Asthma in Pregnancy

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© Springer Nature Singapore Pte Ltd. 2020
A. Sharma (ed.)Labour Room Emergencieshttps://doi.org/10.1007/978-981-10-4953-8_11



11. Bronchial Asthma in Pregnancy



Priti Kumar1, 2  , Sanjay Kumar3   and Malavika Chaturvadi3  


(1)
King Georges Medical College, Lucknow, India

(2)
Department of Obgyn, Career Institute of Medical Sciences, Lucknow, India

(3)
Sunflower Medical Centre, Lucknow, India

 



 

Priti Kumar (Corresponding author)


 

Sanjay Kumar


 

Malavika Chaturvadi


Asthma is reportedly the most common potentially serious yet treatable medical problem to complicate pregnancy occurring in about 3–8% of pregnant women.


The control of maternal asthma is directly proportional to better outcomes in both maternal and fetal.


Large recent studies seem to point to us that asthma follows a rule of thirds during pregnancy—1/third of the pregnant women get better, 1/third of the pregnant women remain the same, and in 1/third of the pregnant women, the symptoms worsen.


It has also been noted that in most pregnant asthmatic women, the same disease course during the first pregnancy is followed during the latest pregnancies.


In a large study, most acute exacerbations of asthma occur between 24th and 36th weeks of gestation, and such acute flare-ups are rare during the last month of gestation.


Ninety percent of pregnant women with adequately controlled asthma have no symptoms during labor, delivery, and puerperium, and most of them will go back to their prepregnancy status within 12 weeks.


11.1 Pregnancy-Induced Physiological Changes


Alterations of the cardiorespiratory physiology that occur during pregnancy contribute to the exacerbation of many respiratory problems in women during their pregnancy.


11.1.1 Respiratory System Changes


11.1.1.1 Anatomical Changes





  1. 1.

    Changes in chest wall conformation.


     

  2. 2.

    Elevation of the diaphragm.


     

  3. 3.

    Respiratory center stimulation due to the effect of progesterone.


     

11.1.1.2 Physiological Changes





  1. 1.

    Increase in tidal volume and minute volume.


     

  2. 2.

    Lung volumes and capacities:


    1. (a)

      Inspiratory capacity and tidal volume increased (due to progesterone).


       

    2. (b)

      FRC, ERV, and RV decrease (due to elevation of diaphragm).



      
$$ \left[\begin{array}{l}\mathrm{FRC},\mathrm{functional}\ \mathrm{residual}\ \mathrm{capacity}\\ {}\mathrm{ERV},\mathrm{expiratory}\ \mathrm{reserve}\ \mathrm{volume}\\ {}\mathrm{RV},\mathrm{residual}\ \mathrm{volume}\end{array}\right] $$

       

    3. (c)

      TLC (total lung capacity)—mild decrease or unchanged.


       

     

In summary, though pulmonary functions are altered in pregnancy, it only induces stress on respiratory function of the pregnant women in the presence of any respiratory disease like asthma.


11.1.1.3 ABG


Because of increased minute ventilation, alveolar ventilation is increased leading to respiratory alkalosis. This gets partially compensated by a metabolic acidosis generated by the kidney.


As a result of this, the gravida’s normal ABG may appear abnormal, i.e., show features s/o respiratory alkalosis. Therefore we must keep in mind that for a pregnant woman:






  • Normal pH: 7.4–7.47.



  • Normal pCO2: 25 mm of Hg–32 mm of Hg.


11.1.2 Cardiovascular System Changes





  1. 1.

    Increased blood volume (20–100% above preconception levels) due to increased plasma volume and increased red cell mass.


     

  2. 2.

    Cardiac output rises by 30–60%.


     

  3. 3.

    Heart rate rises by 10–20 bpm.


     

  4. 4.

    Decreased vascular resistance (progesterone-induced relaxation of smooth muscles) leads to a minor fall in both diastolic blood pressure and systolic blood pressure.


     

11.2 Effects of Asthma on Pregnancy


Poorly controlled maternal asthma raises the risk of:


  1. 1.

    Preterm birth.


     

  2. 2.

    Small for gestational age infants.


     

  3. 3.

    Intrauterine growth restriction.


     

  4. 4.

    Stillbirth.


