Acute exacerbation of bronchial asthma

1. Should oxygen be given to all patients with acute exacerbation of bronchial asthma?

Moderator: The usual practice is to provide oxygen by nasal prongs or face mask to patients with exacerbations of bronchial asthma. The purpose is to ensure that the oxygen saturation of blood is more than 90 percent. Oxygen may not be necessary in mild exacerbations when the SaO2 is well within normal limits.

2. All exacerbations of bronchial asthma are not severe. What are the criteria used to determine if an exacerbation is severe?

Student: In severe exacerbation of bronchial asthma, patients are unable to complete a sentence using one breath and appear tachypnoeic with respiratory rate of more than 25 breaths per minute. They are also tachycardic with pulse rate of more than 120 bpm. Peak expiratory flow rate (PEFR) would be less than 50% of best achievable value. However, in life threatening exacerbation, patients can present with silent chest, cyanosed and poor inspiratory effort. Blood pressure and pulse rate would be reduced, and at the same time altered consciousness can occur.

Moderator: The exacerbation is said to be severe when there is one or more of the following due to the asthma: The patient can only talk in words or phrases; The pulse is more than 120 beats per minute; The respiratory rate is more than 30 per minute; There is pulsus paradoxus which means that the systolic arterial pressure falls by more than 25mm Hg on inspiration; The SaO2 is less than 90 percent or the PaO2 is less than 60mm Hg; The chest is silent on auscultation (this may indicate life threatening asthma if associated with altered mental status or paradoxical chest movement); The FEV1 or the PEFR is less than 40 percent of expected (some guidelines may mention 50 percent).

3. The initial treatment of acute exacerbation of bronchial asthma is inhalation of salbutamol and ipratropium. In a severe exacerbation, how frequently can this be given?

Student: In a severe exacerbation, salbutamol / ipratropium can be given up to 6-10 puffs within 1-2hours. GINA 2010

Moderator: For severe exacerbations, high doses of salbutamol (4 to 8 puffs from a MDI or 2.5 to 5.0mg by Nebuliser) plus ipratropium bromide (500ug) can be given every twenty minutes for 60 to 90 minutes. All patients with acute exacerbation should be reassessed after 60 to 90 minutes of treatment.

4. Is continuous administration of salbutamol / ipratropium better than intermittent administration, for severe exacerbations of asthma?

Student: Recent studies show conflicting results between these 2 mode of administrations. Both mode of treatments has no significant differences in bronchodilator effect & hospital admission, but 1 study says intermittent (on demand) therapy led to shorter hospital stay, fewer neb, less palpitation. Hence, recommend use continuous administration initially then changed to intermittent administration of salbutamol/ipratropium during severe AEBA

Student: Inhalation of Salbutamol/Ipratopium provides prompt relief for acute exacerbation of bronchial asthma by reversing the airflow obstruction. Continuous administration of Salbutamol/Ipratopium might be more effective compared to intermittent administration in patients with severe exacerbations. Studies showed that continuous nebulisation is associated with increased peak flow rate, decreased respiratory rate, heart rate, BP and clinical severity score. However, the benefits of continuous bronchodilatation with Salbultamol/Ipratropium are more marked in severe exacerbations than moderate exacerbation.
References: 1. Steve G.Peters, MD, FCCP. Continous Bronchodilator Therapy. CHEST 2007;131;286-289
2. Carlos A. Camargo, Jr. Gary Rachelefsky, and Michael Schatz. Managing Asthma Exacerbations in the Emergency Department – Summary of the National Asthma Education and Prevention Program Expert Panel Report 3 Guidelines for the Management of Asthma Exacerbation. Proceedings of the American Thoracic Society.2009. Vol.6, pp. 357-366.

Moderator: Some advocate continuous inhalation of salbutamol for severe exacerbations instead of intermittent usage. A Cochrane review of 8 trials had suggested that continuous administration of salbutamol resulted in greater improvement in PEFR and FEV1.

5. Why is ipratropium alone (that is, without salbutamol) not advocated for treatment of acute exacerbations of asthma?

Student: Ipatropium bromide should only be used in acute exacerbations of asthma with a beta agonist because it is only a very weak bronchodilator and may rarely cause paradoxical bronchospasm.

Moderator: Inhaled Ipratropium alone should not be used in acute exacerbations because it is relatively slower in action than salbutamol.

6. In acute exacerbations of asthma, should corticosteroids be only administered intravenously? Is it less effective if given orally?

Student: There is no significant difference in FEV1, length of hospital stay and rate of side effects between oral and intravenous corticosteroid. Both are equally effective in acute exacerbation of bronchial asthma.

Student: Both oral & IV corticosteroids are systemic steroid, having same efficacy (or similar); IV is not more effective than oral corticosteroid, but faster in time of onset of action, therefore in acute setting, IV corticosteroid is given (assumed patient need the anti-inflammatory effect immediately, and assumed patient's b. asthma is poorly controlled despite already on certain dosage of inhaled steroid). After patient's condition stabilized, the IV corticosteroid can be changed to oral. Despite saying similar efficacy, for long term therapy purpose, oral is always preferred over IV due to lesser systemic side effects such as striae, hypertension, it has shorter half life and allow flexible dosage adjustment. GINA 2010

Moderator: In acute exacerbations, oral prednisolone is as effective as intravenous corticosteroids. Intravenous hydrocortisone is often given in acute exacerbations because of the belief that it will act faster. Guidelines recommend 40 to 80mg of prednisolone per day either in a single dose or in two divided doses.

