Asthma in pregnancy: Clinical sciences
Introduction0:00–1:20
Asthma is an obstructive airway disease characterized by increased airway responsiveness to stimuli, reversible airway obstruction, and chronic airway inflammation.
It’s classified as mild, intermittent, or severe and requires close surveillance to ensure adequate oxygenation of the fetus by preventing hypoxic episodes in the patient.
Those with mild and well-controlled moderate asthma tend to do well and have excellent pregnancy outcomes. However, those with severe and poorly controlled asthma may have an increased risk of perinatal complications like preeclampsia, fetal growth restriction, and premature birth.
Additionally, severe asthma exacerbations may cause life-threatening respiratory failure. When counseling patients on treatment options it’s important to use a stepwise approach to medical intervention based on their asthma classification and emphasize that a healthy fetus first requires a healthy patient!
If a patient presents with a chief concern suggesting asthma in pregnancy you should first perform an ABCDE assessment to determine if the patient is stable or unstable.
Unstable patient1:20–2:20
In unstable patients, the first step involves acute management to stabilize the airway, breathing, and circulation. Then, obtain IV access and monitor maternal vital signs.
Also, be sure to assess fetal well-being, depending on the gestational age. If the pregnancy is previable, obtain fetal heart tones via Doppler.
In pregnancies past 22 weeks, perform continuous electronic fetal monitoring and consider a biophysical profile. Finally, if a patient has severe asthma symptoms, including drowsiness, confusion, or an elevated partial pressure of carbon dioxide or PCO2, consider hospitalization with admission to the intensive care unit.
Now that unstable patients are taken care of, let’s talk about stable patients. Start by performing a focused history and physical, as well as spirometry, or pulmonary function testing.
Stable patient2:20–3:26
Patients may report dyspnea, cough, or chest tightness, as well as a known history of asthma. Often symptoms will be worse at night and might be triggered by allergens, infection, or exercise.
On physical exam, you will likely note wheezing or tachypnea. Finally, spirometry might reveal reversible airway obstruction.
Here’s a clinical pearl! Pulmonary function testing is performed with a handheld spirometer.
When performing, instruct your patient to take a maximal breath in, then forcibly exhale all of the air from their lungs into the spirometer.
A flow-volume loop is then generated, which differentiates between obstructive and restrictive lung disease. Before moving on to treatment, you need to assess the severity of your patient's symptoms.
Assess severity3:26–4:17
The four components to take into account include your patient’s symptom frequency per week, number of nighttime awakenings, whether their asthma causes interference with normal activities, and their forced expiratory volume in 1 second, or FEV1 as noted on a peak flow meter.
Also be sure to review any prior asthma-related hospitalizations including ICU admissions, intubations, and emergency room visits; as well as any requirement of unscheduled treatments, including oral corticosteroids.
If a patient has been treated during a prior pregnancy, be sure to ask about how their asthma was managed, as this may predict a future response.
Mild Intermittent4:17–5:02
Okay, let’s look at our first category. Now, if your patient reports having symptoms no more than 2 days per week, nighttime awakenings no more than twice per month, no interference with normal activities, and their FEV1 or peak flow is greater than 80 percent you can diagnose mild intermittent asthma.
Continue to reassess your patient throughout pregnancy as their severity may change which would require adjusting their medications.Alright, let’s move on to our next category.
Mild Persistent5:02–6:04
These patients require daily medication with the preferred method being a low-dose inhaled corticosteroid, or ICS, such as budesonide or fluticasone.
If your patient was well controlled with an ICS prior to pregnancy, it should be continued throughout pregnancy. An alternative option to managing mild persistent asthma is the use of cromolyn, leukotriene receptor antagonists, or theophylline.
Keep in mind that theophylline requires serum monitoring and has a tight therapeutic window. Okay, let’s talk about patients with worsening symptoms who need additional management.
Moderate Persistent6:04–7:48
In this case, the treatment involves daily medication, and might also include a second medication to better control their symptoms.
There are a variety of options for management including a low-dose ICS, plus a long-acting β2-agonist, or LABA, such as salmeterol; or a medium-dose ICS; or a medium-dose ICS in combination with a long acting beta agonist.
Alternatively, you can consider including a low- or medium-dose ICS with either a leukotriene receptor antagonist or theophylline.In addition to the medical treatment, patients with moderate persistent asthma need additional fetal monitoring.
Remember, poor oxygenation in a patient, whether chronic or acute, can cause fetal compromise and fetal growth restriction.
First, you’ll want to obtain a first-trimester dating ultrasound to confirm the correct dating. In addition to their routine anatomy ultrasound, consider serial growth ultrasounds and antenatal testing, like non-stress tests, beginning at 32 weeks of gestation.
Additionally, encourage your patient to be aware of fetal movement starting in the third trimester.Finally, let’s review the subset of patients who have even more severe disease.
Severe Persistent7:48–10:07
If your patient reports symptoms throughout the day, nighttime awakenings at least 4 times per week, significant interference in normal activities such that their ability to perform them is extremely limited, and they have an FEV1 or peak flow less than 60 percent, you can diagnose severe persistent asthma.
The preferred treatment for these patients is a high-dose ICS and a long acting beta agonist. You may also consider adding an oral corticosteroid.
An alternative treatment regimen is a high-dose ICS and theophylline, again with consideration for adding an oral corticosteroid as well.Just like before these patients need additional fetal monitoring with serial growth ultrasounds and antenatal testing.
Finally, encourage your patient to be aware of fetal movement starting in the third trimester.Here are a few clinical pearls regarding labor and delivery!
First, asthma medications should be continued during labor and delivery. Be sure patients are well hydrated and have adequate analgesia to decrease the risk of bronchospasm.
Also, keep in mind that a stress dose of steroids is indicated for patients who are taking or have recently taken oral corticosteroids.
This consists of IV administration of corticosteroids during labor and for 24 hours postpartum to prevent adrenal crisis.
In terms of delivery route, vaginal delivery is considered the safest; however a cesarean delivery may rarely be indicated in a patient with unstable asthma to help improve their respiratory status.
Now, if your patient happens to have a postpartum hemorrhage, as you’re treating them, remember that prostaglandin F2 alpha, or carboprost, is contraindicated in those with asthma or pulmonary disease as it may cause acute bronchospasm.
Finally, keep in mind that asthma medications are safe to continue while breastfeeding.Alright, as a quick recap… Asthma is a chronic condition of the airway characterized by hyperresponsiveness to stimuli, chronic inflammation, and reversible obstruction.
Review10:07–10:55
- "ACOG Practice Bulletin No. 90: Asthma in Pregnancy" Obstet Gynecol (2008)
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