Acute Severe Asthma Medications

1. Acute Severe AsthmaMedications EBL Group 1 Carol, Marina, Sophia & Wendy

2. Acute Severe AsthmaThe first 24 hours • IMMEDIATE: • 60% Oxygen • Nebulised Salbutamol 5mg • 40mg prednisolone • CAN ADD: • Nebulised Atrovent (Ipatropium Bromide) 0.5mg • Aminophylline bolus 250mg IV • CAN CONTINUE: • Nebulised Salbutamol initially every 15-30 minutes • Nebulised Atrovent every 6 hours • Aminophylline infusion 0.5mg/kg/hour

3. Oxygen • Hypoxemia is a preventable cause of many asthma deaths. • BTS asthma guidelines advise oxygen as first line treatment for all cases of acute severe asthma. • Patients with acute severe asthma such as Simon Hope benefit from uncontrolled high flow oxygen.

4. Oxygen cont… • Oxygen should be regarded as a drug because it has the potential for adverse reactions or toxicity. • ‘Oxygen is prescribed for hypoxemic patients to increase alveolar tension and decrease the work of breathing necessary to maintain a given arterial oxygen tension’ (BNF 2006).

5. Oxygen cont… • The concentration of oxygen given to a patient depends on the condition being treated. An inappropriate concentration may have serious effects. • In conditions such as Acute Severe Asthma, high concentration oxygen therapy with concentrations of up to 60% is safe.

6. Principle stores of oxygen in the body

7. Oxygen cont.. • In acute severe asthma, the arterial carbon dioxide (PCo2) is usually subnormal but as asthma deteriorates it may rise. • These patients require high concentrations of oxygen. • If the PCo2 remains high despite other treatment, intermittent positive pressure ventilation needs to be considered.

8. Oxygen cont… • COPD - In a small group of patients with COPD, chronic raised CO2 levels depend on hypoxia to stimulate respiration (Hypoxic Respiratory Drive). • In a normal patient the respiratory drive is raised levels of CO2 in the blood. • Therefore, if a patient with retained CO2 is given high concentrations of oxygen the respiratory drive is not stimulated resulting in apnoea.

9. Oxygen cont… • It is also important to remember that treatment with inhaled agonists (nebulisers) is often given to relieve bronchospasm and improve oxygenation. In acute severe asthma, nebulisation of agonists without oxygen can cause or worsen hypoxaemia.

10. It has been suggested that high concentrations of Oxygen (90-100%) administered to patients for a prolonged period (several days) may cause pulmonary damage. There is little evidence to support this and therefore the use of oxygen to treat severe hypoxia should not be prevented. • (Law & Bukwira 1999)

11. Oxygen delivery devices • High flow oxygen is given via a high flow device providing a fixed (controlled) oxygen concentration. • Variable performance (Nasal cannula) - used for low flow oxygen. May cause discomfort and dryness of the nasal mucosa if used for high flow oxygen. Should not be used for flow rate above 4L/min. • Variable performance (Hudson mask)- delivers a percentage of oxygen that depends on the rate and depth of the patient’s respirations. Used for high concentrations of oxygen greater than 60%.

12. Partial rebreathing masks - has a reservoir bag for oxygen to be delivered beyond 60%. • Non-rebreathing mask - for oxygen delivery of 80% and above. Used to prevent the accumulation of expired gasses and retention of carbon dioxide. • Venturi masks - used to give a fixed, precise flow rate. These are the masks of choice during an acute episode as they provide an accurate concentration of oxygen not dependent upon the patient’s rate and depth of breathing. They also prevent the patient fromre-breathing their own carbon dioxide. Venturi masks are colour coded and deliver 24%, 28%, 35%, 40% and 60% oxygen.

13. Nursing Practice • Oxygen is highly flammable. • Oxygen must be prescribed by a doctor, except in an emergency situation. • The centre of the ball in the flow meter must sit at the level of the flow rate prescribed. • Oxygen therapy dries the mucous membranes of the mouth. Frequent drinks and mouth care must be provided if the oxygen is not being humidified.

14. BronchodilatorsSalbutamol and Ipratropium Bromide • Two main types- • B2 adrenoreceptor stimulant (Sympathomimetics) • Antimuscarinics (anticholinergics)

15. Bronchodilators cont.. • Sympathomimetics interact with the autonomic nervous system usually targeted at neurotransmitter receptors. • Anticholinergics work by blocking the neurotransmitter of the parasympathetic nervous system.

16. Bronchodilators • Bronchodilators act on the nerve signals that govern muscle activity. Sympathomimetics enhance the action of neurotransmitters that encourage muscle relaxation. Anticholinergics block the neurotransmitters that trigger muscle contraction and reduce production of mucus.

17. Bronchodilators cont… • These bronchodilators stimulate the beta 2 receptors in the bronchial smooth muscles by: • Widening the bronchioles • Reducing bronchial oedema • Inhibiting bronchoconstrictive effects of vagus nerve activity.

18. Bronchodilators cont.. • When Salbutamol is given with Ipratropium Bromide (Combivent) it has a greater bronchodilator effect than a single dose of salbutamol.

