INTRODUCTION :
Asthma is defined as a chronic inflammatory disease of the airway that is manifested by hyper responsiveness of airway to a wide variety of stimuli. It tends to be an episodic disease with exacerbations of reversible airway narrowing that are characterized clinically by coughing, wheezing and shortness of breath.
Asthma is probably the most common and potentially life threatening disorder to occur in pregnancy. The worldwide incidence is about 1 to 4%. It complicates in 0.5 to 1.5% of pregnancies and status asthmaticus complicates in 0.2%. In 20% the condition improves, in 30% cases it deteriorates and in 50% cases it remains unchanged.
In pregnancy, bronchodialator action is due to progesterone and cortisol and bronchoconstrictor action is due to reduced residual volume and increased PGF2 α.
There is no evidence that pregnancy has predictable effect on underlying asthma. 1/3rd of asthmatic women can expect worsening of disease at sometime during pregnancy. There is 18% increase in exacerbation of asthma following caesarian delivery compared with vaginal delivery.
EFFECTS OF ASTHMA ON PREGNANCY :
When severe asthma can affect pregnancy outcome . It may lead to abortions preterm labour, LBW, neonatal hypoxia etc.
There is a significant correlation between maternal pulmonary function and foetal birth weight.
Uncontrolled asthma has maternal risks and maternal deaths may be associated with status asthmaticus.
It may lead to life threatening complications like- pnuemothorax, pneumomediastenum, acute cor pulmonale, cardiac arrhythmias and muscle fatigue with respiratory arrest.
PATHOPHYSIOLOGY :
Allergens, respiratory infections, environmental pollutants, occupational exposure, cold air, emotional stress, strenuous exercise, aspirin and β blockers can precipitate asthma.
and secondary mediators like PGs,
thromboxanes and leukotrienes.
Mucus hypersecretion and mucosal edema
CLINICAL COURSE :
Clinically,
It may range from
|
DEATH
Functionally
Ventilation perfusion mismatching and airway narrowing
| Stage | PO2 | PCO2 | pH | FEV1 |
| Mild respiratory alkalosis | Normal | | | 65 – 80 |
| Respiratory alkalosis | | | | 50 – 64 |
| Danger zone | | normal | Normal | 35 – 49 |
| Respiratory acidosis | | | | <35 |
FEV – forced expiratory volume in 1 second
FOETAL EFFECTS :
Maternal alkalosis leads to fetal hypoxaemia well before maternal oxygenation is compromised.
Thus the fetus may be seriously compromised before maternal distress is severe.
This underscores the need for aggressive management of all pregnant women with acute asthma.
Therefore fetal response in effect becomes an indicator of maternal compromise .CLINICAL EVALUATION :
Signs :-
1) 1 Labored breathing
2) 2 Tachycardia
3) 3 Pulsus paradoxus
4) 4 Prolonged expiration and use of accessory muscles of respiration
Fatal signs:-
1) 1 Central cyanosis
2) 2 Altered consciousness
Investigations:-
1) 1 ABG analysis
2) 2 PEFR < 60% of baseline
3) 3 FEV1 < 20% suggestive of severe distress
4) 4 PO2 < 70 mm of Hg at sea level
5) 5 PCO2 > 35 mm of Hg at sea level
6) 6 PCO2 > 40 mm of Hg in pregnancy is suggestive of respiratory failure.
7) 7 pH < 7.35 (indication of hyperventilation and CO2 retention)
P
Preconceptional –
P
p possibility of child becoming asthmatic is 4%
If If 1 parent is asthmatic, the possibility is 8 to 10%
If both parents are asthmatic, the possibility is 30%
A Pregnancy –
A A STEP WISE PLAN is recognized by the
U.U. S. National Asthma Education And Prevention Programme &
British Thoracic Society.
A As told earlier, patient education is of utmost importance.
1) 1.Patient must measure PEFR twice daily.
2) 2.Use of proper inhaler
3) 3. Patient is given a written management plan
4) 4. Use of impermeable pillows
5) 5. Avoid pets at home
6) 6. No carpets in bedrooms
7) 7. Avoid cigarette smoke
If If PEFR reduces by 20% then step up the therapy and patient must see a physician
If If PFER reduces by 50% its an emergency and needs hospitalization.
TREATMENT OF ASTHMA HAS TWO MAJOR GROUPS
RESCUE AGENTS MAINTENANCE AGENTS
Relieve bronchospasm treat airway inflammation
Eg: β2 agonists Eg: steroids, mast cell stabilizers,
and ipratropium methyl xanthenes, leukotriene
| Category | Criteria | Step therapy |
| Mild intermittent PEFR>80% Variability<20% | -symptoms occur twice a week -at night twice a month -exacerbations last for hours to a few days -asymptomatic in between two episodes | -no daily treatment required -inhalation of β2 adrenergic agonists as needed |
| Mild persistant PEFR >80% Variability 20-30% | -symptoms occur more than twice a week -night symptoms more than twice a month -exacerbations may affect daily activity | - inhalation of β2 adrenergic agonists as needed -and daily treatment with inhaled chromolyn or nedochromil or low dose corticosteroids or theophylline |
| Moderate persistant PEFR 60-80% Variability >30% | -symptoms occur daily -night symptoms > once a week | -inhalation of β2 adrenergic agonists as needed -and daily treatment with low to medium dose corticosteroids -and daily treatment with salmeterol/theophylline preparation |
| Severe persistant PEFR <60% Variability >30% | -continual symptoms that limit activity -frequent night symptoms an d actual exacerbations | -inhalation of β2 adrenergic agonists as needed -and daily treatment with high dose corticosteroids -and daily treatment with salmeterol/theophylline preparation -and daily or alternate day treatment with systemic prednisolone |
If plan fails treatment with prednisolone orally for 5 to 10 days.
Intra partum :-
During labour ,exacerbation is rare because of natural outpouring of endogenous steroids and epinephrine associated with stress of delivery.
1) 1;Clinical evaluation of the patient in labour may be inaccurate to predict the severity.
2) 2:Stress dose corticosteroids must be given during labour if the patient had steroids within the previous 4 weeks . HYDROCORTISONE 100mg I.V. 8 hrly.
3) 3:Opoid analgesics must be avoided as they cause bronchconstriction and respiratory depression. FENTANYL is preferred as it is non histaminic releasing narcotic over meperidine and morphine.
4) 4: SYNTOCINON is preferred over ergometrine, because the latter causes bronchoconstriction.
5) 5: PGF2α should not be used as it precipitates bronchospasm.
6) 6: PGE1 and PGE2 can be used locally for induction of labour or abortion.
7) 7: EPIDURAL ANAESTHESIA is preferable to G.A. because of risk of atelectasis and chest infection by latter.
8) 8: If G.A. is given then bronchodialators like HALOTHANE and KETAMINE should be used.
9) 9:ABG analysis may be needed to assess oxygenation, ventilation and acid-base status.(PCO2 > 35mmHg and pH>7.35 indicates CO2 retension)
10) THEOPHYLLINE is used as an adjunct for nocturnal asthma.
Post natal :-
1) 1:Post natal physiotherapy
2) 2: Encourage breast feeding
3) 3: Restart maintenance drug therapy
4) 4: Encourage respiratory therapy to prevent atelectasis
5) 5:BARRIER CONTRACEPTIVES must be encouraged
6) 6:Advice VASECTOMY for terminal measures
Dr. Arpita Masalia
M.S. RESIDENT(GYNAEC)
P.G. SCHOLAR
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