Asthma in Pregnancy

1
Asthma in Pregnancy

• Timothy Hoskins, M.D.
• October 5, 2005

2
Objectives

• Elicit pertinent history from asthma patient
• Perform targeted physical exam to detect findings
  associated with asthma
• Interpret Results of basic PFTs
• FEV1
• Describe differential diagnosis of asthma
• Describe indications for referral of a patient
  with more severe asthma
• Review basic pathophysiology of asthma
• Review treatment of asthma in antepartum,
  chronic, and acute stages

3
Epidemiology of Asthma

• 15 million people in the U.S. have asthma
• 2003 estimated prevalence of asthma in pregnant
  women was 5-9
• According to the National Asthma Education
  Program an additional 10 of the population
  appears to have nonspecific airway hyper
  responsiveness
• Prevalence of asthma appears to be increasing in
  pregnant women
• 0.2 of pregnancies will be complicated by status
  asthmaticus

4
Pathophysiology of Asthma

• Characterized by chronic airway inflammation with
  acute reversible airway obstruction to a variety
  of stimuli
• Obstruction component bronchial smooth muscle
  hyper responsiveness to stimuli
• Inflammatory component Divided into two separate
  responses
• Early asthmatic response medicated by histamine
  occurs within minutes
• Late asthmatic response non histamine related
  occurs over hours

5
Pathophysiology of Asthma

• Chronic Inflammatory Disorder
• Hallmarks reversible airway obstruction for
  bronchial smooth muscle contraction, mucous
  hypersecretion, and mucosal edema
• Mast cell activation by cytokines mediates
  bronchoconstriction by release of histamines,
  prostaglandin D2 and leukotrienes

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Pathophysiology of Asthma

• If left untreated chronic airway inflammation may
  lead to permanent airway changes
• Airway thickening causes irreversible airflow
  limitation and shortened life expectancy

7
Common Asthma Triggers

• URI
• Allergens
• Aerobic Exercise
• Irritants
• Air Pollution
• Strong emotions
• Medications
• Beta blockers

8
Clinical Presentation

• Wheezing
• Dyspnea
• Chest tightness
• Use of accessory respiratory muscle
• Central or peripheral cyanosis
• Tachycardia
• Prolonged expiration
• Altered mental status

9
Differential Diagnosis of Asthma

• Pulmonary
• COPD exacerbation
• Infection
• PE
• Obstruction
• Allergic anaphylaxis
• GERD
• Addisons disease
• Cardiac
• CHF
• Valvular heart disease
• Carcinoid tumor

10
Classification of Asthma by National Asthma
Education Program (NAEP)

• Based on symptoms (wheezing, coughing, dyspnea)
  and objective tests of PFTS
• FEV1
• Volume of air forcibly exhaled during the first
  second of the forced expiratory manuever
• Assesses the degree of obstruction
• Peak expiratory flow rate (PEFR) is most commonly
  used and correlates closely with FEV1

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Modified NAEP Asthma Severity Classification

• Mild Asthma
• Brief (lt1 h) symptomatic exacerbations lt
  twice/week
• PEFR gt 80 of personal best
• FEV1 gt 80 of predicted when asymptomatic
• No nocturnal symptoms

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Modified NAEP Asthma Severity Classification

• Moderate Asthma
• Symptomatic exacerbations gt twice/week
• Exacerbations affect activity levels
• Exacerbations may last for days
• PEFR,FEV range from 60 to 80 of predicted
• Regular medications necessary to control symptoms

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Modified NAEP Asthma Severity Classification

• Severe Asthma
• Continuous symptoms/frequent exacerbations limit
  activity levels
• PEFR,FEV lt60 of expected, and are highly
  variable
• Regular oral corticosteroids necessary to control
  symptoms

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Effects of Pregnancy on Asthma

• No evidence to suggest that pregnancy has a
  predictable effect on underlying asthma
• Two prospective studies (1998) of more than 500
  women found about equal thirds of the group
  either improved, remained unchanged or clearly
  worsened
• Again baseline asthma severity correlated with
  asthma morbidity during pregnancy
• Mild asthma 13 had exacerbation
• Moderate 26 had exacerbation
• Severe 50 had exacerbation

