Question

discuss the standard of practice for asthma

Answer 1

Ans) Standard Management of Status Asthmaticus

• Assessment:

Although a brief history and focused physical examination may be most appropriate when initially stabilizing a patient in respiratory distress, a complete history and physical examination should be completed as soon as possible because important co-morbidities may be revealed that could influence management. Chest radiography and laboratory studies are rarely needed in patients admitted with status asthmaticus. Exceptions include patients with persistent focal findings on auscultation, high fever or toxic appearance, severe chest pain, or other unusual clinical features.

The appropriate initial and ongoing assessment of the severity of the asthma exacerbation is essential. These assessments guide the type, amount, and frequency of treatments, as well as the trajectory of the course of illness.

Many institutions implement asthma pathways that link ongoing assessments and response to therapy to management. Patients are placed along a pathway according to their initial assessment and receive a corresponding therapy. As the patient demonstrates sustained improvement in severity of the asthma signs and symptoms, the intensity of the therapy and monitoring is reduced. When the patient reaches a level of therapy that can be maintained at home and demonstrates stability in his or her signs and symptoms on that home regimen, the patient is medically ready for discharge.

Medications

• Beta Agonists

Inhaled short-acting beta-adrenergic agonists are the mainstay of hospital therapy. They stimulate beta-adrenergic receptors that cause relaxation of bronchial smooth muscle, which decreases airway obstruction. Other effects include stimulation of skeletal muscles (which can result in tremor), stimulation of cardiac muscles (which can cause tachycardia), and stabilization of mast cell membranes (which may decrease release of inflammatory mediators).

Albuterol is a commonly used short-acting selective beta-2-adrenergic agonist available for inhalation in a nebulizer solution or metered-dose inhaler (MDI). With a spacer and proper technique, albuterol administered by MDI is as effective as albuterol administered by nebulizer. Levalbuterol is a preparation that offers the active R-enantiomer of albuterol and is dosed at half the milligram dose of albuterol.

- Epinephrine is a nonselective adrenergic agonist and is most commonly used subcutaneously in patients who fail to respond to albuterol, especially in the early stabilization phase. Terbutaline is a selective beta-2-adrenergic agonist that can be used subcutaneously in place of epinephrine, but can also be administered as a continuous intravenous infusion for patients who deteriorate on inhaled beta-agonist therapy.

• Corticosteroids

Systemic corticosteroids are given routinely in hospitalized patients with an asthma exacerbation or status asthmaticus. Given early in the course of the exacerbation, it may prevent hospitalization, but, regardless, it is continued through the hospital stay to speed recovery and prevent recurrence. Prednisone or prednisolone given orally is standard. Methylprednisolone is the form for intravenous administration, but this is only needed in patients who cannot tolerate the medication orally (see Table 36-2).

• Inhaled Anticholinergics

Ipratropium is the most commonly used inhaled anticholinergic bronchodilator. It is thought to provide additional bronchodilation by blocking cholingeric-mediated bronchoconstriction. Although it has been shown to reduce the rate of hospitalization when administered with albuterol in the emergency department, it has not been shown to provide additional benefit when continued in hospitalized patients.

• Supplemental Oxygen

Asthma produces changes in the lungs that include bronchospasm, airway edema, and increased mucous production, all of which can lead to atelectasis and mucous plugging. This can result in hypoxia, either episodic or more sustained. Supplemental oxygen, delivered through face mask with nebulized treatments or via nasal cannula, is warranted to maintain pulse oximetry levels above 90%. Transient desaturations that clear with cough, repositioning, or activity do not necessarily warrant supplemental oxygen therapy.

• Intravenous Fluids and Electrolytes

Tachypnea and increased work of breathing can lead to inadequate hydration due to diminished oral intake and increased insensible losses. If encouraging oral intake of fluids is not successful, intravenous fluid supplementation may be warranted. Rehydration with intravenous normal saline if needed is an appropriate first step, followed by continuation of appropriate maintenance fluids (eg, D5-0.45NSS with 10 mEq/L potassium chloride) at a standard rate. Patients on continuous or frequent doses of inhaled beta-agonists can develop hypokalemia, so checking serum potassium levels is prudent, especially in patients requiring intravenous fluids.

• Nonstandard Therapies

Additional treatments may be considered if symptoms worsen despite standard therapy. Depending on the expertise or experience of the clinicians or the support available in the setting, consultation with services that provide a higher level of care should be anticipated whenever possible.

Intravenous magnesium sulfate can be considered in patients with severe asthma exacerbations that fail to respond to intensive standard therapy. The desired effects include bronchodilation and mast cell membrane stabilization, but vasodilation can result in significant hypotension.

Heliox is a helium-oxygen gas blend that may improve ventilation and decrease work of breathing due to its lower density compared to air. Studies have been mixed in determining its efficacy in status asthmaticus, and it is often reserved for patients in impending respiratory failure. It has limited utility in patients with hypoxemia, and hypothermia has been an issue in some patients due to heliox’s high thermal conductivity.