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Bronchial Asthma

Study Guide ​

Definition:

  • A chronic condition characterized by reversible airway inflammation, airway hyper-responsiveness, bronchoconstriction, and mucus hypersecretion.


​
Epidemiology:

  • More common in developed countries.

  • Approximately 300 million people worldwide have asthma and the number is expected

to rise to 400 million by 2025.

  • The overall prevalence of asthma in Saudi children ranges between 8-25%. 

Remodeling is a prominent feature of chronic asthma.

Classification of asthma in general (overlapping):

Causes & Risk Factors:​

Pathophysiology:

Clinical Presentation:

Asthma Patients usually complain of episodic attacks of three cardinal symptoms (it is not necessary for all the symptoms to be present):

  • Wheezing

  • Shortness of breath

  • Cough:

    • Nocturnal cough might be the prominent presenting symptom in children.

Various triggers precipitate attacks:

  • Smoking

  • Dust

  • Cold Air

  • Exercise

  • Viral infections 

Aspirininduced asthma should be suspected in patients with asthma & nasal polyps.

Diagnosis & Investigations:

History & physical examination:

  • PE: is usually normal (except for wheezing on auscultation.)

Lung function test:
Spirometry:
The Gold Standard method for diagnosis.

  • Very helpful in assessing the reversibility of asthma.

  • Requires a cooperative patient which is usually > 6Y/O.

  • Diagnosis is made when there is >12% improvement in the FEV1 after the inhalation of bronchodilators (e.g.: beta 2 agonist).

Peak Expiratory Flow Rate (PEFR):

  • Very helpful in assessing the patient’s asthma activity, and long-term assessment

Exercise tests:
Two methods (one of the following):

  1. The patient should run for 6 min on a treadmill while increasing the heart rate to > 160 beats/min.

  2. Cold air challenge, isocapnic hyperventilation, or aerosol challenge with hypertonic saline.

  • Negative test does not rule out asthma.

Histamine or methacoline bronchial provocation test:

  • Proves the presence of airway hyper-responsiveness. 

  • Useful in assessing patients with cough as a prominent feature.

  • Should not be used with poor lung function FEV1<1.5 L.

Chest X-ray: 

  • Not diagnostic, but hyperinflation might be noted.

  • To exclude:

    1. Pneumothorax as it can be as complication.

    2. Pulmonary infiltrates as it might cause acute asthma exacerbation.

Sputum test:

  • Charcot Leiden crystals: eosinophilic inclusions.

  • Curschmann's spirals: spiral plug of mucus.

  •  

Carbon monoxide transfer test is normal in asthmatic patients.

Management:

Goals:

  1. Aborting the symptoms of asthma.

  2. Maintain a normal or near normal lung function.

  3. Reduce the risk of severe acute attacks.

  4. Allow normal growth for children.

  5. Minimize the school absence and maintaining normal physical activity.

  •  First step in the management is identification and elimination of the extrinsic

causes of asthma (allergens).

  • Pharmacological treatment:

    •  According to the severity of the clinical symptoms of asthma:

Most common side effect of SABA is tremors.

Most common side effect of inhaled steroids are oral thrush, hoarseness, and/or throat. 

Complications:

  •  Status asthmaticus:

    • Acute respiratory failure:

      • Due to respiratory muscles fatigue.

    • Pneumothorax, pneumomediastinum, and atelectasis.  

Avoid the use of beta-blockers in asthmatic patients.

Acute Severe Asthma (Status Asthmaticus): 

Definition: exacerbation of the asthma that is not responding to usual medications.
Signs & symptoms:

  • Inability to complete a whole sentence.

  • Respiratory rate ≥ 25 breath/min.

  • Tachycardia ≥110 bpm.

Investigations: 

  • Peak flow meter <60% of predicted normal.

  • Pulse oximetry to monitor oxygen saturation in the blood.

  • ABGs:

    • Increased A-a gradient.

    • Low pH.

  • Chest X-ray:

    • To rule out pneumonia, or pneumothorax. 

Management: 

Life threatening asthma attacks 

usually present with: 

1. Silent chest 

2. confusion or coma 

3. Bradycardia or hypotension

References:​

First author: Roaa Amer 
Second author: Raed Rayani                                                                                  

Publisher: Salman Alahmed

Reviewed by: Musab Al Shareef                                                      Haifa Al Issa

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