7 Asthma, Part 2

Question 1

pathophysiologic hallmark of asthma

Answer 1

a reduction in airway diameter caused by
1) smooth muscle contraction,
2) vascular congestion,
3) bronchial wall edema, and
4) thick secretions

Question 2

most common acute asthma stimulus

Answer 2

viral acute respiratory infections

Question 3

best predictor of hospitalization in patients with acute asthma

Answer 3

Comparing measures of FEV1 or PEFR at ED presentation and 1 hour after treatment

Question 4

important asthma mimickers

Answer 4

Acute heart failure (“cardiac asthma”)
Upper arway obstruction
PE
Aspiration of foreign body or gastric acid

Tumors/disorders causing endobronchial obstruction
Interstitial lung disease
Vocal cord dysfunction

Question 5

most common side effect of beta adrenergic drugs

Answer 5

skeletal muscle tremor

patients may also experience anxiety, headache, hyperglycemia, tachycardia/hypertension

Clinical toxicity is rare and less common than undertreatment complications

Question 6

remarks on MDI

Answer 6

A spacing device attached to the inhaler improves drug disposition; when optimally used, metered-dose inhaler therapy delivers the most drug to target airways, better than nebulized therapy

Question 7

remarks on corticosteroids in asthma

Answer 7

produce beneficial effects by restoring B-adrenergic responsiveness and reducing inflammation

used in all but mild, easily fully reversed episodes of acute asthma

Corticosteroids given within 1 hour of arrival in the ED reduce the need for hospitalization

Question 8

the peak anti-inflammatory effect occurs at least _______ after IV or PO corticosteroid administration

Answer 8

4-8 hours

Question 9

an initial corticosteroid dose of _______ is sufficient

Answer 9

PO prednisone of 40-60 mg
or
IV methylprednisolone of 1mg/kg
[or IV hydrocortisone 5 mg/kg?]

Question 10

In asthma, give patients who are being discharged home after ED treatment a:

Answer 10

5-10 day nontapering course of prednisone (40-60 mg/day in a single daily dose or its equivalent)

or a 2-day course of oral dexamethasone (16 mg/day in a single daily dose)

Question 11

remarks on anticholinergics

Answer 11

Anticholinergics affect large, central airways, whereas B-adrenergic drugs dilate smaller airways

Use an aerosolized ipratropium bromide solution, 0.5 mg, in ED patients with mod-to-severe exacerbation

may decrease rate of hospitalization of mod-to-severe asthma

Question 12

remarks on mechanical ventilation in asthma

Answer 12

mechanical ventilation does not relieve the airflow obstruction - it merely reduces the work of breathing and enables the patient to rest while the airflow obstruction is resolved

Question 13

strategy to reduce air trapping in mechanical ventilation

Answer 13

using rapid inspiratory flow rates at a reduced respiratory frequency (12-14 breaths/min)
- allows adequate time for the expiratory phase

also, it is reasonable to target adequate arterial oxygen saturation (≥90%) without concern for “normalizing” the hypercarbic acidosis. This approach is called controlled mechanical hypoventilation or permissive hypoventilation

Question 14

other remarks on mechanical ventilation in asthma

Answer 14

Ventilation of patients with acute asthma requires sedation

Neuromuscular block agents may be required, but extended use may cause postextubation muscle weakness