Status asthmaticus

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Most about status asthmaticus, you will find from etiology to treatment and ventilator management. This presentation is made with thanks to medscape and other resources.

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Status asthmaticus

  1. 1. Status Asthmaticus Fakhir Raza
  2. 2. Background • Acute Exacerbation • Unresponsive • Mild to Severe form • Trend is towards less number of admissions in intensive care1 • Han P, Cole RP. Evolving differences in the presentation of severe asthma requiring intensive care unit admission. Respiration. Sep-Oct 2004;71(5):458-62.
  3. 3. Treatment goals • Reverse airway obstruction • Correct Hypoxemia • Prevent or treat complications like pneumothorax and respiratory arrest
  4. 4. Etiology
  5. 5. Etiology • Acute Bronchospastic component marked by smooth muscle bronchoconstriction. • Later inflammatory airway swelling and edema
  6. 6. Early bronchospastic response • Exposure to allergen • Mast cell degranulation • Release of histamine, PGD2, LT-C4 • airway smooth muscle contraction, increased capillary permeability, mucus secretion, and activation of neuronal reflexes • Bronchoconstriction typically responds to bronchodilator therapy like beta 2 agonist
  7. 7. Later inflammatory response • Inflammatory mediators prime endothelium and epithelium of bronchial mucosa. • Inflammatory cells like eosinophils, neutrophils and basophils attach to primed endothelium and epithelium and later enter into the tissues • Eosinophils release ECP and MBP which induce desquamation of airway epithelium and expose nerve endings • It leads to further hyper responsiveness.
  8. 8. Later inflammatory response • Airway resistance and obstruction • caused by Bronchospasm, mucus plugging, and edema in the peripheral • Air trapping • results in lung hyperinflation, ventilation/perfusion (V/Q) mismatch, and increased dead space ventilation.
  9. 9. Later inflammatory response • Increase in pleural and intra alveolar pressure and distended alveoli leads to VQ mismatch, hypoxemia and increase in minute ventilation.
  10. 10. Complications • Slow compartments vs fast compartments • Respiratory alkalosis vs hypercarbia • Cardiac arrest • Respiratory failure or arrest • Hypoxemia with hypoxic ischemic central nervous system (CNS) injury • Pneumothorax or pneumomediastinum • Toxicity from medications
  11. 11. Risk factors • Genetic • GERD • Viral infections • Air pollutants • Medications • Cold exposure • Exercise
  12. 12. Prognosis • Generally good except when combined with heart failure or COPD • Poor prognostic factors include delay in starting treatment especially steroids
  13. 13. History • Severe dyspnea or hours or days. • Previous intubation and ventilation
  14. 14. Risk factors for developing status asthmaticus • Increased use of home bronchodilators without improvement or effect • Previous intensive care unit (ICU) admissions, with or without intubation • Asthma exacerbation despite recent or current use of corticosteroids • Frequent emergency department visits and/or hospitalization • Less than 10% improvement in peak expiratory flow rate (PEFR) • History of syncope or seizures during acute exacerbation • Oxygen saturation below 92% despite supplemental oxygen
  15. 15. Asthma with No Wheezing • Silent chest • Severe obstruction • fatigue
  16. 16. Physical Examination • Tachypnea • Wheezing in early stages • Initially expiratory • Later in both phases, may have absent breath sound in advance stage • Use of accessory muscles • Inability to speak more than 1 to 2 words • Decreased oxygen saturation • Tachycardia and Hypertension • Signs of complication, tension pneumothorax, pneumomediastinum • Peak expiratory flow meter measurement
  17. 17. Assessment of severity of asthma exacerbation • Moderate asthma exacerbation: • Increasing symptoms. • PEFR >50-75% best or predicted. • No features of acute severe asthma. • Acute severe asthma - any one of: • PEFR 33-50% best or predicted. • Respiratory rate ≥25 breaths/minute. • Heart rate ≥110 beats/minute. • Inability to complete sentences in one breath. • Life-threatening asthma - any one of the following in a patient with severe asthma: • Clinical signs: altered conscious level, exhaustion, arrhythmia, hypotension, cyanosis, silent chest, poor respiratory effort. • Measurements: PEFR <33% best or predicted, SpO2 <92%, PaO2 <8 kPa, 'normal' PaCO2 (4.6- 6.0 kPa).
  18. 18. Differential diagnosis • In children • Viral infections, bronchiolitis • Foreign body • Congestive heart failure • Extrinsic compression, lymph node, tumor, blood vessel • Tracheomalacia, primary or secondary • Inhalational injury • Other diagnosis, like cystic fibrosis, bronchiectasis etc
  19. 19. Workup • Blood test • CBC, ABG, Electrolytes, RBS, Theophillne level • Chest X-ray • To rule out pneumothorax, pneumomediastinum, heart failure, pneumonia
  20. 20. Complete blood count • CBC with differential to evaluate for pneumonia, ABPA, Churg-Strauss vasculitis • It could vary because of treatment as well with or without neutrophilia • Serum lactate level
  21. 21. Arterial blood gases • If peak expiratory flow rate is less than 30% of predicted or patient best • Signs of fatigue or progressive airflow obstruction • Stages of progression
  22. 22. 4 stages of blood gas progression with status asthmaticus PaCO2 PaO2 Stage 1 Decrease Normal Stage 2 Decrease Decreased Stage 3 NORMAL Decreased Stage 4 High Decreased
  23. 23. Electrolytes and glucose • Hypokalemia as a result of medications • Hyperglycemia and in infants hypoglycemia
