Acute Asthma

Question 1

What is the definition of acute asthma?

Answer 1

Acute onset inflammatory condition of the lung airways

MEDICAL EMERGRANCY

Question 2

How common is acute asthma?

Answer 2

Common

Question 3

What is the pathology of acute asthma?

Answer 3

• Airflow limitation – usually reversible
• Airway hyperesponsiveness to a range of stimuli = airway narrowing due to smooth muscle contraction
• Inflammation of the bronchi
• Mast cells, eosinophils, T lymphocytes and dendritic cells are ↑ in the bronchial wall, mucosal membranes and secretions
• Cells release cytokines which migrate more cells
• Th2 encourages the conversion of antibody production by B lymphocytes to IgE
• Classified as:
• Extrinsic (atopic): allergens identified
• ↑ IgE levels acting on smooth muscle and small blood vessels
• Genetic influence from the IL-4 gene cluster
• Interleukins affect mash and eosinophil cell development and longevity
• Intrinsic: starts in middle age, no definite external cause

Question 4

What are the risk factors/aetiology of acute asthma?

Answer 4

• Childhood exposure to allergens
• Maternal smoking
• Intestinal bacterial and childhood infections
• Growing up in a relatively clean environment
• Acute reaction:
• Irritant dust/vapours/fumes
• Poorly maintained asthma
• Viral infections
• Cold air
• Exercise
• Emotion
• Drugs

Question 5

What are the signs/symptoms of acute asthma?

Answer 5

• Bilateral expiratory polyphonic wheezes
• SOB – inability to complete a sentence in one breath
• Chest tightness
• Reduced chest expansion
• Prolonged expiratory time
• Resp. rate >25 breaths/min
• Heart rate >110 beats/min
• PEFR 33-50% of predicted normal/patient’s best
• Silent chest
• Cyanosis
• Feeble resp. effort
• Exhaustion
• Altered conscious level
• Bradycardia
• Hypotension
• PO2 <8kPa

Question 6

What investigations are conducted for suspected acute asthma?

Answer 6

• Pulse oximetry
• PEFR
• At least 15% airflow limitation
• A ↓ 6 mins after exercise
• Take reading on waking, during the day and before bed
• Before and after treatment in acute cases
• ABG
• U&E’s
• CXR
• Pulmonary shadows associated with allergic bronchopulmonary aspergillosis
• Pnemothroax/pneumonia

Question 7

What are the pharmacological treatments for acute asthma?

Answer 7

• Oxygen
• Salbutamol nebuliser back to back
• Ipratropium bromide 4-6 hourly
• Steroids IV
• Fluids
• Abx – if evidence of infection
• Magnesium sulphate – severe
• Ventilation – severe
• Influenza immunisations

Question 8

What are the non pharmacological treatments for acute asthma?

Answer 8

• Patient and family education
• Smoking cessation advice
• Avoiding triggers
• Self monitoring of PEFR