     

  5. 5.

    Congenital malformations (e.g., spina bifida, VSD and ASD (ventricular/atrial septal defects).


     

  6. 6.

    Chorioamnionitis.


     

  7. 7.

    Gestational diabetes.


     

  8. 8.

    Low APGAR scores.


     

Fetal hypoxia as a result of poor asthmatic control of the gravida can even lead to neonatal respiratory difficulties, fetal brain ischemia, and cerebral palsy. In contrast if asthma is well controlled throughout pregnancy, there is little or no increased risk of adverse maternal and fetal outcomes.


Therefore pregnancy should call for optimizing therapy and maximizing lung function in order to decrease the possibility of acute exacerbation.


11.3 Effects of Pregnancy on Asthma






  • Worsening of asthma during pregnancy may be due to multiple contributory factors—allergen exposure; upper respiratory tract infection, especially rhinitis; gastroesophageal reflux poor compliance of medication, continue smoking illicit drug use; etc.



  • High-risk patients are those who have history of severe preconception asthma and those whose asthma has worsened in earlier pregnancies (Table 11.1).




Table 11.1

Risk factors and triggers involved in asthma























































Endogenous factors


Environmental factors


Genetic predisposition


Indoor allergens


Atopy


Outdoor allergens


Airway hyperresponsiveness


Occupational sensitizers


Gender


Passive smoking


Ethnicity


Respiratory infections


Obesity


Diet


Early viral infections


Acetaminophen (paracetamol)


Triggers


Allergens

 

Upper respiratory tract viral infections

 

Exercise and hyperventilation

 

Cold air

 

Sulfur dioxide and irritant gases

 

Drugs (β blockers, aspirin) stress

 

Irritants (household sprays, paint fumes)

 

Apart from these factors, in pregnancy GERD (gastroesophageal reflux disease) and allergic rhinitis are common triggers.


11.4 Differential Diagnosis for Acute Dyspnea in Pregnancy






  • Physiological dyspnea of pregnancy which is a benign symptom.



  • Pulmonary edema.



  • Pulmonary embolism.



  • Pneumothorax.



  • Pneumonia.



  • Worsening asthma.



  • Severe asthma.



  • Pregnant patients can also suffer from various hematological and cardiac diseases which can produce anemia and lead to dyspnea.



  • Airway obstruction.



  • Amniotic fluid embolism.



  • Acute congestive heart failure (CHF).


11.4.1 Management of the Asthmatic Gravida


The goals of successful asthma management are:


  1. 1.

    Prevention of chronic day and night symptoms.


     

  2. 2.

    Maintenance of optimal pulmonary function and normal activities using therapies with minimal or no adverse side effects.


     

  3. 3.

    Maintain fetal oxygenation by preventing episodes of maternal hypoxia (Table 11.2).


     



Table 11.2

Asthma control








































Characteristic


Controlled (all of the following)


Partly controlled


Uncontrolled


Daytime symptoms


None (≤2/week)


>2/week


Three or more features of partly controlled


Limitation of activities


None


Any

 

Nocturnal symptoms/awakening


None


Any

 

Need for reliever/rescue treatment


None (≤2/week)


>2/week

 

Lung function (PEF or FEV1)


Normal


80% Predicted

 


Abbreviations: FEV 1 forced expiratory volume in 1 s, PEF peak expiratory flow


The best way to achieve these goals is by a multidisciplinary approach that incorporates regular monitoring of clinical symptoms, self-management education, and the correct use of pharmacotherapies.


The British Thoracic Society (BTS) and Global Initiative for Asthma (GINA) recommend continuing pregnant women on the same asthma therapy used prior to the pregnancy, if their asthma is well controlled.


11.5 Clinical Presentation


Patients, both pregnant and nonpregnant, can present with the following symptoms:



  • Cough.



  • Shortness of breath.



  • Tightness in the chest.



  • Noisy, sometimes shallow, breathing.



  • Nocturnal awakenings.



  • Recurrent episodes of symptom complex.



  • Exacerbations possibly provoked by nonspecific stimuli.



  • Personal or family history of other atopic disease (like hay fever, eczema).

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Mar 28, 2021 | Posted by in OBSTETRICS | Comments Off on Asthma in Pregnancy

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