15
Effects of Asthma on Pregnancy

• Controversial results in terms of preeclampsia,
  cesarean delivery, prematurity, IUGR, and
  perinatal mortality rate
• Generally unless there is severe disease, asthma
  has relatively minor effects on pregnancy outcome
• Most studies show slight increase of incidence of
  preeclampsia, pre-term labor, low birthweight
  infants and perinatal mortality

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Effects of Asthma on Pregnancy

• A prospective study by Dombrowski (2000), preterm
  delivery was not increased among pregnancies
  complicated by asthma compared to non-asthmatic
  controls.
• However, the majority of women in the study with
  severe asthma showed an increase of preterm labor
  by two fold.
• Status asthmaticus characterized by resp failure
  substantially increases maternal and perinatal
  mortality
• Bracken (2003) found preterm delivery only
  slightly increased with asthma while IUGR
  increased with severity of asthma

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Antenatal Management

• Asthma history
• Severity of symptoms
• Nocturnal symptoms
• Pregnant patients with mild well controlled
  asthma may receive routine prenatal care
• Moderate and Severe asthma will need more
  frequent visits and consider referral in severe
  cases

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Referral Indications

• To Asthma/Allergy subspecialist
• Diagnosis is severe, persistent asthma
• Diagnosis is unclear
• More complete allergy evaluation is desired
• Asthma is not under control even after
  appropriate avoidance measures are taken and
  medications have been adjusted and redirected
• Life threatening exacerbation

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Management

• Ultimate goal is prevention of hypoxic episodes
  to mother and fetus
• Relies on four components
• Objective measures for accurate monitoring
• Minimizing asthma triggers
• Patient education
• Pharmacologic therapy

20
Objective Measures for Accurate Monitoring

• FEV1 is best single measure of pulmonary function
  but requires a spirometer
• PEFR correlates well with FEV1 and is inexpensive
  as it is measured by peak flow
• Self-monitoring of PEFR aids in detecting early
  signs of deterioration in lung function

21
Minimizing Asthma Triggers

• Use plastic mattress and pillow covers
• Weekly washing of bedding in hot water
• Animal dander control
• Weekly bathing of the pet
• Keeping pets out of the bedroom
• Remove pet from the home
• Cockroach control
• Hardwood flooring
• Avoid tobacco smoke
• Inhibit mite and mold growth by reducing humidity
• Do not be present when home is vacuumed

22
Patient Education

• Understanding that asthma control is important to
  fetal well being
• Reduction of triggers
• Understanding of basic medical management
  including self monitoring

23
Pharmacologic Therapy

• Goals
• Relieve bronchospasms
• Protect airways from irritant stimuli
• Prevent pulmonary and inflammatory response to
  allergen exposure

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Chronic Asthma Management

• Beta agonists
• Inhaled Corticosteroids
• Cromolyn and Nedocromil
• Theophylline
• Leukotriene modifiers

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Beta agonists

• Mild asthma
• Acute exacerbations
• Rapid onset of action
• Can cause tremor, tachicardia, and palpitations

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Inhaled Corticosteroids

• Preferred for persistent asthma
• Goal is to reduce dependence on beta agonists for
  symptomatic relief
• Significantly reduce hospitalization in both
  pregnant and non pregnant women
• Side effects
• Short term steroid use
• Reversible increases in glucose, decreases
  potassium, fluid retention with weight gain, mood
  alterations including rare psychosis,
  hypertension, peptic ulcers, aseptic necrosis of
  the femur, and very rare allergic reactions
• Long term steroid use
• Height and growth, immune suppression,
  hypertension, cataracts, and hirsutism

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Cromolyn and Nedocromil

• Inhibit mast cell degranulation
• Ineffective for acute asthma
• Not superior to inhaled corticosteriods

