eMedicine Specialties > Emergency Medicine > Obstetrics & Gynecology
Pregnancy, Asthma: Treatment & Medication
Updated: Jun 30, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Prehospital Care
- Address the airway status as needed.
- Provide early institution of beta-agonist inhalational therapy.
- Provide supplemental oxygen.
Emergency Department Care
Pregnant patients who present with typical mild exacerbations of asthma may be treated like regular asthmatics with bronchodilator therapy and steroids. However, special attention must be given to pregnant patients who present with severe asthma exacerbations because the resulting maternal hypoxia can have devastating consequences on the fetus.
The American College of Obstetricians and Gynecologist has issued practice guidelines for the management of asthma during pregnancy.2 On June 29, 2009, the American Thoracic Society and the European Respiratory Society jointly released new official standards on asthma evaluation for clinical trials and practice.1 The Medscape Medical News article, New Guidelines Issued for Asthma Assessment, has a more detailed discussion.
As always in the ED, address the ABCs. The patient should be placed on a cardiac monitor and pulse oximetry. The threshold of intubation should be low to prevent/limit hypoxic episodes to the fetus. Intubate and mechanically ventilate the following patients:
- Those in or near respiratory arrest
- Those failing to respond to treatment as evidenced by
- Hypoxemia despite supplemental oxygen
- Increasing CO2 retention
- Persistent/worsening level of consciousness
- Hemodynamic instability
The key to treating asthma in the pregnant patient is to frequently assess the patient, the severity of the attack, and the patient’s response to treatment.
- Hypoxia, acidosis, unequal breath sounds, pneumothorax, and atypical features serve as warning signs of severe exacerbations.
- Inhaled beta2-agonists are the mainstay of treatment.
- Beta2-agonist, inhaled and/or subcutaneous, is typically given 3 doses over 60-90 minutes.
- Beta-adrenergic blocking agents should be avoided due to bronchospastic effect.
- Early use of systemic steroids has been shown to reduce the length of stay in the ED and the admission rate; the effect of steroids is seen within 4-6 hours of the institution of therapy.
- Supply supplemental oxygen to maintain oxygen saturation higher than 95%.
- Intravenous fluids can help loosen and clear secretions.
- Fetal monitoring becomes important after 20 weeks of gestation in severe cases.
- Tranquilizers and sedatives should be avoided because of their respiratory depressant effect.
- Antihistamines are not useful in the treatment of asthma.
- Mucolytic agents increase bronchospasm.
- Mechanical ventilation
- Less than 1% of all asthmatics require mechanical ventilation.
- Asthmatics have higher complication rates from mechanical ventilation.
- Increased airway resistance may result in extremely high peak airway pressures, barotraumas, and hemodynamic impairment.
- Mucus plugging is common, increasing airway resistance, atelectasis, and the incidence of secondary pneumonia.
- Paradoxical increases in bronchospasm from aggravation by the endotracheal tube may occur.
- Ventilation setting
- Typical ventilator settings may lead to stacked breaths and increased airway pressures.
- Decrease the I:E ratio and set low respiratory rate to allow for adequate expiration.
Consultations
Consult an obstetrician.
Medication
Almost all antiasthma drugs are safe to use in pregnancy and during breastfeeding. In fact, undertreating is a frequent occurrence for the pregnant patient because patients are worried about the medication effects on the fetus.
Outpatient management of asthma is similar for the pregnant patient as it is for the nonpregnant patient. Beta-adrenergic agonists remain the mainstay of treating exacerbations and handling mild forms of asthma. For moderate-persistent asthma, a beta-adrenergic agonist combined with an inhaled anti-inflammatory agent or inhaled corticosteroid is recommended for treatment. In severe asthma, oral corticosteroids and beta-agonists are recommended.
Corticosteroids can be used in the acute and outpatient setting and have been shown to be relatively safe in pregnancy. The intravenous, intramuscular, and oral preparations can be used for the acute exacerbation, whereas the inhaled preparations are reserved for outpatient maintenance therapy.
A longer-acting beta2-adrenoreceptor agonist (eg, salmeterol), whose bronchodilator effects last at least 12 hours, is an effective treatment of nocturnal asthma.
Historically, methylxanthines and oral beta-agonists have been used to treat asthma. Both have been shown to be safe in pregnancy but have fallen out of favor for newer medicines and the inhaled forms, respectively.
Magnesium sulfate is another medication that is safe to use in pregnancy. It works as a smooth muscle relaxant of the airway.
Epinephrine is the one drug that should be avoided in the pregnant patient. In general, epinephrine is used only in the most severe asthma exacerbations. However, in pregnancy, its use is best avoided since it can lead to possible congenital malformations, fetal tachycardia, and vasoconstriction of the uteroplacental circulation.Bronchodilators
Achieve short-term relief most effectively, increasing airway caliber by relaxing airway smooth muscle. Beta2-receptor agonists are widely used and have less systemic effects than nonselective agonists. They are effective after an inhaled or oral dose and have a long duration of action. Albuterol, terbutaline, metaproterenol, and bitolterol are available as metered-dose inhalers. Salmeterol, also a beta2-adrenoreceptor agonist, has a long duration of action (at least 12 h). Therefore, it is an effective agent for the treatment of nocturnal asthma.