19. Forms of Bronchodilators • Inhaler • Nebuliser • Intravenous • Inhalation works rapidly to provide immediate symptom relief but is more expensive. • IV administration is reserved for severe illness. The rate of infusion is 3-20mcg/min depending on heart rate.

20. Bronchodilators cont.. • However, a nebuliser is the preferred method of administration for Simon as he has an acute exacerbation of asthma. This has a rapid onset of 5-10 minutes and can last up to 4 hours. Nebulisers allow delivery of large doses of drug with minimal effort required from the patient. • The nebuliser would be given driven by oxygen.

21. Side effects of Bronchodilators • Stimulates the beta receptors in other parts of the body such as heart and skeletal muscles. • Tachycardia • Tremors • Hypertension • Hypocalcaemia

22. Contraindications • Patients who have heart problems, hypertension or an overactive thyroid gland. • Smoking • Patients with urinary retention (Ipratropium).

23. Corticosteroids • Corticosteroids consist of the glucorticoid and mineralocorticoid hormones synthesized in the adrenal cortex and the drugs derived from them. • Corticosteroids suppress the immune system, inflammatory process and hypersensitivity responses and provide symptom relief in acute conditions such as asthma.

24. Corticosteroids cont… • Corticosteroids are lipid soluble and they cross cell membranes rapidly. • Corticosteroids increase the risk of infections including those associated with live vaccines. • Corticosteroids control the immune response, metabolic pathways, fluid and electrolyte balance, cardiovascular and central nervous systems.

25. Corticosteroids cont… • Corticosteroids should only be prescribed if beta 2 agonists are needed for symptom relief more than once each day and a period of 4-6 week trial. • Corticosteroids adversely affect plasma lipid concentrations, which should be monitored.

26. Corticosteroids • Corticosteroids reduce the inflammatory and allergic aspects of asthma and decrease bronchospasm in severe and persistent asthma (Greenstein 2004). • Corticosteroids are also used to prevent symptoms of asthma. • Simon was given oral prednisolone prior to his emergency admission where he was given hydrocortisone 200mg IV.

27. Corticosteroids cont.. • According to the British Thoracic Society guidelines for the management of Acute Severe Asthma, Oral prednisolone 40-50mg daily for at least 5 days should be given. • Or Hydrocortisone 400mg IV daily in 4 divided doses.

28. Corticosteroids • Hydrocortisone - Given to reduce inflammation and allergic reactions (Greenstein 2004, Downie et al 2003). • Even though it was given IV it takes several hours to be effective.

29. Increased risk of infections Nutrition: increase in appetite, risk of hypertension - foods rich in salt should be avoided Loss of potassium causing muscle weakness Constipation Cardiac complications Salt and water retention Risk of osteoporosis Cardiovascular disease Diabetes High cholesterol Congested heart failure Increased risk of thrombosis Adverse effects of Corticosteroids

30. Gastrointestinal e.g peptic ulceration Abdominal distension Acute pancreatitis Oesophageal ulceration Psychological dependence Depression Insomnia psychosis Aggravation of epilepsy Thinning of the skin and skin bruising Impaired hearing Fluid and electrolyte disturbances thromboembolism Side effects of Corticosteroids

31. Corticosteroids • Patients who deteriorate rapidly usually respond well to corticosteroids (BNF 2005). • Acute attacks should be treated with short courses usually with high doses for a few days. Patients should be weaned off gradually. However, it can be stopped immediately in mild exacerbations. • Caution should be taken in hypertensive patients, diabetic patients, heart failure. • Corticosteroids interact with anti-coagulants, aspirin, NSAID’s and alcohol.

32. Methylxanthines • Aminophylline is from the group of drugs known as Methylanthines is a derivate of theophylline and closely related to caffeine. • It directly relaxes the smooth muscle of the bronchi and pulmonary blood vessels.

33. Aminophlline • Aminophlline inhibits the enzyme phosphodiesterase in bronchial muscle causing it to relax, thus relieving bronchospasm. It is also used as an additional bronchodilator to beta 2 receptor agonists.

34. Aminophylline cont.. • In asthma, it has a resultant increase in bronchial smooth muscle cell activity leading to bronchodilation. • In COPD, it enhances cardiovascular performance.

35. Aminophylline can be given slowly intravenously as a single dose of 250mg to terminate an acute attack. It can also be given as a loading dose followed by an infusion by pump. • Aminophylline is given in tablet form slow release b.d.

36. Insomnia Anxiety Nervousness Epigastric effects Nausea / vomiting tachycardia Adverse reactions - (dose related) Nervous system over stimulation Convulsions Ventricular arrhythmias Side effects

37. Needs careful use as there is only a small difference between a therapeutic and toxic dose. • The rate of elimination depends on a number of factors including weight, sex, age, concurrent disease and other medication and may vary considerably.

38. Nursing Interventions • Check if patient is taking methyalxanthine orally. • Plasma levels should be checked at intervals as a guide to dosage. • Warn patient not to drive if feeling dizzy or light headed. • Advise patient to limit intake of tea, coca cola, coffee and chocolate which all contain caffeine which can affect the theophylline metabolic state. • Swallow whole without chewing to control gastric irritation. • Advise patient to avoid smoking as it alters the serum levels.

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