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Table 2 Clinical and functional assessment of severe asthma exacerbations

From: Clinical review: Severe asthma

Variable

Severe exacerbation

Imminent respiratory arrest

Symptoms

  

   Dyspnea

At rest

 

   Speech

Single words, not sentences of phrases

 

   Alertness

Agitated

Drowsy or confused

Signs

  

   Respiratory rate

>30 breaths/min

 

   Heart rate

>120 beats/min

Bradycardia

   Pulsus paradoxus

>25 mmHg

Absence (muscle fatigue)

   Use of accessory muscles

Evident

Abdominal paradox

   Wheeze

Present – loud

'Silent chest'

Functional assessment

  

   PEF

<50% of predicted

 

   PaO2

<60 mmHg

 

   PaCO2

>42 mmHg

 

   SaO2

<90%

 
  1. PaCO2, arterial carbon dioxide; PaO2, arterial oxygen; PEF, peak expiratory flow; SaO2, oxygen saturation. Adapted from the National Heart, Lung and Blood Institute report [1].