Albuterol (Proventil, Ventolin)
Beta-agonist for bronchospasm refractory to epinephrine. Relaxes bronchial smooth muscle by action on beta2-receptors with little effect on cardiac muscle contractility.
Adult
2-3 puffs q4-6h (90 mcg/inhalation); not to exceed 12 inhalations/d
Pediatric
<12 years: Not established
>12 years: Administer as in adults
Beta-adrenergic blockers antagonize effects; inhaled ipratropium may increase duration of bronchodilatation by albuterol; cardiovascular effects may increase with MAOIs, inhaled anesthetics, tricyclic antidepressants, and sympathomimetic agents
Documented hypersensitivity; irregular heart rhythm
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in hyperthyroidism, diabetes mellitus, and cardiovascular disorders
Salmeterol (Serevent)
By relaxing the smooth muscles of the bronchioles in conditions associated with bronchitis, emphysema, asthma, or bronchiectasis, can relieve bronchospasms. Effect also may facilitate expectoration.
Adverse effects are more likely to occur with high or more frequent doses than recommended.
Adult
2 puffs (42 mcg) bid
Pediatric
<12 years: Not established
>12 years: Administer as in adults
Concomitant use of beta-blockers may decrease bronchodilating, and vasodilating effects of beta-agonists such as salmeterol; concurrent administration with methyldopa may increase pressor response; coadministration with oxytocic drugs may result in severe hypotension; ECG changes and hypokalemia resulting from diuretics may worsen when coadministered with salmeterol
Documented hypersensitivity; angina; tachycardia; cardiac arrhythmias associated with tachycardia
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Not indicated to treat acute asthmatic symptoms
Beta2-adrenergic agonist agents
These agents are used in the acute severe asthmatic attack.
Terbutaline (Brethaire, Brethine, Bricanyl)
Acts directly on beta2-adrenergic receptors to relax bronchial smooth muscle, relieving bronchospasm and reducing airway resistance.
Adult
0.25 mg/dose SC q15-30min once; not to exceed 0.5 mg/q4h
Alternatively: 0.0005-0.01 mg/kg/dose SC; not to exceed 0.3 mg/dose q15-20min for 3 doses
Pediatric
<12 years:
0.05 mg/kg/dose PO tid initially and increase gradually to 0.15 mg/kg/dose tid; not to exceed 0.15 mg/kg/dose tid/qid or 5 mg/24 h
12-15 years: 2.5 mg q6h PO tid; not to exceed 7.5 mg/24 h
>15 years: 5 mg/dose q6h PO tid and reduce to 2.5 mg q6h if side effects occur; not to exceed 15 mg/24 h
Concomitant use with beta-blockers may inhibit bronchodilating, cardiac, and vasodilating effects of beta-agonists; concomitant administration of MAO inhibitors with beta-sympathomimetics may result in a hypertensive crisis; concurrent administration of oxytocic drugs such as ergonovine with terbutaline may result in severe hypotension
Documented hypersensitivity; tachycardia resulting from cardiac arrhythmias
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Through intracellular shunting, terbutaline may decrease serum potassium levels, which can produce adverse cardiovascular effects; decrease is usually transient and may not require supplementation
Anticholinergic
These agents are particularly beneficial for patients with coexistent heart disease in whom beta-adrenergic stimulation may be dangerous.
Ipratropium (Atrovent)
Chemically related to atropine. Has antisecretory properties, and when applied locally, inhibits secretions from serous and seromucous glands lining the nasal mucosa.
Adult
2-3 puffs q4-6h (18 mcg/inhalation)
Pediatric
Administer as in adults
Drugs with anticholinergic properties (eg, dronabinol) may increase toxicity; albuterol increases effects of ipratropium
Documented hypersensitivity
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Not indicated for acute episodes of bronchospasm; caution in narrow-angle glaucoma, prostatic hypertrophy, and bladder neck obstruction
Methylxanthine
Importance of theophylline as an antiasthmatic agent is decreasing because adrenoreceptor agonists and anti-inflammatory drugs are successful. Theophylline has a very narrow therapeutic window.
Theophylline (Theo-Dur, Aminophylline)
Potentiates exogenous catecholamines and stimulates endogenous catecholamine release and diaphragmatic muscular relaxation, which, in turn, stimulates bronchodilation.
For bronchodilation, near toxic (>20 mg/dL) levels usually are required.
