Asthma Flashcards

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1
Q

Asthma Definition

A

A chronic, reversible, episodic respiratory condition caused by oedema, mucus plugging, and smooth muscle spasm of bronchioles. Characterised by SOB, wheeze and cough. Triggered by hypersensitivity of the bronchioles in response to allergen.

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2
Q

Early-phase Asthma Pathophysiology

A
  • Allergen exposure triggers IgE receptors on mast cells, resulting in release of histamine and inflammatory mediations.
  • Bronchoconstriction is therefore precipitated by histamine (H1 receptors) and ACh (cholinergic receptors) - further causing bronchial smooth muscle contraction.
  • Oedema occurs due to increased permeability of bronchial capillaries, leading to bronchial oedema and mucus production.
  • Gas trapping causes hyperinflation and increased intrathoracis pressure > decreased venus return due to collapse > decreased preload and CO = VQ mismatch = hyperaemia = respiratory acidosis and decreased cerebral perfusion.
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3
Q

Late-phase asthma pathophysiology

A
  • Late phase is characterised by further bronchoconstriction, oedema and mucous plugging due to the recruitment of further inflammatory markers - basophils, eosinophils and neutrophils.
  • These mediators cause damage to epithelium of the airway resulting in further exocytosis of mast cells and basophils, causing an acute airway hyper-responsiveness.
  • Damage exposes to nerves which cause cough, increased mucus production and oedema.
  • Further impairment of mucociliary escalator resulting in widespread mucous plugging (increased production, decreased clearance)
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4
Q

Asthma signs & symptoms

A
  • Expiratory wheeze and/or inspiratory wheeze
  • Chest tightness
  • Decreases SpO2
  • SOB
  • Cough
  • Prolonged expiratory phase
  • Tachypnoea
  • Tachycardia
  • Hypercapnia
  • Hypoxia
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5
Q

Why 1 min of apnoea in asthmatic arrest patients?

A
  • Allow passive gas exchange and expiration air/gases
  • Reduce hyperinflation and decrease intrathoracic pressure
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6
Q

High-risk asthmatic patients

A
  • Initial moderate or severe / life threatening presentation
  • Previous episode requiring intubation / ICU admission
  • History of heart failure
  • Bilateral crepitations on auscultation
  • Pregnancy
  • No improvement in PEFR and / or symptomatic post-treatment
  • No previous diagnosis of asthma or airways disorder.
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7
Q

Asthma red flags

A

Dyspnoea
Cannot speak in sentences
SpO2 <94%
Increased RR
Increased WOB
Accessory muscle use
Silent chest
Worsening wheeze, cough or chest tightness
Reliever is not helping
Drowsy, confused or exhausted
Pale, clammy and/or cyanotic

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8
Q

Causes of cardiac arrest in asthmatics

A
  • Mucous plugging and oedema preventing gas exchange
  • Hyperinflation, increasing intrathoracic pressure
  • Cardiac arrythmias due to hypoxia or electrolyte abnormality
  • Tension Pneumothorax
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9
Q

Asthma management for adults: mild/moderate

A
  • adult: Salbutamol 12 puffs Q20mins
  • Ipratropium 8 puffs every 20mins MAX. 3
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10
Q

Asthma management for adults: Severe

A
  • As mild/moderate by increase salbutamol frequency to 5-10 mins
  • Neb if MDI not tolerated: 10mg salbutamol, then 5mg at 5min intervals; ipratoprium 500mcg every 5 mins for 3.
  • Dexamethasone 8mg PO/IV/IM
  • MgSO4
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11
Q

Asthma management for adults: Life-threatening

A
  • First line: Adrenaline 500mcg every 5 mins
  • Nebulised salbutamol and ipratropium
  • NaCl up to 20mg/kg
  • Dexamethasone
  • MgSO4
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12
Q

Asthma management for adults: unconscious or loss of CO

A
  • 1 min period of apnoea
  • IPPV with 100% O2: ventilate 5-8/min to allow for prolonged expiratory phase.
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13
Q

Asthma management for paediatrics: Mild/moderate

A
  • 1-6 years: salbutamol 6 puffs Q20mins
  • > 6 years 12 puffs
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14
Q

Asthma management for paediatrics: Severe

A
  • Salbutamol as Mild.moderate increasing frequency to Q5-10mins.
  • Ipratropium: 1-6 years - 4 puffs every 20mins (max. 3); >6 years - 8 puffs
  • Use neb if MDI unavilable
  • Dexamethasone 600mcg/kg max. 8mg
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15
Q

Asthma management for paediatrics: life-threatening

A
  • Adrenaline 10mcg.kg (max. 500mcg)
  • Salbutamol and ipratropium nebs
  • NaCl up to 20ml/kg
  • Dexamethasone
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16
Q

Asthma management for paediatrics: Unconsicous/loss of CO

A

= 30 sec apnoea
- IPPV with 100% O2
- Inflant: 15-20 /min - every 3-4 secs
- Small child: 10-15/min - 4-6 secs
- Large child: 8-12/min

17
Q

Asthma differential diagnosis

A

COPD
Anaphylaxis
Pneumonia
Viral infection
PE
Bronchiectasis
APO
FBAO

18
Q

Salbutamol MOI

A

Short acting beta agonst. Binds to beta 2 receptors, stimulating sympathetic nerve fibres to increase contraction resulting in bronchodilator.

19
Q

Ipratropium MOI

A

Short acting muscarinic antagonist (antimuscarinic). Binds to muscarinic receptors within bronchus, inhibiting ACh, resulting in a reduction in bronchospasm and promoting bronchodilator.

20
Q

Asthma - Mild/moderate symptoms

A
  • can walk
  • Talking in full sentences
  • SpO2 >94%
  • Nil accessory muscle use
  • Nil increased WOB
  • Wheeze
  • SOB
21
Q

Asthma - Severe symptoms

A
  • Accessory muscle use/increased WOB
  • Tracheal tugging
  • SpO2 90-94%
  • Talking in phrases/words
  • Significant SOB
  • Altered conscious state
  • Tripod positioning
22
Q

Asthma - Life threatening symptoms

A
  • Reduced conscious state/collapse
  • Cyanosis
  • SpO2 <90%
  • Exhaustion
  • Unable to speak
  • Poor respiratory effort
  • Silent chest
23
Q

Why adrenaline is given in life-threatening asthmatic patients?

A

Beta-2 agonist effects - bronchodilation; decreases degranulation of mast cells.
Alpha adrenergic effects - increases CO; decrease angio-odemea.