Acute Severe Asthma Flashcards

1
Q

How does acute severe asthma present?

A

Acute breathlessness and wheeze

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2
Q

What should be asked about in the history of acute severe asthma?

A
  • Usual and recent treatment
  • Previous acute episodes and their severity
  • Best peak expiratory flow rate
  • Previous admissions to ICU
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3
Q

What are the differential diagnoses of acute severe asthma?

A
  • Acute infective exacerbation of COPD
  • Pulmonary oedema
  • Upper respiratory tract obstruction
  • Pulmonary embolus
  • Anaphylaxis
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4
Q

What investigations should be done in a patient with acute severe asthma?

A
  • PEF if possible
  • ABG if saturations <92% or life-threatening features
  • CXR if suspicion of pneumothorax, infection, or life-threatening attack
    FBC
  • U&E
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5
Q

How is acute severe asthma managed?

A
  1. Assess severity of attack
  2. Supplmental oxygen
  3. Salbutamol 5mg or terbutaline 10mg nebulised with oxygen
  4. If severe/life-threatening, ipratropium 0.5mg/6h added to nebulisers
  5. Hydrocortisone 100mg IV, or prednisolone 40-50mg PO
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6
Q

What are the criteria for a severe acute asthma attack?

A
  • Unable to complete sentences in one breath
  • Respiratory rate >25/min
  • Pulse rate >110bpm
  • PEF 33-50% of predicted or best
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7
Q

What are the criteria for a life-threatening asthma attack?

A
  • PEF <33% of predicted or best
  • Silent chest
  • Cyanosis
  • Feeble respiratory effort
  • Arrhythmias or hypotension
  • Exhausion, confusion, or coma
  • Normal/high PaCO2, PaO2 of <8kPa or sats <92%
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8
Q

What should be done if a patient presents with a severe or life-threatening asthma attack?

A

Warn ICU

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9
Q

What oxygen saturations are aimed for in a patient having an acute severe asthma attack?

A

92%

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10
Q

How often should a patient with acute severe asthma be reassessed after initial management?

A

Every 15 minutes

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11
Q

What should be done on reassessment of a patient with acute severe asthma?

A
  • Monitor PEF
  • Monitor ECG and check for arrhythmias
  • Consider single dose of magnesium sulphate 1.2-2g IV over 20min in those with severe/life-threatening features without good initial reponse to therapy
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12
Q

What should be done if PEF <75% on reassessment of a patient with acute severe asthma?

A

Repeat salbutamol nebulisers every 15-30 minutes, or 10mg/h continuously. Add ipratropium if not already given

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13
Q

What should be done if a patient with acute severe asthma is not improving after management?

A
  • Refer to ICU for consideration of ventilatory support and intensification of medical therapy
  • Consider IV salbutamol
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14
Q

What features suggest that IV salbutamol should be considered in a patient with acute severe asthma who is not improving?

A
  • Deteriorating PEF
  • Persistent/worsening hypoxia
  • Hypercapnia
  • ABG showing low pH
  • Exhausion, feeble respiratory effort
  • Drowsiness, confusion, altered conscious level
  • Respiratory arrest
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15
Q

What should be done if a patient with acute severe asthma is improving 15-30 minutes after treatment?

A
  • Continue nebulised salbutamol every 4-6 hours
  • Prednisolone 40-50mg PO OD for 5-7 days
  • Monitor peak flow and oxygen saturations
  • If PEF >75% 1 hour after initial treatment, consider discharge with outpatient follow up
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16
Q

Are antibiotics routinely used in acute asthma?

A

No

17
Q

What criteria must be fulfilled before a patient who had acute severe asthma is discharged?

A
  • Stable on discharge medication for 24hours
  • Had inhaler technique checked
  • Peak flow rate >75% predicted or best, with diurnal variability <25%
  • Must be on steroid (inhaled and oral) and bronchodilator therapy
  • Must have their own PEF meter and written management plan
  • GP appointment organised within 2 days
  • Respiratory clinic appointment within 4 weeks
18
Q

What are the side effects of salbutamol?

A
  • Tachycardia
  • Arrhythmias
  • Tremor
  • Decreased potassium
19
Q

Describe the use of aminophylline in acute severe asthma

A

It is used much less frequently, and is not routinely recommended, however it may be initiated by respiratory teams or ICU

20
Q

What is the mechanism of action of aminophylline?

A

It inhibits phosphodiesterase, and so increases cAMP

21
Q

What are the side effects of aminophylline?

A
  • Tachycardia
  • Arrhythmias
  • Nausea
  • Seizures
22
Q

What safety precautions should be taken when giving a patient aminophylline?

A
  • Monitor ECG
  • Aim for plasma concentration 10-20mcg/mL
  • Measure plasma potassium
  • Don’t load patients already on oral preparations
  • Stick with one brand
23
Q

Why should you aim for a aminophylline plasma concentration of 10-20mcg/mL?

A

Because serious toxicities, including hypotension, arrhythmias, and cardiac arrest, can occur at concentrations of >25mcg/mL

24
Q

Why do you need to measure plasma potassium with aminophylline?

A

Because it can decrease potassium levels

25
Q

Why should you stick with one brand of aminophylline?

A

Because bioavailability varies