1. Acute Severe Asthma By: Kane Guthrie

2. Objectives Pathophysiology of ASA Assessing the patient with ASA Emergency department management NIV vs Mechanical Ventilation in ASA

3. Case Study

4. Case Study

5. Vital Signs

6. Epidemiology of Asthma Over 2.2 million Aussie’s have asthma Over 400 hundred die each year Highest risk of death >70years Severe acute asthma is a life threatening condition.

7. Pathophysiology

8. Acute Severe Asthma 2 distinct phenotypes of ASA identified:

9. Differential Dx:

10. Assessment

11. Assessing Severity

12. Investigations Diagnostic test generally provide limited information, compared to clinical assessment

13. CXR Limited Use Hyperinflation 5-10% Infiltrates 5% PTX <1% Pnemomediastinum <1%

14. Blood Gas Respiratory alkalosis typical Inaccurate predictor of outcome Seldom alters treatment plan Clinical assessment gives better information Painful

15. Pulse Oximetry Simple, less invasive and painful, compared to blo0d gas. Provides continuous o2 measurement Aim >Spo2 94%

16. PEFM Objective measurement of lung function Useful to assess response to treatment Limited role in ASA

17. Complications of ASA

18. ED Management The sick and dying asthmatic!!!

19. Nursing Care Apply o2/neb (humidified) Monitor BP,HR,RR, Spo2, EtCo2, Temp, GCS IVC x2 Monitor electrolytes/arrhythmias closely ECG FBC IDC

20. o2 Asthmatic die from hypoxia Keep Sp02 > 94% A slight ∧ in Pco2 may occur, (not clinically significant)

21. Bronchodilators Salbutamol First line therapy Nebulizer (back to back nebs) Dose? Not improving consider IV (back door) Monitor K Salbutamol toxicity= ∧Lactic acidosis

22. Anticholinergics Ipratropium bromide Blocks muscarinic receptors in smooth muscle, resulting in bronchodilation Dose: 500mcg Can give up to 3 dose’s initially then ever 4/24

23. Mg Controversial Best evidence is in the sick/dying asthmatic Cause smooth relaxation, inhibits histamine & acetylcholine release from nerve endings Indicated when bronchodilators are failing Dose: 2-4mg over 30-60mins

24. Steroids Prednisolone vs Hydrocortisone Given within 1st hour greatly reduces hospital admission Target airway oedema and secretions via anti-inflammatory role Dose: Pred 50mg PO, Hydrocort 100-200mg IV

25. Adrenaline Given via Neb or IV Alpha effects target ∨ airway oedema Beta effect target ∨bronchodilation Used as a rescue therapy in the hypotensive, poor responding asthmatic Dose: Neb 1-6mg in 3ml Nacl Dose: IV 6mg in 100mls 5% dextrose (1-15mls/Hr), “also push dose’s 0.10-0.50mcg”.

26. AB’s Not routinely indicated Give Underlying pneumonia/bacterial cause Preventing VAP

27. Airway Management

28. NIV Becoming more popular, (research, case reports) Unloads resp muscles, augments alveolar ventilation until asthma resolves. CPAP vs BiPAP Start with low IPAP & EPAP Good indicator which patients need intubating

29. What the literature says on NIV. Clinical Evidence:

30. Mechanical VentilationIndications

31. Intubating Ketamine for bronchodilator effects Use rapid sequence intubation Fluid bolus before (pre-load) Allow permissive hypercapnea

32. Challenges of Mechanical Ventilation Effective pre-oxygenation difficult No margin for error or delay Need to be intubated by most senior person available Develop high Intrathoracic pressure after RSI Intubation causes higher mortality via= lung hyperinflation, VILI, cardiovascular collapse.

33. The BIG issue Asthmatics require prolonged expiratory times Severe asthma pt initiates inspir before expir ceases Results in increase lung volume, auto-peep and hyperinflation Minimizing hyperinflation and avoiding excessive airway pressures are the goals Use low RR and prolonged exhalation times Allow Co2 to rise, but keep pH .7.15 Monitor (P plat) >30 cm H20 against expir time

34. Initial Ventilator Settings Assist control mode Tidal volume 7-8mL/kg (use ideal body weight) RR 10-12bpm Fi02: 100% PEEP: 0cm H20 Patients require deep sedation to tolerate the Vent.

35. Crashing Ventilated Asthmatic D.O.P.E.S.

36. Take Home Points Assessment skills are paramount Maximizing therapy to prevent MV is the GOAL!!! Mg works in the sick asthmatic NIV works Experience makes a big difference These patients will challenge you

37. Questions

38. Thank-you