Adult
600-900 mg/d PO bid/tid
Pediatric
3-4 mg/kg PO q6h
Aminoglutethimide, barbiturates, carbamazepine, ketoconazole, loop diuretics, charcoal, hydantoins, phenobarbital, phenytoin, rifampin, isoniazid, and sympathomimetics may decrease effects of theophylline; theophylline effects may increase with allopurinol, beta-blockers, ciprofloxacin, corticosteroids, disulfiram, quinolones, thyroid hormones, ephedrine, carbamazepine, cimetidine, erythromycin, macrolides, propranolol, and interferon
Documented hypersensitivity; uncontrolled arrhythmias; peptic ulcers; hyperthyroidism; uncontrolled seizure disorders
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in peptic ulcer, hypertension, tachyarrhythmias, hyperthyroidism, and compromised cardiac function; do not inject IV solution faster than 25 mg/min; patients with pulmonary edema or liver dysfunction are at greater risk of toxicity because of reduced drug clearance
Corticosteroids
This category includes the oral corticosteroids (eg, prednisone), inhaled corticosteroids (eg, beclomethasone, flunisolide, triamcinolone), and cromolyn and nedocromil. Clinical studies have consistently shown the efficacy of corticosteroid use.
Aerosol use is the most effective way to decrease the systemic effects of corticosteroid therapy. Their chronic use reduces symptoms and improves pulmonary function in patients with mild asthma. If bronchodilator therapy is not sufficient, inhaled corticosteroids should be started.
Systemic corticosteroids are reserved for patients who require more urgent treatment. Conversely, cromolyn and nedocromil inhibit antigen- and exercise-induced asthma. They can be indicated as the first-line anti-inflammatory medication for the treatment of asthma.
Prednisone (Deltasone, Sterapred, Orasone)
Immunosuppressant for treatment of autoimmune disorders; may decrease inflammation by reversing increased capillary permeability and suppressing PMN activity.
Adult
5-60 mg/d PO qd or divided bid/qid; taper over 2 wk, as symptoms resolve
Pediatric
1-2 mg/kg PO qd or divided bid/qid; taper over 2 wk, as symptoms resolve
Coadministration with estrogens may decrease prednisone clearance; concurrent use with digoxin may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism of glucocorticoids (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics
Documented hypersensitivity; viral, fungal, tubercular skin, or connective tissue infections; peptic ulcer disease; hepatic dysfunction; GI disease
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Abrupt discontinuation of glucocorticoids may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections may occur with glucocorticoid use
Beclomethasone (Beclovent, Beconase, Vancenase)
Inhibits bronchoconstriction mechanisms, produces direct smooth muscle relaxation, may decrease number and activity of inflammatory cells, in turn, decreasing airway hyper-responsiveness.
Adult
2-5 puffs qid (42 mcg/puff)
Pediatric
1-2 puffs qid (42 mcg/puff)
Coadministration with ketoconazole may increase plasma levels but not to an apparently clinically significant level
Documented hypersensitivity; bronchospasm; status asthmaticus; other types of acute episodes of asthma
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Weight gain, increased bruising, cushingoid features, acneiform lesions, mental disturbances, and cataracts may occur (taper medication slowly if these changes occur)
Cromolyn (Intal)
Inhibits degranulation of sensitized mast cells following exposure to specific antigens.
Adult
2-4 puffs qid (0.8 mg/spray)
Pediatric
<5 years: Not established
>5 years: Administer as in adults
None reported
Documented hypersensitivity
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Do not use in severe renal or hepatic impairment; symptoms may reoccur when withdrawing drug
More on Pregnancy, Asthma |
| Overview: Pregnancy, Asthma |
| Differential Diagnoses & Workup: Pregnancy, Asthma |
 Treatment & Medication: Pregnancy, Asthma |
| Follow-up: Pregnancy, Asthma |
| References |
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References
[Guideline] Reddel HK, Taylor DR, Bateman ED, et al. An official American Thoracic Society/european Respiratory Society statement: asthma control and exacerbations: standardizing endpoints for clinical asthma trials and clinical practice. Am J Respir Crit Care Med. Jul 1 2009;180(1):59-99. [Medline].
[Guideline] American College of Obstetricians and Gynecologists (ACOG). Asthma in pregnancy. ACOG practice bulletin; no. 90. Washington (DC): American College of Obstetricians and Gynecologists (ACOG). Feb 2008;[Full Text].
Sly RM, O'Donnell R. Stabilization of asthma mortality. Ann Allergy Asthma Immunol. Apr 1997;78(4):347-54. [Medline].
Hornby PJ, Abrahams TP. Pulmonary pharmacology. Clin Obstet Gynecol. Mar 1996;39(1):17-35. [Medline].
Mabie WC. Asthma in pregnancy. Clin Obstet Gynecol. Mar 1996;39(1):56-69. [Medline].
Mays M, Leiner S. Asthma. A comprehensive review. J Nurse Midwifery. May-Jun 1995;40(3):256-68. [Medline].
Nelson-Piercy C, Moore-Gillon J. Asthma in pregnancy. Br J Hosp Med. Feb 7-20 1996;55(3):115-7. [Medline].
Rey E, Boulet LP. Asthma in pregnancy. BMJ. Mar 17 2007;334(7593):582-5. [Medline].
Further Reading
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