Factors to consider include:
- pulse rate: (1)
- if the tachycardia is persistently 120 to 140 beats per minute the patient is still in danger
- a falling pulse rate is an ominous feature
- appearance of patient: (2)
- character of breathing
- facial expression
- position in bed
- peak flow rate: (2)
- is an objective measurement of progress
- it can be measured before and after nebulisers
- estimation of blood gas tensions:
- it is necessary to monitor the PaO2 and PaCO2
- a rise in the PaCO2 suggests respiratory failure and intermittent positive pressure ventilation should be considered
Life-threatening asthma is any one of the following in a patient with severe asthma: (2)
- Silent chest
- Cyanosis
- Poor respiratory effort
- Arrhythmia
- Hypotension
- Exhaustion
- Altered consciousness
- PEF <33% of best or predicted
- SpO2 <92%
- PaO2 <8 kPa (<60 mmHg)
- ‘Normal’ PaCO2 (4.6-6.0 kPa [35-45 mmHg]) - raised PaCO2 is a marker of near-fatal asthma.
Acute severe asthma is a patient presenting with any one of the following (and no features of life-threatening asthma): (2)
Patient can’t complete a sentence without taking a breath
Respiratory rate ≥25/minute
Pulse rate ≥ 110 beats per minute
PEF 33% to 50% of best (use % predicted if recent best unknown).
Indications for moderate asthma are: (2)
Speech normal
Respiratory rate <25 breaths/minute
Pulse rate <110 beats per minute
PEF 50% to 75% of best or predicted.
References
- Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. 2023 [internet publication].
- British Thoracic Society; Scottish Intercollegiate Guidelines Network. British guideline on the management of asthma: a national clinical guideline. Jul 2019 [internet publication]