Table 75-3.

Clinical Classification of Severity for Asthma Exacerbation

	Severity of Exacerbation
	Mild	Moderate	Severe	Impending Respiratory Failure
Symptoms
Breathlessness	While walking	While talking (infants: softer, shorter cry; difficulty feeding)	While at rest (infants: stop feeding)
Positioning	Can lie down	Prefers sitting	Sits upright
Speaks in	Sentences	Phrases	Words
Alertness	May be agitated	Usually agitated	Usually agitated	Drowsy or confused
Signs
Respiratory rate	Increased	Increased	Often >30/min
Use of accessory muscles, suprasternal retractions	Usually not	Commonly	Usually	Paradoxical thoracoabdominal movement
Wheezing	Moderate, often only end expiratory	Loud, throughout exhalation	Usually loud, throughout inhalation and exhalation	Absence of wheezing
Pulse/min	<100	100-120	>120	Tachycardia or bradycardia
Pulsus paradoxus	Absent (<10 mm Hg)	May be present (10-25 mm Hg)	Often present (>25 mm Hg for an adult, 20-40 mm Hg for a child)	Absence suggests respiratory muscle fatigue
Functional Assessment
PEF, % predicted or % personal best	80%	∼50%-80%	<50% of predicted or personal best
PaO2 (on room air)	Normal (test not usually necessary)	>60 mm Hg (test not usually necessary)	<60 mm Hg, possible cyanosis
And/or PaCO2	<42 mm Hg	<42 mm Hg	>42 mm Hg, possible respiratory failure
SaO2 (on room air) at sea level	>95%	91%-95%	<91 %

Asthma exacerbation usually includes several parameters, but not necessarily all. These parameters serve only as general guidelines because many have not been systemically studied.

Adapted from Moss MH, Gern JE, Lemanske RF Jr: Asthma in infancy and childhood. In Adkinson NF Jr, Yunginger JW, Busse WW, et al (eds): Middleton's Allergy Principles and Practice, 6th ed. Philadelphia, CV Mosby, 2003. Available at http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf.p107.