GP Flashcards
Define Asthma
Chronic cough, dyspnoea and wheeze, characterised by reversible airway obstruction, airway hypersensitivity and inflamed bronchioles
This can be allergic/IgE mediated, or non IgE mediated (exercise, cold air and stress)
Pathophysiology of asthma
Allergen picked up by dendritic cells and presented to Th2 cells, which respond by releasing cytokines, releasing IgE which bind to mast cells, causing mast cell degranulation. This releases histamine, leukotrienes, prostaglandin.
This causes chronic airway inflammation causing:
- Bronchoconstriction and smooth muscle spasm
- Mucus hypersecretion
Common triggers of asthma
- Pollen, dust mites, grass
- Cold air
- Exercise
- Pets
- Tobacco smoke
- Occupational allergens (bakers, manufacturers, lab work, welding)
- Household mould
Signs/symptoms of asthma
Episodic shortness of breath, usually after trigger exposure.
- Diurnal PEFR variation (worse at night/early morning)
- Usually dry cough
- Expiratory wheezing/dyspnoea
- Chest tightness
Asthma patient mucus microscopy result
Will contain spiral mucus plugs - casts from small bronchioles
Investigations in Asthma
Spirometry:
-FEV1/FVC <80% (obstructive picture)
- Bronchdilator reversibility
FeNO (Fraction of exhaled Nitric Oxide) - 40ppb in adults, 35 in kids. (parts per billion)
GOLD: PEFR - measure multiple times a day for 2-4 weeks. >20% variability diagnostic
Patient taking regular aspirin/NSAIDs comes in with asthma-esque symptoms. What is this suggestive of?
Samter’s triad
What is Samter’s triad
Inflammation and swelling of the airways in response to aspirin or NSAIDs
Leads to:
- Chronic asthma-esque history
- Recurrent nasal polyps
- Aspirin intolerance
Asthma management algorithm
1) SABA (Salbutamol)
2) SABA + lowdose ICS (beclometasone)
3) SABA + lowdose ICS + LTRA (montelukast)
4) SABA + lowdose ICS + LABA (Salmeterol) + LTRA in adults, - LTRA in kids.
What are the goals of stepwise management in asthma
- Aim to use the lowest effective doses possible, only stepping up if previous treatment ineffective
- Step down treatment every 3 months and reasess
- Annual asthma reviews for stable asthma
Give the PEFR, speech, resp and cardio ranges of moderate, severe and life threatening asthma exacerbations
PEFR
- M - 50-75% of best/predicted
- S - 33-50%
- LT - <33%
Speech
- M - normal
- S - cant complete sentences
- LT - Silent, exhausted, confused, coma
Resp
- M - RR<25/min
- S - RR>25/min
- LT - O2 sats <92%, chest silent, reduced respiratory effort or cyanosis
Cardio
- M - Pulse <110
- S - Pulse >110
- LT - Bradycardia, dysrhythmia, hypotension
Signs of acute asthma exacerbation
- Progressively worsening dyspnoea
- Accessory muscle usage
- Tachypnoea
- Cyanosis
- Silent chest
Define bronchodilator reversibility
> 12% increase in FEV1, and >200ml increase in FVC
Management of acute asthma attack
Hospital if life threatening or near-fatal asthma attack (High pCO2/need for ventilation), or if bronchodilator irreversible.
- Salbutamol up to 10mg/hour (1 puff every 30-60 seconds up to 10 puffs)
- Ipratropium bromide (SAMA)
- 3-5 days oral prednisolone for ALL kids with exacerbation
- MgSO4 if PEFR <50% and no bronchodilator response
Checks to do at annual asthma review
- Inhaler technique
- Symptom scoring
- Check HPC
- Review treatment
- Check growth in children, and potentially do spirometry
Extrinsic pathway of coagulation cascade
3,7,10
endothelial damage = 3 (tissue factor) -> 3a.
3a = 7 -> 7a
7a + calcium -> activate 10 to 10a
Intrinsic pathway of coagulation cascade
12,11,9,8,10
Collagen exposure causes activation of 12 -> 12a
12a = 11 -> 11a
11a activates 8 and 9 to 8a and 9a.
8a and 9a activate 10 to 10a.
Common pathway of coagulation cascade
10a and 5a and calcium -> 2 to 2a (thrombin).
2a activates 1 (fibrinogen) to 1a (fibrin)
2a activates Stabilising factor (13) to 13a, which forms stable clot with 1a and calcium.
What is PT, and how is this used to calculate INR. Reasons INR may be raised
Prothrombin time - Coagulation speed through extrinsic pathway (3,7,10)
INR = (patient’s PT/reference PT)
Vit K deficiency, Anticoags, liver disease, disseminated intravascular coagulation
What is APTT and what conditions affect this BUT NOT PT
Activated Partial Thromboplastin Time
Coagulation speed through intrinsic pathway
Affected by:
haemophilia A, B and Von Willebrand Disease
What is acute bronchitis
Self limiting chest infection. Assoicated with oedematous large airways and sputum productions, may cause wheeze but no other focal chest signs (crackles, dullness to percussion, bronchial breathing etc).
How does bronchitis present
Cough
Sore throat
Rhinorrhoea
Wheeze (not always present)
Investigations and management in bronchitis
Clinical diagnosis
Analgesia, fluid intake.
Only do antibiotics if:
- Systemically very unwell
- Pre-existing comorbidities
- CRP 20-100
What is allergic rhinitis
IgE mediated T1 hypersensitivity reaction. Environmental allergens cause allergic inflammatory response in nasal mucosa.
Can be:
- Seasonal (hay fever)
- Perennial (year round - dust etc)
- Occupational (school/work etc)