AsthmaBMJ 2010; 341 doi: https://doi.org/10.1136/bmj.c3779 (Published 21 July 2010) Cite this as: BMJ 2010;341:c3779
This week’s question is on asthma and is taken from the OnExamination revision questions for the MRCP Part 1 exam.
Which of the following signs and symptoms, if any, indicate a severe asthmatic attack in a teenager?
A A peak expiratory flow rate of less than 50% of predicted rate
B A respiratory rate of more than 25 breaths a minute
C A PaCO2 of more than 37.5 mm Hg (5.0 kPa)
D A PaO2 of 67.5 mm Hg (9 kPa)
E Loud expiratory and inspiratory wheezes
Answers A, B, C, and D are correct; answer E is incorrect.
Defining asthma severity is difficult, as accounts in the literature vary. However, severity can be estimated using the “5 Ps”:
Pulse rapid (or slow)
PaCO2 normal or high
Peak expiratory flow rate less than 50% of predicted rate
Pulsus paradoxus (that is, blood pressure declines as the patient inhales and increases as the patient exhales)
The following signs are also indicative:
Silent chest (suggests life threatening asthma if present)
Respiratory rate of more than 25 breaths a minute
The British Thoracic Society1 defines acute severe asthma as any one of the following:
Peak expiratory flow rate of less than 50% of predicted rate
Respiratory rate of 25 breaths a minute or more
Pulse rate of 110 beats a minute or more
Cannot complete sentences in one breath
Cite this as: BMJ 2010;341:c3779
For the MRCP Part 1 OnExamination question of the day go to http://onexamination.com/General-Medicine/mrcp-part-1/question-of-the-day