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Theophylline

• Bronchodilator with a possible anti-inflammatory
  component
• Used much less frequently now that inhaled
  steroids became available.
• No known teratogenic effects
• Long duration of action
• Used as additional therapy when beta agonists and
  anti-inflammatory agents do not adequately
  control symptoms

29
Leukotriene Modifiers

• Category C
• Little experience with use in pregnancy
• Given orally for maintence not effective in acute
  setting
• Often used in conjunction with oral
  corticosteroids to obtain minimal steroid dose
• Ducharme in 2002 reviewed all randomized trials
  conducted through 2001
• Concluded these agents only slightly improved
  control

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Step Therapy

• Least number of medications needed to control
  symptoms should be used
• Increase number and frequency of medications with
  increasing severity
• Systemic corticosteroids are indicated for
  exacerbations not responding to initial beta
  agonist therapy regardless of asthma severity

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Home Management of Acute Asthma Exacerbations

• Use inhaled albuterol two to four puffs and check
  PEFR in 20 minutes
• If PEFR lt50 predicted or symptoms are severe
• obtain emergency care
• If PEFR 50 to 70 predicted
• Repeat albuterol treatment, check PEFR in 20
  minutes
• If PEFR remains lt70 predicted Contact caregiver
  or go for emergency care
• If PEFR gt70 predicted
• Continue inhaled albuterol (two to four puffs q3
  4h for 6-12h as needed)
• If decreased fetal movement
• Contact caregiver or go for emergency care

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Emergency Assessment and Management of Asthma
Exacerbations

• Initial Evaluation
• History
• Examination
• PEFR
• Oximetry
• Fetal monitoring if potentially viable

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Emergency Assessment and Management of Asthma
Exacerbations

• Initial treatment
• Inhaled beta2 agonist (3 doses over 60-90
  minutes)
• Oxygen to maintain saturation gt 95
• If no wheezing and PEFR or FEV1 gt 70 baseline,
  discharge with follow up

34
Emergency Assessment and Management of Asthma
Exacerbations

• If oximetry lt50 FEV1, lt1.0 liter, or PEFR lt 100
  liters/min upon presentation
• Continue nebulized albuterol
• Start intravenous corticosteroids
• Obtain arterial blood gases
• Admit to intensive care unit
• Possible intubation

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Emergency Assessment and Management of Asthma
Exacerbations

• If PEFR or FEV1 gt 40 but lt70 baseline after
  beta 2 agonist
• Obtain arterial blood gases
• Continue inhaled beta 2 agonist every 1-4 hours
• Start intravenous corticosteroids in most cases
• Hospital admission in most cases

36
Labor and Delivery

• Asthma usually quiesent thought to be due to
  increase in cortisol
• Continue regular asthma medications
• Adequate hydration and analgesia to reduce
  bronchospasm
• Stress doses of corticosteroids are indicated for
  patients given systemic steroids within preceding
  four weeks

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Labor and Delivery (continued)

• Establish baseline PEFR on admit and serially
  thereafter if symptoms develop
• Prostaglandin E1 and E2 may be used for cervical
  ripening, PPH
• Hemabate may cause bronchospasms and should be
  avoided

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PROLOG Sample Question

• A 22-year old, G2, P1, at 11 WGA has history of
  chronic asthma. Currently she has symptoms of
  wheezing and difficulty breathing 2 or 3 times
  per month and has never required hospitalization.
  She does not have nocturnal symptoms and is free
  of symptoms b/t exacerbations. To control her
  asthma, you prescribe
• A) daily inhaled beta2 agonist
• B) inhaled beta2 agonist prn
• C) daily inhaled corticosteroid
• D) daily inhaled corticosteroid prn
• E) daily inhaled cromolyn sodium

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Bibliography

• Williams Obstetrics 22nd edition pgs 1060-1064
• Up to Date.com Management of Asthma
• Marx Rosens Emergency Medicine Concepts and
  Clinical Practice 5th edition
• Maternal-Fetal Medicine Principles and Practice
  4th edition pgs 962-967