition
- enzyme supplements, high calorie dietary supplements, 
Screening DM
Chest PT
Avoidance of hypoxia
Growth scans

Prolonged attempts at pushing / second stage may precipitate pneumothoraces

Question 27

In severe restrictive lung disease, what gives an indirect assessment of the degree of hypoxia?

Answer 27

Polycythemia

Which in itself, is associated with an increased risk of thrombosis due to hyperviscosity

Question 28

What is the treatment for women with ILD in pregnancy?

Answer 28

Immunosuppression