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Flashcards in Status asthmaticus Deck (25)
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1
Q

What are goals of management for status asthmaticus?

A

Management goals for status asthmaticus are (1) to reverse airway obstruction rapidly through the aggressive use of beta2-agonist agents and early use of corticosteroids, (2) to correct hypoxemia by monitoring and administering supplemental oxygen, and (3) to prevent or treat complications such as pneumothorax and respiratory arrest

2
Q

What is status asthmaticus?

A

Status asthmaticus is considered a medical emergency. It is the extreme form of an asthma exacerbation that can result in hypoxemia, hypercarbia, and secondary respiratory failure. In practice, the role of the physician is to prevent this from happening through patient compliance with controller medications (eg, steroid inhalers) in an outpatient setting.

3
Q

What are symptoms of status asthmaticus?

A

Patients report chest tightness, rapidly progressive shortness of breath, dry cough, and wheezing and may have increased their beta-agonist intake (either inhaled or nebulized) to as often as every few minutes

4
Q

What is the clinical presentation of status asthmaticus?

A

Typically, patients present a few days after the onset of a viral respiratory illness, following exposure to a potent allergen or irritant, or after exercise in a cold environment. Frequently, patients have underused or have been underprescribed anti-inflammatory therapy. Illicit drug use may play a role in poor adherence to anti-inflammatory therapy.

5
Q

What causes status asthmaticus?

A

Exposure to an allergen or trigger causes a characteristic form of airway inflammation in susceptible individuals, exemplified by mast cell degranulation, release of inflammatory mediators, infiltration by eosinophils, and activated T lymphocytes.

6
Q

What are the 2 phases of the pathogenesis of status asthmaticus?

A

Physiologically, acute asthma has two components: an early, acute bronchospastic aspect marked by smooth muscle bronchoconstriction and a later inflammatory component resulting in airway swelling and edema.

7
Q

What is the role of the immune system in the pathogenesis of status asthmaticus?

A

Within minutes of exposure to an allergen, mast cell degranulation is observed along with the release of inflammatory mediators, including histamine, prostaglandin D2, and leukotriene C4. These substances cause airway smooth muscle contraction, increased capillary permeability, mucus secretion, and activation of neuronal reflexes. The early asthmatic response is characterized by bronchoconstriction that is generally responsive to bronchodilators, such as beta2-agonist agents.

8
Q

What causes increased airway resistance and obstruction in the pathogenesis of status asthmaticus?

A

Bronchospasm, mucus plugging, and edema in the peripheral airways result in increased airway resistance and obstruction. Air trapping results in lung hyperinflation, ventilation/perfusion (V/Q) mismatch, and increased dead space ventilation. The lung becomes inflated near the end-inspiratory end of the pulmonary compliance curve, with decreased compliance and increased work of breathing.

The increased pleural and intra-alveolar pressures that result from obstruction and hyperinflation, together with the mechanical forces of the distended alveoli, eventually lead to a decrease in alveolar perfusion. The combination of atelectasis and decreased perfusion leads to V/Q mismatch within lung units. The V/Q mismatch and resultant hypoxemia trigger an increase in minute ventilation.

9
Q

What does the absence of wheezing suggest in status asthmaticus?

A

Determine whether the patient has a severe asthma exacerbation without wheezing (ie, the silent chest). Such patients may have such severe airway obstruction or be so fatigued that they are unable to generate enough airflow to wheeze. This is an ominous sign of impending respiratory failure.

10
Q

What is the progression of consciousness in patients with status asthmaticus?

A

The patient’s level of consciousness may progress from lethargy to agitation, air hunger, and even syncope and seizures. If untreated, prolonged airway obstruction and marked increase in the work of breathing may eventually lead to bradycardia, hypoventilation, and even cardiorespiratory arrest.

11
Q

What are the initial physical findings in status asthmaticus?

A

Patients are usually tachypneic upon examination and, in the early stages of status asthmaticus, may have significant wheezing. Initially, wheezing is heard only during expiration, but wheezing later occurs during expiration and inspiration.

The chest is hyperexpanded, and accessory muscles, particularly the sternocleidomastoid, scalene, and intercostal muscles, are used. Later, as bronchoconstriction worsens, the wheezing may disappear, which may indicate severe airflow obstruction.

12
Q

Which physical findings are characteristic of later stages of status asthmaticus?

A

An inability to speak more than one or two words at a time may also be observed in the later stages of an acute asthma episode. Ventilation/perfusion mismatch results in decreased oxygen saturation and hypoxia. Vital signs may show tachycardia and hypertension. The peak flow rate should be included in the vital signs in patients who are able to cooperate and who are able to tolerate the peak flow maneuver without significant distress.

13
Q

What is the role of peak flow rate in the evaluation of status asthmaticus?

