Acute severe asthma


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Acute severe asthma

  1. 1. Acute Severe Asthma<br />By: Kane Guthrie<br />
  2. 2. Objectives<br />Pathophysiology of ASA<br />Assessing the patient with ASA<br />Emergency department management<br />NIV vs Mechanical Ventilation in ASA<br />
  3. 3. Case Study<br />
  4. 4. Case Study <br />
  5. 5. Vital Signs<br />
  6. 6. Epidemiology of Asthma<br />Over 2.2 million Aussie’s have asthma<br />Over 400 hundred die each year<br />Highest risk of death >70years<br />Severe acute asthma is a life threatening condition.<br />
  7. 7. Pathophysiology<br />
  8. 8. Acute Severe Asthma<br />2 distinct phenotypes of ASA identified:<br />
  9. 9. Differential Dx:<br />
  10. 10. Assessment<br />
  11. 11. Assessing Severity<br />
  12. 12. Investigations<br />Diagnostic test generally provide limited information, compared to clinical assessment<br />
  13. 13. CXR<br />Limited Use<br />Hyperinflation 5-10%<br />Infiltrates 5%<br />PTX <1%<br />Pnemomediastinum <1%<br />
  14. 14. Blood Gas<br />Respiratory alkalosis typical<br />Inaccurate predictor of outcome<br />Seldom alters treatment plan<br />Clinical assessment gives better information<br />Painful<br />
  15. 15. Pulse Oximetry<br />Simple, less invasive and painful, compared to blo0d gas.<br />Provides continuous o2 measurement<br />Aim >Spo2 94%<br />
  16. 16. PEFM<br />Objective measurement of lung function<br />Useful to assess response to treatment<br />Limited role in ASA<br />
  17. 17. Complications of ASA<br />
  18. 18. ED Management<br />The sick and dying asthmatic!!!<br />
  19. 19. Nursing Care<br />Apply o2/neb (humidified)<br />Monitor BP,HR,RR, Spo2, EtCo2, Temp, GCS<br />IVC x2<br />Monitor electrolytes/arrhythmias closely<br />ECG<br />FBC<br />IDC<br />
  20. 20. o2<br />Asthmatic die from hypoxia<br />Keep Sp02 > 94%<br />A slight ∧ in Pco2 may occur, (not clinically significant)<br />
  21. 21. Bronchodilators<br />Salbutamol<br />First line therapy <br />Nebulizer (back to back nebs)<br />Dose?<br />Not improving consider IV (back door)<br />Monitor K<br />Salbutamol toxicity= ∧Lactic acidosis<br />
  22. 22. Anticholinergics<br />Ipratropium bromide<br />Blocks muscarinic receptors in smooth muscle, resulting in bronchodilation<br />Dose: 500mcg<br />Can give up to 3 dose’s initially then ever 4/24<br />
  23. 23. Mg<br />Controversial<br />Best evidence is in the sick/dying asthmatic<br />Cause smooth relaxation, inhibits histamine & acetylcholine release from nerve endings<br />Indicated when bronchodilators are failing<br />Dose: 2-4mg over 30-60mins<br />
  24. 24. Steroids<br />Prednisolone vs Hydrocortisone<br />Given within 1st hour greatly reduces hospital admission<br />Target airway oedema and secretions via anti-inflammatory role<br />Dose: Pred 50mg PO, Hydrocort 100-200mg IV<br />
  25. 25. Adrenaline<br />Given via Neb or IV<br />Alpha effects target ∨ airway oedema<br />Beta effect target ∨bronchodilation<br />Used as a rescue therapy in the hypotensive, poor responding asthmatic<br />Dose: Neb 1-6mg in 3ml Nacl<br />Dose: IV 6mg in 100mls 5% dextrose (1-15mls/Hr), “also push dose’s 0.10-0.50mcg”.<br />
  26. 26. AB’s<br />Not routinely indicated<br />Give<br />Underlying pneumonia/bacterial cause<br />Preventing VAP<br />
  27. 27. Airway Management<br />
  28. 28. NIV<br />Becoming more popular, (research, case reports)<br />Unloads resp muscles, augments alveolar ventilation until asthma resolves.<br />CPAP vs BiPAP<br />Start with low IPAP & EPAP<br />Good indicator which patients need intubating<br />
  29. 29. What the literature says on NIV.<br />Clinical Evidence:<br />
  30. 30. Mechanical VentilationIndications<br />
  31. 31. Intubating<br />Ketamine for bronchodilator effects<br />Use rapid sequence intubation<br />Fluid bolus before (pre-load)<br />Allow permissive hypercapnea<br />
  32. 32. Challenges of Mechanical Ventilation<br />Effective pre-oxygenation difficult<br />No margin for error or delay<br />Need to be intubated by most senior person available<br />Develop high Intrathoracic pressure after RSI<br />Intubation causes higher mortality via= lung hyperinflation, VILI, cardiovascular collapse.<br />
  33. 33. The BIG issue<br />Asthmatics require prolonged expiratory times<br />Severe asthma pt initiates inspir before expir ceases<br />Results in increase lung volume, auto-peep and hyperinflation<br />Minimizing hyperinflation and avoiding excessive airway pressures are the goals<br />Use low RR and prolonged exhalation times<br />Allow Co2 to rise, but keep pH .7.15 <br />Monitor (P plat) >30 cm H20 against expir time<br />
  34. 34. Initial Ventilator Settings<br />Assist control mode<br />Tidal volume 7-8mL/kg (use ideal body weight)<br />RR 10-12bpm<br />Fi02: 100%<br />PEEP: 0cm H20<br />Patients require deep sedation to tolerate the Vent.<br />
  35. 35. Crashing Ventilated Asthmatic<br />D.O.P.E.S.<br />
  36. 36. Take Home Points<br />Assessment skills are paramount<br />Maximizing therapy to prevent MV is the GOAL!!!<br />Mg works in the sick asthmatic<br />NIV works<br />Experience makes a big difference<br />These patients will challenge you<br />
  37. 37. Questions<br />
  38. 38. Thank-you<br />