ACUTE SEVERE ASTHMAStatus Asthmaticus

Introduction Status asthmaticus is an acute exacerbation of asthma that

remains unresponsive to initial treatment with bronchodilators.

Status asthmaticus can vary from a mild form to a severe form with bronchospasm, airway inflammation, and mucus plugging that can cause difficulty breathing, carbon dioxide retention, hypoxemia, and respiratory failure.

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.

Pathophysiology

The airway obstruction is due to a combination of factors that include spasm of airway smooth muscle, edema of airway mucosa, increased mucus secretion, cellular (eosinophilic and lymphocytic)

infiltration of the airway walls, and injury and desquamation of the airway

epithelium.

Risk factors

Genetic predisposition GERD Viral infections Air pollutants - Such as dust, cigarette smoke, and industrial

pollutants Medications - Including beta-blockers, aspirin, and

nonsteroidal anti-inflammatory drugs (NSAIDs) Cold temperature Exercise

Asthma is one of the most common chronic diseases worldwide with an estimated 300 million affected individuals

Prevalence is increasing in many countries, especially in children Asthma is a major cause of school and work absence Health care expenditure on asthma is very high

Developed economies might expect to spend 1-2 percent of total health care expenditures on asthma.

Developing economies likely to face increased demand due to increasing prevalence of asthma

Poorly controlled asthma is expensive However, investment in prevention medication is likely to yield cost savings

in emergency care The prevalence in Tanzania is 1-8%

Burden of asthma

GINA 2015

Clinical Presentation - History Presence of current illness, such as upper respiratory tract infection or pneumonia History of chronic respiratory diseases (eg, bronchopulmonary dysplasia, chronic lung disease of

infancy) History of allergies Family history of asthma Known triggering factors – smoke, pets Home medications - Obtain a detailed list of medications being taken at home and, if possible, their

timing and dosage History of increased use of home bronchodilator treatment without improvement or effect History of previous intensive care unit (ICU) admissions, with or without intubation and mechanical

ventilatory support Asthma exacerbation despite recent or current use of corticosteroids Frequent emergency department visits and/or hospitalization (implies poor control) History of syncope or seizures during acute exacerbation

Physical examination Tachypneic with significant wheezing Hyperexpanded chest with use of accessory muscles (intercostal and

subcostal retratctions) Pulsus paradoxus Inability to complete a sentence, sits hunched forward Tachycardia and hypertension (PR >120 bpm) O2 saturation (on air) < 90% PEF ≤50% predicted or best level of consciousness may progress from lethargy to agitation, air hunger,

and even syncope and seizures Life threatening features – inability to speak, bradycardia, silent chest,

normal or reduced respiratory rate, cyanosis, PEF ≤33% predicted or best

Laboratory studies The selection of laboratory studies depends on historical data and

patient condition. Tests that should be performed in patients with status asthmaticus include the following:

Complete blood count (CBC) Arterial blood gas (ABG) Serum electrolyte levels Serum glucose levels Peak expiratory flow measurement Chest radiographs Electrocardiogram (in older patients)

Management

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

The first line of therapy is bronchodilator treatment with a beta2-agonist. 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.

Salbutamol solution 0.5% or 5 mg/mL nebulized by compressed oxygen or Salbutamol via a spacer 2 puffs repeated every 20-30 minutes

Oxygen, via a mask or nasal prongs, oxygen therapy can be easily titrated to maintain the patient's oxygen saturation above 92% (>95% in pregnant patients or those with cardiac disease)

Set up an IV line for rehydration and possible IV medication, Hydration, with intravenous normal saline at a reasonable rate, is essential. Special attention to the patient's electrolyte status is important.

Determine hydration status for amount of fluids required (not <2L/24hrs) Steroids: Prednisolone orally 40-60mg daily or IV hydrocortisone 200mg 6hry

(nebulized: controversial) DO NOT give drugs that sedate the patient e.g. valium

Add nebulized ipratropium bromide (500mcg) to B 2 agonist treatment for patients with acute severe or life-threatening asthma or those with a poor initial response to B 2 agonist therapy.

Consider a single dose of IV magnesium sulphate (1.2–2g IVI over 20min) after consultation with senior medical staff, for patients with acute severe asthma without a good initial response to inhaled bronchodilator therapy or for those with life-threatening or near-fatal asthma.

Use IV aminophylline only after consultation with senior medical staff. Some individual patients with near-fatal or life-threatening asthma with a poor response to initial therapy may gain additional benefit. The loading dose of IVI aminophylline is 5mg/kg over 20min unless on maintenance therapy, in which case check blood theophylline level and start IVI of aminophylline at 0.5–0.7mg/kg/hr.

IV salbutamol is an alternative in severe asthma, after consultation with senior staff. Draw up 5mg salbutamol into 500mL 5 % dextrose and run at a rate of 30–60mL/hr.

Avoid ‘routine’ antibiotics.

ICU admission criteriaIndications for ICU admission include the following:Altered sensoriumUse of continuous inhaled beta-agonist therapyExhaustionMarkedly decreased air entryRising PCO 2 despite treatmentPresence of high-risk factors for a severe attackFailure to improve despite adequate therapy

Prevention

Compliance with medications Avoid triggers