Asthma Flashcards
Asthma
What is asthma in one sentence?
a chronic and inflammatory respiratory pathology characterised by recurring bronchial hyperresponsiveness and consequent airway narrowing, following exposure to specific triggers
Asthma
What are some typical asthma triggers?
- Cold air
- Exercise
- Allergens
- Aspirin or other COX-1 inhibitors
- Viral infections
Asthma
What 3 typical symptoms are caused by the narrowing of the bronchi.
dyspnoea, high-pitched wheezing and/or cough
Asthma
What in a pt history might make asthma a more likely differential?
- relieved by bronchodilators or elimination of trigger
- intermittent and episodic
- worse at night
- diagnosed in childhood
Asthma
How is a diagnosis of asthma made?
History
- dyspnoea, expiratory wheezing, cough (after exposure)
- airflow obstruction confirmed by spirometry with bronchodilator reversibility testing and Fractional exhaled nitric oxide
Asthma
Name some differentials and how they might present differently to asthma
- COPD: the airflow obstruction is persistent and irreversible, the patient is generally older and a smoker (more than 20 pack years)
- Exertional dyspnoea
- Cardiomyopathies, coronary artery disease or pericarditis if chest pain or any cardiac symptoms added to classic asthma symptoms
- Bronchial carcinoma
- Aspiration of foreign body
Asthma
What might spirometry show?
Reduced FEV₁:FVC ratio (usually less than 0.7)
Reversibility test: after an initial spirometry test with obstructive characteristics, administration of a short-acting bronchodilator and repetition of spirometry after 15 mins would show reversibility of airflow obstruction. To be certain of reversibility, FEV₁ would have to increase 12% or more with respect to the original value.
Bronchoprovocation test: used if spirometry test results are normal and involves administration of methacholine to provoke bronchoconstriction.
Asthma
How might we used PEF for asthma diagnosis?
PEF is a poor diagnostic tool as it may not demonstrate airflow obstruction even if it is present on spirometry.
If PEF is lower than the predicted value, it could be indicative of asthma (unspecific).
If reduced PEF improves more than 20% after administration of a short-acting bronchodilator it is more specific for asthma diagnosis.
Asthma
What might bloods show?
eosoinophilia (but not part of diagnosis)
Asthma
Although allergy tests are not part of asthma diagnosis , what tests might help us identify triggers?
- Eosinophil count
- Total serum IgE
- Prick test
Asthma
What are some bedside signs of severe asthma exacerbation?
- Tachypnoea (> 30 breaths/minute)
- Tachycardia (> 120 beats/minute)
- Use of accessory muscles to breathe
- Sweating
- Extreme dyspnoea
- Pulsus paradoxus
Asthma
What tests are important to do when dealing with a pt in resp distress?
What might they show?
PEF, pulse oximetry and secondarily, arterial blood gas (ABG)
Hypoxaemia with PaO2 < 60 mmHg or SpO2 < 90% are signs of a severe asthma attack.
The respiratory drive will be increased in an acute asthma attack resulting in hyperventilation and hypocapnia initially, with progressive hypercapnia if the obstruction is not resolved.
Asthma
What does emergency management consist of?
- Resolving airflow obstruction: a combination of an inhaled bronchodilator and systemic glucocorticoid (effect of steroids is clinically seen up to 6 hours after administration)
- Correcting hypoxaemia: supplemental oxygen, usually nasal cannula suffices
*If after 1 hour the symptoms have resolved and PEF > 80% of the predicted value, the patient is fit for discharge. *
Asthma
How do we manage intermittent asthma? (prescribing)
SABA as needed
Salbutamol
How do we manage mild persistent asthma? (prescribing)
SABA
+
low dose ICS
or
low dose ICS + LABA
or
leukotriene ICS (if glucocortcoid not recommended)
