CLINICAL PRESENTATION

An acute asthma presentation is due to a decrease in expiratory airflow and is characterized by progressive symp ­

toms of shortness of breath, a nonproductive cough, and

89

• Pea k expiratory flow rate and forced expiratory vol ume

in 1 second are objective measures of the severity of a

patient's asthma exacerbation and should be followed

serially to measure improvement.

wheezing in all lung fields. Symptoms may develop over a

period of hours, days, or weeks, but often there is an acute

worsening that prompts the patient to seek medical care.

The most common trigger of acute asthma is an upper

respiratory tract infection, but other factors may lead to

sudden worsening of symptoms (Table 21-1).

..... History

Obtaining a thorough history may not be possible in an

acute asthma exacerbation. A focused history should be

obtained in parallel with initiation of therapy to reverse

Table 21-1. Acute asthma triggers.

Environmental allergens

Exercise-induced

Gastroesophageal reflux disease

Tobacco smoke

Occupational exposures

Inhaled irritants

Stress-induced

Environmental changes (weather)

Air pollutants

CHAPTER 21

Table 21-2. Risk factors for morta l ity in asthma.

Chronic steroid usage

>2 canisters of short acting beta-2 agonists per month

2"2 hospital izations in the past year

2"3 emergency department visits in the past year

History of intensive care unit admissions

Previous intubations for asthma

Cardiopulmonary comorbidities

Illicit drug use

low socioeconomic status or inner-city residence

airflow obstruction, regardless of the trigger. Once the

patient has improved and is able to provide more history,

an attempt should be made to characterize the triggering

event, rapidity of symptom onset, and the severity of the

exacerbation, which will help guide further treatment

and disposition. Characterization of the severity of the

patient's underlying asthma may help predict mortality

(Table 21-2).

Attempting to define the patient's underlying longterm asthma control does not aid in the management of an

acute exacerbation, but will be important to understand

when prescribing outpatient therapeutic regimen and

follow-up. Patients should be asked about the frequency

and duration of their current asthma symptoms and recent

beta-agonist usage.

Numerous medical conditions can present in a similar

fashion to asthma, including pulmonary embolism (PE),

pneumonia, congestive heart failure (CHF), acute myocardial infarction (AMI), or chronic obstructive pulmonary

disease (COPD). The initial history should focus on differentiating asthma from other life-threatening causes of

shortness of breath and wheezing.

...... Physical Examination

Patients may present with a wide spectrum of severity,

from an increase in coughing to obvious respiratory distress with tachypnea and accessory muscle use. Mental

status should be assessed initially because alterations in

consciousness may affect the patient's ability to protect

their airway. A diminished level of consciousness is an

indicator of impending respiratory arrest. The neck

should be palpated for tracheal deviation and crepitus, as

might occur with spontaneous pneumothorax. The lung

exam is variable and demonstrates prolonged expiration

with wheezing. However, the severity of the airflow

obstruction cannot be gauged by the loudness of the

wheezing. The patient who is audibly wheezing may still

have good air movement on auscultation, whereas the

quiet sounding chest with little air movement is a sign of

severe disease because there is not enough airflow to produce a wheeze. Percussion of the thorax reveals hyperresonance due to air trapping. Evaluation of extremity

edema will help differentiate asthma from other causes of

difficulty breathing.