Asthma Flashcards
(20 cards)
Define Asthma
Asthma is a chronic inflammatory disease of the airways.
What is asthma characterised by?
It is characterised by airflow obstruction, bronchial hyper-responsiveness, and airway remodelling. It is a reversible.
What triggers Asthma?
Allergens, cold air, exercise, pollutants
In short, describe the pathophysiological process of Asthma
- Irritant exposure
- Mast cell degranulation
- Immune mediators released
- Bronchoconstriction, mucus hypersecretion, airway obstruction, air trapping
- Ventilation-perfusion mis-match. Hypoxaemia, hypoxia
- Airway remodelling
What is bronchial hyper-responsiveness?
When airways constrict excessively in response to various stimuli
Common signs and symptoms of asthma?
Wheezing, dyspnea, chest tightness, coughing + sputum, tachycardia - hypoxaemia, tachypnoea
Relevant nursing assessments for Asthma?
Respiratory rate + effort breathing
SpO2
Vital signs
Peak expiratory flow rate
Lung ascultation
Why use a spacer of nebuliser?
To deliver drugs directly to lungs for rapid onset.
Nebuliser - improve drug deposition and reduce oropharyngeal side effects such as dry mouth.
Spacer - useful for when patient too uncoordinated with inhalation due to dyspnoea. More effective to deliver full dosage of drugs
Why osculate the lobes of the lungs?
The phases of asthma involve bronchoconstriction, mucus hypersecretion & mucosal edema. This causes the airway to narrow having turbulent airflow. This means that different breath sounds are produced.
1. Wheezing
2. Absent sounds
3. Crackles
Osculating detects infection location, severity and response to treatment.
What does wheezing represent?
Indicates a narrow airway due to bronchoconstriction, mucosal edema and mucus hypersecretion
What does absent breath sounds on occultation mean?
Indicated a severe obstruction of the airway. Gas exchange severely effected in site - possible hypoxaemia and hypoxia.
What does crackles on oscultation indicate?
It indicates mucus accumulation
What is hydrocortisone? Why IV?
IV: ensures rapid onset when inhalants not effective - severe dyspnoea. Prevents respiratory failure.
Hydrocortisone is a systemic corticosteroid that
1. Suppresses the inflammatory cytokines & easinophils activity
2. Reduces mucous all edema + capillary permeability
3. Restores B2 receptor sensitivity. It enhances salbutamol (inhalant) effectiveness.
What does salbutamol do in a case of asthma?
Stimulates B2 receptors on bronchial smooth muscle to relax and dilate. It improves airflow and reduces dyspnoea.
Why monitor fluid balance in Asthma?
Due to tachypnoea, fluid is loss through increased respirations as well as administration of corticosteroids (hydrocortiosone) increasing dehydration.
Adequate hydration = thinning of secretions for easier expectoration, prevents mucus plugging and supports airway clearance
What happens in the inflammatory response?
Phagocytes stimulate activation of eosinophils and CD4+T cells which then recruits mast cells. Mast cells then degranulate, releasing immune mediators e.g. histamine.
What does the immune mediators cause?
Vasodilation of vascular smooth muscle - increasing capillary permeability causing airway edema. Capillaries leak fluid into interstitial spaces.
Mucus hypersecretion - goblet cells and submucosal glands produce thick, sticky mucus. Ciliary function becomes impaired causing mucus plug and ineffective airway clearance.
Broncho hyper-responsiveness e.g Bronchoconstriction - bronchial smooth muscle contracts causing bronco spasms further narrowing the airway
Explain the process of airway remodelling in persistent asthma:
- Thickening of basement membrane
- Goblet cell hyperplasia
- Smooth muscle hypertrophy
- Reduced reversibility of airway obstruction
What is air trapping? How does it occur?
Due to narrowed bronchi + excessive mucus secretions, air can enter alveoli but not leave effectively. This results in hyperinflation of the lungs, increased work of breathing and a ventilation-perfusion mismatch. Patient is at risk of hypoxaemia (PaO2 decreased), hypoxia and hyper apnea (PaCO2 increased in blood).
What occurs to gas exchange?
Limited expiratory airflow as air is trapped distal to the bronchi which is also constricted. The trapped air mixes with inspired air in the alveoli so there is an overall decrease of gas exchange across the aveolar-capillary membrane.