7. How long should systemic corticosteroids be given after an acute exacerbation of asthma?

Student: After an acute exacerbation, systemic corticosteroid should be continued orally for 5-10 days without tapering the dose.

Moderator: Oral prednisolone may be needed for up to ten days. One must make sure that the bronchial asthma is no longer in a severe category (clinical and PEFR measurements) before stopping oral steroids.

8. Magnesium sulphate is sometimes used for acute exacerbations of asthma. When should it be used?

Student: Intravenous administration of Magnesium sulphate may improve bronchodilation and airflow and at the same time improves the pulmonary function. The role of IV Magnesium sulphate appears to provide clinical benefits and lowering the rate of hospital admission in severe acute exacerbation of asthma. A large multicenter study of 248 subjects showed that treatment with IV magnesium sulphate is beneficial when used as an adjunct to standard therapy in subjects with acute severe asthma, but not in less severe airway obstruction. (Silverman RA, Osborn H, Runge J, et al. IV magnesium sulphate in the treatment of acute severe asthma: a multicenter randomized controlled trial. Chest. 2002;122:489-497.)

Moderator: Intravenous magnesium sulphate (2grams IV for an adult) can be given for those who still have evidence of severe exacerbation after 60 to 90 minutes of initial treatment with bronchodilators and steroids.

9. Should all patients who present to the A&E department with an acute exacerbation of asthma be admitted?

Student: Not all patients require admission to the ward. Certain group of patients such as
those with severe or life-threatening exacerbation, moderate exacerbation (a. condition worsen or PEFR <50% after being given nebulised beta agonist … b. Condition does not improve after 2 times of nebulised beta agonist or PEFT<75% after 2 doses) will need to be admitted. Also, patients who live in a relatively far proximity from a health care facility need to be admitted.

Moderator: Not all patients who present to the emergency room with an acute exacerbation need to be admitted. When a patient improves with treatment and the PEFR is sustained for more than one hour above 70 percent (four hours after initiating treatment), the patient can be sent home to continue treatment. On the other hand, those who continue to have severe symptoms or a PEFR below 40 percent or a PaCO2 above 42mm Hg, four hours after treatment is begun definitely need admission.

10. What is your opinion about the use of theophyllines, antibiotics and mucolytic agents in acute exacerbations of asthma?

Student: Clinical practice guidelines recommend against empiric antibiotic therapy for the treatment of an asthma exacerbation as antibiotics do not treat acute exacerbations of bronchial asthma. However if the patient have coexisting bacterial pneumonia or other bacterial infection such as sinusitis which require antibiotic treatment, the use of antibiotic is then indicated as it will treat the underlying conditions which may have triggered the acute attack. Most respiratory infections that trigger an exacerbation of asthma are viral rather than bacterial. Therefore antibiotics should not be given routinely to every patient with acute exacerbation of bronchial asthma.

Mucolytic agents, such as N-acetylcysteine and potassium iodide, should be avoided because they may worsen cough or airflow obstruction. (reference: GINA guidelines 2010).

A Cochrane Review published in 2001 considered the magnitude of the effect of addition of intravenous aminophylline to beta2 agonists in adult patients with acute asthma treated in the emergency setting. In this review, there was no statistically significant effect of aminophylline on airflow outcomes at any time period. Besides that, use of theophylline is associated with severe and potentially fatal side effects, particularly in those on long-term therapy with sustained-release theophylline. Furthermore, the bronchodilator effect of theophylline is less than that of beta2 agonist. Up till now, no study has shown the benefits of theophylline as add on treatment in adults with severe asthma exacerbations. In view of the effectiveness and relative safety of rapid-acting beta2 agonists, theophylline has a minimal role in the management of acute asthma. The available evidence supports the views expressed in the most recent GINA guidelines 2010, that aminophylline should be a last resort choice, considered only when the first-line treatments (inhaled bronchodilators and systemic steroids) have proven to be ineffective in the individual patient. Ref.: Parameswaran K, Belda J Rowe BH. Addition of intravenous aminophylline to beta2-agonists in adults with acute asthma. The Cochrane Database of Systematic Reviews 2000, Issue 4.

Moderator: Theophyllines, antibiotics and mucolytic agents are not routinely recommended in acute exacerbations.

11. When patients with severe exacerbations of asthma need ventilation, what should you know about the ventilator settings?

Student: In conditions where patients with severe exacerbation bronchial asthma requiring ventilation, the ventilator settings is vital to avoid excessive lung inflation which can be minimized by allowing adequate time for exhalation. …The basic principles are as follows:
1. Ventilation should initially be on the continuous mandatory ventilation (CMV) mode
2. employ low tidal volumes (8-10mls/kg) with low respiratory rate of 10-14 breaths per minute to decrease the minute ventilation for a prolong expiratory time
3. increase the inspiratory flow rate (60 L/min or more) and use the square flow wave form to shorten the inspiratory time
4. inspiratory/ expiratory ratio is reduced to 1:5
When these principles are applied, it reduces the risk of pneumothorax and systemic hypotension.

Moderator: Patients with altered mental status, exhaustion, and / or hypercapnia, should be intubated and ventilated. High positive pressures during ventilation should be avoided because of risk of barotrauma to the lungs.

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