  24. 24. Need for hospitalization • If after treatment PEF and FEV1 is between 50% to 70% • If less than 50% then intensive care admission is indicated National Heart, Lung, and Blood Institute. Managing exacerbations of asthma. In: National Asthma Education and Prevention Program (NAEPP). Expert panel report 3: guidelines for the diagnosis and management of asthma. National Guideline Clearinghouse
  25. 25. Response to treatment • Response to treatment is assessed by Pulse oximetry and spirometry
  26. 26. Impulse Oscillometry Testing • Almost independent of patient cooperation • Valid for all ages from 4 years and older children, adult and geriatric patients. • Quite breathing i.e Tidal volume breathing for 30 seconds • It measures impedance at different frequencies indicative of central and peripheral airway resistance. • Bronchodilator therapy often does not reach the peripheral airways. IOS can provide objective response to drug therapy even when FEV1 can't.
  27. 27. Impulse Oscillometry Testing
  28. 28. Histologic finding • Autopsy of patients dying in few hours showed Neutrophil infiltration • Those who die in days showed Eosinophilic infiltration. • Extensive mucus production and severe bronchial smooth muscle hypertrophy
  29. 29. Treatment • Mainstay of treatment of status asthmaticus are beta 2 agonist, systemic steroids and theophyllines. • Pregnant and non pregnant are treated in the same manner • Fluid replacement, hypokalemia and hypophosphatemia are important to treat. • Routine use of antibiotics is discouraged • Oxygen monitoring and therapy • Maintain SatO2 above 92% except in pregnant and cardiac patients where maintain above 95%. • Endotracheal intubation, ventilation and chest tube placement as needed. • ECMO when needed.
  30. 30. Beta2 Agonists • Albuterol neubulizer continuously 10 – 15 mg/hour or q5 to 20 min • Albuterol MDI 4 puff with chamber 15 to 30 minute interval • Endotracheal epinephrine has no role. • Intravenous beta2 agonist when inhalation is not possible • Epinephrine 0.3 to 0.5mg subcutaneously (caution in CHF and history of arrhythmias)
  31. 31. Anticholinergics • Ipratropium bromide every 4 to 6 hours • Synergistic effect with beta2 agonist. • Does not cross blood brain barrier like atropine
  32. 32. Glucocorticoids • Most important treatment in status asthmaticus • decrease mucus production • Improve oxygenation • Reduce beta-agonist or theophylline requirements • Decrease bronchial hypersensitivity • Help to regenerate the bronchial epithelial cells. • Oral and IV have same onset of action • No role of nebulized steroids • Name any ten Adverse effects of steroids
  33. 33. Bronchodilators • Methylxanthines theophylline, aminophylline • bronchodilatation, increased diaphragmatic function, and central stimulation of breathing • Narrow therapeutic index, needs monitoring • Smokers and patients on phenytoin need higher doses • Side effects, nausea, vomiting, palpitation • 6mg/kg loading followed by 1mg/kg/hour
  34. 34. Bronchodilators • Magnesium Sulfate • relax smooth muscle and hence cause bronchodilation • Usually 1 gm to 2.5gm is administered as a single dose. • No studies on repeated doses • More effective in children. 40mg/kg over 20 minutes
  35. 35. Sedatives • Usually reserved for intubated patients • In very agitated patients on high bronchodilator therapy a dose of lorazepam 0.5mg to 1mg intravenous
  36. 36. Therapies for severe and resistant status despite mechanical ventilation • Ketamine • Inhaled anesthetic agents • NMBA • Other treatments in case reports and personal experiences
  37. 37. Extracorporeal life support • high risk of developing refractory status asthmaticus. • Patients with a history of multiple incubations • Respiratory failure requiring intubation within 6 hours of admission • Hemodynamic instability • Neurologic impairment at the time of admission • Duration of respiratory failure greater than 12 hours despite maximal medical therapy. • Practiced in limited centers of the world • references 1. Mikkelsen ME, Pugh ME, Hansen-Flaschen JH, Woo YJ, Sager JS. Emergency extracorporeal life support for asphyxic status asthmaticus. Respir Care. Nov 2007;52(11):1525-9 2. Coleman NE, Dalton HJ. Extracorporeal life support for status asthmaticus: the breath of life that's often forgotten. Crit Care. 2009;13(2):136 3. Hebbar KB, Petrillo-Albarano T, Coto-Puckett W, Heard M, Rycus PT, Fortenberry JD. Experience with use of extracorporeal life support for severe refractory status asthmaticus in children. Crit Care. 2009;13(2):R29
  38. 38. Non invasive ventilation • Limited to weaning from ventilation • Not effective in most of the acute cases unlike acute exacerbation of COPD
  39. 39. Mechanical ventilation • Indications --- already discussed • Considerations • Low volume, lower rate, I:E 1:3-4, addition of PEEP to prevent airway collapse during expiration (cautiously) • Heavy sedation • Steroids and NMBA can cause prolong paralysis • Monitor flow volume loop, exhaled tidal volume, autoPEEP • Decreased cardiac output due to decreased preload, diastolic hypotension • Fluid and judicious use of noradrenaline / phenylephrine • Arterial line for repeated blood gases • Replace electrolytes
  40. 40. Heliox • Mixture of Helium and Oxygen • Effective when percentage of Helium is at least 60%, so limiting its use when FiO2 requirement is high • It has more laminar flow and less turbulence in small airways so the Oxygen reach to lower airways besides nebulized aerosols. • No effect on caliber of bronchi.
  41. 41. A word about transfer, prevention and long term care • Features of stability • Monitorting FEV1 and IOS
  42. 42. Comments and suggestion
  43. 43. Thank you and JazakAllah • I am thankful to Medscape and internet to prepare this presentation beside my teachers.

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