A

The peak flow rate is a standard measure of airflow obstruction and is relatively simple to perform. Most patients with more than a mild exacerbation of asthma have hypoxia and decreased oxygen saturation due to V/Q mismatch. Oxygen saturation may increase following the use of bronchodilators secondary to an increase in V/Q mismatch. Some patients prefer to remain seated and leaning forward, rather than assuming a supine position.

14
Q

What is the significance of a finding retractions and abdominal muscle usage in status asthmaticus?

A

Retractions (ie, intercostal and subcostal) and the use of abdominal muscles may be observed in patients with status asthmaticus. The use of accessory muscles has been shown to correlate with the severity of airflow obstruction. An abnormally prolonged expiratory phase with audible wheezing can be observed. Patients with moderate to severe asthma are often unable to speak in full sentences.

15
Q

What are cardiovascular symptoms of status asthmaticus?

A

Cardiovascular symptoms may include tachycardia or hypertension in mild to moderate asthma. With worsening hypoxemia, hypercarbia, marked air trapping, and hyperinflation, the ventricular stroke volume is compromised and hypotension and bradycardia may be observed.

16
Q

Why does wheezing occur in status asthmaticus?

A

Wheezing occurs from air moving through narrowed, obstructed airways. Thus exhalation results in turbulent airflow and produces wheezes. Although asthma is the most common cause of wheezing, anything that causes airway obstruction and narrowing that results in turbulent airflow may generate wheezes. Therefore, not all wheezing is asthma.

17
Q

What labs should be obtained for patients with status asthmaticus?

A

Complete blood cell (CBC) count

Arterial blood gas (ABG) analysis

Serum electrolyte levels

Serum glucose levels

Peak expiratory flow measurement

Chest radiography

18
Q

What are treatment options for control of bronchoconstriction and inflammation in status asthmaticus?

A

After confirming the diagnosis and assessing the severity of an asthma attack, direct treatment toward controlling bronchoconstriction and inflammation. Beta-agonists, corticosteroids, and theophylline are mainstays in the treatment of status asthmaticus.

19
Q

How is fluid replacement used in the treatment of status asthmaticus?

A

Hydration, with intravenous normal saline at a reasonable rate, is essential. Special attention to the patient’s electrolyte status is important.

20
Q

How is oxygen therapy administered in status asthmaticus?

A

Oxygen therapy is essential, with hypoxia being the leading cause of death in children with asthma. Oxygen therapy can be administered via a nasal canula or mask, although patients with dyspnea often do not like masks. With the advent of pulse oximetry, oxygen therapy can be easily titrated to maintain the patient’s oxygen saturation above 92%

21
Q

What is the first line of therapy for status asthmaticus?

A

The first line of therapy is bronchodilator treatment with a beta2-agonist, typically albuterol. Handheld nebulizer treatments may be administered either continuously (10-15 mg/h) or by frequent timing (eg, q5-20min), depending on the severity of the bronchospasm.

22
Q

What dose of albuterol should be administered for the treatment of status asthmaticus?

A

The dose of albuterol for intermittent dosing is 0.3-0.5 mL of a 0.5% formulation mixed with 2.5 mL of normal saline. Many of these preparations are available in a premixed form with a concentration of 0.083%.

Studies have also demonstrated an excellent response to the well-supervised use of albuterol via an MDI with a chamber. The dose is 4 puffs, repeated at 15- to 30-minute intervals as needed. Most patients respond within 1 hour of treatment.

23
Q

What is the most effective route of delivery for beta2-agonists in the treatment of status asthmaticus?

A

The nebulized, inhaled route of administration is generally the most effective route of delivery for beta2-agonists. Inhaled beta-agonists can be administered intermittently or as continuous, nebulized aerosol in a monitored setting. Some patients with severe, refractory status asthmaticus may benefit from the addition of beta-agonists delivered intravenously.

24
Q

What is the role of glucocorticosteroids in the treatment of status asthmaticus?

A

Glucocorticosteroids are the most important treatment for status asthmaticus. [28] These agents can decrease mucus production, improve oxygenation, reduce beta-agonist or theophylline requirements, and activate properties that may prevent late bronchoconstrictive responses to allergies and provocation.

In addition, corticosteroids can decrease bronchial hypersensitivity, reduce the recovery of eosinophils and mast cells in bronchioalveolar lavage fluid, decrease the number of activated lymphocytes, and help to regenerate the bronchial epithelial cells.

25
Q

How are glucocorticosteroids administered in the treatment of status asthmaticus, and what dose should methylprednisolone be delivered?

A

Corticosteroids may be administered intravenously or orally. Although most practitioners administer corticosteroids intravenously during status asthmaticus, some studies indicate that early administration of oral corticosteroids may be just as effective.

Methylprednisolone 1 mg/kg/dose q6h